Merge pull request #915 from wycats/ast-update

Ast update

20 files changed, 1119 insertions, 922 deletions

diff --git a/docs/compiler-api.md b/docs/compiler-api.md
new file mode 100644
index 0000000..5431a98
--- /dev/null
+++ b/docs/compiler-api.md
@@ -0,0 +1,228 @@
+# Handlebars Compiler APIs
+
+There are a number of formal APIs that tool implementors may interact with.
+
+## AST
+
+Other tools may interact with the formal AST as defined below. Any JSON structure matching this pattern may be used and passed into the `compile` and `precompile` methods in the same way as the text for a template.
+
+AST structures may be generated either with the `Handlebars.parse` method and then manipulated, via the `Handlebars.AST` objects of the same name, or constructed manually as a generic JavaScript object matching the structure defined below.
+
+```javascript
+var ast = Handlebars.parse(myTemplate);
+
+// Modify ast
+
+Handlebars.precompile(ast);
+```
+
+
+### Basic
+
+```java
+interface Node {
+    type: string;
+    loc: SourceLocation | null;
+}
+
+interface SourceLocation {
+    source: string | null;
+    start: Position;
+    end: Position;
+}
+
+interface Position {
+    line: uint >= 1;
+    column: uint >= 0;
+}
+```
+
+### Programs
+
+```java
+interface Program <: Node {
+    type: "Program";
+    body: [ Statement ];
+    
+    blockParams: [ string ];
+}
+```
+
+### Statements
+
+```java
+interface Statement <: Node { }
+
+interface MustacheStatement <: Statement {
+    type: "MustacheStatement";
+    sexpr: SubExpression;
+    escaped: boolean;
+
+    strip: StripFlags | null;
+}
+
+interface BlockStatement <: Statement {
+    type: "BlockStatement";
+    sexpr: SubExpression;
+    program: Program | null;
+    inverse: Program | null;
+
+    openStrip: StripFlags | null;
+    inverseStrip: StripFlags | null;
+    closeStrip: StripFlags | null;
+}
+
+interface PartialStatement <: Statement {
+    type: "PartialStatement";
+    sexpr: SubExpression;
+    
+    indent: string;
+    strip: StripFlags | null;
+}
+
+interface ContentStatement <: Statement {
+    type: "ContentStatement";
+    value: string;
+    original: string;
+}
+
+interface CommentStatement <: Statement {
+    type: "CommentStatement";
+    value: string;
+
+    strip: StripFlags | null;
+}
+```
+
+### Expressions
+
+```java
+interface Expression <: Node { }
+```
+
+##### SubExpressions
+
+```java
+interface SubExpression <: Expression {
+    type: "SubExpression";
+    path: PathExpression;
+    params: [ Expression ];
+    hash: Hash;
+    
+    isHelper: true | null;
+}
+```
+
+`isHelper` is not required and is used to disambiguate between cases such as `{{foo}}` and `(foo)`, which have slightly different call behaviors.
+
+##### Paths
+
+```java
+interface PathExpression <: Expression {
+    type: "PathExpression";
+    data: boolean;
+    depth: uint >= 0;
+    parts: [ string ];
+    original: string;
+}
+```
+
+- `data` is true when the given expression is a `@data` reference.
+- `depth` is an integer representation of which context the expression references. `0` represents the current context, `1` would be `../`, etc.
+- `parts` is an array of the names in the path. `foo.bar` would be `['foo', 'bar']`. Scope references, `.`, `..`, and `this` should be omitted from this array.
+- `original` is the path as entered by the user. Separator and scope references are left untouched.
+
+
+##### Literals
+
+```java
+interface Literal <: Expression { }
+
+interface StringLiteral <: Literal {
+    type: "StringLiteral";
+    value: string;
+    original: string;
+}
+
+interface BooleanLiteral <: Literal {
+    type: "BooleanLiteral";
+    value: boolean;
+    original: boolean;
+}
+
+interface NumberLiteral <: Literal {
+    type: "NumberLiteral";
+    value: number;
+    original: number;
+}
+```
+
+
+### Miscellaneous
+
+```java
+interface Hash <: Node {
+    type: "Hash";
+    pairs: [ HashPair ];
+}
+
+interface HashPair <: Node {
+    type: "HashPair";
+    key: string;
+    value: Expression;
+}
+
+interface StripFlags {
+    open: boolean;
+    close: boolean;
+}
+```
+
+`StripFlags` are used to signify whitespace control character that may have been entered on a given statement.
+
+## AST Visitor
+
+`Handlebars.Visitor` is available as a base class for general interaction with AST structures. This will by default traverse the entire tree and individual methods may be overridden to provide specific responses to particular nodes.
+
+Recording all referenced partial names:
+
+```javascript
+var Visitor = Handlebars.Visitor;
+
+function ImportScanner() {
+  this.partials = [];
+}
+ImportScanner.prototype = new Visitor();
+
+ImportScanner.prototype.PartialStatement = function(partial) {
+  this.partials.push({request: partial.sexpr.original});
+
+  Visitor.prototype.PartialStatement.call(this, partial);
+};
+
+var scanner = new ImportScanner();
+scanner.accept(ast);
+```
+
+## JavaScript Compiler
+
+The `Handlebars.JavaScriptCompiler` object has a number of methods that may be customized to alter the output of the compiler:
+
+```javascript
+function MyCompiler() {
+  Handlebars.JavaScriptCompiler.apply(this, arguments);
+}
+MyCompiler.prototype = Object.create(Handlebars.JavaScriptCompiler);
+
+MyCompiler.nameLookup = function(parent, name, type) {
+  if (type === 'partial') {
+    return 'MyPartialList[' + JSON.stringify(name) ']';
+  } else {
+    return Handlebars.JavaScriptCompiler.prototype.nameLookup.call(this, parent, name, type);
+  }
+};
+
+var env = Handlebars.create();
+env.JavaScriptCompiler = MyCompiler;
+env.compile('my template');
+```
diff --git a/lib/handlebars/compiler/ast.js b/lib/handlebars/compiler/ast.js
index 0bc70e9..72a56aa 100644
--- a/lib/handlebars/compiler/ast.js
+++ b/lib/handlebars/compiler/ast.js
@@ -1,195 +1,111 @@
 import Exception from "../exception";
 
-function LocationInfo(locInfo) {
-  locInfo = locInfo || {};
-  this.firstLine   = locInfo.first_line;
-  this.firstColumn = locInfo.first_column;
-  this.lastColumn  = locInfo.last_column;
-  this.lastLine    = locInfo.last_line;
-}
-
 var AST = {
-  ProgramNode: function(statements, blockParams, strip, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "program";
-    this.statements = statements;
+  Program: function(statements, blockParams, strip, locInfo) {
+    this.loc = locInfo;
+    this.type = 'Program';
+    this.body = statements;
+
     this.blockParams = blockParams;
     this.strip = strip;
   },
 
-  MustacheNode: function(rawParams, hash, open, strip, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "mustache";
-    this.strip = strip;
-
-    // Open may be a string parsed from the parser or a passed boolean flag
-    if (open != null && open.charAt) {
-      // Must use charAt to support IE pre-10
-      var escapeFlag = open.charAt(3) || open.charAt(2);
-      this.escaped = escapeFlag !== '{' && escapeFlag !== '&';
-    } else {
-      this.escaped = !!open;
-    }
-
-    if (rawParams instanceof AST.SexprNode) {
-      this.sexpr = rawParams;
-    } else {
-      // Support old AST API
-      this.sexpr = new AST.SexprNode(rawParams, hash);
-    }
-
-    // Support old AST API that stored this info in MustacheNode
-    this.id = this.sexpr.id;
-    this.params = this.sexpr.params;
-    this.hash = this.sexpr.hash;
-    this.eligibleHelper = this.sexpr.eligibleHelper;
-    this.isHelper = this.sexpr.isHelper;
-  },
-
-  SexprNode: function(rawParams, hash, locInfo) {
-    LocationInfo.call(this, locInfo);
-
-    this.type = "sexpr";
-    this.hash = hash;
-
-    var id = this.id = rawParams[0];
-    var params = this.params = rawParams.slice(1);
+  MustacheStatement: function(sexpr, escaped, strip, locInfo) {
+    this.loc = locInfo;
+    this.type = 'MustacheStatement';
 
-    // a mustache is definitely a helper if:
-    // * it is an eligible helper, and
-    // * it has at least one parameter or hash segment
-    this.isHelper = !!(params.length || hash);
-
-    // a mustache is an eligible helper if:
-    // * its id is simple (a single part, not `this` or `..`)
-    this.eligibleHelper = this.isHelper || id.isSimple;
-
-    // if a mustache is an eligible helper but not a definite
-    // helper, it is ambiguous, and will be resolved in a later
-    // pass or at runtime.
-  },
+    this.sexpr = sexpr;
+    this.escaped = escaped;
 
-  PartialNode: function(partialName, context, hash, strip, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type         = "partial";
-    this.partialName  = partialName;
-    this.context      = context;
-    this.hash = hash;
     this.strip = strip;
-
-    this.strip.inlineStandalone = true;
   },
 
-  BlockNode: function(sexpr, program, inverse, strip, locInfo) {
-    LocationInfo.call(this, locInfo);
+  BlockStatement: function(sexpr, program, inverse, openStrip, inverseStrip, closeStrip, locInfo) {
+    this.loc = locInfo;
 
-    this.type = 'block';
+    this.type = 'BlockStatement';
     this.sexpr = sexpr;
     this.program  = program;
     this.inverse  = inverse;
-    this.strip = strip;
 
-    if (inverse && !program) {
-      this.isInverse = true;
-    }
+    this.openStrip = openStrip;
+    this.inverseStrip = inverseStrip;
+    this.closeStrip = closeStrip;
   },
 
-  ContentNode: function(string, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "content";
-    this.original = this.string = string;
+  PartialStatement: function(sexpr, strip, locInfo) {
+    this.loc = locInfo;
+    this.type = 'PartialStatement';
+    this.sexpr = sexpr;
+    this.indent = '';
+
+    this.strip = strip;
   },
 
-  HashNode: function(pairs, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "hash";
-    this.pairs = pairs;
+  ContentStatement: function(string, locInfo) {
+    this.loc = locInfo;
+    this.type = 'ContentStatement';
+    this.original = this.value = string;
   },
 
-  IdNode: function(parts, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "ID";
-
-    var original = "",
-        dig = [],
-        depth = 0,
-        depthString = '';
-
-    for(var i=0,l=parts.length; i<l; i++) {
-      var part = parts[i].part;
-      original += (parts[i].separator || '') + part;
-
-      if (part === ".." || part === "." || part === "this") {
-        if (dig.length > 0) {
-          throw new Exception("Invalid path: " + original, this);
-        } else if (part === "..") {
-          depth++;
-          depthString += '../';
-        } else {
-          this.isScoped = true;
-        }
-      } else {
-        dig.push(part);
-      }
-    }
+  CommentStatement: function(comment, strip, locInfo) {
+    this.loc = locInfo;
+    this.type = 'CommentStatement';
+    this.value = comment;
 
-    this.original = original;
-    this.parts    = dig;
-    this.string   = dig.join('.');
-    this.depth    = depth;
-    this.idName   = depthString + this.string;
+    this.strip = strip;
+  },
 
-    // an ID is simple if it only has one part, and that part is not
-    // `..` or `this`.
-    this.isSimple = parts.length === 1 && !this.isScoped && depth === 0;
+  SubExpression: function(path, params, hash, locInfo) {
+    this.loc = locInfo;
 
-    this.stringModeValue = this.string;
+    this.type = 'SubExpression';
+    this.path = path;
+    this.params = params || [];
+    this.hash = hash;
   },
 
-  PartialNameNode: function(name, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "PARTIAL_NAME";
-    this.name = name.original;
-  },
+  PathExpression: function(data, depth, parts, original, locInfo) {
+    this.loc = locInfo;
+    this.type = 'PathExpression';
 
-  DataNode: function(id, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "DATA";
-    this.id = id;
-    this.stringModeValue = id.stringModeValue;
-    this.idName = '@' + id.stringModeValue;
+    this.data = data;
+    this.original = original;
+    this.parts    = parts;
+    this.depth    = depth;
   },
 
-  StringNode: function(string, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "STRING";
+  StringLiteral: function(string, locInfo) {
+    this.loc = locInfo;
+    this.type = 'StringLiteral';
     this.original =
-      this.string =
-      this.stringModeValue = string;
+      this.value = string;
   },
 
-  NumberNode: function(number, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "NUMBER";
+  NumberLiteral: function(number, locInfo) {
+    this.loc = locInfo;
+    this.type = 'NumberLiteral';
     this.original =
-      this.number = number;
-    this.stringModeValue = Number(number);
+      this.value = Number(number);
   },
 
-  BooleanNode: function(bool, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "BOOLEAN";
-    this.bool = bool;
-    this.stringModeValue = bool === "true";
+  BooleanLiteral: function(bool, locInfo) {
+    this.loc = locInfo;
+    this.type = 'BooleanLiteral';
+    this.original =
+      this.value = bool === 'true';
   },
 
-  CommentNode: function(comment, strip, locInfo) {
-    LocationInfo.call(this, locInfo);
-    this.type = "comment";
-    this.comment = comment;
-
-    this.strip = strip;
-    strip.inlineStandalone = true;
+  Hash: function(pairs, locInfo) {
+    this.loc = locInfo;
+    this.type = 'Hash';
+    this.pairs = pairs;
+  },
+  HashPair: function(key, value, locInfo) {
+    this.loc = locInfo;
+    this.type = 'HashPair';
+    this.key = key;
+    this.value = value;
   }
 };
 
diff --git a/lib/handlebars/compiler/base.js b/lib/handlebars/compiler/base.js
index 1378463..ff237ec 100644
--- a/lib/handlebars/compiler/base.js
+++ b/lib/handlebars/compiler/base.js
@@ -1,5 +1,6 @@
 import parser from "./parser";
 import AST from "./ast";
+import WhitespaceControl from "./whitespace-control";
 module Helpers from "./helpers";
 import { extend } from "../utils";
 
@@ -8,11 +9,17 @@ export { parser };
 var yy = {};
 extend(yy, Helpers, AST);
 
-export function parse(input) {
+export function parse(input, options) {
   // Just return if an already-compile AST was passed in.
-  if (input.constructor === AST.ProgramNode) { return input; }
+  if (input.type === 'Program') { return input; }
 
   parser.yy = yy;
 
