first underscore.js commit -- pulled out from documentcloud's core.js

underscore.js

@@ -0,0 +1,368 @@
+// Javascript can be so much more pleasant when it's functional -- re-implement
+// a bunch of utility methods from Prototype and Steele's Functional...
+window._ = {
+
+  // The cornerstone, an each implementation.
+  // Handles objects implementing forEach, _each, arrays, and raw objects.
+  each : function(obj, iterator, context) {
+    var index = 0;
+    try {
+      if (obj.forEach) {
+        obj.forEach(iterator, context);
+      } else if (obj.length) {
+        for (var i=0; i<obj.length; i++) {
+          iterator.call(context, obj[i], i);
+        }
+      } else if (obj._each) {
+        obj._each(function(value) {
+          iterator.call(context, value, index++);
+        });
+      } else {
+        var i = 0;
+        for (var key in obj) {
+          var value = obj[key], pair = [key, value];
+          pair.key = key;
+          pair.value = value;
+          iterator.call(context, pair, i++);
+        }
+      }
+    } catch(e) {
+      if (e != '__break__') throw e;
+    }
+    return obj;
+  },
+
+  // Determine whether all of the elements match a truth test. Delegate to
+  // Javascript 1.6's every(), if it is present.
+  all : function(obj, iterator, context) {
+    if (obj.every) return obj.every(iterator, context);
+    var result = true;
+    _.each(obj, function(value, index) {
+      result = result && !!iterator.call(context, value, index);
+      if (!result) throw '__break__';
+    });
+    return result;
+  },
+
+  // Determine if at least one element in the object matches a truth test. Use
+  // Javascript 1.6's some(), if it exists.
+  any : function(obj, iterator, context) {
+    if (obj.some) return obj.some(iterator, context);
+    var result = false;
+    _.each(obj, function(value, index) {
+      if (result = !!iterator.call(context, value, index)) throw '__break__';
+    });
+    return result;
+  },
+
+  // Return the results of applying the iterator to each element. Use Javascript
+  // 1.6's version of map, if possible.
+  map : function(obj, iterator, context) {
+    if (obj.map) return obj.map(iterator, context);
+    var results = [];
+    _.each(obj, function(value, index) {
+      results.push(iterator.call(context, value, index));
+    });
+    return results;
+  },
+
+  // Return the first value which passes a truth test.
+  detect : function(obj, iterator, context) {
+    var result;
+    _.each(obj, function(value, index) {
+      if (iterator.call(context, value, index)) {
+        result = value;
+        throw '__break__';
+      }
+    });
+    return result;
+  },
+
+  // Return all the elements that pass a truth test. Use Javascript 1.6's
+  // filter(), if it exists.
+  select : function(obj, iterator, context) {
+    if (obj.filter) return obj.filter(iterator, context);
+    var results = [];
+    _.each(obj, function(value, index) {
+      if (iterator.call(context, value, index)) results.push(value);
+    });
+    return results;
+  },
+
+  // Determine if a given value is included in the object, based on '=='.
+  include : function(obj, target) {
+    if (_.isArray(obj)) if (obj.indexOf(target) != -1) return true;
+    var found = false;
+    _.each(obj, function(value) {
+      if (value == target) {
+        found = true;
+        throw '__break__';
+      }
+    });
+    return found;
+  },
+
+  // Aka reduce. Inject builds up a single result from a list of values.
+  inject : function(obj, memo, iterator, context) {
+    _.each(obj, function(value, index) {
+      memo = iterator.call(context, memo, value, index);
+    });
+    return memo;
+  },
+
+  // Invoke a method with arguments on every item in a collection.
+  invoke : function(obj, method) {
+    var args = _.toArray(arguments).slice(2);
+    return _.map(obj, function(value) {
+      return (method ? value[method] : value).apply(value, args);
+    });
+  },
+
+  // Return the maximum item or (item-based computation).
