user/src/com/google/gwt/resources/css/ast/CssNodeCloner.java - gwt - Git at Google

 /*
  * Copyright 2009 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.resources.css.ast;

 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
 import java.util.Stack;

 /**
  * Clones CssNodes.
  */
 public class CssNodeCloner extends CssVisitor {

   /**
    * Clone a list of nodes.
    */
   public static <T extends CssNode> List<T> clone(Class<T> clazz, List<T> nodes) {

     // Push a fake context that will contain the cloned node
     List<CssNode> topContext = new ArrayList<CssNode>();
     final List<CssProperty> topProperties = new ArrayList<CssProperty>();
     final List<CssSelector> topSelectors = new ArrayList<CssSelector>();

     CssNodeCloner cloner = new CssNodeCloner();
     cloner.curentNodes.push(topContext);
     cloner.currentHasProperties = new HasProperties() {
       public List<CssProperty> getProperties() {
         return topProperties;
       }
     };
     cloner.currentHasSelectors = new HasSelectors() {
       public List<CssSelector> getSelectors() {
         return topSelectors;
       }
     };

     // Process the nodes
     cloner.accept(nodes);

     /*
      * Return the requested data. Different AST nodes will have been collected
      * in different parts of the initial context.
      */
     List<?> toIterate;
     if (CssProperty.class.isAssignableFrom(clazz)) {
       toIterate = topProperties;
     } else if (CssSelector.class.isAssignableFrom(clazz)) {
       toIterate = topSelectors;
     } else {
       toIterate = topContext;
     }

     assert toIterate.size() == nodes.size() : "Wrong number of nodes in top "
         + "context. Expecting: " + nodes.size() + " Found: " + toIterate.size();

     // Create the final return value
     List<T> toReturn = new ArrayList<T>(toIterate.size());
     for (Object node : toIterate) {
       assert clazz.isInstance(node) : "Return type mismatch. Expecting: "
           + clazz.getName() + " Found: " + node.getClass().getName();

       // Cast to the correct type to avoid an unchecked generic cast
       toReturn.add(clazz.cast(node));
     }

     return toReturn;
   }

   /**
    * Clone a single node.
    */
   public static <T extends CssNode> T clone(Class<T> clazz, T node) {
     return clone(clazz, Collections.singletonList(node)).get(0);
   }

   private HasProperties currentHasProperties;

   private HasSelectors currentHasSelectors;

   private final Stack<List<CssNode>> curentNodes = new Stack<List<CssNode>>();

   private CssNodeCloner() {
   }

   @Override
   public void endVisit(CssMediaRule x, Context ctx) {
     popNodes(x);
   }

   @Override
   public void endVisit(CssNoFlip x, Context ctx) {
     popNodes(x);
   }

   @Override
   public void endVisit(CssStylesheet x, Context ctx) {
     popNodes(x);
   }

   @Override
   public boolean visit(CssDef x, Context ctx) {
     CssDef newDef = new CssDef(x.getKey());
     newDef.getValues().addAll(x.getValues());

     addToNodes(newDef);
     return true;
   }

   @Override
   public boolean visit(CssEval x, Context ctx) {
     assert x.getValues().size() == 1;
     assert x.getValues().get(0).isExpressionValue() != null;

     String value = x.getValues().get(0).isExpressionValue().getExpression();
     CssEval newEval = new CssEval(x.getKey(), value);
     addToNodes(newEval);
     return true;
   }

   @Override
   public boolean visit(CssExternalSelectors x, Context ctx) {
     CssExternalSelectors newExternals = new CssExternalSelectors();
     newExternals.getClasses().addAll(x.getClasses());
     addToNodes(newExternals);
     return true;
   }

   /**
    * A CssIf has two lists of nodes, so we want to handle traversal in this
    * visitor.
    */
   @Override
   public boolean visit(CssIf x, Context ctx) {
     CssIf newIf = new CssIf();

     if (x.getExpression() != null) {
       newIf.setExpression(x.getExpression());
     } else {
       newIf.setProperty(x.getPropertyName());

       String[] newValues = new String[x.getPropertyValues().length];
       System.arraycopy(x.getPropertyValues(), 0, newValues, 0, newValues.length);
       newIf.setPropertyValues(newValues);

       newIf.setNegated(x.isNegated());
     }

     // Handle the "then" part
     pushNodes(newIf);
     accept(x.getNodes());
     popNodes(x, newIf);