-  return parser.parse(input);
+  // Altering the shared object here, but this is ok as parser is a sync operation
+  yy.locInfo = function(locInfo) {
+    return new yy.SourceLocation(options && options.srcName, locInfo);
+  };
+
+  var strip = new WhitespaceControl();
+  return strip.accept(parser.parse(input));
 }
diff --git a/lib/handlebars/compiler/code-gen.js b/lib/handlebars/compiler/code-gen.js
index 7d1b4ca..0fddb7c 100644
--- a/lib/handlebars/compiler/code-gen.js
+++ b/lib/handlebars/compiler/code-gen.js
@@ -79,18 +79,18 @@ CodeGen.prototype = {
   },
 
   empty: function(loc) {
-    loc = loc || this.currentLocation || {};
-    return new SourceNode(loc.firstLine, loc.firstColumn, this.srcFile);
+    loc = loc || this.currentLocation || {start:{}};
+    return new SourceNode(loc.start.line, loc.start.column, this.srcFile);
   },
   wrap: function(chunk, loc) {
     if (chunk instanceof SourceNode) {
       return chunk;
     }
 
-    loc = loc || this.currentLocation || {};
+    loc = loc || this.currentLocation || {start:{}};
     chunk = castChunk(chunk, this, loc);
 
-    return new SourceNode(loc.firstLine, loc.firstColumn, this.srcFile, chunk);
+    return new SourceNode(loc.start.line, loc.start.column, this.srcFile, chunk);
   },
 
   functionCall: function(fn, type, params) {
@@ -99,7 +99,7 @@ CodeGen.prototype = {
   },
 
   quotedString: function(str) {
-    return '"' + str
+    return '"' + (str + '')
       .replace(/\\/g, '\\\\')
       .replace(/"/g, '\\"')
       .replace(/\n/g, '\\n')
@@ -113,7 +113,10 @@ CodeGen.prototype = {
 
     for (var key in obj) {
       if (obj.hasOwnProperty(key)) {
-        pairs.push([this.quotedString(key), ':', castChunk(obj[key], this)]);
+        var value = castChunk(obj[key], this);
+        if (value !== 'undefined') {
+          pairs.push([this.quotedString(key), ':', value]);
+        }
       }
     }
 
diff --git a/lib/handlebars/compiler/compiler.js b/lib/handlebars/compiler/compiler.js
index 1e5d07a..5ba0916 100644
--- a/lib/handlebars/compiler/compiler.js
+++ b/lib/handlebars/compiler/compiler.js
@@ -3,6 +3,26 @@ import {isArray} from "../utils";
 
 var slice = [].slice;
 
+
+// a mustache is definitely a helper if:
+// * it is an eligible helper, and
+// * it has at least one parameter or hash segment
+function helperExpr(sexpr) {
+  return !!(sexpr.isHelper || sexpr.params.length || sexpr.hash);
+}
+
+function scopedId(path) {
+  return (/^\.|this\b/).test(path.original);
+}
+
+// an ID is simple if it only has one part, and that part is not
+// `..` or `this`.
+function simpleId(path) {
+  var part = path.parts[0];
+
+  return path.parts.length === 1 && !scopedId(path) && !path.depth;
+}
+
 export function Compiler() {}
 
 // the foundHelper register will disambiguate helper lookup from finding a
@@ -74,12 +94,12 @@ Compiler.prototype = {
     return this[node.type](node);
   },
 
-  program: function(program) {
-    var statements = program.statements;
-
-    for(var i=0, l=statements.length; i<l; i++) {
-      this.accept(statements[i]);
+  Program: function(program) {
+    var body = program.body;
+    for(var i=0, l=body.length; i<l; i++) {
+      this.accept(body[i]);
     }
+
     this.isSimple = l === 1;
 
     this.depths.list = this.depths.list.sort(function(a, b) {
@@ -107,24 +127,19 @@ Compiler.prototype = {
     return guid;
   },
 
-  block: function(block) {
+  BlockStatement: function(block) {
     var sexpr = block.sexpr,
         program = block.program,
         inverse = block.inverse;
 
-    if (program) {
-      program = this.compileProgram(program);
-    }
-
-    if (inverse) {
-      inverse = this.compileProgram(inverse);
-    }
+    program = program && this.compileProgram(program);
+    inverse = inverse && this.compileProgram(inverse);
 
     var type = this.classifySexpr(sexpr);
 
-    if (type === "helper") {
+    if (type === 'helper') {
       this.helperSexpr(sexpr, program, inverse);
-    } else if (type === "simple") {
+    } else if (type === 'simple') {
       this.simpleSexpr(sexpr);
 
       // now that the simple mustache is resolved, we need to
@@ -132,7 +147,7 @@ Compiler.prototype = {
       this.opcode('pushProgram', block, program);
       this.opcode('pushProgram', block, inverse);
       this.opcode('emptyHash', block);
-      this.opcode('blockValue', block, sexpr.id.original);
+      this.opcode('blockValue', block, sexpr.path.original);
     } else {
       this.ambiguousSexpr(sexpr, program, inverse);
 
@@ -147,54 +162,30 @@ Compiler.prototype = {
     this.opcode('append', block);
   },
 
-  hash: function(hash) {
-    var pairs = hash.pairs, i, l;
-
-    this.opcode('pushHash', hash);
-
-    for(i=0, l=pairs.length; i<l; i++) {
-      this.pushParam(pairs[i][1]);
-    }
-    while(i--) {
-      this.opcode('assignToHash', hash, pairs[i][0]);
-    }
-    this.opcode('popHash', hash);
-  },
-
-  partial: function(partial) {
-    var partialName = partial.partialName;
+  PartialStatement: function(partial) {
+    var partialName = partial.sexpr.path.original;
     this.usePartial = true;
 
-    if (partial.hash) {
-      this.accept(partial.hash);
-    } else {
-      this.opcode('pushLiteral', partial, 'undefined');
+    var params = partial.sexpr.params;
+    if (params.length > 1) {
+      throw new Exception('Unsupported number of partial arguments: ' + params.length, partial);
+    } else if (!params.length) {
+      params.push({type: 'PathExpression', parts: [], depth: 0});
     }
 
-    if (partial.context) {
-      this.accept(partial.context);
-    } else {
-      this.opcode('getContext', partial, 0);
-      this.opcode('pushContext', partial);
-    }
+    this.setupFullMustacheParams(partial.sexpr, undefined, undefined, true);
 
     var indent = partial.indent || '';
     if (this.options.preventIndent && indent) {
       this.opcode('appendContent', partial, indent);
       indent = '';
     }
-    this.opcode('invokePartial', partial, partialName.name, indent);
+    this.opcode('invokePartial', partial, partialName, indent);
     this.opcode('append', partial);
   },
 
-  content: function(content) {
-    if (content.string) {
-      this.opcode('appendContent', content, content.string);
-    }
-  },
-
-  mustache: function(mustache) {
-    this.sexpr(mustache.sexpr);
+  MustacheStatement: function(mustache) {
+    this.accept(mustache.sexpr);
 
     if(mustache.escaped && !this.options.noEscape) {
       this.opcode('appendEscaped', mustache);
@@ -203,106 +194,107 @@ Compiler.prototype = {
     }
   },
 
+  ContentStatement: function(content) {
+    if (content.value) {
+      this.opcode('appendContent', content, content.value);
+    }
+  },
+
+  CommentStatement: function() {},
+
+  SubExpression: function(sexpr) {
+    var type = this.classifySexpr(sexpr);
+
+    if (type === 'simple') {
+      this.simpleSexpr(sexpr);
+    } else if (type === 'helper') {
+      this.helperSexpr(sexpr);
+    } else {
+      this.ambiguousSexpr(sexpr);
+    }
+  },
   ambiguousSexpr: function(sexpr, program, inverse) {
-    var id = sexpr.id,
-        name = id.parts[0],
+    var path = sexpr.path,
+        name = path.parts[0],
         isBlock = program != null || inverse != null;
 
-    this.opcode('getContext', sexpr, id.depth);
+    this.opcode('getContext', sexpr, path.depth);
 
     this.opcode('pushProgram', sexpr, program);
     this.opcode('pushProgram', sexpr, inverse);
 
-    this.ID(id);
+    this.accept(path);
 
     this.opcode('invokeAmbiguous', sexpr, name, isBlock);
   },
 
   simpleSexpr: function(sexpr) {
-    var id = sexpr.id;
-
-    if (id.type === 'DATA') {
-      this.DATA(id);
-    } else if (id.parts.length) {
-      this.ID(id);
-    } else {
-      // Simplified ID for `this`
-      this.addDepth(id.depth);
-      this.opcode('getContext', sexpr, id.depth);
-      this.opcode('pushContext', sexpr);
-    }
-
+    this.accept(sexpr.path);
     this.opcode('resolvePossibleLambda', sexpr);
   },
 
   helperSexpr: function(sexpr, program, inverse) {
     var params = this.setupFullMustacheParams(sexpr, program, inverse),
-        id = sexpr.id,
-        name = id.parts[0];
+        path = sexpr.path,
+        name = path.parts[0];
 
     if (this.options.knownHelpers[name]) {
       this.opcode('invokeKnownHelper', sexpr, params.length, name);
     } else if (this.options.knownHelpersOnly) {
       throw new Exception("You specified knownHelpersOnly, but used the unknown helper " + name, sexpr);
     } else {
-      id.falsy = true;
+      path.falsy = true;
 
-      this.ID(id);
-      this.opcode('invokeHelper', sexpr, params.length, id.original, id.isSimple);
-    }
-  },
-
-  sexpr: function(sexpr) {
-    var type = this.classifySexpr(sexpr);
-
-    if (type === "simple") {
-      this.simpleSexpr(sexpr);
-    } else if (type === "helper") {
-      this.helperSexpr(sexpr);
-    } else {
-      this.ambiguousSexpr(sexpr);
+      this.accept(path);
+      this.opcode('invokeHelper', sexpr, params.length, path.original, simpleId(path));
     }
   },
 
-  ID: function(id) {
-    this.addDepth(id.depth);
-    this.opcode('getContext', id, id.depth);
+  PathExpression: function(path) {
+    this.addDepth(path.depth);
+    this.opcode('getContext', path, path.depth);
 
-    var name = id.parts[0];
+    var name = path.parts[0];
     if (!name) {
       // Context reference, i.e. `{{foo .}}` or `{{foo ..}}`
-      this.opcode('pushContext', id);
+      this.opcode('pushContext', path);
+    } else if (path.data) {
+      this.options.data = true;
+      this.opcode('lookupData', path, path.depth, path.parts);
     } else {
-      this.opcode('lookupOnContext', id, id.parts, id.falsy, id.isScoped);
+      this.opcode('lookupOnContext', path, path.parts, path.falsy, scopedId(path));
     }
   },
 
-  DATA: function(data) {
-    this.options.data = true;
-    this.opcode('lookupData', data, data.id.depth, data.id.parts);
+  StringLiteral: function(string) {
+    this.opcode('pushString', string, string.value);
   },
 
-  STRING: function(string) {
-    this.opcode('pushString', string, string.string);
+  NumberLiteral: function(number) {
+    this.opcode('pushLiteral', number, number.value);
   },
 
-  NUMBER: function(number) {
-    this.opcode('pushLiteral', number, number.number);
+  BooleanLiteral: function(bool) {
+    this.opcode('pushLiteral', bool, bool.value);
   },
 
-  BOOLEAN: function(bool) {
-    this.opcode('pushLiteral', bool, bool.bool);
-  },
+  Hash: function(hash) {
+    var pairs = hash.pairs, i, l;
+
+    this.opcode('pushHash', hash);
 
-  comment: function() {},
+    for (i=0, l=pairs.length; i<l; i++) {
+      this.pushParam(pairs[i].value);
+    }
+    while (i--) {
+      this.opcode('assignToHash', hash, pairs[i].key);
+    }
+    this.opcode('popHash', hash);
+  },
 
   // HELPERS
   opcode: function(name, node) {
-    var loc = {
-      firstLine: node.firstLine, firstColumn: node.firstColumn,
-      lastLine: node.lastLine, lastColumn: node.lastColumn
-    };
-    this.opcodes.push({ opcode: name, args: slice.call(arguments, 2), loc: loc });
+    this.opcodes.push({ opcode: name, args: slice.call(arguments, 2), loc: node.loc });
   },
 
   addDepth: function(depth) {
@@ -315,14 +307,21 @@ Compiler.prototype = {
   },
 
   classifySexpr: function(sexpr) {
-    var isHelper   = sexpr.isHelper;
-    var isEligible = sexpr.eligibleHelper;
-    var options    = this.options;
+    // a mustache is an eligible helper if:
+    // * its id is simple (a single part, not `this` or `..`)
+    var isHelper = helperExpr(sexpr);
+
+    // if a mustache is an eligible helper but not a definite
+    // helper, it is ambiguous, and will be resolved in a later
+    // pass or at runtime.
+    var isEligible = isHelper || simpleId(sexpr.path);
+
+    var options = this.options;
 
     // if ambiguous, we can possibly resolve the ambiguity now
     // An eligible helper is one that does not have a complex path, i.e. `this.foo`, `../foo` etc.
     if (isEligible && !isHelper) {
-      var name = sexpr.id.parts[0];
+      var name = sexpr.path.parts[0];
 
       if (options.knownHelpers[name]) {
         isHelper = true;
@@ -331,9 +330,9 @@ Compiler.prototype = {
       }
     }
 
-    if (isHelper) { return "helper"; }
-    else if (isEligible) { return "ambiguous"; }
-    else { return "simple"; }
+    if (isHelper) { return 'helper'; }
+    else if (isEligible) { return 'ambiguous'; }
+    else { return 'simple'; }
   },
 
   pushParams: function(params) {
@@ -343,27 +342,47 @@ Compiler.prototype = {
   },
 
   pushParam: function(val) {
+    var value = val.value != null ? val.value : val.original || '';
+
+    // Force helper evaluation
+    if (val.type === 'SubExpression') {
+      val.isHelper = true;
+    }
+
     if (this.stringParams) {
+      if (value.replace) {
+        value = value
+            .replace(/^(\.?\.\/)*/g, '')
+            .replace(/\//g, '.');
+      }
+
       if(val.depth) {
         this.addDepth(val.depth);
       }
       this.opcode('getContext', val, val.depth || 0);
-      this.opcode('pushStringParam', val, val.stringModeValue, val.type);
+      this.opcode('pushStringParam', val, value, val.type);
 
-      if (val.type === 'sexpr') {
-        // Subexpressions get evaluated and passed in
+      if (val.type === 'SubExpression') {
+        // SubExpressions get evaluated and passed in
         // in string params mode.
-        this.sexpr(val);
+        this.accept(val);
       }
     } else {
       if (this.trackIds) {
-        this.opcode('pushId', val, val.type, val.idName || val.stringModeValue);
+        value = val.original || value;
+        if (value.replace) {
+          value = value
+              .replace(/^\.\//g, '')
+              .replace(/^\.$/g, '');
+        }
+
+        this.opcode('pushId', val, val.type, value);
       }
       this.accept(val);
     }
   },
 
