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Diffstat (limited to 'trunk/infrastructure/rhino1_7R1/examples/DynamicScopes.java')
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1 files changed, 204 insertions, 0 deletions
diff --git a/trunk/infrastructure/rhino1_7R1/examples/DynamicScopes.java b/trunk/infrastructure/rhino1_7R1/examples/DynamicScopes.java new file mode 100644 index 0000000..10d53ac --- /dev/null +++ b/trunk/infrastructure/rhino1_7R1/examples/DynamicScopes.java @@ -0,0 +1,204 @@ +/* -*- Mode: java; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- + * + * ***** BEGIN LICENSE BLOCK ***** + * Version: MPL 1.1/GPL 2.0 + * + * The contents of this file are subject to the Mozilla Public License Version + * 1.1 (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * http://www.mozilla.org/MPL/ + * + * Software distributed under the License is distributed on an "AS IS" basis, + * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License + * for the specific language governing rights and limitations under the + * License. + * + * The Original Code is Rhino code, released + * May 6, 1998. + * + * The Initial Developer of the Original Code is + * Netscape Communications Corporation. + * Portions created by the Initial Developer are Copyright (C) 1997-2000 + * the Initial Developer. All Rights Reserved. + * + * Contributor(s): + * Norris Boyd + * + * Alternatively, the contents of this file may be used under the terms of + * the GNU General Public License Version 2 or later (the "GPL"), in which + * case the provisions of the GPL are applicable instead of those above. If + * you wish to allow use of your version of this file only under the terms of + * the GPL and not to allow others to use your version of this file under the + * MPL, indicate your decision by deleting the provisions above and replacing + * them with the notice and other provisions required by the GPL. If you do + * not delete the provisions above, a recipient may use your version of this + * file under either the MPL or the GPL. + * + * ***** END LICENSE BLOCK ***** */ + +import org.mozilla.javascript.*; + +/** + * Example of controlling the JavaScript with multiple scopes and threads. + */ +public class DynamicScopes { + + static boolean useDynamicScope; + + static class MyFactory extends ContextFactory + { + protected boolean hasFeature(Context cx, int featureIndex) + { + if (featureIndex == Context.FEATURE_DYNAMIC_SCOPE) { + return useDynamicScope; + } + return super.hasFeature(cx, featureIndex); + } + } + + static { + ContextFactory.initGlobal(new MyFactory()); + } + + + /** + * Main entry point. + * + * Set up the shared scope and then spawn new threads that execute + * relative to that shared scope. Try to run functions with and + * without dynamic scope to see the effect. + * + * The expected output is + * <pre> + * sharedScope + * nested:sharedScope + * sharedScope + * nested:sharedScope + * sharedScope + * nested:sharedScope + * thread0 + * nested:thread0 + * thread1 + * nested:thread1 + * thread2 + * nested:thread2 + * </pre> + * The final three lines may be permuted in any order depending on + * thread scheduling. + */ + public static void main(String[] args) + { + Context cx = Context.enter(); + try { + // Precompile source only once + String source = "" + +"var x = 'sharedScope';\n" + +"function f() { return x; }\n" + // Dynamic scope works with nested function too + +"function initClosure(prefix) {\n" + +" return function test() { return prefix+x; }\n" + +"}\n" + +"var closure = initClosure('nested:');\n" + +""; + Script script = cx.compileString(source, "sharedScript", 1, null); + + useDynamicScope = false; + runScripts(cx, script); + useDynamicScope = true; + runScripts(cx, script); + } finally { + Context.exit(); + } + } + + static void runScripts(Context cx, Script script) + { + // Initialize the standard objects (Object, Function, etc.) + // This must be done before scripts can be executed. The call + // returns a new scope that we will share. + ScriptableObject sharedScope = cx.initStandardObjects(null, true); + + // Now we can execute the precompiled script against the scope + // to define x variable and f function in the shared scope. + script.exec(cx, sharedScope); + + // Now we spawn some threads that execute a script that calls the + // function 'f'. The scope chain looks like this: + // <pre> + // ------------------ ------------------ + // | per-thread scope | -prototype-> | shared scope | + // ------------------ ------------------ + // ^ + // | + // parentScope + // | + // ------------------ + // | f's activation | + // ------------------ + // </pre> + // Both the shared scope and the per-thread scope have variables 'x' + // defined in them. If 'f' is compiled with dynamic scope enabled, + // the 'x' from the per-thread scope will be used. Otherwise, the 'x' + // from the shared scope will be used. The 'x' defined in 'g' (which + // calls 'f') should not be seen by 'f'. + final int threadCount = 3; + Thread[] t = new Thread[threadCount]; + for (int i=0; i < threadCount; i++) { + String source2 = "" + +"function g() { var x = 'local'; return f(); }\n" + +"java.lang.System.out.println(g());\n" + +"function g2() { var x = 'local'; return closure(); }\n" + +"java.lang.System.out.println(g2());\n" + +""; + t[i] = new Thread(new PerThread(sharedScope, source2, + "thread" + i)); + } + for (int i=0; i < threadCount; i++) + t[i].start(); + // Don't return in this thread until all the spawned threads have + // completed. + for (int i=0; i < threadCount; i++) { + try { + t[i].join(); + } catch (InterruptedException e) { + } + } + } + + static class PerThread implements Runnable { + + PerThread(Scriptable sharedScope, String source, String x) { + this.sharedScope = sharedScope; + this.source = source; + this.x = x; + } + + public void run() { + // We need a new Context for this thread. + Context cx = Context.enter(); + try { + // We can share the scope. + Scriptable threadScope = cx.newObject(sharedScope); + threadScope.setPrototype(sharedScope); + + // We want "threadScope" to be a new top-level + // scope, so set its parent scope to null. This + // means that any variables created by assignments + // will be properties of "threadScope". + threadScope.setParentScope(null); + + // Create a JavaScript property of the thread scope named + // 'x' and save a value for it. + threadScope.put("x", threadScope, x); + cx.evaluateString(threadScope, source, "threadScript", 1, null); + } finally { + Context.exit(); + } + } + private Scriptable sharedScope; + private String source; + private String x; + } + +} + |