2.4/dev/core/src/com/google/gwt/dev/jjs/impl/HandleCrossFragmentReferences.java - gwt - Git at Google

 /*
  * Copyright 2010 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
  * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
  * License for the specific language governing permissions and limitations under
  * the License.
  */
 package com.google.gwt.dev.jjs.impl;

 import com.google.gwt.core.ext.BadPropertyValueException;
 import com.google.gwt.core.ext.PropertyOracle;
 import com.google.gwt.core.ext.TreeLogger;
 import com.google.gwt.dev.jjs.SourceInfo;
 import com.google.gwt.dev.js.ast.JsBinaryOperation;
 import com.google.gwt.dev.js.ast.JsBinaryOperator;
 import com.google.gwt.dev.js.ast.JsContext;
 import com.google.gwt.dev.js.ast.JsFunction;
 import com.google.gwt.dev.js.ast.JsModVisitor;
 import com.google.gwt.dev.js.ast.JsName;
 import com.google.gwt.dev.js.ast.JsNameRef;
 import com.google.gwt.dev.js.ast.JsObjectLiteral;
 import com.google.gwt.dev.js.ast.JsProgram;
 import com.google.gwt.dev.js.ast.JsVars;
 import com.google.gwt.dev.js.ast.JsVars.JsVar;
 import com.google.gwt.dev.js.ast.JsVisitor;

 import java.util.HashSet;
 import java.util.Iterator;
 import java.util.LinkedHashMap;
 import java.util.LinkedHashSet;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;

 /**
  * Rewrite JavaScript to better handle references from one code fragment to
  * another. For any function defined off the initial download and accessed from
  * a different island than the one it's defined on, predefine a variable in the
  * initial download to hold its definition.
  */
 public class HandleCrossFragmentReferences {
   /**
    * Find out which islands define and use each named function or variable. This
    * visitor is not smart about which definitions and uses matter. It blindly
    * records all of them.
    */
   private class FindNameReferences extends JsVisitor {
     Map<JsName, Set<Integer>> islandsDefining = new LinkedHashMap<JsName, Set<Integer>>();
     Map<JsName, Set<Integer>> islandsUsing = new LinkedHashMap<JsName, Set<Integer>>();
     private int currentIsland;

     @Override
     public void endVisit(JsFunction x, JsContext ctx) {
       JsName name = x.getName();
       if (name != null) {
         definitionSeen(name);
       }
     }

     @Override
     public void endVisit(JsNameRef x, JsContext ctx) {
       if (x.getQualifier() == null) {
         JsName name = x.getName();
         if (name != null) {
           referenceSeen(name);
         }
       }
     }

     @Override
     public void endVisit(JsVars x, JsContext ctx) {
       for (JsVar var : x) {
         JsName name = var.getName();
         if (name != null) {
           definitionSeen(name);
         }
       }
     }

     @Override
     public boolean visit(JsProgram x, JsContext ctx) {
       for (int i = 0; i < x.getFragmentCount(); i++) {
         currentIsland = i;
         accept(x.getFragmentBlock(i));
       }

       return false;
     }

     private void definitionSeen(JsName name) {
       /*
        * Support multiple definitions, because local variables can reuse the
        * same name.
        */
       Set<Integer> defs = islandsDefining.get(name);
       if (defs == null) {
         defs = new LinkedHashSet<Integer>();
         islandsDefining.put(name, defs);
       }
       defs.add(currentIsland);
     }

     private void referenceSeen(JsName name) {
       Set<Integer> refs = islandsUsing.get(name);
       if (refs == null) {
         refs = new HashSet<Integer>();
         islandsUsing.put(name, refs);
       }
       refs.add(currentIsland);
     }
   }