-  setupFullMustacheParams: function(sexpr, program, inverse) {
+  setupFullMustacheParams: function(sexpr, program, inverse, omitEmpty) {
     var params = sexpr.params;
     this.pushParams(params);
 
@@ -371,9 +390,9 @@ Compiler.prototype = {
     this.opcode('pushProgram', sexpr, inverse);
 
     if (sexpr.hash) {
-      this.hash(sexpr.hash);
+      this.accept(sexpr.hash);
     } else {
-      this.opcode('emptyHash', sexpr);
+      this.opcode('emptyHash', sexpr, omitEmpty);
     }
 
     return params;
@@ -381,7 +400,7 @@ Compiler.prototype = {
 };
 
 export function precompile(input, options, env) {
-  if (input == null || (typeof input !== 'string' && input.constructor !== env.AST.ProgramNode)) {
+  if (input == null || (typeof input !== 'string' && input.type !== 'Program')) {
     throw new Exception("You must pass a string or Handlebars AST to Handlebars.precompile. You passed " + input);
   }
 
@@ -393,13 +412,13 @@ export function precompile(input, options, env) {
     options.useDepths = true;
   }
 
-  var ast = env.parse(input);
+  var ast = env.parse(input, options);
   var environment = new env.Compiler().compile(ast, options);
   return new env.JavaScriptCompiler().compile(environment, options);
 }
 
 export function compile(input, options, env) {
-  if (input == null || (typeof input !== 'string' && input.constructor !== env.AST.ProgramNode)) {
+  if (input == null || (typeof input !== 'string' && input.type !== 'Program')) {
     throw new Exception("You must pass a string or Handlebars AST to Handlebars.compile. You passed " + input);
   }
 
@@ -415,7 +434,7 @@ export function compile(input, options, env) {
   var compiled;
 
   function compileInput() {
-    var ast = env.parse(input);
+    var ast = env.parse(input, options);
     var environment = new env.Compiler().compile(ast, options);
     var templateSpec = new env.JavaScriptCompiler().compile(environment, options, undefined, true);
     return env.template(templateSpec);
diff --git a/lib/handlebars/compiler/helpers.js b/lib/handlebars/compiler/helpers.js
index 50a3c53..1daddf6 100644
--- a/lib/handlebars/compiler/helpers.js
+++ b/lib/handlebars/compiler/helpers.js
@@ -1,9 +1,21 @@
 import Exception from "../exception";
 
+export function SourceLocation(source, locInfo) {
+  this.source = source;
+  this.start = {
+    line: locInfo.first_line,
+    column: locInfo.first_column
+  };
+  this.end = {
+    line: locInfo.last_line,
+    column: locInfo.last_column
+  };
+}
+
 export function stripFlags(open, close) {
   return {
-    left: open.charAt(2) === '~',
-    right: close.charAt(close.length-3) === '~'
+    open: open.charAt(2) === '~',
+    close: close.charAt(close.length-3) === '~'
   };
 }
 
@@ -12,222 +24,91 @@ export function stripComment(comment) {
                 .replace(/-?-?~?\}\}$/, '');
 }
 
-export function prepareRawBlock(openRawBlock, content, close, locInfo) {
+export function preparePath(data, parts, locInfo) {
   /*jshint -W040 */
-  if (openRawBlock.sexpr.id.original !== close) {
-    var errorNode = {
-      firstLine: openRawBlock.sexpr.firstLine,
-      firstColumn: openRawBlock.sexpr.firstColumn
-    };
-
-    throw new Exception(openRawBlock.sexpr.id.original + " doesn't match " + close, errorNode);
+  locInfo = this.locInfo(locInfo);
+
+  var original = data ? '@' : '',
+      dig = [],
+      depth = 0,
+      depthString = '';
+
+  for(var i=0,l=parts.length; i<l; i++) {
+    var part = parts[i].part;
+    original += (parts[i].separator || '') + part;
+
+    if (part === '..' || part === '.' || part === 'this') {
+      if (dig.length > 0) {
+        throw new Exception('Invalid path: ' + original, {loc: locInfo});
+      } else if (part === '..') {
+        depth++;
+        depthString += '../';
+      }
+    } else {
+      dig.push(part);
+    }
   }
 
-  var program = new this.ProgramNode([content], null, {}, locInfo);
-
-  return new this.BlockNode(openRawBlock.sexpr, program, undefined, undefined, locInfo);
+  return new this.PathExpression(data, depth, dig, original, locInfo);
 }
 
-export function prepareBlock(openBlock, program, inverseAndProgram, close, inverted, locInfo) {
+export function prepareMustache(sexpr, open, strip, locInfo) {
   /*jshint -W040 */
-  // When we are chaining inverse calls, we will not have a close path
-  if (close && close.path && openBlock.sexpr.id.original !== close.path.original) {
-    var errorNode = {
-      firstLine: openBlock.sexpr.firstLine,
-      firstColumn: openBlock.sexpr.firstColumn
-    };
+  // Must use charAt to support IE pre-10
+  var escapeFlag = open.charAt(3) || open.charAt(2),
+      escaped = escapeFlag !== '{' && escapeFlag !== '&';
 
-    throw new Exception(openBlock.sexpr.id.original + ' doesn\'t match ' + close.path.original, errorNode);
-  }
+  return new this.MustacheStatement(sexpr, escaped, strip, this.locInfo(locInfo));
+}
 
-  program.blockParams = openBlock.blockParams;
+export function prepareRawBlock(openRawBlock, content, close, locInfo) {
+  /*jshint -W040 */
+  if (openRawBlock.sexpr.path.original !== close) {
+    var errorNode = {loc: openRawBlock.sexpr.loc};
 
-  // Safely handle a chained inverse that does not have a non-conditional inverse
-  // (i.e. both inverseAndProgram AND close are undefined)
-  if (!close) {
-    close = {strip: {}};
+    throw new Exception(openRawBlock.sexpr.path.original + " doesn't match " + close, errorNode);
   }
 
-  // Find the inverse program that is involed with whitespace stripping.
-  var inverse = inverseAndProgram && inverseAndProgram.program,
-      firstInverse = inverse,
-      lastInverse = inverse;
-  if (inverse && inverse.inverse) {
-    firstInverse = inverse.statements[0].program;
+  locInfo = this.locInfo(locInfo);
+  var program = new this.Program([content], null, {}, locInfo);
 
-    // Walk the inverse chain to find the last inverse that is actually in the chain.
-    while (lastInverse.inverse) {
-      lastInverse = lastInverse.statements[lastInverse.statements.length-1].program;
-    }
-  }
-
-  var strip = {
-    left: openBlock.strip.left,
-    right: close.strip.right,
+  return new this.BlockStatement(
+      openRawBlock.sexpr, program, undefined,
+      {}, {}, {},
+      locInfo);
+}
 
-    // Determine the standalone candiacy. Basically flag our content as being possibly standalone
-    // so our parent can determine if we actually are standalone
-    openStandalone: isNextWhitespace(program.statements),
-    closeStandalone: isPrevWhitespace((firstInverse || program).statements)
-  };
+export function prepareBlock(openBlock, program, inverseAndProgram, close, inverted, locInfo) {
+  /*jshint -W040 */
+  // When we are chaining inverse calls, we will not have a close path
+  if (close && close.path && openBlock.sexpr.path.original !== close.path.original) {
+    var errorNode = {loc: openBlock.sexpr.loc};
 
-  if (openBlock.strip.right) {
-    omitRight(program.statements, null, true);
+    throw new Exception(openBlock.sexpr.path.original + ' doesn\'t match ' + close.path.original, errorNode);
   }
 
-  if (inverse) {
-    var inverseStrip = inverseAndProgram.strip;
+  program.blockParams = openBlock.blockParams;
 
-    if (inverseStrip.left) {
-      omitLeft(program.statements, null, true);
-    }
+  var inverse,
+      inverseStrip;
 
-    if (inverseStrip.right) {
-      omitRight(firstInverse.statements, null, true);
-    }
-    if (close.strip.left) {
-      omitLeft(lastInverse.statements, null, true);
+  if (inverseAndProgram) {
+    if (inverseAndProgram.chain) {
+      inverseAndProgram.program.body[0].closeStrip = close.strip || close.openStrip;
     }
 
-    // Find standalone else statments
-    if (isPrevWhitespace(program.statements)
-        && isNextWhitespace(firstInverse.statements)) {
-
-      omitLeft(program.statements);
-      omitRight(firstInverse.statements);
-    }
-  } else {
-    if (close.strip.left) {
-      omitLeft(program.statements, null, true);
-    }
+    inverseStrip = inverseAndProgram.strip;
+    inverse = inverseAndProgram.program;
   }
 
   if (inverted) {
-    return new this.BlockNode(openBlock.sexpr, inverse, program, strip, locInfo);
-  } else {
-    return new this.BlockNode(openBlock.sexpr, program, inverse, strip, locInfo);
-  }
-}
-
-
-export function prepareProgram(statements, isRoot) {
-  for (var i = 0, l = statements.length; i < l; i++) {
-    var current = statements[i],
-        strip = current.strip;
-
-    if (!strip) {
-      continue;
-    }
-
-    var _isPrevWhitespace = isPrevWhitespace(statements, i, isRoot, current.type === 'partial'),
-        _isNextWhitespace = isNextWhitespace(statements, i, isRoot),
-
-        openStandalone = strip.openStandalone && _isPrevWhitespace,
-        closeStandalone = strip.closeStandalone && _isNextWhitespace,
-        inlineStandalone = strip.inlineStandalone && _isPrevWhitespace && _isNextWhitespace;
-
-    if (strip.right) {
-      omitRight(statements, i, true);
-    }
-    if (strip.left) {
-      omitLeft(statements, i, true);
-    }
-
-    if (inlineStandalone) {
-      omitRight(statements, i);
-
-      if (omitLeft(statements, i)) {
-        // If we are on a standalone node, save the indent info for partials
-        if (current.type === 'partial') {
-          // Pull out the whitespace from the final line
-          current.indent = (/([ \t]+$)/).exec(statements[i-1].original)[1];
-        }
-      }
-    }
-    if (openStandalone) {
-      omitRight((current.program || current.inverse).statements);
-
-      // Strip out the previous content node if it's whitespace only
-      omitLeft(statements, i);
-    }
-    if (closeStandalone) {
-      // Always strip the next node
-      omitRight(statements, i);
-
-      omitLeft((current.inverse || current.program).statements);
-    }
-  }
-
-  return statements;
-}
-
-function isPrevWhitespace(statements, i, isRoot) {
-  if (i === undefined) {
-    i = statements.length;
-  }
-
-  // Nodes that end with newlines are considered whitespace (but are special
-  // cased for strip operations)
-  var prev = statements[i-1],
-      sibling = statements[i-2];
-  if (!prev) {
-    return isRoot;
-  }
-
-  if (prev.type === 'content') {
-    return (sibling || !isRoot ? (/\r?\n\s*?$/) : (/(^|\r?\n)\s*?$/)).test(prev.original);
-  }
-}
-function isNextWhitespace(statements, i, isRoot) {
-  if (i === undefined) {
-    i = -1;
-  }
-
-  var next = statements[i+1],
-      sibling = statements[i+2];
-  if (!next) {
-    return isRoot;
-  }
-
-  if (next.type === 'content') {
-    return (sibling || !isRoot ? (/^\s*?\r?\n/) : (/^\s*?(\r?\n|$)/)).test(next.original);
-  }
-}
-
-// Marks the node to the right of the position as omitted.
-// I.e. {{foo}}' ' will mark the ' ' node as omitted.
-//
-// If i is undefined, then the first child will be marked as such.
-//
-// If mulitple is truthy then all whitespace will be stripped out until non-whitespace
-// content is met.
-function omitRight(statements, i, multiple) {
-  var current = statements[i == null ? 0 : i + 1];
-  if (!current || current.type !== 'content' || (!multiple && current.rightStripped)) {
-    return;
-  }
-
-  var original = current.string;
-  current.string = current.string.replace(multiple ? (/^\s+/) : (/^[ \t]*\r?\n?/), '');
-  current.rightStripped = current.string !== original;
-}
-
-// Marks the node to the left of the position as omitted.
-// I.e. ' '{{foo}} will mark the ' ' node as omitted.
-//
-// If i is undefined then the last child will be marked as such.
-//
-// If mulitple is truthy then all whitespace will be stripped out until non-whitespace
-// content is met.
-function omitLeft(statements, i, multiple) {
-  var current = statements[i == null ? statements.length - 1 : i - 1];
-  if (!current || current.type !== 'content' || (!multiple && current.leftStripped)) {
-    return;
+    inverted = inverse;
+    inverse = program;
+    program = inverted;
   }
 
-  // We omit the last node if it's whitespace only and not preceeded by a non-content node.
-  var original = current.string;
-  current.string = current.string.replace(multiple ? (/\s+$/) : (/[ \t]+$/), '');
-  current.leftStripped = current.string !== original;
-  return current.leftStripped;
+  return new this.BlockStatement(
+      openBlock.sexpr, program, inverse,
+      openBlock.strip, inverseStrip, close && (close.strip || close.openStrip),
+      this.locInfo(locInfo));
 }
diff --git a/lib/handlebars/compiler/javascript-compiler.js b/lib/handlebars/compiler/javascript-compiler.js
index ba84a3e..db19778 100644
--- a/lib/handlebars/compiler/javascript-compiler.js
+++ b/lib/handlebars/compiler/javascript-compiler.js
@@ -136,7 +136,7 @@ JavaScriptCompiler.prototype = {
       if (!asObject) {
         ret.compiler = JSON.stringify(ret.compiler);
 
-        this.source.currentLocation = {firstLine: 1, firstColumn: 0};
+        this.source.currentLocation = {start: {line: 1, column: 0}};
         ret = this.objectLiteral(ret);
 
         if (options.srcName) {
@@ -275,7 +275,7 @@ JavaScriptCompiler.prototype = {
   blockValue: function(name) {
     var blockHelperMissing = this.aliasable('helpers.blockHelperMissing'),
         params = [this.contextName(0)];
-    this.setupParams(name, 0, params);
+    this.setupHelperArgs(name, 0, params);
 
     var blockName = this.popStack();
     params.splice(1, 0, blockName);
@@ -293,7 +293,7 @@ JavaScriptCompiler.prototype = {
     // We're being a bit cheeky and reusing the options value from the prior exec
     var blockHelperMissing = this.aliasable('helpers.blockHelperMissing'),
         params = [this.contextName(0)];
-    this.setupParams('', 0, params, true);
+    this.setupHelperArgs('', 0, params, true);
 
     this.flushInline();
 
