feat: Add utilities#assert [#95469256]

DOMRenderer previously had methods for asserting state.

Putting those methods on the prototype makes it impossible for the
minifier to do any kind of dead-code elimination.

This commit adds an assert utility function used in order to check
if a certain condition is met.

Checking for NODE_ENV and not including the passed in error message
in the thrown error should be trivial and only needs to be done once
in the more generic assert function.

Author: alexanderGugel

dom-renderers/DOMRenderer.js

@@ -30,6 +30,7 @@ var PathUtils = require('../core/Path');
 var vendorPrefix = require('../utilities/vendorPrefix');
 var CallbackStore = require('../utilities/CallbackStore');
 var eventMap = require('./events/EventMap');
+var assert = require('../utilities/assert');
 
 var TRANSFORM = null;
 
@@ -93,7 +94,6 @@ function DOMRenderer (element, selector, compositor) {
     this._lastEv = null;
 }
 
-
 /**
  * Attaches an EventListener to the element associated with the passed in path.
  * Prevents the default browser action on all subsequent events if
@@ -110,11 +110,26 @@ function DOMRenderer (element, selector, compositor) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.subscribe = function subscribe(type) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._listen(type);
     this._target.subscribe[type] = true;
 };
 
+/**
+ * Unsubscribes from all events that are of the specified type.
+ *
+ * @method
+ *
+ * @param  {String} type    Event type to unsubscribe from.
+ * @return {undefined}      undefined
+ */
+DOMRenderer.prototype.unsubscribe = function unsubscribe(type) {
+    assert(this._target, 'No target loaded');
+
+    this._listen(type);
+    this._target.subscribe[type] = false;
+};
+
 /**
  * Used to preventDefault if an event of the specified type is being emitted on
  * the currently loaded target.
@@ -125,7 +140,8 @@ DOMRenderer.prototype.subscribe = function subscribe(type) {
  * @return {undefined}      undefined
  */
 DOMRenderer.prototype.preventDefault = function preventDefault(type) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
+
     this._listen(type);
     this._target.preventDefault[type] = true;
 };
@@ -142,7 +158,8 @@ DOMRenderer.prototype.preventDefault = function preventDefault(type) {
  * @return {undefined}      undefined
  */
 DOMRenderer.prototype.allowDefault = function allowDefault(type) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
+
     this._listen(type);
     this._target.preventDefault[type] = false;
 };
@@ -163,7 +180,7 @@ DOMRenderer.prototype.allowDefault = function allowDefault(type) {
  * @return {undefined}      undefined
  */
 DOMRenderer.prototype._listen = function _listen(type) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
 
     if (
         !this._target.listeners[type] && !this._root.listeners[type]
@@ -175,19 +192,6 @@ DOMRenderer.prototype._listen = function _listen(type) {
     }
 };
 
-/**
- * Unsubscribes from all events that are of the specified type.
- *
- * @method
- *
- * @param {String} type DOM event type (e.g. click, mouseover).
- * @return {undefined} undefined
- */
-DOMRenderer.prototype.unsubscribe = function unsubscribe(type) {
-    this._assertTargetLoaded();
-    this._target.subscribe[type] = false;
-};
-
 /**
  * Function to be added using `addEventListener` to the corresponding
  * DOMElement.
@@ -236,7 +240,6 @@ DOMRenderer.prototype._triggerEvent = function _triggerEvent(ev) {
     }
 };
 
-
 /**
  * getSizeOf gets the dom size of a particular DOM element.  This is
  * needed for render sizing in the scene graph.
@@ -308,55 +311,6 @@ DOMRenderer.prototype.draw = function draw(renderState) {
     }
 };
 
-
-/**
- * Internal helper function used for ensuring that a path is currently loaded.
- *
- * @method
- * @private
- *
- * @return {undefined} undefined
- */
-DOMRenderer.prototype._assertPathLoaded = function _asserPathLoaded() {
-    if (!this._path) throw new Error('path not loaded');
-};
-
-/**
- * Internal helper function used for ensuring that a parent is currently loaded.
- *
- * @method
- * @private
- *
- * @return {undefined} undefined
- */
-DOMRenderer.prototype._assertParentLoaded = function _assertParentLoaded() {
-    if (!this._parent) throw new Error('parent not loaded');
-};
-
-/**
- * Internal helper function used for ensuring that children are currently
- * loaded.
- *
- * @method
- * @private
- *
- * @return {undefined} undefined
- */
-DOMRenderer.prototype._assertChildrenLoaded = function _assertChildrenLoaded() {
-    if (!this._children) throw new Error('children not loaded');
-};
-
-/**
- * Internal helper function used for ensuring that a target is currently loaded.
- *
- * @method  _assertTargetLoaded
- *
- * @return {undefined} undefined
- */
-DOMRenderer.prototype._assertTargetLoaded = function _assertTargetLoaded() {
-    if (!this._target) throw new Error('No target loaded');
-};
-
 /**
  * Finds and sets the parent of the currently loaded element (path).
  *
@@ -366,7 +320,7 @@ DOMRenderer.prototype._assertTargetLoaded = function _assertTargetLoaded() {
  * @return {ElementCache} Parent element.
  */
 DOMRenderer.prototype.findParent = function findParent () {
-    this._assertPathLoaded();
+    assert(this._path, 'No path loaded');
 
     var path = this._path;
     var parent;
@@ -454,7 +408,7 @@ DOMRenderer.prototype.insertEl = function insertEl (tagName) {
 
         this.findParent();
 