     /*
      * Push the "else" part as though it were its own node, but don't add it as
      * its own top-level node.
      */
     CollapsedNode oldElseNodes = new CollapsedNode(x.getElseNodes());
     CollapsedNode newElseNodes = new CollapsedNode(newIf.getElseNodes());
     pushNodes(newElseNodes, false);
     accept(oldElseNodes);
     popNodes(oldElseNodes, newElseNodes);

     return false;
   }

   @Override
   public boolean visit(CssMediaRule x, Context ctx) {
     CssMediaRule newRule = new CssMediaRule();
     newRule.getMedias().addAll(newRule.getMedias());

     pushNodes(newRule);
     return true;
   }

   @Override
   public boolean visit(CssNoFlip x, Context ctx) {
     pushNodes(new CssNoFlip());
     return true;
   }

   @Override
   public boolean visit(CssPageRule x, Context ctx) {
     CssPageRule newRule = new CssPageRule();
     newRule.setPseudoPage(x.getPseudoPage());
     addToNodes(newRule);
     return true;
   }

   @Override
   public boolean visit(CssProperty x, Context ctx) {
     CssProperty newProperty = new CssProperty(x.getName(), x.getValues(),
         x.isImportant());
     currentHasProperties.getProperties().add(newProperty);
     return true;
   }

   @Override
   public boolean visit(CssFontFace x, Context ctx) {
     CssFontFace newRule = new CssFontFace();
     addToNodes(newRule);
     return true;
   }

   @Override
   public boolean visit(CssRule x, Context ctx) {
     CssRule newRule = new CssRule();
     addToNodes(newRule);
     return true;
   }

   @Override
   public boolean visit(CssSelector x, Context ctx) {
     CssSelector newSelector = new CssSelector(x.getSelector());
     currentHasSelectors.getSelectors().add(newSelector);
     return true;
   }

   @Override
   public boolean visit(CssSprite x, Context ctx) {
     CssSprite newSprite = new CssSprite();
     newSprite.setResourceFunction(x.getResourceFunction());
     addToNodes(newSprite);
     return true;
   }

   @Override
   public boolean visit(CssStylesheet x, Context ctx) {
     CssStylesheet newSheet = new CssStylesheet();
     pushNodes(newSheet);
     return true;
   }

   @Override
   public boolean visit(CssUrl x, Context ctx) {
     assert x.getValues().size() == 1;
     assert x.getValues().get(0).isDotPathValue() != null;
     CssUrl newUrl = new CssUrl(x.getKey(),
         x.getValues().get(0).isDotPathValue());
     addToNodes(newUrl);
     return true;
   }

   @Override
   public boolean visit(CssUnknownAtRule x, Context ctx) {
     CssUnknownAtRule newRule = new CssUnknownAtRule(x.getRule());
     addToNodes(newRule);
     return true;
   }

   /**
    * Add a cloned node instance to the output.
    */
   private void addToNodes(CssNode node) {
     curentNodes.peek().add(node);

     currentHasProperties = node instanceof HasProperties ? (HasProperties) node
         : null;
     currentHasSelectors = node instanceof HasSelectors ? (HasSelectors) node
         : null;
   }

   /**
    * Remove a frame.
    *
    * @param original the node that was being cloned so that validity checks may
    *          be performed
    */
   private List<CssNode> popNodes(HasNodes original) {
     List<CssNode> toReturn = curentNodes.pop();

     if (toReturn.size() != original.getNodes().size()) {
       throw new RuntimeException("Insufficient number of nodes for a "
           + original.getClass().getName() + " Expected: "
           + original.getNodes().size() + " Found: " + toReturn.size());
     }

     return toReturn;
   }

   /**
    * Remove a frame.
    *
    * @param original the node that was being cloned so that validity checks may
    *          be performed
    * @param expected the HasNodes whose nodes were being populated by the frame
    *          being removed.
    */
   private List<CssNode> popNodes(HasNodes original, HasNodes expected) {
     List<CssNode> toReturn = popNodes(original);

     if (toReturn != expected.getNodes()) {
       throw new RuntimeException("Incorrect parent node list popped");
     }

     return toReturn;
   }

   /**
    * Push a new frame, adding the new parent as a child of the current parent.
    */
   private <T extends CssNode & HasNodes> void pushNodes(T parent) {
     pushNodes(parent, true);
   }

   /**
    * Push a new frame.
    *
    * @param addToNodes if <code>true</code> add the new parent node as a child
    *          of the current parent.
    */
   private <T extends CssNode & HasNodes> void pushNodes(T parent,
       boolean addToNodes) {
     if (addToNodes) {
       addToNodes(parent);
     }
     this.curentNodes.push(parent.getNodes());
   }
 }
	/*
	* Copyright 2009 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.resources.css.ast;

	import java.util.ArrayList;
	import java.util.Collections;
	import java.util.List;
	import java.util.Stack;