   /**
    * Rewrite var and function declarations as assignments, if their name is
    * accessed cross-island. Rewrite refs to such names correspondingly.
    */
   private class RewriteDeclsAndRefs extends JsModVisitor {
     @Override
     public void endVisit(JsFunction x, JsContext ctx) {
       if (namesToPredefine.contains(x.getName())) {
         JsBinaryOperation asg =
             new JsBinaryOperation(x.getSourceInfo(), JsBinaryOperator.ASG, makeRefViaJslink(x
                 .getName(), x.getSourceInfo()), x);
         x.setName(null);
         ctx.replaceMe(asg);
       }
     }

     @Override
     public void endVisit(JsNameRef x, JsContext ctx) {
       if (namesToPredefine.contains(x.getName())) {
         ctx.replaceMe(makeRefViaJslink(x.getName(), x.getSourceInfo()));
       }
     }

     @Override
     public void endVisit(JsVars x, JsContext ctx) {
       if (!ctx.canInsert()) {
         return;
       }

       /*
        * Loop through each var and see if it was predefined. If so, then remove
        * the var. If the var has an initializer, then add back an assignment
        * statement to initialize it. If there is no initializer, then don't add
        * anything back; the var will still have undefined as its initial value,
        * just like before.
        *
        * A complication is that the variables that are predefined might be
        * interspersed with variables that are not. That means the general result
        * of this transformation has alternating var lists and assignment
        * statements. The currentVar variable holds the most recently inserted
        * statement, if that statement was a JsVars; otherwise it holds null.
        */

       JsVars currentVar = null;
       Iterator<JsVar> varsIterator = x.iterator();
       while (varsIterator.hasNext()) {
         JsVar var = varsIterator.next();
         if (namesToPredefine.contains(var.getName())) {
           // The var was predefined
           if (var.getInitExpr() != null) {
             // If it has an initializer, add an assignment statement
             JsBinaryOperation asg =
                 new JsBinaryOperation(var.getSourceInfo(), JsBinaryOperator.ASG, makeRefViaJslink(
                     var.getName(), var.getSourceInfo()), var.getInitExpr());
             ctx.insertBefore(asg.makeStmt());
             currentVar = null;
           }
         } else {
           // The var was not predefined; add it to a var list
           if (currentVar == null) {
             currentVar = new JsVars(x.getSourceInfo());
             ctx.insertBefore(currentVar);
           }
           currentVar.add(var);
         }
       }

       ctx.removeMe();
     }

     private JsNameRef makeRefViaJslink(JsName name, SourceInfo sourceInfo) {
       JsNameRef ref = name.makeRef(sourceInfo);
       ref.setQualifier(jslink.makeRef(sourceInfo));
       return ref;
     }
   }

   public static String PROP_PREDECLARE_VARS = "compiler.predeclare.cross.fragment.references";

   public static void exec(TreeLogger logger, JsProgram jsProgram, PropertyOracle[] propertyOracles) {
     new HandleCrossFragmentReferences(logger, jsProgram, propertyOracles).execImpl();
   }

   private static boolean containsOtherThan(Set<Integer> set, int allowed) {
     for (int elem : set) {
       if (elem != allowed) {
         return true;
       }
     }
     return false;
   }

   private JsName jslink;
   private final JsProgram jsProgram;
   private final TreeLogger logger;
   private final Set<JsName> namesToPredefine = new LinkedHashSet<JsName>();
   private final PropertyOracle[] propertyOracles;

   private HandleCrossFragmentReferences(TreeLogger logger, JsProgram jsProgram,
       PropertyOracle[] propertyOracles) {
     this.logger = logger;
     this.jsProgram = jsProgram;
     this.propertyOracles = propertyOracles;
   }

   private void chooseNamesToPredefine(Map<JsName, Set<Integer>> map,
       Map<JsName, Set<Integer>> islandsUsing) {
     for (Entry<JsName, Set<Integer>> entry : map.entrySet()) {
       JsName name = entry.getKey();
       Set<Integer> defIslands = entry.getValue();
       if (defIslands.size() != 1) {
         // Only rewrite global variables, which should have exactly one
         // definition
         continue;
       }
       int defIsland = defIslands.iterator().next();
       if (defIsland == 0) {
         // Variables defined on the base island can be accessed directly from
         // other islands
         continue;
       }
       Set<Integer> useIslands = islandsUsing.get(name);
       if (useIslands == null) {
         // The variable is never used. Leave it alone.
         continue;
       }

       if (containsOtherThan(islandsUsing.get(name), defIsland)) {
         namesToPredefine.add(name);
       }
     }
   }