+  max : function(obj, iterator, context) {
+    var result;
+    _.each(obj, function(value, index) {
+      value = iterator ? iterator.call(context, value, index) : value;
+      if (result == null || value >= result) result = value;
+    });
+    return result;
+  },
+
+  // Return the minimum element (or element-based computation).
+  min : function(obj, iterator, context) {
+    var result;
+    _.each(obj, function(value, index) {
+      value = iterator ? iterator.call(context, value, index) : value;
+      if (result == null || value < result) result = value;
+    });
+    return result;
+  },
+
+  // Optimized version of a common use case of map: fetching a property.
+  pluck : function(obj, key) {
+    var results = [];
+    _.each(obj, function(value){ results.push(value[key]); });
+    return results;
+  },
+
+  // Return all the elements for which a truth test fails.
+  reject : function(obj, iterator, context) {
+    var results = [];
+    _.each(obj, function(value, index) {
+      if (!iterator.call(context, value, index)) results.push(value);
+    });
+    return results;
+  },
+
+  // Sort the object's values by a criteria produced by an iterator.
+  sortBy : function(obj, iterator, context) {
+    return _.pluck(_.map(obj, function(value, index) {
+      return {
+        value : value,
+        criteria : iterator.call(context, value, index)
+      };
+    }).sort(function(left, right) {
+      var a = left.criteria, b = right.criteria;
+      return a < b ? -1 : a > b ? 1 : 0;
+    }), 'value');
+  },
+
+  // Use a comparator function to figure out at what index an object should
+  // be inserted so as to maintain order. Uses binary search.
+  sortedIndex : function(array, comparator, obj) {
+    var low = 0, high = array.length;
+    while (low < high) {
+      var mid = (low + high) >> 1;
+      comparator(array[mid], obj) < 0 ? low = mid + 1 : high = mid;
+    }
+    return low;
+  },
+
+  // Convert anything iterable into a real, live array.
+  toArray : function(iterable) {
+    if (!iterable) return [];
+    if (_.isArray(iterable)) return iterable;
+    return _.map(iterable, function(val){ return val; });
+  },
+
+  // Return the number of elements in an object.
+  size : function(obj) {
+    _.toArray(obj).length;
+  },
+
+  //------------- The following methods only apply to arrays. -----------------
+
+  // Get the first element of an array.
+  first : function(array) {
+    return array[0];
+  },
+
+  // Get the last element of an array.
+  last : function(array) {
+    return array[array.length - 1];
+  },
+
+  // Trim out all falsy values from an array.
+  compact : function(array) {
+    return _.select(array, function(value){ return !!value; });
+  },
+
+  // Return a completely flattened version of an array.
+  flatten : function(array) {
+    return _.inject(array, [], function(memo, value) {
+      if (_.isArray(value)) return memo.concat(_.flatten(value));
+      memo.push(value);
+      return memo;
+    });
+  },
+
+  // Return a version of the array that does not contain the specified value.
+  without : function(array) {
+    var values = array.slice.call(arguments, 0);
+    return _.select(function(value){ return !_.include(values, value); });
+  },
+
+  // Produce a duplicate-free version of the array. If the array has already
+  // been sorted, you have the option of using a faster algorithm.
+  uniq : function(array, sorted) {
+    return _.inject(array, [], function(memo, el, i) {
+      if (0 == i || (sorted ? _.last(memo) != el : !_.include(memo, el))) memo.push(el);
+      return memo;
+    });
+  },
+
+  // Produce an array that contains every item shared between two given arrays.
+  intersect : function(array1, array2) {
+    return _.select(_.uniq(array1), function(item1) {
+      return _.detect(array2, function(item2) { return item1 === item2; });
+    });
+  },
+
+  // If the browser doesn't supply us with indexOf, we might need this function.
+  // Return the position of the first occurence of an item in an array,
+  // or -1 if the item is not included in the array.
+  // indexOf : function(array, item) {
+  //   var length = array.length;
+  //   for (i=0; i<length; i++) if (array[i] === item) return i;
+  //   return -1;
+  // }
+
+  /* ---------------- The following methods apply to objects ---------------- */
+
+  // Retrieve the names of an object's properties.