	/**
	* Clones CssNodes.
	*/
	public class CssNodeCloner extends CssVisitor {

	/**
	* Clone a list of nodes.
	*/
	public static <T extends CssNode> List<T> clone(Class<T> clazz, List<T> nodes) {

	// Push a fake context that will contain the cloned node
	List<CssNode> topContext = new ArrayList<CssNode>();
	final List<CssProperty> topProperties = new ArrayList<CssProperty>();
	final List<CssSelector> topSelectors = new ArrayList<CssSelector>();

	CssNodeCloner cloner = new CssNodeCloner();
	cloner.curentNodes.push(topContext);
	cloner.currentHasProperties = new HasProperties() {
	public List<CssProperty> getProperties() {
	return topProperties;
	}
	};
	cloner.currentHasSelectors = new HasSelectors() {
	public List<CssSelector> getSelectors() {
	return topSelectors;
	}
	};

	// Process the nodes
	cloner.accept(nodes);

	/*
	* Return the requested data. Different AST nodes will have been collected
	* in different parts of the initial context.
	*/
	List<?> toIterate;
	if (CssProperty.class.isAssignableFrom(clazz)) {
	toIterate = topProperties;
	} else if (CssSelector.class.isAssignableFrom(clazz)) {
	toIterate = topSelectors;
	} else {
	toIterate = topContext;
	}

	assert toIterate.size() == nodes.size() : "Wrong number of nodes in top "
	+ "context. Expecting: " + nodes.size() + " Found: " + toIterate.size();

	// Create the final return value
	List<T> toReturn = new ArrayList<T>(toIterate.size());
	for (Object node : toIterate) {
	assert clazz.isInstance(node) : "Return type mismatch. Expecting: "
	+ clazz.getName() + " Found: " + node.getClass().getName();

	// Cast to the correct type to avoid an unchecked generic cast
	toReturn.add(clazz.cast(node));
	}

	return toReturn;
	}

	/**
	* Clone a single node.
	*/
	public static <T extends CssNode> T clone(Class<T> clazz, T node) {
	return clone(clazz, Collections.singletonList(node)).get(0);
	}

	private HasProperties currentHasProperties;

	private HasSelectors currentHasSelectors;

	private final Stack<List<CssNode>> curentNodes = new Stack<List<CssNode>>();

	private CssNodeCloner() {
	}

	@Override
	public void endVisit(CssMediaRule x, Context ctx) {
	popNodes(x);
	}

	@Override
	public void endVisit(CssNoFlip x, Context ctx) {
	popNodes(x);
	}

	@Override
	public void endVisit(CssStylesheet x, Context ctx) {
	popNodes(x);
	}

	@Override
	public boolean visit(CssDef x, Context ctx) {
	CssDef newDef = new CssDef(x.getKey());
	newDef.getValues().addAll(x.getValues());

	addToNodes(newDef);
	return true;
	}

	@Override
	public boolean visit(CssEval x, Context ctx) {
	assert x.getValues().size() == 1;
	assert x.getValues().get(0).isExpressionValue() != null;

	String value = x.getValues().get(0).isExpressionValue().getExpression();
	CssEval newEval = new CssEval(x.getKey(), value);
	addToNodes(newEval);
	return true;
	}

	@Override
	public boolean visit(CssExternalSelectors x, Context ctx) {
	CssExternalSelectors newExternals = new CssExternalSelectors();
	newExternals.getClasses().addAll(x.getClasses());
	addToNodes(newExternals);
	return true;
	}

	/**
	* A CssIf has two lists of nodes, so we want to handle traversal in this
	* visitor.
	*/
	@Override
	public boolean visit(CssIf x, Context ctx) {
	CssIf newIf = new CssIf();

	if (x.getExpression() != null) {
	newIf.setExpression(x.getExpression());
	} else {
	newIf.setProperty(x.getPropertyName());

	String[] newValues = new String[x.getPropertyValues().length];
	System.arraycopy(x.getPropertyValues(), 0, newValues, 0, newValues.length);
	newIf.setPropertyValues(newValues);

	newIf.setNegated(x.isNegated());
	}

	// Handle the "then" part
	pushNodes(newIf);
	accept(x.getNodes());
	popNodes(x, newIf);