   /**
    * Define the jslink object that will be used to fix up cross-island
    * references.
    */
   private void defineJsLink() {
     SourceInfo info = jsProgram.createSourceInfoSynthetic(HandleCrossFragmentReferences.class);
     jslink = jsProgram.getScope().declareName("jslink");
     JsVars vars = new JsVars(info);
     JsVar var = new JsVar(info, jslink);
     var.setInitExpr(new JsObjectLiteral(info));
     vars.add(var);
     jsProgram.getFragmentBlock(0).getStatements().add(0, vars);
   }

   private void execImpl() {
     if (jsProgram.getFragmentCount() == 1) {
       return;
     }
     if (!shouldPredeclareReferences()) {
       return;
     }
     defineJsLink();
     FindNameReferences findNameReferences = new FindNameReferences();
     findNameReferences.accept(jsProgram);
     chooseNamesToPredefine(findNameReferences.islandsDefining, findNameReferences.islandsUsing);
     new RewriteDeclsAndRefs().accept(jsProgram);
   }

   /**
    * Check the property oracles for whether references should be predeclared or
    * not. If any of them say yes, then do the rewrite.
    */
   private boolean shouldPredeclareReferences() {
     for (PropertyOracle props : propertyOracles) {
       try {
         String propValue =
             props.getSelectionProperty(logger, PROP_PREDECLARE_VARS).getCurrentValue();
         if (Boolean.parseBoolean(propValue)) {
           return true;
         }
       } catch (BadPropertyValueException e) {
         // Property not defined; don't rewrite
       }
     }

     return false;
   }
 }
	/*
	* Copyright 2010 Google Inc.
	*
	* Licensed under the Apache License, Version 2.0 (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.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
	* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
	* License for the specific language governing permissions and limitations under
	* the License.
	*/
	package com.google.gwt.dev.jjs.impl;

	import com.google.gwt.core.ext.BadPropertyValueException;
	import com.google.gwt.core.ext.PropertyOracle;
	import com.google.gwt.core.ext.TreeLogger;
	import com.google.gwt.dev.jjs.SourceInfo;
	import com.google.gwt.dev.js.ast.JsBinaryOperation;
	import com.google.gwt.dev.js.ast.JsBinaryOperator;
	import com.google.gwt.dev.js.ast.JsContext;
	import com.google.gwt.dev.js.ast.JsFunction;
	import com.google.gwt.dev.js.ast.JsModVisitor;
	import com.google.gwt.dev.js.ast.JsName;
	import com.google.gwt.dev.js.ast.JsNameRef;
	import com.google.gwt.dev.js.ast.JsObjectLiteral;
	import com.google.gwt.dev.js.ast.JsProgram;
	import com.google.gwt.dev.js.ast.JsVars;
	import com.google.gwt.dev.js.ast.JsVars.JsVar;
	import com.google.gwt.dev.js.ast.JsVisitor;

	import java.util.HashSet;
	import java.util.Iterator;
	import java.util.LinkedHashMap;
	import java.util.LinkedHashSet;
	import java.util.Map;
	import java.util.Map.Entry;
	import java.util.Set;

	/**
	* Rewrite JavaScript to better handle references from one code fragment to
	* another. For any function defined off the initial download and accessed from
	* a different island than the one it's defined on, predefine a variable in the
	* initial download to hold its definition.
	*/
	public class HandleCrossFragmentReferences {
	/**
	* Find out which islands define and use each named function or variable. This
	* visitor is not smart about which definitions and uses matter. It blindly
	* records all of them.
	*/
	private class FindNameReferences extends JsVisitor {
	Map<JsName, Set<Integer>> islandsDefining = new LinkedHashMap<JsName, Set<Integer>>();
	Map<JsName, Set<Integer>> islandsUsing = new LinkedHashMap<JsName, Set<Integer>>();
	private int currentIsland;