@@ -460,7 +460,7 @@ JavaScriptCompiler.prototype = {
 
     // If it's a subexpression, the string result
     // will be pushed after this opcode.
-    if (type !== 'sexpr') {
+    if (type !== 'SubExpression') {
       if (typeof string === 'string') {
         this.pushString(string);
       } else {
@@ -469,9 +469,7 @@ JavaScriptCompiler.prototype = {
     }
   },
 
-  emptyHash: function() {
-    this.pushStackLiteral('{}');
-
+  emptyHash: function(omitEmpty) {
     if (this.trackIds) {
       this.push('{}'); // hashIds
     }
@@ -479,6 +477,7 @@ JavaScriptCompiler.prototype = {
       this.push('{}'); // hashContexts
       this.push('{}'); // hashTypes
     }
+    this.pushStackLiteral(omitEmpty ? 'undefined' : '{}');
   },
   pushHash: function() {
     if (this.hash) {
@@ -611,16 +610,22 @@ JavaScriptCompiler.prototype = {
   // This operation pops off a context, invokes a partial with that context,
   // and pushes the result of the invocation back.
   invokePartial: function(name, indent) {
-    var params = [this.nameLookup('partials', name, 'partial'), "'" + indent + "'", "'" + name + "'", this.popStack(), this.popStack(), "helpers", "partials"];
+    var params = [],
+        options = this.setupParams(name, 1, params, false);
 
-    if (this.options.data) {
-      params.push("data");
-    } else if (this.options.compat) {
-      params.push('undefined');
+    if (indent) {
+      options.indent = JSON.stringify(indent);
     }
+    options.helpers = 'helpers';
+    options.partials = 'partials';
+
+    params.unshift(this.nameLookup('partials', name, 'partial'));
+
     if (this.options.compat) {
-      params.push('depths');
+      options.depths = 'depths';
     }
+    options = this.objectLiteral(options);
+    params.push(options);
 
     this.push(this.source.functionCall('this.invokePartial', '', params));
   },
@@ -659,9 +664,9 @@ JavaScriptCompiler.prototype = {
   },
 
   pushId: function(type, name) {
-    if (type === 'ID' || type === 'DATA') {
+    if (type === 'PathExpression') {
       this.pushString(name);
-    } else if (type === 'sexpr') {
+    } else if (type === 'SubExpression') {
       this.pushStackLiteral('true');
     } else {
       this.pushStackLiteral('null');
@@ -881,7 +886,7 @@ JavaScriptCompiler.prototype = {
 
   setupHelper: function(paramSize, name, blockHelper) {
     var params = [],
-        paramsInit = this.setupParams(name, paramSize, params, blockHelper);
+        paramsInit = this.setupHelperArgs(name, paramSize, params, blockHelper);
     var foundHelper = this.nameLookup('helpers', name, 'helper');
 
     return {
@@ -892,8 +897,8 @@ JavaScriptCompiler.prototype = {
     };
   },
 
-  setupParams: function(helper, paramSize, params, useRegister) {
-    var options = {}, contexts = [], types = [], ids = [], param, inverse, program;
+  setupParams: function(helper, paramSize, params) {
+    var options = {}, contexts = [], types = [], ids = [], param;
 
     options.name = this.quotedString(helper);
     options.hash = this.popStack();
@@ -906,8 +911,8 @@ JavaScriptCompiler.prototype = {
       options.hashContexts = this.popStack();
     }
 
-    inverse = this.popStack();
-    program = this.popStack();
+    var inverse = this.popStack(),
+        program = this.popStack();
 
     // Avoid setting fn and inverse if neither are set. This allows
     // helpers to do a check for `if (options.fn)`
@@ -943,7 +948,11 @@ JavaScriptCompiler.prototype = {
     if (this.options.data) {
       options.data = "data";
     }
+    return options;
+  },
 
+  setupHelperArgs: function(helper, paramSize, params, useRegister) {
+    var options = this.setupParams(helper, paramSize, params, true);
     options = this.objectLiteral(options);
     if (useRegister) {
       this.useRegister('options');
diff --git a/lib/handlebars/compiler/printer.js b/lib/handlebars/compiler/printer.js
index e93652c..b549d61 100644
--- a/lib/handlebars/compiler/printer.js
+++ b/lib/handlebars/compiler/printer.js
@@ -21,22 +21,22 @@ PrintVisitor.prototype.pad = function(string) {
   return out;
 };
 
-PrintVisitor.prototype.program = function(program) {
-  var out = "",
-      statements = program.statements,
+PrintVisitor.prototype.Program = function(program) {
+  var out = '',
+      body = program.body,
       i, l;
 
   if (program.blockParams) {
-    var blockParams = "BLOCK PARAMS: [";
+    var blockParams = 'BLOCK PARAMS: [';
     for(i=0, l=program.blockParams.length; i<l; i++) {
-       blockParams += " " + program.blockParams[i];
+       blockParams += ' ' + program.blockParams[i];
     }
-    blockParams += " ]";
+    blockParams += ' ]';
     out += this.pad(blockParams);
   }
 
-  for(i=0, l=statements.length; i<l; i++) {
-    out = out + this.accept(statements[i]);
+  for(i=0, l=body.length; i<l; i++) {
+    out = out + this.accept(body[i]);
   }
 
   this.padding--;
@@ -44,21 +44,25 @@ PrintVisitor.prototype.program = function(program) {
   return out;
 };
 
-PrintVisitor.prototype.block = function(block) {
+PrintVisitor.prototype.MustacheStatement = function(mustache) {
+  return this.pad('{{ ' + this.accept(mustache.sexpr) + ' }}');
+};
+
+PrintVisitor.prototype.BlockStatement = function(block) {
   var out = "";
 
-  out = out + this.pad("BLOCK:");
+  out = out + this.pad('BLOCK:');
   this.padding++;
   out = out + this.pad(this.accept(block.sexpr));
   if (block.program) {
-    out = out + this.pad("PROGRAM:");
+    out = out + this.pad('PROGRAM:');
     this.padding++;
     out = out + this.accept(block.program);
     this.padding--;
   }
   if (block.inverse) {
     if (block.program) { this.padding++; }
-    out = out + this.pad("{{^}}");
+    out = out + this.pad('{{^}}');
     this.padding++;
     out = out + this.accept(block.inverse);
     this.padding--;
@@ -69,7 +73,27 @@ PrintVisitor.prototype.block = function(block) {
   return out;
 };
 
-PrintVisitor.prototype.sexpr = function(sexpr) {
+PrintVisitor.prototype.PartialStatement = function(partial) {
+  var sexpr = partial.sexpr,
+      content = 'PARTIAL:' + sexpr.path.original;
+  if(sexpr.params[0]) {
+    content += ' ' + this.accept(sexpr.params[0]);
+  }
+  if (sexpr.hash) {
+    content += ' ' + this.accept(sexpr.hash);
+  }
+  return this.pad('{{> ' + content + ' }}');
+};
+
+PrintVisitor.prototype.ContentStatement = function(content) {
+  return this.pad("CONTENT[ '" + content.value + "' ]");
+};
+
+PrintVisitor.prototype.CommentStatement = function(comment) {
+  return this.pad("{{! '" + comment.value + "' }}");
+};
+
+PrintVisitor.prototype.SubExpression = function(sexpr) {
   var params = sexpr.params, paramStrings = [], hash;
 
   for(var i=0, l=params.length; i<l; i++) {
@@ -80,71 +104,37 @@ PrintVisitor.prototype.sexpr = function(sexpr) {
 
   hash = sexpr.hash ? " " + this.accept(sexpr.hash) : "";
 
-  return this.accept(sexpr.id) + " " + params + hash;
+  return this.accept(sexpr.path) + " " + params + hash;
 };
 
-PrintVisitor.prototype.mustache = function(mustache) {
-  return this.pad("{{ " + this.accept(mustache.sexpr) + " }}");
-};
-
-PrintVisitor.prototype.partial = function(partial) {
-  var content = this.accept(partial.partialName);
-  if(partial.context) {
-    content += " " + this.accept(partial.context);
-  }
-  if (partial.hash) {
-    content += " " + this.accept(partial.hash);
-  }
-  return this.pad("{{> " + content + " }}");
+PrintVisitor.prototype.PathExpression = function(id) {
+  var path = id.parts.join('/');
+  return (id.data ? '@' : '') + 'PATH:' + path;
 };
 
-PrintVisitor.prototype.hash = function(hash) {
-  var pairs = hash.pairs;
-  var joinedPairs = [], left, right;
-
-  for(var i=0, l=pairs.length; i<l; i++) {
-    left = pairs[i][0];
-    right = this.accept(pairs[i][1]);
-    joinedPairs.push( left + "=" + right );
-  }
 
-  return "HASH{" + joinedPairs.join(", ") + "}";
+PrintVisitor.prototype.StringLiteral = function(string) {
+  return '"' + string.value + '"';
 };
 
-PrintVisitor.prototype.STRING = function(string) {
-  return '"' + string.string + '"';
+PrintVisitor.prototype.NumberLiteral = function(number) {
+  return "NUMBER{" + number.value + "}";
 };
 
-PrintVisitor.prototype.NUMBER = function(number) {
-  return "NUMBER{" + number.number + "}";
+PrintVisitor.prototype.BooleanLiteral = function(bool) {
+  return "BOOLEAN{" + bool.value + "}";
 };
 
-PrintVisitor.prototype.BOOLEAN = function(bool) {
-  return "BOOLEAN{" + bool.bool + "}";
-};
+PrintVisitor.prototype.Hash = function(hash) {
+  var pairs = hash.pairs;
+  var joinedPairs = [], left, right;
 
-PrintVisitor.prototype.ID = function(id) {
-  var path = id.parts.join("/");
-  if(id.parts.length > 1) {
-    return "PATH:" + path;
-  } else {
-    return "ID:" + path;
+  for (var i=0, l=pairs.length; i<l; i++) {
+    joinedPairs.push(this.accept(pairs[i]));
   }
-};
-
-PrintVisitor.prototype.PARTIAL_NAME = function(partialName) {
-    return "PARTIAL:" + partialName.name;
-};
 
-PrintVisitor.prototype.DATA = function(data) {
-  return "@" + this.accept(data.id);
+  return 'HASH{' + joinedPairs.join(', ') + '}';
 };
-
-PrintVisitor.prototype.content = function(content) {
-  return this.pad("CONTENT[ '" + content.string + "' ]");
+PrintVisitor.prototype.HashPair = function(pair) {
+  return pair.key + '=' + this.accept(pair.value);
 };
-
-PrintVisitor.prototype.comment = function(comment) {
-  return this.pad("{{! '" + comment.comment + "' }}");
-};
-
diff --git a/lib/handlebars/compiler/visitor.js b/lib/handlebars/compiler/visitor.js
index a4eb2b4..c0cfab6 100644
--- a/lib/handlebars/compiler/visitor.js
+++ b/lib/handlebars/compiler/visitor.js
@@ -4,64 +4,63 @@ Visitor.prototype = {
   constructor: Visitor,
 
   accept: function(object) {
-    return object && this[object.type] && this[object.type](object);
+    return object && this[object.type](object);
   },
 
-  program: function(program) {
-    var statements = program.statements,
+  Program: function(program) {
+    var body = program.body,
         i, l;
 
-    for(i=0, l=statements.length; i<l; i++) {
-      this.accept(statements[i]);
+    for(i=0, l=body.length; i<l; i++) {
+      this.accept(body[i]);
     }
   },
 
-  block: function(block) {
-    this.accept(block.mustache);
+  MustacheStatement: function(mustache) {
+    this.accept(mustache.sexpr);
+  },
+
+  BlockStatement: function(block) {
+    this.accept(block.sexpr);
     this.accept(block.program);
     this.accept(block.inverse);
   },
 
-  mustache: function(mustache) {
-    this.accept(mustache.sexpr);
+  PartialStatement: function(partial) {
+    this.accept(partial.partialName);
+    this.accept(partial.context);
+    this.accept(partial.hash);
   },
 
-  sexpr: function(sexpr) {
+  ContentStatement: function(content) {},
+  CommentStatement: function(comment) {},
+
+  SubExpression: function(sexpr) {
     var params = sexpr.params, paramStrings = [], hash;
 
-    this.accept(sexpr.id);
+    this.accept(sexpr.path);
     for(var i=0, l=params.length; i<l; i++) {
       this.accept(params[i]);
     }
     this.accept(sexpr.hash);
   },
 
