/*
* 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.common.css.compiler.passes;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Lists;
import com.google.common.css.compiler.ast.CssCompilerPass;
import com.google.common.css.compiler.ast.CssCompositeValueNode;
import com.google.common.css.compiler.ast.CssConstantReferenceNode;
import com.google.common.css.compiler.ast.CssDefinitionNode;
import com.google.common.css.compiler.ast.CssLiteralNode;
import com.google.common.css.compiler.ast.CssTree;
import com.google.common.css.compiler.ast.CssValueNode;
import com.google.common.css.compiler.ast.DefaultTreeVisitor;
import com.google.common.css.compiler.ast.ErrorManager;
import com.google.common.css.compiler.ast.GssError;
import com.google.common.css.compiler.ast.MutatingVisitController;
import com.google.common.css.compiler.ast.Proxiable;
import java.util.List;
import javax.annotation.Nullable;
/**
* Compiler pass that replaces the constant references with the right values.
*
* @author oana@google.com (Oana Florescu)
*/
public class ReplaceConstantReferences extends DefaultTreeVisitor
implements CssCompilerPass {
private final MutatingVisitController visitController;
private final ConstantDefinitions constantDefinitions;
private final boolean removeDefs;
private final ErrorManager errorManager;
private final boolean allowUndefinedConstants;
/**
* This constructor is only used by other projects.
* It should not be used in new code.
*/
public ReplaceConstantReferences(CssTree tree,
@Nullable ConstantDefinitions constantDefinitions) {
this(tree, constantDefinitions, true /* removeDefs */,
null /* errorManager*/, true /* allowUndefinedConstants */);
}
/**
* This constructor is only used by other projects.
* It should not be used in new code.
*/
public ReplaceConstantReferences(CssTree tree,
@Nullable ConstantDefinitions constantDefinitions, boolean removeDefs) {
this(tree, constantDefinitions, removeDefs, null /* errorManager*/,
true /* allowUndefinedConstants */);
}
public ReplaceConstantReferences(CssTree tree,
@Nullable ConstantDefinitions constantDefinitions, boolean removeDefs,
ErrorManager errorManager, boolean allowUndefinedConstants) {
Preconditions.checkArgument(allowUndefinedConstants
|| errorManager != null);
this.visitController = tree.getMutatingVisitController();
this.constantDefinitions = constantDefinitions;
this.removeDefs = removeDefs;
this.errorManager = errorManager;
this.allowUndefinedConstants = allowUndefinedConstants;
}
@Override
public boolean enterDefinition(CssDefinitionNode node) {
if (removeDefs) {
visitController.removeCurrentNode();
}
return !removeDefs;
}
@Override
public boolean enterValueNode(CssValueNode node) {
if (node instanceof CssConstantReferenceNode) {
replaceConstantReference((CssConstantReferenceNode) node);
}
return true;
}
@Override
public boolean enterArgumentNode(CssValueNode node) {
return enterValueNode(node);
}
@VisibleForTesting
void replaceConstantReference(CssConstantReferenceNode node) {
if (constantDefinitions == null) {
return;
}
CssDefinitionNode constantNode =
constantDefinitions.getConstantDefinition(node.getValue());
if (constantNode == null) {
if (!allowUndefinedConstants) {
errorManager.report(new GssError("GSS constant not defined: "
+ node.getValue(), node.getSourceCodeLocation()));
}
return;
}
List<CssValueNode> params = constantNode.getParameters();
List<CssValueNode> temp = Lists.newArrayListWithCapacity(params.size());
boolean inFunArgs = node.inFunArgs();
boolean intermediate = false;
for (CssValueNode n : params) {
if (inFunArgs && intermediate) {
// Usually, the parser consumes whitespace and lets tree
// structure suffice to distinguish elements of the AST. But
// functions are different: the parser adds CssLiteralNode(" ")
// between function args. Here we are looking at a sequence
// of values parsed from a @def (where we do not represent
// whitespace explicitly) and a use/reference that occurs in a
// function (where we do represent whitespace explicitly). So,
// we need to reconstitute the whitespace nodes.
// TODO(user): change the parser to eliminate special cases
// for function args
temp.add(new CssLiteralNode(" ", n.getSourceCodeLocation()));
}
if (n instanceof Proxiable) {
@SuppressWarnings("unchecked")
Proxiable<CssValueNode> proxiable = (Proxiable<CssValueNode>) n;
temp.add(proxiable.createProxy());
} else {
temp.add(n.deepCopy());
}
intermediate = true;
}
// The composite value is used so that we can store nodes with different
// separators in one another. visitController.replaceCurrentBlockChildWith
// will unwrap the value if it can in the current context.
CssCompositeValueNode tempNode = new CssCompositeValueNode(
temp, CssCompositeValueNode.Operator.SPACE,
node.getSourceCodeLocation());
visitController.replaceCurrentBlockChildWith(
Lists.newArrayList(tempNode), true);
}
@Override
public void runPass() {
// Replace the original custom function node with a proxy to stop
// propagation of changes of the original node to nodes that proxy it.
if (constantDefinitions != null) {
for (String constantName : constantDefinitions.getConstantsNames()) {
CssDefinitionNode node =
constantDefinitions.getConstantDefinition(constantName);
List<CssValueNode> params = node.getParameters();
for (int i = 0; i < params.size(); i++) {
CssValueNode n = params.get(i);
if (n instanceof Proxiable) {
@SuppressWarnings("unchecked")
Proxiable<CssValueNode> proxiable = (Proxiable<CssValueNode>) n;
node.replaceChildAt(i, ImmutableList.of(proxiable.createProxy()));
}
}
}
}
visitController.startVisit(this);
}
}