	@Override
	public void endVisit(JsFunction x, JsContext ctx) {
	JsName name = x.getName();
	if (name != null) {
	definitionSeen(name);
	}
	}

	@Override
	public void endVisit(JsNameRef x, JsContext ctx) {
	if (x.getQualifier() == null) {
	JsName name = x.getName();
	if (name != null) {
	referenceSeen(name);
	}
	}
	}

	@Override
	public void endVisit(JsVars x, JsContext ctx) {
	for (JsVar var : x) {
	JsName name = var.getName();
	if (name != null) {
	definitionSeen(name);
	}
	}
	}

	@Override
	public boolean visit(JsProgram x, JsContext ctx) {
	for (int i = 0; i < x.getFragmentCount(); i++) {
	currentIsland = i;
	accept(x.getFragmentBlock(i));
	}

	return false;
	}

	private void definitionSeen(JsName name) {
	/*
	* Support multiple definitions, because local variables can reuse the
	* same name.
	*/
	Set<Integer> defs = islandsDefining.get(name);
	if (defs == null) {
	defs = new LinkedHashSet<Integer>();
	islandsDefining.put(name, defs);
	}
	defs.add(currentIsland);
	}

	private void referenceSeen(JsName name) {
	Set<Integer> refs = islandsUsing.get(name);
	if (refs == null) {
	refs = new HashSet<Integer>();
	islandsUsing.put(name, refs);
	}
	refs.add(currentIsland);
	}
	}

	/**
	* Rewrite var and function declarations as assignments, if their name is
	* accessed cross-island. Rewrite refs to such names correspondingly.
	*/
	private class RewriteDeclsAndRefs extends JsModVisitor {
	@Override
	public void endVisit(JsFunction x, JsContext ctx) {
	if (namesToPredefine.contains(x.getName())) {
	JsBinaryOperation asg =
	new JsBinaryOperation(x.getSourceInfo(), JsBinaryOperator.ASG, makeRefViaJslink(x
	.getName(), x.getSourceInfo()), x);
	x.setName(null);
	ctx.replaceMe(asg);
	}
	}

	@Override
	public void endVisit(JsNameRef x, JsContext ctx) {
	if (namesToPredefine.contains(x.getName())) {
	ctx.replaceMe(makeRefViaJslink(x.getName(), x.getSourceInfo()));
	}
	}

	@Override
	public void endVisit(JsVars x, JsContext ctx) {
	if (!ctx.canInsert()) {
	return;
	}

	/*
	* Loop through each var and see if it was predefined. If so, then remove
	* the var. If the var has an initializer, then add back an assignment
	* statement to initialize it. If there is no initializer, then don't add
	* anything back; the var will still have undefined as its initial value,
	* just like before.
	*
	* A complication is that the variables that are predefined might be
	* interspersed with variables that are not. That means the general result
	* of this transformation has alternating var lists and assignment
	* statements. The currentVar variable holds the most recently inserted
	* statement, if that statement was a JsVars; otherwise it holds null.
	*/

	JsVars currentVar = null;
	Iterator<JsVar> varsIterator = x.iterator();
	while (varsIterator.hasNext()) {
	JsVar var = varsIterator.next();
	if (namesToPredefine.contains(var.getName())) {
	// The var was predefined
	if (var.getInitExpr() != null) {
	// If it has an initializer, add an assignment statement
	JsBinaryOperation asg =
	new JsBinaryOperation(var.getSourceInfo(), JsBinaryOperator.ASG, makeRefViaJslink(
	var.getName(), var.getSourceInfo()), var.getInitExpr());
	ctx.insertBefore(asg.makeStmt());
	currentVar = null;
	}
	} else {
	// The var was not predefined; add it to a var list
	if (currentVar == null) {
	currentVar = new JsVars(x.getSourceInfo());
	ctx.insertBefore(currentVar);
	}
	currentVar.add(var);
	}
	}