-  hash: function(hash) {
+  PathExpression: function(path) {},
+
+  StringLiteral: function(string) {},
+  NumberLiteral: function(number) {},
+  BooleanLiteral: function(bool) {},
+
+  Hash: function(hash) {
     var pairs = hash.pairs;
 
     for(var i=0, l=pairs.length; i<l; i++) {
-      this.accept(pairs[i][1]);
+      this.accept(pairs[i]);
     }
   },
-
-  partial: function(partial) {
-    this.accept(partial.partialName);
-    this.accept(partial.context);
-    this.accept(partial.hash);
-  },
-  PARTIAL_NAME: function(partialName) {},
-
-  DATA: function(data) {
-    this.accept(data.id);
-  },
-
-  STRING: function(string) {},
-  NUMBER: function(number) {},
-  BOOLEAN: function(bool) {},
-  ID: function(id) {},
-
-  content: function(content) {},
-  comment: function(comment) {}
+  HashPair: function(pair) {
+    this.accept(pair.value);
+  }
 };
 
 export default Visitor;
diff --git a/lib/handlebars/compiler/whitespace-control.js b/lib/handlebars/compiler/whitespace-control.js
new file mode 100644
index 0000000..e10eb15
--- /dev/null
+++ b/lib/handlebars/compiler/whitespace-control.js
@@ -0,0 +1,210 @@
+import Visitor from "./visitor";
+
+function WhitespaceControl() {
+}
+WhitespaceControl.prototype = new Visitor();
+
+WhitespaceControl.prototype.Program = function(program) {
+  var isRoot = !this.isRootSeen;
+  this.isRootSeen = true;
+
+  var body = program.body;
+  for (var i = 0, l = body.length; i < l; i++) {
+    var current = body[i],
+        strip = this.accept(current);
+
+    if (!strip) {
+      continue;
+    }
+
+    var _isPrevWhitespace = isPrevWhitespace(body, i, isRoot),
+        _isNextWhitespace = isNextWhitespace(body, i, isRoot),
+
+        openStandalone = strip.openStandalone && _isPrevWhitespace,
+        closeStandalone = strip.closeStandalone && _isNextWhitespace,
+        inlineStandalone = strip.inlineStandalone && _isPrevWhitespace && _isNextWhitespace;
+
+    if (strip.close) {
+      omitRight(body, i, true);
+    }
+    if (strip.open) {
+      omitLeft(body, i, true);
+    }
+
+    if (inlineStandalone) {
+      omitRight(body, i);
+
+      if (omitLeft(body, i)) {
+        // If we are on a standalone node, save the indent info for partials
+        if (current.type === 'PartialStatement') {
+          // Pull out the whitespace from the final line
+          current.indent = (/([ \t]+$)/).exec(body[i-1].original)[1];
+        }
+      }
+    }
+    if (openStandalone) {
+      omitRight((current.program || current.inverse).body);
+
+      // Strip out the previous content node if it's whitespace only
+      omitLeft(body, i);
+    }
+    if (closeStandalone) {
+      // Always strip the next node
+      omitRight(body, i);
+
+      omitLeft((current.inverse || current.program).body);
+    }
+  }
+
+  return program;
+};
+WhitespaceControl.prototype.BlockStatement = function(block) {
+  this.accept(block.program);
+  this.accept(block.inverse);
+
+  // Find the inverse program that is involed with whitespace stripping.
+  var program = block.program || block.inverse,
+      inverse = block.program && block.inverse,
+      firstInverse = inverse,
+      lastInverse = inverse;
+
+  if (inverse && inverse.chained) {
+    firstInverse = inverse.body[0].program;
+
+    // Walk the inverse chain to find the last inverse that is actually in the chain.
+    while (lastInverse.chained) {
+      lastInverse = lastInverse.body[lastInverse.body.length-1].program;
+    }
+  }
+
+  var strip = {
+    open: block.openStrip.open,
+    close: block.closeStrip.close,
+
+    // Determine the standalone candiacy. Basically flag our content as being possibly standalone
+    // so our parent can determine if we actually are standalone
+    openStandalone: isNextWhitespace(program.body),
+    closeStandalone: isPrevWhitespace((firstInverse || program).body)
+  };
+
+  if (block.openStrip.close) {
+    omitRight(program.body, null, true);
+  }
+
+  if (inverse) {
+    var inverseStrip = block.inverseStrip;
+
+    if (inverseStrip.open) {
+      omitLeft(program.body, null, true);
+    }
+
+    if (inverseStrip.close) {
+      omitRight(firstInverse.body, null, true);
+    }
+    if (block.closeStrip.open) {
+      omitLeft(lastInverse.body, null, true);
+    }
+
+    // Find standalone else statments
+    if (isPrevWhitespace(program.body)
+        && isNextWhitespace(firstInverse.body)) {
+
+      omitLeft(program.body);
+      omitRight(firstInverse.body);
+    }
+  } else {
+    if (block.closeStrip.open) {
+      omitLeft(program.body, null, true);
+    }
+  }
+
+  return strip;
+};
+
+WhitespaceControl.prototype.MustacheStatement = function(mustache) {
+  return mustache.strip;
+};
+
+WhitespaceControl.prototype.PartialStatement = 
+    WhitespaceControl.prototype.CommentStatement = function(node) {
+  var strip = node.strip || {};
+  return {
+    inlineStandalone: true,
+    open: strip.open,
+    close: strip.close
+  };
+};
+
+
+function isPrevWhitespace(body, i, isRoot) {
+  if (i === undefined) {
+    i = body.length;
+  }
+
+  // Nodes that end with newlines are considered whitespace (but are special
+  // cased for strip operations)
+  var prev = body[i-1],
+      sibling = body[i-2];
+  if (!prev) {
+    return isRoot;
+  }
+
+  if (prev.type === 'ContentStatement') {
+    return (sibling || !isRoot ? (/\r?\n\s*?$/) : (/(^|\r?\n)\s*?$/)).test(prev.original);
+  }
+}
+function isNextWhitespace(body, i, isRoot) {
+  if (i === undefined) {
+    i = -1;
+  }
+
+  var next = body[i+1],
+      sibling = body[i+2];
+  if (!next) {
+    return isRoot;
+  }
+
+  if (next.type === 'ContentStatement') {
+    return (sibling || !isRoot ? (/^\s*?\r?\n/) : (/^\s*?(\r?\n|$)/)).test(next.original);
+  }
+}
+
+// Marks the node to the right of the position as omitted.
+// I.e. {{foo}}' ' will mark the ' ' node as omitted.
+//
+// If i is undefined, then the first child will be marked as such.
+//
+// If mulitple is truthy then all whitespace will be stripped out until non-whitespace
+// content is met.
+function omitRight(body, i, multiple) {
+  var current = body[i == null ? 0 : i + 1];
+  if (!current || current.type !== 'ContentStatement' || (!multiple && current.rightStripped)) {
+    return;
+  }
+
+  var original = current.value;
+  current.value = current.value.replace(multiple ? (/^\s+/) : (/^[ \t]*\r?\n?/), '');
+  current.rightStripped = current.value !== original;
+}
+
+// Marks the node to the left of the position as omitted.
+// I.e. ' '{{foo}} will mark the ' ' node as omitted.
+//
+// If i is undefined then the last child will be marked as such.
+//
+// If mulitple is truthy then all whitespace will be stripped out until non-whitespace
+// content is met.
+function omitLeft(body, i, multiple) {
+  var current = body[i == null ? body.length - 1 : i - 1];
+  if (!current || current.type !== 'ContentStatement' || (!multiple && current.leftStripped)) {
+    return;
+  }
+
+  // We omit the last node if it's whitespace only and not preceeded by a non-content node.
+  var original = current.value;
+  current.value = current.value.replace(multiple ? (/\s+$/) : (/[ \t]+$/), '');
+  current.leftStripped = current.value !== original;
+  return current.leftStripped;
+}
+
+export default WhitespaceControl;
diff --git a/lib/handlebars/exception.js b/lib/handlebars/exception.js
index 8c5c2f6..3fde1c1 100644
--- a/lib/handlebars/exception.js
+++ b/lib/handlebars/exception.js
@@ -2,11 +2,14 @@
 var errorProps = ['description', 'fileName', 'lineNumber', 'message', 'name', 'number', 'stack'];
 
 function Exception(message, node) {
-  var line;
-  if (node && node.firstLine) {
-    line = node.firstLine;
-
-    message += ' - ' + line + ':' + node.firstColumn;
+  var loc = node && node.loc,
+      line,
+      column;
+  if (loc) {
+    line = loc.start.line;
+    column = loc.start.column;
+
+    message += ' - ' + line + ':' + column;
   }
 
   var tmp = Error.prototype.constructor.call(this, message);
@@ -16,9 +19,9 @@ function Exception(message, node) {
     this[errorProps[idx]] = tmp[errorProps[idx]];
   }
 
-  if (line) {
+  if (loc) {
     this.lineNumber = line;
-    this.column = node.firstColumn;
+    this.column = column;
   }
 }
 
diff --git a/lib/handlebars/runtime.js b/lib/handlebars/runtime.js
index 05759cb..455dd33 100644
--- a/lib/handlebars/runtime.js
+++ b/lib/handlebars/runtime.js
@@ -35,36 +35,35 @@ export function template(templateSpec, env) {
   // for external users to override these as psuedo-supported APIs.
   env.VM.checkRevision(templateSpec.compiler);
 
-  var invokePartialWrapper = function(partial, indent, name, context, hash, helpers, partials, data, depths) {
-    if (hash) {
-      context = Utils.extend({}, context, hash);
+  var invokePartialWrapper = function(partial, context, options) {
+    if (options.hash) {
+      context = Utils.extend({}, context, options.hash);
     }
     if (!partial) {
-      partial = partials[name];
+      partial = options.partials[options.name];
     }
 
-    var result = env.VM.invokePartial.call(this, partial, name, context, helpers, partials, data, depths);
+    var result = env.VM.invokePartial.call(this, partial, context, options);
 
     if (result == null && env.compile) {
-      var options = { helpers: helpers, partials: partials, data: data, depths: depths };
-      partials[name] = env.compile(partial, templateSpec.compilerOptions, env);
-      result = partials[name](context, options);
+      options.partials[options.name] = env.compile(partial, templateSpec.compilerOptions, env);
+      result = options.partials[options.name](context, options);
     }
     if (result != null) {
-      if (indent) {
+      if (options.indent) {
         var lines = result.split('\n');
         for (var i = 0, l = lines.length; i < l; i++) {
           if (!lines[i] && i + 1 === l) {
             break;
           }
 
-          lines[i] = indent + lines[i];
+          lines[i] = options.indent + lines[i];
         }
         result = lines.join('\n');
       }
       return result;
     } else {
-      throw new Exception("The partial " + name + " could not be compiled when running in runtime-only mode");
+      throw new Exception("The partial " + options.name + " could not be compiled when running in runtime-only mode");
     }
   };
 
@@ -172,11 +171,11 @@ export function program(container, i, fn, data, depths) {
   return prog;
 }
 
-export function invokePartial(partial, name, context, helpers, partials, data, depths) {
-  var options = { partial: true, helpers: helpers, partials: partials, data: data, depths: depths };
+export function invokePartial(partial, context, options) {
+  options.partial = true;
 
   if(partial === undefined) {
-    throw new Exception("The partial " + name + " could not be found");
+    throw new Exception("The partial " + options.name + " could not be found");
   } else if(partial instanceof Function) {
     return partial(context, options);
   }
diff --git a/spec/ast.js b/spec/ast.js
index ef2ef68..d464cf1 100644
--- a/spec/ast.js
+++ b/spec/ast.js
@@ -5,69 +5,34 @@ describe('ast', function() {
   }
 
   var LOCATION_INFO = {
-    last_line: 0,
-    first_line: 0,
-    first_column: 0,
-    last_column: 0
+    start: {
+      line: 1,
+      column: 1
+    },
+    end: {
+      line: 1,
+      column: 1
+    }
   };
 
   function testLocationInfoStorage(node){
-    var properties = [ 'firstLine', 'lastLine', 'firstColumn', 'lastColumn' ],
-        property,
-        propertiesLen = properties.length,
-        i;
-
-    for (i = 0; i < propertiesLen; i++){
-      property = properties[0];
-      equals(node[property], 0);
-    }
+    equals(node.loc.start.line, 1);
+    equals(node.loc.start.column, 1);
+    equals(node.loc.end.line, 1);
+    equals(node.loc.end.column, 1);
   }
 
-  describe('MustacheNode', function() {
-    function testEscape(open, expected) {
-      var mustache = new handlebarsEnv.AST.MustacheNode([{}], {}, open, false);
-      equals(mustache.escaped, expected);
-    }
-
+  describe('MustacheStatement', function() {
     it('should store args', function() {
       var id = {isSimple: true},
           hash = {},
-          mustache = new handlebarsEnv.AST.MustacheNode([id, 'param1'], hash, '', false, LOCATION_INFO);
-      equals(mustache.type, 'mustache');
-      equals(mustache.hash, hash);
+          mustache = new handlebarsEnv.AST.MustacheStatement({}, true, {}, LOCATION_INFO);
+      equals(mustache.type, 'MustacheStatement');
       equals(mustache.escaped, true);
-      equals(mustache.id, id);
-      equals(mustache.params.length, 1);
-      equals(mustache.params[0], 'param1');
-      equals(!!mustache.isHelper, true);
       testLocationInfoStorage(mustache);
     });
-    it('should accept token for escape', function() {
-      testEscape('{{', true);
-      testEscape('{{~', true);
-      testEscape('{{#', true);
-      testEscape('{{~#', true);
-      testEscape('{{/', true);
-      testEscape('{{~/', true);
-      testEscape('{{^', true);
-      testEscape('{{~^', true);
-      testEscape('{', true);
-      testEscape('{', true);
-
-      testEscape('{{&', false);
-      testEscape('{{~&', false);
-      testEscape('{{{', false);
-      testEscape('{{~{', false);
-    });
-    it('should accept boolean for escape', function() {
-      testEscape(true, true);
-      testEscape({}, true);
-
-      testEscape(false, false);
-      testEscape(undefined, false);
-    });
   });
-  describe('BlockNode', function() {
+  describe('BlockStatement', function() {
     it('should throw on mustache mismatch', function() {
       shouldThrow(function() {
         handlebarsEnv.parse("\n  {{#foo}}{{/bar}}");
@@ -75,175 +40,129 @@ describe('ast', function() {
     });
 
     it('stores location info', function(){
-      var sexprNode = new handlebarsEnv.AST.SexprNode([{ original: 'foo'}], null);
-      var mustacheNode = new handlebarsEnv.AST.MustacheNode(sexprNode, null, '{{', {});
-      var block = new handlebarsEnv.AST.BlockNode(mustacheNode,
-                                                  {statements: [], strip: {}}, {statements: [], strip: {}},
-                                                  {
-                                                    strip: {},
-                                                    path: {original: 'foo'}
-                                                  },
-                                                  LOCATION_INFO);
+      var sexprNode = new handlebarsEnv.AST.SubExpression([{ original: 'foo'}], null);
+      var mustacheNode = new handlebarsEnv.AST.MustacheStatement(sexprNode, false, {});
+      var block = new handlebarsEnv.AST.BlockStatement(
+            mustacheNode,
+            {body: []},
+            {body: []},
+            {},
+            {},
+            {},
+            LOCATION_INFO);
       testLocationInfoStorage(block);
     });
   });
-  describe('IdNode', function() {
-    it('should throw on invalid path', function() {
-      shouldThrow(function() {
-        new handlebarsEnv.AST.IdNode([
-          {part: 'foo'},
-          {part: '..'},
-          {part: 'bar'}
-        ], {first_line: 1, first_column: 1});
-      }, Handlebars.Exception, "Invalid path: foo.. - 1:1");
-      shouldThrow(function() {
-        new handlebarsEnv.AST.IdNode([
-          {part: 'foo'},
-          {part: '.'},
-          {part: 'bar'}
-        ], {first_line: 1, first_column: 1});
-      }, Handlebars.Exception, "Invalid path: foo. - 1:1");
-      shouldThrow(function() {
-        new handlebarsEnv.AST.IdNode([
-          {part: 'foo'},
-          {part: 'this'},
-          {part: 'bar'}
-        ], {first_line: 1, first_column: 1});
-      }, Handlebars.Exception, "Invalid path: foothis - 1:1");
-    });
-
+  describe('PathExpression', function() {
     it('stores location info', function(){
-      var idNode = new handlebarsEnv.AST.IdNode([], LOCATION_INFO);
+      var idNode = new handlebarsEnv.AST.PathExpression(false, 0, [], 'foo', LOCATION_INFO);
       testLocationInfoStorage(idNode);
     });
   });
 