+  keys : function(obj) {
+    return _.pluck(obj, 'key');
+  },
+
+  // Retrieve the values of an object's properties.
+  values : function(obj) {
+    return _.pluck(obj, 'value');
+  },
+
+  // Extend a given object with all of the properties in a source object.
+  extend : function(destination, source) {
+    for (var property in source) destination[property] = source[property];
+    return destination;
+  },
+
+  // Create a (shallow-cloned) duplicate of an object.
+  clone : function(obj) {
+    return _.extend({}, obj);
+  },
+
+  // Is a given value a DOM element?
+  isElement : function(obj) {
+    return !!(obj && obj.nodeType == 1);
+  },
+
+  // Is a given value a real Array?
+  isArray : function(obj) {
+    return Object.prototype.toString.call(obj) == '[object Array]';
+  },
+
+  // Is a given value a Function?
+  isFunction : function(obj) {
+    return typeof obj == 'function';
+  },
+
+  // Is a given variable undefined?
+  isUndefined : function(obj) {
+    return typeof obj == 'undefined';
+  },
+
+  // Convert any value into printable string form.
+  toString : function(obj) {
+    return obj == null ? '' : String(obj);
+  },
+
+  // Create a function bound to a given object (assigning 'this', and arguments,
+  // optionally).
+  bind : function(func, context) {
+    if (!context) return func;
+    var args = _.toArray(arguments).slice(2);
+    return function() {
+      var a = args.concat(_.toArray(arguments));
+      return func.apply(context, a);
+    };
+  },
+
+  // Bind all of an object's methods to that object. Useful for ensuring that 
+  // all callbacks defined on an object belong to it.
+  bindAll : function() {
+    var args = _.toArray(arguments);
+    var context = args.pop();
+    _.each(args, function(methodName) {
+      context[methodName] = _.bind(context[methodName], context);
+    });
+  },
+
+  // Generate a unique integer id (unique within the entire client session).
+  // Useful for temporary DOM ids.
+  uniqueId : function(prefix) {
+    var id = this._idCounter = (this._idCounter || 0) + 1;
+    return prefix ? prefix + id : id;
+  },
+
+  // Perform a deep comparison to check if two objects are equal.
+  isEqual : function(a, b) {
+    // Check object identity.
+    if (a === b) return true;
+    // Different types?
+    var at = typeof(a), bt = typeof(b);
+    if (at != bt) return false;
+    // Basic equality test (watch out for coercions).
+    if (a == b) return true;
+    // One of them implements an isEqual()?
+    if (a.isEqual) return a.isEqual(b);
+    // Nothing else worked, deep compare the contents.
+    return at === 'object' && _.isEqualContents(a, b);
+  },
+
+  // Objects have equal contents if they have the same keys, and all the values
+  // are equal (as defined by _.isEqual).
+  _isEqualContents : function(a, b) {
+    var aKeys = _.keys(a), bKeys = _.keys(b);
+    if (aKeys.length != bKeys.length) return false;
+    for (var key in a) if (!_.isEqual(a[key], b[key])) return false;
+    return true; 
+  },
+
+  // Javascript templating a-la ERB, pilfered from John Resig's 
+  // "Secrets of the Javascript Ninja", page 83.
+  template : function(str, data) {
+    var fn = new Function('obj', 
+      'var p=[],print=function(){p.push.apply(p,arguments);};' +
+      'with(obj){p.push(\'' +
+      str
+        .replace(/[\r\t\n]/g, " ") 
+        .split("<%").join("\t") 
+        .replace(/((^|%>)[^\t]*)'/g, "$1\r") 
+        .replace(/\t=(.*?)%>/g, "',$1,'") 
+        .split("\t").join("');") 
+        .split("%>").join("p.push('") 
+        .split("\r").join("\\'") 
+    + "');}return p.join('');");
+    return data ? fn(data) : fn;  
+  }
+
+};