exports.attach = function(Handlebars) {

// BEGIN(BROWSER)

Handlebars.AST = {};

Handlebars.AST.ProgramNode = function(statements, inverse) {
  this.type = "program";
  this.statements = statements;
  if(inverse) { this.inverse = new Handlebars.AST.ProgramNode(inverse); }
};

Handlebars.AST.MustacheNode = function(rawParams, hash, unescaped) {
  this.type = "mustache";
  this.escaped = !unescaped;
  this.hash = hash;

  var id = this.id = rawParams[0];
  var params = this.params = rawParams.slice(1);

  // a mustache is an eligible helper if:
  // * its id is simple (a single part, not `this` or `..`)
  var eligibleHelper = this.eligibleHelper = id.isSimple;

  // a mustache is definitely a helper if:
  // * it is an eligible helper, and
  // * it has at least one parameter or hash segment
  this.isHelper = eligibleHelper && (params.length || hash);

  // 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.
};

Handlebars.AST.PartialNode = function(id, context) {
  this.type    = "partial";

  // TODO: disallow complex IDs

  this.id      = id;
  this.context = context;
};

var verifyMatch = function(open, close) {
  if(open.original !== close.original) {
    throw new Handlebars.Exception(open.original + " doesn't match " + close.original);
  }
};

Handlebars.AST.BlockNode = function(mustache, program, inverse, close) {
  verifyMatch(mustache.id, close);
  this.type = "block";
  this.mustache = mustache;
  this.program  = program;
  this.inverse  = inverse;

  if (this.inverse && !this.program) {
    this.isInverse = true;
  }
};

Handlebars.AST.ContentNode = function(string) {
  this.type = "content";
  this.string = string;
};

Handlebars.AST.HashNode = function(pairs) {
  this.type = "hash";
  this.pairs = pairs;
};

Handlebars.AST.IdNode = function(parts) {
  this.type = "ID";
  this.original = parts.join(".");

  var dig = [], depth = 0;

  for(var i=0,l=parts.length; i<l; i++) {
    var part = parts[i];

    if(part === "..") { depth++; }
    else if(part === "." || part === "this") { this.isScoped = true; }
    else { dig.push(part); }
  }

  this.parts    = dig;
  this.string   = dig.join('.');
  this.depth    = depth;

  // 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;
};

Handlebars.AST.DataNode = function(id) {
  this.type = "DATA";
  this.id = id;
};

Handlebars.AST.StringNode = function(string) {
  this.type = "STRING";
  this.string = string;
};

Handlebars.AST.IntegerNode = function(integer) {
  this.type = "INTEGER";
  this.integer = integer;
};

Handlebars.AST.BooleanNode = function(bool) {
  this.type = "BOOLEAN";
  this.bool = bool;
};

Handlebars.AST.CommentNode = function(comment) {
  this.type = "comment";
  this.comment = comment;
};

// END(BROWSER)

return Handlebars;
};