-  describe("HashNode", function(){
-
+  describe('Hash', function(){
     it('stores location info', function(){
-      var hash = new handlebarsEnv.AST.HashNode([], LOCATION_INFO);
+      var hash = new handlebarsEnv.AST.Hash([], LOCATION_INFO);
       testLocationInfoStorage(hash);
     });
   });
 
-  describe("ContentNode", function(){
-
+  describe('ContentStatement', function(){
     it('stores location info', function(){
-      var content = new handlebarsEnv.AST.ContentNode("HI", LOCATION_INFO);
+      var content = new handlebarsEnv.AST.ContentStatement("HI", LOCATION_INFO);
       testLocationInfoStorage(content);
     });
   });
 
-  describe("CommentNode", function(){
-
+  describe('CommentStatement', function(){
     it('stores location info', function(){
-      var comment = new handlebarsEnv.AST.CommentNode("HI", {}, LOCATION_INFO);
+      var comment = new handlebarsEnv.AST.CommentStatement("HI", {}, LOCATION_INFO);
       testLocationInfoStorage(comment);
     });
   });
 
-  describe("NumberNode", function(){
-
+  describe('NumberLiteral', function(){
     it('stores location info', function(){
-      var integer = new handlebarsEnv.AST.NumberNode("6", LOCATION_INFO);
+      var integer = new handlebarsEnv.AST.NumberLiteral("6", LOCATION_INFO);
       testLocationInfoStorage(integer);
     });
   });
 
-  describe("StringNode", function(){
-
+  describe('StringLiteral', function(){
     it('stores location info', function(){
-      var string = new handlebarsEnv.AST.StringNode("6", LOCATION_INFO);
+      var string = new handlebarsEnv.AST.StringLiteral("6", LOCATION_INFO);
       testLocationInfoStorage(string);
     });
   });
 
-  describe("BooleanNode", function(){
-
+  describe('BooleanLiteral', function(){
     it('stores location info', function(){
-      var bool = new handlebarsEnv.AST.BooleanNode("true", LOCATION_INFO);
+      var bool = new handlebarsEnv.AST.BooleanLiteral("true", LOCATION_INFO);
       testLocationInfoStorage(bool);
     });
   });
 
-  describe("DataNode", function(){
-
-    it('stores location info', function(){
-      var data = new handlebarsEnv.AST.DataNode("YES", LOCATION_INFO);
-      testLocationInfoStorage(data);
-    });
-  });
-
-  describe("PartialNameNode", function(){
-
-    it('stores location info', function(){
-      var pnn = new handlebarsEnv.AST.PartialNameNode({original: "YES"}, LOCATION_INFO);
-      testLocationInfoStorage(pnn);
-    });
-  });
-
-  describe("PartialNode", function(){
-
+  describe('PartialStatement', function(){
     it('stores location info', function(){
-      var pn = new handlebarsEnv.AST.PartialNode("so_partial", {}, {}, {}, LOCATION_INFO);
+      var pn = new handlebarsEnv.AST.PartialStatement('so_partial', {}, LOCATION_INFO);
       testLocationInfoStorage(pn);
     });
   });
 
-  describe('ProgramNode', function(){
+  describe('Program', function(){
     it('storing location info', function(){
-      var pn = new handlebarsEnv.AST.ProgramNode([], null, {}, LOCATION_INFO);
+      var pn = new handlebarsEnv.AST.Program([], null, {}, LOCATION_INFO);
       testLocationInfoStorage(pn);
     });
   });
 
   describe("Line Numbers", function(){
-    var ast, statements;
+    var ast, body;
 
     function testColumns(node, firstLine, lastLine, firstColumn, lastColumn){
-      equals(node.firstLine, firstLine);
-      equals(node.lastLine, lastLine);
-      equals(node.firstColumn, firstColumn);
-      equals(node.lastColumn, lastColumn);
+      equals(node.loc.start.line, firstLine);
+      equals(node.loc.start.column, firstColumn);
+      equals(node.loc.end.line, lastLine);
+      equals(node.loc.end.column, lastColumn);
     }
 
     ast = Handlebars.parse("line 1 {{line1Token}}\n line 2 {{line2token}}\n line 3 {{#blockHelperOnLine3}}\nline 4{{line4token}}\n" +
                            "line5{{else}}\n{{line6Token}}\n{{/blockHelperOnLine3}}");
-    statements = ast.statements;
+    body = ast.body;
 
     it('gets ContentNode line numbers', function(){
-      var contentNode = statements[0];
+      var contentNode = body[0];
       testColumns(contentNode, 1, 1, 0, 7);
     });
 
-    it('gets MustacheNode line numbers', function(){
-      var mustacheNode = statements[1];
+    it('gets MustacheStatement line numbers', function(){
+      var mustacheNode = body[1];
       testColumns(mustacheNode, 1, 1, 7, 21);
     });
 
     it('gets line numbers correct when newlines appear', function(){
-      testColumns(statements[2], 1, 2, 21, 8);
+      testColumns(body[2], 1, 2, 21, 8);
     });
 
-    it('gets MustacheNode line numbers correct across newlines', function(){
-      var secondMustacheNode = statements[3];
-      testColumns(secondMustacheNode, 2, 2, 8, 22);
+    it('gets MustacheStatement line numbers correct across newlines', function(){
+      var secondMustacheStatement = body[3];
+      testColumns(secondMustacheStatement, 2, 2, 8, 22);
      });
 
      it('gets the block helper information correct', function(){
-       var blockHelperNode = statements[5];
+       var blockHelperNode = body[5];
        testColumns(blockHelperNode, 3, 7, 8, 23);
      });
 
      it('correctly records the line numbers the program of a block helper', function(){
-       var blockHelperNode = statements[5],
+       var blockHelperNode = body[5],
            program = blockHelperNode.program;
 
        testColumns(program, 3, 5, 8, 5);
      });
 
      it('correctly records the line numbers of an inverse of a block helper', function(){
-       var blockHelperNode = statements[5],
+       var blockHelperNode = body[5],
            inverse = blockHelperNode.inverse;
 
        testColumns(inverse, 5, 7, 5, 0);
@@ -254,118 +173,118 @@ describe('ast', function() {
     describe('mustache', function() {
       it('does not mark mustaches as standalone', function() {
         var ast = Handlebars.parse('  {{comment}} ');
-        equals(!!ast.statements[0].string, true);
-        equals(!!ast.statements[2].string, true);
+        equals(!!ast.body[0].value, true);
+        equals(!!ast.body[2].value, true);
       });
     });
     describe('blocks', function() {
       it('marks block mustaches as standalone', function() {
         var ast = Handlebars.parse(' {{# comment}} \nfoo\n {{else}} \n  bar \n  {{/comment}} '),
-            block = ast.statements[1];
+            block = ast.body[1];
 
-        equals(ast.statements[0].string, '');
+        equals(ast.body[0].value, '');
 
-        equals(block.program.statements[0].string, 'foo\n');
-        equals(block.inverse.statements[0].string, '  bar \n');
+        equals(block.program.body[0].value, 'foo\n');
+        equals(block.inverse.body[0].value, '  bar \n');
 
-        equals(ast.statements[2].string, '');
+        equals(ast.body[2].value, '');
       });
       it('marks initial block mustaches as standalone', function() {
         var ast = Handlebars.parse('{{# comment}} \nfoo\n {{/comment}}'),
-            block = ast.statements[0];
+            block = ast.body[0];
 
-        equals(block.program.statements[0].string, 'foo\n');
+        equals(block.program.body[0].value, 'foo\n');
       });
       it('marks mustaches with children as standalone', function() {
         var ast = Handlebars.parse('{{# comment}} \n{{foo}}\n {{/comment}}'),
-            block = ast.statements[0];
+            block = ast.body[0];
 
-        equals(block.program.statements[0].string, '');
-        equals(block.program.statements[1].id.original, 'foo');
-        equals(block.program.statements[2].string, '\n');
+        equals(block.program.body[0].value, '');
+        equals(block.program.body[1].sexpr.path.original, 'foo');
+        equals(block.program.body[2].value, '\n');
       });
       it('marks nested block mustaches as standalone', function() {
         var ast = Handlebars.parse('{{#foo}} \n{{# comment}} \nfoo\n {{else}} \n  bar \n  {{/comment}} \n{{/foo}}'),
-            statements = ast.statements[0].program.statements,
-            block = statements[1];
+            body = ast.body[0].program.body,
+            block = body[1];
 
-        equals(statements[0].string, '');
+        equals(body[0].value, '');
 
-        equals(block.program.statements[0].string, 'foo\n');
-        equals(block.inverse.statements[0].string, '  bar \n');
+        equals(block.program.body[0].value, 'foo\n');
+        equals(block.inverse.body[0].value, '  bar \n');
 
-        equals(statements[0].string, '');
+        equals(body[0].value, '');
       });
       it('does not mark nested block mustaches as standalone', function() {
         var ast = Handlebars.parse('{{#foo}} {{# comment}} \nfoo\n {{else}} \n  bar \n  {{/comment}} {{/foo}}'),
-            statements = ast.statements[0].program.statements,
-            block = statements[1];
+            body = ast.body[0].program.body,
+            block = body[1];
 
-        equals(statements[0].omit, undefined);
+        equals(body[0].omit, undefined);
 
-        equals(block.program.statements[0].string, ' \nfoo\n');
-        equals(block.inverse.statements[0].string, '  bar \n  ');
+        equals(block.program.body[0].value, ' \nfoo\n');
+        equals(block.inverse.body[0].value, '  bar \n  ');
 
-        equals(statements[0].omit, undefined);
+        equals(body[0].omit, undefined);
       });
       it('does not mark nested initial block mustaches as standalone', function() {
         var ast = Handlebars.parse('{{#foo}}{{# comment}} \nfoo\n {{else}} \n  bar \n  {{/comment}}{{/foo}}'),
-            statements = ast.statements[0].program.statements,
-            block = statements[0];
+            body = ast.body[0].program.body,
+            block = body[0];
 
-        equals(block.program.statements[0].string, ' \nfoo\n');
-        equals(block.inverse.statements[0].string, '  bar \n  ');
+        equals(block.program.body[0].value, ' \nfoo\n');
+        equals(block.inverse.body[0].value, '  bar \n  ');
 
-        equals(statements[0].omit, undefined);
+        equals(body[0].omit, undefined);
       });
 
       it('marks column 0 block mustaches as standalone', function() {
         var ast = Handlebars.parse('test\n{{# comment}} \nfoo\n {{else}} \n  bar \n  {{/comment}} '),
-            block = ast.statements[1];
+            block = ast.body[1];
 
-        equals(ast.statements[0].omit, undefined);
+        equals(ast.body[0].omit, undefined);
 
-        equals(block.program.statements[0].string, 'foo\n');
-        equals(block.inverse.statements[0].string, '  bar \n');
+        equals(block.program.body[0].value, 'foo\n');
+        equals(block.inverse.body[0].value, '  bar \n');
 
-        equals(ast.statements[2].string, '');
+        equals(ast.body[2].value, '');
       });
     });
     describe('partials', function() {
       it('marks partial as standalone', function() {
         var ast = Handlebars.parse('{{> partial }} ');
-        equals(ast.statements[1].string, '');
+        equals(ast.body[1].value, '');
       });
       it('marks indented partial as standalone', function() {
         var ast = Handlebars.parse('  {{> partial }} ');
-        equals(ast.statements[0].string, '');
-        equals(ast.statements[1].indent, '  ');
-        equals(ast.statements[2].string, '');
+        equals(ast.body[0].value, '');
+        equals(ast.body[1].indent, '  ');
+        equals(ast.body[2].value, '');
       });
       it('marks those around content as not standalone', function() {
         var ast = Handlebars.parse('a{{> partial }}');
-        equals(ast.statements[0].omit, undefined);
+        equals(ast.body[0].omit, undefined);
 
         ast = Handlebars.parse('{{> partial }}a');
-        equals(ast.statements[1].omit, undefined);
+        equals(ast.body[1].omit, undefined);
       });
     });
     describe('comments', function() {
       it('marks comment as standalone', function() {
         var ast = Handlebars.parse('{{! comment }} ');
-        equals(ast.statements[1].string, '');
+        equals(ast.body[1].value, '');
       });
       it('marks indented comment as standalone', function() {
         var ast = Handlebars.parse('  {{! comment }} ');
-        equals(ast.statements[0].string, '');
-        equals(ast.statements[2].string, '');
+        equals(ast.body[0].value, '');
+        equals(ast.body[2].value, '');
       });
       it('marks those around content as not standalone', function() {
         var ast = Handlebars.parse('a{{! comment }}');
-        equals(ast.statements[0].omit, undefined);
+        equals(ast.body[0].omit, undefined);
 
         ast = Handlebars.parse('{{! comment }}a');
-        equals(ast.statements[1].omit, undefined);
+        equals(ast.body[1].omit, undefined);
       });
     });
   });
diff --git a/spec/compiler.js b/spec/compiler.js
index eead00b..f9eba28 100644
--- a/spec/compiler.js
+++ b/spec/compiler.js
@@ -41,7 +41,7 @@ describe('compiler', function() {
     });
 
     it('can utilize AST instance', function() {
-      equal(Handlebars.compile(new Handlebars.AST.ProgramNode([ new Handlebars.AST.ContentNode("Hello")], null, {}))(), 'Hello');
+      equal(Handlebars.compile(new Handlebars.AST.Program([ new Handlebars.AST.ContentStatement("Hello")], null, {}))(), 'Hello');
     });
 
     it("can pass through an empty string", function() {
@@ -60,7 +60,7 @@ describe('compiler', function() {
     });
 
     it('can utilize AST instance', function() {
-      equal(/return "Hello"/.test(Handlebars.precompile(new Handlebars.AST.ProgramNode([ new Handlebars.AST.ContentNode("Hello")]), null, {})), true);
+      equal(/return "Hello"/.test(Handlebars.precompile(new Handlebars.AST.Program([ new Handlebars.AST.ContentStatement("Hello")]), null, {})), true);
     });
 
     it("can pass through an empty string", function() {
diff --git a/spec/parser.js b/spec/parser.js
index 0569229..26eb4dd 100644
--- a/spec/parser.js
+++ b/spec/parser.js
@@ -10,19 +10,19 @@ describe('parser', function() {
   }
 
