Move page lexer to separate module

Allow lexer to be used independently of page parser/renderer

1 files changed, 63 insertions, 0 deletions

diff --git a/lib/parse/lex.js b/lib/parse/lex.js
new file mode 100644
index 0000000..941e537
--- /dev/null
+++ b/lib/parse/lex.js
@@ -0,0 +1,63 @@
+var _ = require('lodash');
+var marked = require('marked');
+
+// Split a page up into sections (lesson, exercises, ...)
+function splitSections(nodes) {
+    var section = [];
+
+    return _.reduce(nodes, function(sections, el) {
+        if(el.type === 'hr') {
+            sections.push(section);
+            section = [];
+        } else {
+            section.push(el);
+        }
+
+        return sections;
+    }, []).concat([section]); // Add remaining nodes
+}
+
+// What is the type of this section
+function sectionType(nodes, idx) {
+    var codeNodes = _.filter(nodes, {
+        type: 'code'
+    }).length;
+
+    if(codeNodes === 3 && (idx % 2) == 1) {
+        return 'exercise';
+    }
+
+    return 'normal';
+}
+
+function lexPage(src) {
+    // Lex file
+    var nodes = marked.lexer(src);
+
+    return _.chain(splitSections(nodes))
+    .map(function(section, idx) {
+        // Detect section type
+        section.type = sectionType(section, idx);
+        return section;
+    })
+    .filter(function(section) {
+        return !_.isEmpty(section);
+    })
+    .reduce(function(sections, section) {
+        var last = _.last(sections);
+
+        // Merge normal sections together
+        if(last && last.type === section.type && last.type === 'normal') {
+            last.push.apply(last, [{'type': 'hr'}].concat(section));
+        } else {
+            // Add to list of sections
+            sections.push(section);
+        }
+
+        return sections;
+    }, [])
+    .value();
+}
+
+// Exports
+module.exports = lexPage;