	/*
	* Push the "else" part as though it were its own node, but don't add it as
	* its own top-level node.
	*/
	CollapsedNode oldElseNodes = new CollapsedNode(x.getElseNodes());
	CollapsedNode newElseNodes = new CollapsedNode(newIf.getElseNodes());
	pushNodes(newElseNodes, false);
	accept(oldElseNodes);
	popNodes(oldElseNodes, newElseNodes);

	return false;
	}

	@Override
	public boolean visit(CssMediaRule x, Context ctx) {
	CssMediaRule newRule = new CssMediaRule();
	newRule.getMedias().addAll(newRule.getMedias());

	pushNodes(newRule);
	return true;
	}

	@Override
	public boolean visit(CssNoFlip x, Context ctx) {
	pushNodes(new CssNoFlip());
	return true;
	}

	@Override
	public boolean visit(CssPageRule x, Context ctx) {
	CssPageRule newRule = new CssPageRule();
	newRule.setPseudoPage(x.getPseudoPage());
	addToNodes(newRule);
	return true;
	}

	@Override
	public boolean visit(CssProperty x, Context ctx) {
	CssProperty newProperty = new CssProperty(x.getName(), x.getValues(),
	x.isImportant());
	currentHasProperties.getProperties().add(newProperty);
	return true;
	}

	@Override
	public boolean visit(CssFontFace x, Context ctx) {
	CssFontFace newRule = new CssFontFace();
	addToNodes(newRule);
	return true;
	}

	@Override
	public boolean visit(CssRule x, Context ctx) {
	CssRule newRule = new CssRule();
	addToNodes(newRule);
	return true;
	}

	@Override
	public boolean visit(CssSelector x, Context ctx) {
	CssSelector newSelector = new CssSelector(x.getSelector());
	currentHasSelectors.getSelectors().add(newSelector);
	return true;
	}

	@Override
	public boolean visit(CssSprite x, Context ctx) {
	CssSprite newSprite = new CssSprite();
	newSprite.setResourceFunction(x.getResourceFunction());
	addToNodes(newSprite);
	return true;
	}

	@Override
	public boolean visit(CssStylesheet x, Context ctx) {
	CssStylesheet newSheet = new CssStylesheet();
	pushNodes(newSheet);
	return true;
	}

	@Override
	public boolean visit(CssUrl x, Context ctx) {
	assert x.getValues().size() == 1;
	assert x.getValues().get(0).isDotPathValue() != null;
	CssUrl newUrl = new CssUrl(x.getKey(),
	x.getValues().get(0).isDotPathValue());
	addToNodes(newUrl);
	return true;
	}

	@Override
	public boolean visit(CssUnknownAtRule x, Context ctx) {
	CssUnknownAtRule newRule = new CssUnknownAtRule(x.getRule());
	addToNodes(newRule);
	return true;
	}

	/**
	* Add a cloned node instance to the output.
	*/
	private void addToNodes(CssNode node) {
	curentNodes.peek().add(node);

	currentHasProperties = node instanceof HasProperties ? (HasProperties) node
	: null;
	currentHasSelectors = node instanceof HasSelectors ? (HasSelectors) node
	: null;
	}

	/**
	* Remove a frame.
	*
	* @param original the node that was being cloned so that validity checks may
	* be performed
	*/
	private List<CssNode> popNodes(HasNodes original) {
	List<CssNode> toReturn = curentNodes.pop();

	if (toReturn.size() != original.getNodes().size()) {
	throw new RuntimeException("Insufficient number of nodes for a "
	+ original.getClass().getName() + " Expected: "
	+ original.getNodes().size() + " Found: " + toReturn.size());
	}

	return toReturn;
	}

	/**
	* Remove a frame.
	*
	* @param original the node that was being cloned so that validity checks may
	* be performed
	* @param expected the HasNodes whose nodes were being populated by the frame
	* being removed.
	*/
	private List<CssNode> popNodes(HasNodes original, HasNodes expected) {
	List<CssNode> toReturn = popNodes(original);

	if (toReturn != expected.getNodes()) {
	throw new RuntimeException("Incorrect parent node list popped");
	}

	return toReturn;
	}

	/**
	* Push a new frame, adding the new parent as a child of the current parent.
	*/
	private <T extends CssNode & HasNodes> void pushNodes(T parent) {
	pushNodes(parent, true);
	}

	/**
	* Push a new frame.
	*
	* @param addToNodes if <code>true</code> add the new parent node as a child
	* of the current parent.
	*/
	private <T extends CssNode & HasNodes> void pushNodes(T parent,
	boolean addToNodes) {
	if (addToNodes) {
	addToNodes(parent);
	}
	this.curentNodes.push(parent.getNodes());
	}
	}