   it('parses simple mustaches', function() {
-    equals(ast_for('{{foo}}'), "{{ ID:foo [] }}\n");
-    equals(ast_for('{{foo?}}'), "{{ ID:foo? [] }}\n");
-    equals(ast_for('{{foo_}}'), "{{ ID:foo_ [] }}\n");
-    equals(ast_for('{{foo-}}'), "{{ ID:foo- [] }}\n");
-    equals(ast_for('{{foo:}}'), "{{ ID:foo: [] }}\n");
+    equals(ast_for('{{foo}}'), "{{ PATH:foo [] }}\n");
+    equals(ast_for('{{foo?}}'), "{{ PATH:foo? [] }}\n");
+    equals(ast_for('{{foo_}}'), "{{ PATH:foo_ [] }}\n");
+    equals(ast_for('{{foo-}}'), "{{ PATH:foo- [] }}\n");
+    equals(ast_for('{{foo:}}'), "{{ PATH:foo: [] }}\n");
   });
 
   it('parses simple mustaches with data', function() {
-    equals(ast_for("{{@foo}}"), "{{ @ID:foo [] }}\n");
+    equals(ast_for("{{@foo}}"), "{{ @PATH:foo [] }}\n");
   });
 
   it('parses simple mustaches with data paths', function() {
-    equals(ast_for("{{@../foo}}"), "{{ @ID:foo [] }}\n");
+    equals(ast_for("{{@../foo}}"), "{{ @PATH:foo [] }}\n");
   });
 
   it('parses mustaches with paths', function() {
@@ -30,70 +30,72 @@ describe('parser', function() {
   });
 
   it('parses mustaches with this/foo', function() {
-    equals(ast_for("{{this/foo}}"), "{{ ID:foo [] }}\n");
+    equals(ast_for("{{this/foo}}"), "{{ PATH:foo [] }}\n");
   });
 
   it('parses mustaches with - in a path', function() {
-    equals(ast_for("{{foo-bar}}"), "{{ ID:foo-bar [] }}\n");
+    equals(ast_for("{{foo-bar}}"), "{{ PATH:foo-bar [] }}\n");
   });
 
   it('parses mustaches with parameters', function() {
-    equals(ast_for("{{foo bar}}"), "{{ ID:foo [ID:bar] }}\n");
+    equals(ast_for("{{foo bar}}"), "{{ PATH:foo [PATH:bar] }}\n");
   });
 
   it('parses mustaches with string parameters', function() {
-    equals(ast_for("{{foo bar \"baz\" }}"), '{{ ID:foo [ID:bar, "baz"] }}\n');
+    equals(ast_for("{{foo bar \"baz\" }}"), '{{ PATH:foo [PATH:bar, "baz"] }}\n');
   });
 
   it('parses mustaches with NUMBER parameters', function() {
-    equals(ast_for("{{foo 1}}"), "{{ ID:foo [NUMBER{1}] }}\n");
+    equals(ast_for("{{foo 1}}"), "{{ PATH:foo [NUMBER{1}] }}\n");
   });
 
   it('parses mustaches with BOOLEAN parameters', function() {
-    equals(ast_for("{{foo true}}"), "{{ ID:foo [BOOLEAN{true}] }}\n");
-    equals(ast_for("{{foo false}}"), "{{ ID:foo [BOOLEAN{false}] }}\n");
+    equals(ast_for("{{foo true}}"), "{{ PATH:foo [BOOLEAN{true}] }}\n");
+    equals(ast_for("{{foo false}}"), "{{ PATH:foo [BOOLEAN{false}] }}\n");
   });
 
   it('parses mutaches with DATA parameters', function() {
-    equals(ast_for("{{foo @bar}}"), "{{ ID:foo [@ID:bar] }}\n");
+    equals(ast_for("{{foo @bar}}"), "{{ PATH:foo [@PATH:bar] }}\n");
   });
 
   it('parses mustaches with hash arguments', function() {
-    equals(ast_for("{{foo bar=baz}}"), "{{ ID:foo [] HASH{bar=ID:baz} }}\n");
-    equals(ast_for("{{foo bar=1}}"), "{{ ID:foo [] HASH{bar=NUMBER{1}} }}\n");
-    equals(ast_for("{{foo bar=true}}"), "{{ ID:foo [] HASH{bar=BOOLEAN{true}} }}\n");
-    equals(ast_for("{{foo bar=false}}"), "{{ ID:foo [] HASH{bar=BOOLEAN{false}} }}\n");
-    equals(ast_for("{{foo bar=@baz}}"), "{{ ID:foo [] HASH{bar=@ID:baz} }}\n");
+    equals(ast_for("{{foo bar=baz}}"), "{{ PATH:foo [] HASH{bar=PATH:baz} }}\n");
+    equals(ast_for("{{foo bar=1}}"), "{{ PATH:foo [] HASH{bar=NUMBER{1}} }}\n");
+    equals(ast_for("{{foo bar=true}}"), "{{ PATH:foo [] HASH{bar=BOOLEAN{true}} }}\n");
+    equals(ast_for("{{foo bar=false}}"), "{{ PATH:foo [] HASH{bar=BOOLEAN{false}} }}\n");
+    equals(ast_for("{{foo bar=@baz}}"), "{{ PATH:foo [] HASH{bar=@PATH:baz} }}\n");
 
-    equals(ast_for("{{foo bar=baz bat=bam}}"), "{{ ID:foo [] HASH{bar=ID:baz, bat=ID:bam} }}\n");
-    equals(ast_for("{{foo bar=baz bat=\"bam\"}}"), '{{ ID:foo [] HASH{bar=ID:baz, bat="bam"} }}\n');
+    equals(ast_for("{{foo bar=baz bat=bam}}"), "{{ PATH:foo [] HASH{bar=PATH:baz, bat=PATH:bam} }}\n");
+    equals(ast_for("{{foo bar=baz bat=\"bam\"}}"), '{{ PATH:foo [] HASH{bar=PATH:baz, bat="bam"} }}\n');
 
-    equals(ast_for("{{foo bat='bam'}}"), '{{ ID:foo [] HASH{bat="bam"} }}\n');
+    equals(ast_for("{{foo bat='bam'}}"), '{{ PATH:foo [] HASH{bat="bam"} }}\n');
 
-    equals(ast_for("{{foo omg bar=baz bat=\"bam\"}}"), '{{ ID:foo [ID:omg] HASH{bar=ID:baz, bat="bam"} }}\n');
-    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=1}}"), '{{ ID:foo [ID:omg] HASH{bar=ID:baz, bat="bam", baz=NUMBER{1}} }}\n');
-    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=true}}"), '{{ ID:foo [ID:omg] HASH{bar=ID:baz, bat="bam", baz=BOOLEAN{true}} }}\n');
-    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=false}}"), '{{ ID:foo [ID:omg] HASH{bar=ID:baz, bat="bam", baz=BOOLEAN{false}} }}\n');
+    equals(ast_for("{{foo omg bar=baz bat=\"bam\"}}"), '{{ PATH:foo [PATH:omg] HASH{bar=PATH:baz, bat="bam"} }}\n');
+    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=1}}"), '{{ PATH:foo [PATH:omg] HASH{bar=PATH:baz, bat="bam", baz=NUMBER{1}} }}\n');
+    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=true}}"), '{{ PATH:foo [PATH:omg] HASH{bar=PATH:baz, bat="bam", baz=BOOLEAN{true}} }}\n');
+    equals(ast_for("{{foo omg bar=baz bat=\"bam\" baz=false}}"), '{{ PATH:foo [PATH:omg] HASH{bar=PATH:baz, bat="bam", baz=BOOLEAN{false}} }}\n');
   });
 
   it('parses contents followed by a mustache', function() {
-    equals(ast_for("foo bar {{baz}}"), "CONTENT[ \'foo bar \' ]\n{{ ID:baz [] }}\n");
+    equals(ast_for("foo bar {{baz}}"), "CONTENT[ \'foo bar \' ]\n{{ PATH:baz [] }}\n");
   });
 
   it('parses a partial', function() {
     equals(ast_for("{{> foo }}"), "{{> PARTIAL:foo }}\n");
+    equals(ast_for("{{> 'foo' }}"), "{{> PARTIAL:foo }}\n");
+    equals(ast_for("{{> 1 }}"), "{{> PARTIAL:1 }}\n");
   });
 
   it('parses a partial with context', function() {
-    equals(ast_for("{{> foo bar}}"), "{{> PARTIAL:foo ID:bar }}\n");
+    equals(ast_for("{{> foo bar}}"), "{{> PARTIAL:foo PATH:bar }}\n");
   });
 
   it('parses a partial with hash', function() {
-    equals(ast_for("{{> foo bar=bat}}"), "{{> PARTIAL:foo HASH{bar=ID:bat} }}\n");
+    equals(ast_for("{{> foo bar=bat}}"), "{{> PARTIAL:foo HASH{bar=PATH:bat} }}\n");
   });
 
   it('parses a partial with context and hash', function() {
-    equals(ast_for("{{> foo bar bat=baz}}"), "{{> PARTIAL:foo ID:bar HASH{bat=ID:baz} }}\n");
+    equals(ast_for("{{> foo bar bat=baz}}"), "{{> PARTIAL:foo PATH:bar HASH{bat=PATH:baz} }}\n");
   });
 
   it('parses a partial with a complex name', function() {
@@ -109,47 +111,47 @@ describe('parser', function() {
   });
 
   it('parses an inverse section', function() {
-    equals(ast_for("{{#foo}} bar {{^}} baz {{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    CONTENT[ ' baz ' ]\n");
+    equals(ast_for("{{#foo}} bar {{^}} baz {{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    CONTENT[ ' baz ' ]\n");
   });
 
   it('parses an inverse (else-style) section', function() {
-    equals(ast_for("{{#foo}} bar {{else}} baz {{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    CONTENT[ ' baz ' ]\n");
+    equals(ast_for("{{#foo}} bar {{else}} baz {{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    CONTENT[ ' baz ' ]\n");
   });
 
   it('parses multiple inverse sections', function() {
-    equals(ast_for("{{#foo}} bar {{else if bar}}{{else}} baz {{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    BLOCK:\n      ID:if [ID:bar]\n      PROGRAM:\n      {{^}}\n        CONTENT[ ' baz ' ]\n");
+    equals(ast_for("{{#foo}} bar {{else if bar}}{{else}} baz {{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n    BLOCK:\n      PATH:if [PATH:bar]\n      PROGRAM:\n      {{^}}\n        CONTENT[ ' baz ' ]\n");
   });
 
   it('parses empty blocks', function() {
-    equals(ast_for("{{#foo}}{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n");
+    equals(ast_for("{{#foo}}{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n");
   });
 
   it('parses empty blocks with empty inverse section', function() {
-    equals(ast_for("{{#foo}}{{^}}{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n  {{^}}\n");
+    equals(ast_for("{{#foo}}{{^}}{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n  {{^}}\n");
   });
 
   it('parses empty blocks with empty inverse (else-style) section', function() {
-    equals(ast_for("{{#foo}}{{else}}{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n  {{^}}\n");
+    equals(ast_for("{{#foo}}{{else}}{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n  {{^}}\n");
   });
 
   it('parses non-empty blocks with empty inverse section', function() {
-    equals(ast_for("{{#foo}} bar {{^}}{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n");
+    equals(ast_for("{{#foo}} bar {{^}}{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n");
   });
 
   it('parses non-empty blocks with empty inverse (else-style) section', function() {
-    equals(ast_for("{{#foo}} bar {{else}}{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n");
+    equals(ast_for("{{#foo}} bar {{else}}{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    CONTENT[ ' bar ' ]\n  {{^}}\n");
   });
 
   it('parses empty blocks with non-empty inverse section', function() {
-    equals(ast_for("{{#foo}}{{^}} bar {{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n  {{^}}\n    CONTENT[ ' bar ' ]\n");
+    equals(ast_for("{{#foo}}{{^}} bar {{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n  {{^}}\n    CONTENT[ ' bar ' ]\n");
   });
 
   it('parses empty blocks with non-empty inverse (else-style) section', function() {
-    equals(ast_for("{{#foo}}{{else}} bar {{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n  {{^}}\n    CONTENT[ ' bar ' ]\n");
+    equals(ast_for("{{#foo}}{{else}} bar {{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n  {{^}}\n    CONTENT[ ' bar ' ]\n");
   });
 
   it('parses a standalone inverse section', function() {
-    equals(ast_for("{{^foo}}bar{{/foo}}"), "BLOCK:\n  ID:foo []\n  {{^}}\n    CONTENT[ 'bar' ]\n");
+    equals(ast_for("{{^foo}}bar{{/foo}}"), "BLOCK:\n  PATH:foo []\n  {{^}}\n    CONTENT[ 'bar' ]\n");
   });
   it('throws on old inverse section', function() {
     shouldThrow(function() {
@@ -158,13 +160,12 @@ describe('parser', function() {
   });
 
   it('parses block with block params', function() {
-    equals(ast_for("{{#foo as |bar baz|}}content{{/foo}}"), "BLOCK:\n  ID:foo []\n  PROGRAM:\n    BLOCK PARAMS: [ bar baz ]\n    CONTENT[ 'content' ]\n");
+    equals(ast_for("{{#foo as |bar baz|}}content{{/foo}}"), "BLOCK:\n  PATH:foo []\n  PROGRAM:\n    BLOCK PARAMS: [ bar baz ]\n    CONTENT[ 'content' ]\n");
   });
 
   it('parses inverse block with block params', function() {
-    equals(ast_for("{{^foo as |bar baz|}}content{{/foo}}"), "BLOCK:\n  ID:foo []\n  {{^}}\n    BLOCK PARAMS: [ bar baz ]\n    CONTENT[ 'content' ]\n");
+    equals(ast_for("{{^foo as |bar baz|}}content{{/foo}}"), "BLOCK:\n  PATH:foo []\n  {{^}}\n    BLOCK PARAMS: [ bar baz ]\n    CONTENT[ 'content' ]\n");
   });
-
   it("raises if there's a Parse error", function() {
     shouldThrow(function() {
       ast_for("foo{{^}}bar");
@@ -184,6 +185,18 @@ describe('parser', function() {
     }, Error, /goodbyes doesn't match hellos/);
   });
 
