Support for replacing has() tests with true or false in optimizer.

jrburke · jrburke · commit 6f50598c6473 · 2011-01-04T23:57:29.000-08:00
diff --git a/build/jslib/pragma.js b/build/jslib/pragma.js
@@ -12,6 +12,7 @@
 var pragma = {
     conditionalRegExp: /(exclude|include)Start\s*\(\s*["'](\w+)["']\s*,(.*)\)/,
     useStrictRegExp: /['"]use strict['"];/g,
+    hasRegExp: /has\s*\(\s*['"]([^'"]+)['"]\)/g,
 
     removeStrict: function (contents, config) {
         return config.useStrict ? contents : contents.replace(pragma.useStrictRegExp, '');
@@ -29,6 +30,16 @@ var pragma = {
             //when dojo no longer needs conversion:
             kwArgs = pragmas;
 
+        //Replace has references if desired
+        if (config.has) {
+            fileContents = fileContents.replace(pragma.hasRegExp, function (match, test) {
+                if (test in config.has) {
+                    return !!config.has[test];
+                }
+                return match;
+            });
+        }
+
         //If pragma work is not desired, skip it.
         if (config.skipPragmas) {
             return pragma.removeStrict(fileContents, config);
diff --git a/build/tests/hasTestModule.build.js b/build/tests/hasTestModule.build.js
@@ -0,0 +1,10 @@
+({
+    baseUrl: "./",
+    optimize: "none",
+    name: "hasTestModule",
+    out: "builds/hasTestModule.js",
+    has: {
+        aTrueValue: true,
+        aFalseValue: false
+    }
+})
diff --git a/build/tests/hasTestModule.js b/build/tests/hasTestModule.js
@@ -0,0 +1,30 @@
+/**
+ * Just a test module that tests has replacements. Not usable on its own.
+ */
+define(function (require) {
+    var foo, bar, baz, blurp, bat, blip;
+
+    if (has("aTrueValue")) {
+        foo = "is true";
+    } else {
+        foo = "is false";
+    }
+
+    if (has("aFalseValue")) {
+        bar = "is true";
+    } else {
+        bar = "is false";
+    }
+
+    if (has("some skipped value")) {
+        baz = "what";
+    } else {
+        baz = "ever";
+    }
+
+    blurp = has("aTrueValue") ? "OK" : "FAIL";
+    bat = has ('aFalseValue') ? "FAIL" : "OK";
+    blip = has("some skipped value") ? "what" : "ever";
+
+    return foo + bar + baz + blurp + bat + blip;
+});
diff --git a/docs/optimization.html b/docs/optimization.html
@@ -9,7 +9,8 @@ <h1>RequireJS Optimization Tool</h1>
 <li class="hbox"><a href="#shallow">Shallow exclusions for fast development</a><span class="spacer boxFlex"></span><span class="sect">&sect; 5</span></li>
 <li class="hbox"><a href="#onecss">Optimizing one CSS file</a><span class="spacer boxFlex"></span><span class="sect">&sect; 6</span></li>
 <li class="hbox"><a href="#wholeproject">Optimizing a whole project</a><span class="spacer boxFlex"></span><span class="sect">&sect; 7</span></li>
-<li class="hbox"><a href="#options">All configuration options</a><span class="spacer boxFlex"></span><span class="sect">&sect; 8</span></li>
+<li class="hbox"><a href="#hasjs">Integration with has.js</a><span class="spacer boxFlex"></span><span class="sect">&sect; 8</span></li>
+<li class="hbox"><a href="#options">All configuration options</a><span class="spacer boxFlex"></span><span class="sect">&sect; 9</span></li>
 </ul>
 
 <span class="note">Note: RequireJS comes with an optimization tool that does the following</span>
@@ -223,7 +224,51 @@ <h2><a name="wholeproject">Optimizing a whole project</a><span class="sectionMar
 </div>
 
 <div class="section">
-<h2><a name="options">All configuration options</a><span class="sectionMark">&sect; 8</span></h2>
+<h2><a name="hasjs">Integration with has.js</a><span class="sectionMark">&sect; 8</span></h2>
+
+<p><a href="https://github.com/phiggins42/has.js">has.js</a> is a great tool to that adds easy feature detection for your project. There is some optimizer support for optimizing code paths for has.js tests.</p>
+
+<p>If your code uses tests like the following:</p>
+
+<pre><code>
+if (has("someThing")) {
+    //use native someThing
+} else {
+    //do some workaround
+}
+</code></pre>
+
+<p>You can define a <b>has</b> object in the build config with true or false values for some has() tests, and the optmizer will replace the has() test with the true or false value.</p>
+
+<p>If your build profile looked like so:</p>
+
+<pre><code>
+({
+    baseUrl: "./",
+    name: "hasTestModule",
+    out: "builds/hasTestModule.js",
+    has: {
+        someThing: true
+    }
+})
+</code></pre>
+
+<p>Then the optimizer will transform the above code sample to:</p>
+
+<pre><code>
+if (true) {
+    //use native someThing
+} else {
+    //do some workaround
+}
+</code></pre>
+
+<p>Then, if you use the default <b>optimize</b> setting that uses Closure Compiler, Closure Compiler will optimize out the dead code branch! So you can do custom builds of your code that are optimized for a set of has() tests.</p>
+
+</div>
+
+<div class="section">
+<h2><a name="options">All configuration options</a><span class="sectionMark">&sect; 9</span></h2>
 
 <p>There is an <a href="http://github.com/jrburke/requirejs/blob/master/build/example.build.js">example.build.js</a> file in the requirejs/build directory that details all of the allowed optimization tool configuration options.</p>
 </div>
diff --git a/tests/README.md b/tests/README.md
@@ -35,6 +35,7 @@ Try manual testing:
 * ../build.sh indexBuilder.build.js - confirm plugin write calls are done.
 * ../build.sh text.build.js - confirm plugin write calls are done.
 * ../build.sh i18n.build.js - confirm plugin required the nls/en-us-surfer/colors module.
+* ../build.sh hasTestModule.build.js - confirm plugin required the nls/en-us-surfer/colors module.
 
 # Sample jQuery project
 