-        this._assertParentLoaded();
+        assert(this._parent, 'No parent loaded');
 
         if (this._parent.void)
             throw new Error(
@@ -481,7 +435,6 @@ DOMRenderer.prototype.insertEl = function insertEl (tagName) {
     }
 };
 
-
 /**
  * Sets a property on the currently loaded target.
  *
@@ -493,11 +446,10 @@ DOMRenderer.prototype.insertEl = function insertEl (tagName) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setProperty = function setProperty (name, value) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._target.element.style[name] = value;
 };
 
-
 /**
  * Sets the size of the currently loaded target.
  * Removes any explicit sizing constraints when passed in `false`
@@ -514,7 +466,7 @@ DOMRenderer.prototype.setProperty = function setProperty (name, value) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setSize = function setSize (width, height) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
 
     this.setWidth(width);
     this.setHeight(height);
@@ -534,7 +486,7 @@ DOMRenderer.prototype.setSize = function setSize (width, height) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setWidth = function setWidth(width) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
 
     var contentWrapper = this._target.content;
 
@@ -567,7 +519,7 @@ DOMRenderer.prototype.setWidth = function setWidth(width) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setHeight = function setHeight(height) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
 
     var contentWrapper = this._target.content;
 
@@ -597,7 +549,7 @@ DOMRenderer.prototype.setHeight = function setHeight(height) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setAttribute = function setAttribute(name, value) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._target.element.setAttribute(name, value);
 };
 
@@ -611,7 +563,7 @@ DOMRenderer.prototype.setAttribute = function setAttribute(name, value) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setContent = function setContent(content) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
 
     if (this._target.formElement) {
         this._target.element.value = content;
@@ -635,7 +587,6 @@ DOMRenderer.prototype.setContent = function setContent(content) {
     );
 };
 
-
 /**
  * Sets the passed in transform matrix (world space). Inverts the parent's world
  * transform.
@@ -647,11 +598,10 @@ DOMRenderer.prototype.setContent = function setContent(content) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.setMatrix = function setMatrix (transform) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._target.element.style[TRANSFORM] = this._stringifyMatrix(transform);
 };
 
-
 /**
  * Adds a class to the classList associated with the currently loaded target.
  *
@@ -662,11 +612,10 @@ DOMRenderer.prototype.setMatrix = function setMatrix (transform) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.addClass = function addClass(domClass) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._target.element.classList.add(domClass);
 };
 
-
 /**
  * Removes a class from the classList associated with the currently loaded
  * target.
@@ -678,11 +627,10 @@ DOMRenderer.prototype.addClass = function addClass(domClass) {
  * @return {undefined} undefined
  */
 DOMRenderer.prototype.removeClass = function removeClass(domClass) {
-    this._assertTargetLoaded();
+    assert(this._target, 'No target loaded');
     this._target.element.classList.remove(domClass);
 };
 
-
 /**
  * Stringifies the passed in matrix for setting the `transform` property.
  *

package.json

@@ -46,13 +46,18 @@
     "tap-closer": "^1.0.0",
     "tape": "^4.0.0",
     "tap-spec": "^4.0.0",
+    "escodegen": "^1.6.1",
+    "esprima": "^2.2.0",
+    "replace-method": "0.0.0",
+    "through": "^2.3.7",
     "uglify-js": "^2.4.17"
   },
   "dependencies": {
     "glslify": "^2.0.0"
   },
   "browserify": {
     "transform": [
+      ["./scripts/optimize-assertions", { "stripErrors": false, "preCheck": true }],
       "glslify"
     ]
   }

scripts/optimize-assertions.js

@@ -0,0 +1,83 @@
+var replaceMethod = require('replace-method');
+var codegen = require('escodegen');
+var esprima = require('esprima');
+var through = require('through');
+
+/**
+ * Browserify transform used for transforming `assert()` function calls.
+ *
+ * @param  {String} file                Original filename of the current source
+ *                                      file.
+ * @param  {Object} options             Configuration object.
+ * @param  {Boolean} [stripErrors=true] Boolean value indicating if the error
+ *                                      messages should be excluded from the
+ *                                      bundle.
+ * @param  {Boolean} [preCheck=true]    Avoid `assert` function call.
+ * @return {Stream}                     `through` stream.
+ */
+var optimizeAssertionsTransform = function(file, options) {
+    options = options || {};
+
+    if (options.stripErrors == null)
+        options.stripErrors = true;
+
+    if (options.preCheck == null)
+        options.preCheck = true;
+
+    var stream = through(write, end);
+    var source = '';
+
+    function write(chunk) {
+        source += chunk;
+    }
+
+    function end() {
+        var ast;
+
+        try {
+            ast = esprima.parse(source);
+        }
+        catch (e) {
+            return stream.emit('error', e);
+        }
+
+        var src = replaceMethod(ast);
+        src.replace(['assert'], function(node) {
+            if (options.stripErrors) {
+                node.arguments.length = 1;
+            }
+
+            if (options.preCheck) {
+                node = {
+                    'type': 'IfStatement',
+                    'test': {
+                        'type': 'UnaryExpression',
+                        'operator': '!',
+                        'argument': node.arguments[0],
+                        'prefix': true
+                    },
+                    'consequent': node,
+                    'alternate': null
+                };
+            }
+
+            return node;
+        });
+
+        var code;
+
+        try {
+            code = codegen.generate(ast);
+        }
+        catch (e) {
+            return stream.emit('error', e);
+        }
+
+        stream.queue(code);
+        stream.queue(null);
+    }
+
+    return stream;
+};
+
+module.exports = optimizeAssertionsTransform;