Add task for parsing examples

tasks/parse-examples.js

@@ -0,0 +1,146 @@
+var fs = require('fs');
+var path = require('path');
+
+var async = require('async');
+var Parser = require('htmlparser2').Parser;
+
+
+var exampleDir = path.join(__dirname, '..', 'examples');
+
+
+/**
+ * List all .html files in the example directory (excluding index.html).
+ * @param {function(Error, Array.<string>)} callback Called with any error or
+ *     the list of paths to examples.
+ */
+function listExamples(callback) {
+  fs.readdir(exampleDir, function(err, items) {
+    if (err) {
+      return callback(err);
+    }
+    var examplePaths = items.filter(function(item) {
+      return /\.html$/i.test(item) && item !== 'index.html';
+    }).map(function(item) {
+      return path.join(exampleDir, item);
+    });
+    callback(null, examplePaths);
+  });
+}
+
+
+/**
+ * Parse info from examples.
+ * @param {Array.<string>} examplePaths Paths to examples.
+ * @param {function(Error, Array.<Object>)} callback Called with any error or
+ *     the list of example info objects.
+ */
+function parseExamples(examplePaths, callback) {
+  async.map(examplePaths, function(examplePath, next) {
+    fs.readFile(examplePath, function(err, data) {
+      if (err) {
+        return next(err);
+      }
+      var name = path.basename(examplePath);
+      var info = {
+        link: name,
+        example: name,
+        title: '',
+        shortdesc: '',
+        tags: ''
+      };
+      var key;
+      var parser = new Parser({
+        onopentag: function(name, attrs) {
+          if (attrs.id in info) {
+            key = attrs.id;
+          } else {
+            key = undefined;
+          }
+        },
+        ontext: function(text) {
+          if (key) {
+            info[key] = text.replace(/\n/g, '').trim();
+          }
+        },
+        onclosetag: function(name) {
+          key = undefined;
+        },
+        onerror: function(err2) {
+          var message = 'Trouble parsing ' + examplePath + '\n' + err2.message;
+          next(new Error(message));
+        }
+      });
+      parser.write(data.toString('utf8'));
+      parser.end();
+      next(null, info);
+    });
+  }, callback);
+}
+
+
+/**
+ * Create an inverted index of keywords from examples.  Property names are
+ * lowercased words.  Property values are objects mapping example index to word
+ * count.
+ * @param {Array.<Object>} exampleInfos Array of example info objects.
+ * @return {Object} Word index.
+ */
+function createWordIndex(exampleInfos) {
+  var index = {};
+  var keys = ['shortdesc', 'title', 'tags'];
+  exampleInfos.forEach(function(info, i) {
+    keys.forEach(function(key) {
+      var text = info[key];
+      var words = text ? text.split(/\W+/) : [];
+      words.forEach(function(word) {
+        if (word) {
+          word = word.toLowerCase();
+          var counts = index[word];
+          if (counts) {
+            if (index in counts) {
+              counts[i] += 1;
+            } else {
+              counts[i] = 1;
+            }
+          } else {
+            counts = {};
+            counts[i] = 1;
+            index[word] = counts;
+          }
+        }
+      });
+    });
+  });
+  return index;
+}
+
+
+/**
+ * Write the example-list.js file with example info and word index.
+ * @param {Array.<Object>} exampleInfos Array of example info objects.
+ * @param {function(Error)} callback Called with any error.
+ */
+function writeExampleList(exampleInfos, callback) {
+  var info = {
+    examples: exampleInfos,
+    index: createWordIndex(exampleInfos)
+  };
+  var indexPath = path.join(exampleDir, 'example-list.js');
+  var str = 'var info = ' + JSON.stringify(info);
+  fs.writeFile(indexPath, str, callback);
+}
+
+
+/**
+ * List examples, parse them, and write example list.
+ */
+async.waterfall([
+  listExamples,
+  parseExamples,
+  writeExampleList
+], function(err) {
+  if (err) {
+    console.error(err);
+    process.exit(1);
+  }
+});