	ctx.removeMe();
	}

	private JsNameRef makeRefViaJslink(JsName name, SourceInfo sourceInfo) {
	JsNameRef ref = name.makeRef(sourceInfo);
	ref.setQualifier(jslink.makeRef(sourceInfo));
	return ref;
	}
	}

	public static String PROP_PREDECLARE_VARS = "compiler.predeclare.cross.fragment.references";

	public static void exec(TreeLogger logger, JsProgram jsProgram, PropertyOracle[] propertyOracles) {
	new HandleCrossFragmentReferences(logger, jsProgram, propertyOracles).execImpl();
	}

	private static boolean containsOtherThan(Set<Integer> set, int allowed) {
	for (int elem : set) {
	if (elem != allowed) {
	return true;
	}
	}
	return false;
	}

	private JsName jslink;
	private final JsProgram jsProgram;
	private final TreeLogger logger;
	private final Set<JsName> namesToPredefine = new LinkedHashSet<JsName>();
	private final PropertyOracle[] propertyOracles;

	private HandleCrossFragmentReferences(TreeLogger logger, JsProgram jsProgram,
	PropertyOracle[] propertyOracles) {
	this.logger = logger;
	this.jsProgram = jsProgram;
	this.propertyOracles = propertyOracles;
	}

	private void chooseNamesToPredefine(Map<JsName, Set<Integer>> map,
	Map<JsName, Set<Integer>> islandsUsing) {
	for (Entry<JsName, Set<Integer>> entry : map.entrySet()) {
	JsName name = entry.getKey();
	Set<Integer> defIslands = entry.getValue();
	if (defIslands.size() != 1) {
	// Only rewrite global variables, which should have exactly one
	// definition
	continue;
	}
	int defIsland = defIslands.iterator().next();
	if (defIsland == 0) {
	// Variables defined on the base island can be accessed directly from
	// other islands
	continue;
	}
	Set<Integer> useIslands = islandsUsing.get(name);
	if (useIslands == null) {
	// The variable is never used. Leave it alone.
	continue;
	}

	if (containsOtherThan(islandsUsing.get(name), defIsland)) {
	namesToPredefine.add(name);
	}
	}
	}

	/**
	* Define the jslink object that will be used to fix up cross-island
	* references.
	*/
	private void defineJsLink() {
	SourceInfo info = jsProgram.createSourceInfoSynthetic(HandleCrossFragmentReferences.class);
	jslink = jsProgram.getScope().declareName("jslink");
	JsVars vars = new JsVars(info);
	JsVar var = new JsVar(info, jslink);
	var.setInitExpr(new JsObjectLiteral(info));
	vars.add(var);
	jsProgram.getFragmentBlock(0).getStatements().add(0, vars);
	}

	private void execImpl() {
	if (jsProgram.getFragmentCount() == 1) {
	return;
	}
	if (!shouldPredeclareReferences()) {
	return;
	}
	defineJsLink();
	FindNameReferences findNameReferences = new FindNameReferences();
	findNameReferences.accept(jsProgram);
	chooseNamesToPredefine(findNameReferences.islandsDefining, findNameReferences.islandsUsing);
	new RewriteDeclsAndRefs().accept(jsProgram);
	}

	/**
	* Check the property oracles for whether references should be predeclared or
	* not. If any of them say yes, then do the rewrite.
	*/
	private boolean shouldPredeclareReferences() {
	for (PropertyOracle props : propertyOracles) {
	try {
	String propValue =
	props.getSelectionProperty(logger, PROP_PREDECLARE_VARS).getCurrentValue();
	if (Boolean.parseBoolean(propValue)) {
	return true;
	}
	} catch (BadPropertyValueException e) {
	// Property not defined; don't rewrite
	}
	}

	return false;
	}
	}