+  it('should handle invalid paths', function() {
+    shouldThrow(function() {
+      ast_for("{{foo/../bar}}");
+    }, Error, /Invalid path: foo\/\.\. - 1:2/);
+    shouldThrow(function() {
+      ast_for("{{foo/./bar}}");
+    }, Error, /Invalid path: foo\/\. - 1:2/);
+    shouldThrow(function() {
+      ast_for("{{foo/this/bar}}");
+    }, Error, /Invalid path: foo\/this - 1:2/);
+  });
+
   it('knows how to report the correct line number in errors', function() {
     shouldThrow(function() {
       ast_for("hello\nmy\n{{foo}");
@@ -201,7 +214,7 @@ describe('parser', function() {
 
   describe('externally compiled AST', function() {
     it('can pass through an already-compiled AST', function() {
-      equals(ast_for(new Handlebars.AST.ProgramNode([new Handlebars.AST.ContentNode("Hello")], null)), "CONTENT[ \'Hello\' ]\n");
+      equals(ast_for(new Handlebars.AST.Program([new Handlebars.AST.ContentStatement("Hello")], null)), "CONTENT[ \'Hello\' ]\n");
     });
   });
 });
diff --git a/spec/partials.js b/spec/partials.js
index a1e0538..b150942 100644
--- a/spec/partials.js
+++ b/spec/partials.js
@@ -23,6 +23,12 @@ describe('partials', function() {
     shouldCompileToWithPartials(string, [hash, {}, {dude: partial}], true, "Dudes:  Empty");
   });
 
+  it('partials with duplicate parameters', function() {
+    shouldThrow(function() {
+      CompilerContext.compile('Dudes: {{>dude dudes foo bar=baz}}');
+    }, Error, 'Unsupported number of partial arguments: 2 - 1:7');
+  });
+
   it("partials with parameters", function() {
     var string = "Dudes: {{#dudes}}{{> dude others=..}}{{/dudes}}";
     var partial = "{{others.foo}}{{name}} ({{url}}) ";
diff --git a/spec/string-params.js b/spec/string-params.js
index 2e88cf1..4704a84 100644
--- a/spec/string-params.js
+++ b/spec/string-params.js
@@ -1,3 +1,4 @@
+/*global CompilerContext */
 describe('string params mode', function() {
   it("arguments to helpers can be retrieved from options hash in string form", function() {
     var template = CompilerContext.compile('{{wycats is.a slave.driver}}', {stringParams: true});
@@ -56,9 +57,9 @@ describe('string params mode', function() {
 
     var helpers = {
       tomdale: function(desire, noun, trueBool, falseBool, options) {
-        equal(options.types[0], 'STRING', "the string type is passed");
-        equal(options.types[1], 'ID', "the expression type is passed");
-        equal(options.types[2], 'BOOLEAN', "the expression type is passed");
+        equal(options.types[0], 'StringLiteral', "the string type is passed");
+        equal(options.types[1], 'PathExpression', "the expression type is passed");
+        equal(options.types[2], 'BooleanLiteral', "the expression type is passed");
         equal(desire, "need", "the string form is passed for strings");
         equal(noun, "dad.joke", "the string form is passed for expressions");
         equal(trueBool, true, "raw booleans are passed through");
@@ -76,21 +77,21 @@ describe('string params mode', function() {
 
     var helpers = {
       tomdale: function(exclamation, options) {
-        equal(exclamation, "he.says");
-        equal(options.types[0], "ID");
-
-        equal(options.hashTypes.desire, "STRING");
-        equal(options.hashTypes.noun, "ID");
-        equal(options.hashTypes.bool, "BOOLEAN");
-        equal(options.hash.desire, "need");
-        equal(options.hash.noun, "dad.joke");
+        equal(exclamation, 'he.says');
+        equal(options.types[0], 'PathExpression');
+
+        equal(options.hashTypes.desire, 'StringLiteral');
+        equal(options.hashTypes.noun, 'PathExpression');
+        equal(options.hashTypes.bool, 'BooleanLiteral');
+        equal(options.hash.desire, 'need');
+        equal(options.hash.noun, 'dad.joke');
         equal(options.hash.bool, true);
-        return "Helper called";
+        return 'Helper called';
       }
     };
 
     var result = template({}, { helpers: helpers });
-    equal(result, "Helper called");
+    equal(result, 'Helper called');
   });
 
   it("hash parameters get context information", function() {
@@ -101,7 +102,7 @@ describe('string params mode', function() {
     var helpers = {
       tomdale: function(exclamation, options) {
         equal(exclamation, "he.says");
-        equal(options.types[0], "ID");
+        equal(options.types[0], 'PathExpression');
 
         equal(options.contexts.length, 1);
         equal(options.hashContexts.noun, context);
@@ -164,8 +165,8 @@ describe('string params mode', function() {
 
     var helpers = {
       foo: function(bar, options) {
-        equal(bar, 'bar');
-        equal(options.types[0], 'DATA');
+        equal(bar, '@bar');
+        equal(options.types[0], 'PathExpression');
         return 'Foo!';
       }
     };
diff --git a/spec/subexpressions.js b/spec/subexpressions.js
index 5c9fdfc..1fb8775 100644
--- a/spec/subexpressions.js
+++ b/spec/subexpressions.js
@@ -1,4 +1,4 @@
-/*global CompilerContext, shouldCompileTo */
+/*global CompilerContext, Handlebars, shouldCompileTo, shouldThrow */
 describe('subexpressions', function() {
   it("arg-less helper", function() {
     var string   = "{{foo (bar)}}!";
@@ -135,7 +135,7 @@ describe('subexpressions', function() {
       t: function(defaultString) {
         return new Handlebars.SafeString(defaultString);
       }
-    }
+    };
     shouldCompileTo(string, [{}, helpers], '<input aria-label="Name" placeholder="Example User" />');
   });
 
@@ -159,7 +159,7 @@ describe('subexpressions', function() {
       t: function(defaultString) {
         return new Handlebars.SafeString(defaultString);
       }
-    }
+    };
     shouldCompileTo(string, [context, helpers], '<input aria-label="Name" placeholder="Example User" />');
   });  
 
@@ -170,14 +170,14 @@ describe('subexpressions', function() {
       snog: function(a, b, options) {
         equals(a, 'foo');
         equals(options.types.length, 2, "string params for outer helper processed correctly");
-        equals(options.types[0], 'sexpr', "string params for outer helper processed correctly");
-        equals(options.types[1], 'ID', "string params for outer helper processed correctly");
+        equals(options.types[0], 'SubExpression', "string params for outer helper processed correctly");
+        equals(options.types[1], 'PathExpression', "string params for outer helper processed correctly");
         return a + b;
       },
 
       blorg: function(a, options) {
         equals(options.types.length, 1, "string params for inner helper processed correctly");
-        equals(options.types[0], 'ID', "string params for inner helper processed correctly");
+        equals(options.types[0], 'PathExpression', "string params for inner helper processed correctly");
         return a;
       }
     };
@@ -196,7 +196,7 @@ describe('subexpressions', function() {
 
     var helpers  = {
       blog: function(options) {
-        equals(options.hashTypes.fun, 'sexpr');
+        equals(options.hashTypes.fun, 'SubExpression');
         return "val is " + options.hash.fun;
       },
       bork: function() {
diff --git a/spec/visitor.js b/spec/visitor.js
index b64dc56..66c3b68 100644
--- a/spec/visitor.js
+++ b/spec/visitor.js
@@ -14,33 +14,29 @@ describe('Visitor', function() {
     // Simply run the thing and make sure it does not fail and that all of the
     // stub methods are executed
     var visitor = new Handlebars.Visitor();
-    visitor.accept(Handlebars.parse('{{#foo (bar 1 "1" true) foo=@data}}{{!comment}}{{> bar }} {{/foo}}'));
+    visitor.accept(Handlebars.parse('{{foo}}{{#foo (bar 1 "1" true) foo=@data}}{{!comment}}{{> bar }} {{/foo}}'));
   });
 
   it('should traverse to stubs', function() {
     var visitor = new Handlebars.Visitor();
 
-    visitor.PARTIAL_NAME = function(partialName) {
-      equal(partialName.name, 'bar');
+    visitor.StringLiteral = function(string) {
+      equal(string.value, '2');
     };
-
-    visitor.STRING = function(string) {
-      equal(string.string, '2');
-    };
-    visitor.NUMBER = function(number) {
-      equal(number.stringModeValue, 1);
+    visitor.NumberLiteral = function(number) {
+      equal(number.value, 1);
     };
-    visitor.BOOLEAN = function(bool) {
-      equal(bool.stringModeValue, true);
+    visitor.BooleanLiteral = function(bool) {
+      equal(bool.value, true);
     };
-    visitor.ID = function(id) {
-      equal(id.original, 'foo.bar');
+    visitor.PathExpression = function(id) {
+      equal(/foo\.bar$/.test(id.original), true);
     };
-    visitor.content = function(content) {
-      equal(content.string, ' ');
+    visitor.ContentStatement = function(content) {
+      equal(content.value, ' ');
     };
-    visitor.comment = function(comment) {
-      equal(comment.comment, 'comment');
+    visitor.CommentStatement = function(comment) {
+      equal(comment.value, 'comment');
     };
 
     visitor.accept(Handlebars.parse('{{#foo.bar (foo.bar 1 "2" true) foo=@foo.bar}}{{!comment}}{{> bar }} {{/foo.bar}}'));
diff --git a/src/handlebars.yy b/src/handlebars.yy
index 775d5ca..0b2062e 100644
--- a/src/handlebars.yy
+++ b/src/handlebars.yy
@@ -5,11 +5,11 @@
 %%
 
 root
-  : program EOF { yy.prepareProgram($1.statements, true); return $1; }
+  : program EOF { return $1; }
   ;
 
 program
-  : statement* -> new yy.ProgramNode(yy.prepareProgram($1), null, {}, @$)
+  : statement* -> new yy.Program($1, null, {}, yy.locInfo(@$))
   ;
 
 statement
@@ -18,11 +18,11 @@ statement
   | rawBlock -> $1
   | partial -> $1
   | content -> $1
-  | COMMENT -> new yy.CommentNode(yy.stripComment($1), yy.stripFlags($1, $1), @$)
+  | COMMENT -> new yy.CommentStatement(yy.stripComment($1), yy.stripFlags($1, $1), yy.locInfo(@$))
   ;
 
 content
-  : CONTENT -> new yy.ContentNode($1, @$)
+  : CONTENT -> new yy.ContentStatement($1, yy.locInfo(@$))
   ;
 
 rawBlock
@@ -47,7 +47,7 @@ openInverse
   ;
 
 openInverseChain
-  : OPEN_INVERSE_CHAIN sexpr CLOSE -> new yy.MustacheNode($2, null, $1, yy.stripFlags($1, $3), @$)
+  : OPEN_INVERSE_CHAIN sexpr CLOSE -> yy.prepareMustache($2, $1, yy.stripFlags($1, $3), @$)
   ;
 
 inverseAndProgram
@@ -57,9 +57,8 @@ inverseAndProgram
 inverseChain
   : openInverseChain program inverseChain? {
     var inverse = yy.prepareBlock($1, $2, $3, $3, false, @$),
-        program = new yy.ProgramNode(yy.prepareProgram([inverse]), null, {}, @$);
-
-    program.inverse = inverse;
+        program = new yy.Program([inverse], null, {}, yy.locInfo(@$));
+    program.chained = true;
 
     $$ = { strip: $1.strip, program: program, chain: true };
   }
@@ -73,53 +72,52 @@ closeBlock
 mustache
   // Parsing out the '&' escape token at AST level saves ~500 bytes after min due to the removal of one parser node.
   // This also allows for handler unification as all mustache node instances can utilize the same handler
-  : OPEN sexpr CLOSE -> new yy.MustacheNode($2, null, $1, yy.stripFlags($1, $3), @$)
-  | OPEN_UNESCAPED sexpr CLOSE_UNESCAPED -> new yy.MustacheNode($2, null, $1, yy.stripFlags($1, $3), @$)
+  : OPEN sexpr CLOSE -> yy.prepareMustache($2, $1, yy.stripFlags($1, $3), @$)
+  | OPEN_UNESCAPED sexpr CLOSE_UNESCAPED -> yy.prepareMustache($2, $1, yy.stripFlags($1, $3), @$)
   ;
 
 partial
-  : OPEN_PARTIAL partialName param hash? CLOSE -> new yy.PartialNode($2, $3, $4, yy.stripFlags($1, $5), @$)
-  | OPEN_PARTIAL partialName hash? CLOSE -> new yy.PartialNode($2, undefined, $3, yy.stripFlags($1, $4), @$)
+  : OPEN_PARTIAL sexpr CLOSE -> new yy.PartialStatement($2, yy.stripFlags($1, $3), yy.locInfo(@$))
   ;
 
 sexpr
-  : path param* hash? -> new yy.SexprNode([$1].concat($2), $3, @$)
-  | dataName -> new yy.SexprNode([$1], null, @$)
+  : helperName param* hash? -> new yy.SubExpression($1, $2, $3, yy.locInfo(@$))
+  | dataName -> new yy.SubExpression($1, null, null, yy.locInfo(@$))
   ;
 
 param
   : path -> $1
-  | STRING -> new yy.StringNode($1, @$)
-  | NUMBER -> new yy.NumberNode($1, @$)
-  | BOOLEAN -> new yy.BooleanNode($1, @$)
+  | STRING -> new yy.StringLiteral($1, yy.locInfo(@$))
+  | NUMBER -> new yy.NumberLiteral($1, yy.locInfo(@$))
+  | BOOLEAN -> new yy.BooleanLiteral($1, yy.locInfo(@$))
   | dataName -> $1
-  | OPEN_SEXPR sexpr CLOSE_SEXPR {$2.isHelper = true; $$ = $2;}
+  | OPEN_SEXPR sexpr CLOSE_SEXPR -> $2
   ;
 
 hash
-  : hashSegment+ -> new yy.HashNode($1, @$)
+  : hashSegment+ -> new yy.Hash($1, yy.locInfo(@$))
   ;
 
 hashSegment
-  : ID EQUALS param -> [$1, $3]
+  : ID EQUALS param -> new yy.HashPair($1, $3, yy.locInfo(@$))
   ;
 
 blockParams
   : OPEN_BLOCK_PARAMS ID+ CLOSE_BLOCK_PARAMS -> $2
   ;
 
-partialName
-  : path -> new yy.PartialNameNode($1, @$)
-  | STRING -> new yy.PartialNameNode(new yy.StringNode($1, @$), @$)
-  | NUMBER -> new yy.PartialNameNode(new yy.NumberNode($1, @$))
+helperName
+  : path -> $1
+  | STRING -> new yy.StringLiteral($1, yy.locInfo(@$)), yy.locInfo(@$)
+  | NUMBER -> new yy.NumberLiteral($1, yy.locInfo(@$))
   ;
 
 dataName
-  : DATA path -> new yy.DataNode($2, @$)
+  : DATA pathSegments -> yy.preparePath(true, $2, @$)
   ;
 
 path
-  : pathSegments -> new yy.IdNode($1, @$)
+  : pathSegments -> yy.preparePath(false, $1, @$)
   ;
 
 pathSegments