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Closure Compiler is a JavaScript optimizing compiler. It parses your
JavaScript, analyzes it, removes dead code and rewrites and minimizes
what's left. It also checks syntax, variable references, and types, and
warns about common JavaScript pitfalls. It is used in many of Google's
JavaScript apps, including Gmail, Google Web Search, Google Maps, and
Google Docs.
/*
* Copyright 2009 The Closure Compiler Authors.
*
* 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.javascript.jscomp;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.GwtIncompatible;
import com.google.javascript.jscomp.CoverageInstrumentationPass.CoverageReach;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import java.util.Map;
/**
* This class implements a traversal to instrument an AST for code coverage.
*/
@GwtIncompatible("FileInstrumentationData")
class CoverageInstrumentationCallback extends
NodeTraversal.AbstractPostOrderCallback {
private final Map instrumentationData;
private final CoverageReach reach;
static final String ARRAY_NAME_PREFIX = "JSCompiler_lcov_data_";
public CoverageInstrumentationCallback(
Map instrumentationData,
CoverageReach reach) {
this.instrumentationData = instrumentationData;
this.reach = reach;
}
/**
* Returns the name of the source file from which the given node originates.
* @param traversal the traversal
* @return the name of the file it originates from
*/
private static String getFileName(NodeTraversal traversal) {
return traversal.getSourceName();
}
/**
* Returns a string that can be used as array name. The name is based on the
* source filename of the AST node.
*/
private String createArrayName(NodeTraversal traversal) {
return ARRAY_NAME_PREFIX
+ CoverageUtil.createIdentifierFromText(getFileName(traversal));
}
/**
* Creates and return a new instrumentation node. The instrumentation Node is
* of the form: "arrayName[lineNumber] = true;"
* Note 1: Node returns a 1-based line number.
* Note 2: Line numbers in instrumentation are made 0-based. This is done to
* map to their bit representation in BitField. Thus, there's a one-to-one
* correspondence of the line number seen on instrumented files and their bit
* encodings.
*
* @return an instrumentation node corresponding to the line number
*/
private Node newInstrumentationNode(NodeTraversal traversal, Node node) {
int lineNumber = node.getLineno();
String arrayName = createArrayName(traversal);
// Create instrumentation Node
Node getElemNode = IR.getelem(
IR.name(arrayName),
IR.number(lineNumber - 1)); // Make line number 0-based
Node exprNode = IR.exprResult(IR.assign(getElemNode, IR.trueNode()));
// Note line as instrumented
String fileName = getFileName(traversal);
if (!instrumentationData.containsKey(fileName)) {
instrumentationData.put(fileName,
new FileInstrumentationData(fileName, arrayName));
}
instrumentationData.get(fileName).setLineAsInstrumented(lineNumber);
return exprNode.useSourceInfoIfMissingFromForTree(node);
}
/**
* Create and return a new array declaration node. The array name is
* generated based on the source filename, and declaration is of the form:
* "var arrayNameUsedInFile = [];"
*/
private Node newArrayDeclarationNode(NodeTraversal traversal) {
return IR.var(
IR.name(createArrayName(traversal)),
IR.arraylit());
}
/**
* @return a Node containing file specific setup logic.
*/
private Node newHeaderNode(NodeTraversal traversal, Node srcref) {
String fileName = getFileName(traversal);
String arrayName = createArrayName(traversal);
FileInstrumentationData data = instrumentationData.get(fileName);
checkNotNull(data);
String objName = CoverageInstrumentationPass.JS_INSTRUMENTATION_OBJECT_NAME;
// var JSCompiler_lcov_data_xx = [];
// __jscov['executedLines'].push(JSCompiler_lcov_data_xx);
// __jscov['instrumentedLines'].push(hex-data);
// __jscov['fileNames'].push(filename);
return IR.block(
newArrayDeclarationNode(traversal),
IR.exprResult(
IR.call(
IR.getprop(IR.getelem(IR.name(objName), IR.string("executedLines")), "push"),
IR.name(arrayName))),
IR.exprResult(
IR.call(
IR.getprop(
IR.getelem(IR.name(objName), IR.string("instrumentedLines")), "push"),
IR.string(data.getInstrumentedLinesAsHexString()))),
IR.exprResult(
IR.call(
IR.getprop(IR.getelem(IR.name(objName), IR.string("fileNames")), "push"),
IR.string(fileName))))
.useSourceInfoIfMissingFromForTree(srcref);
}
/**
* Instruments the JS code by inserting appropriate nodes into the AST. The
* instrumentation logic is tuned to collect "line coverage" data only.
*/
@Override
public void visit(NodeTraversal traversal, Node node, Node parent) {
// SCRIPT node is special - it is the root of the AST for code from a file.
// Append code to declare and initialize structures used in instrumentation.
if (node.isScript()) {
String fileName = getFileName(traversal);
if (instrumentationData.get(fileName) != null) {
if (node.hasChildren() && node.getFirstChild().isModuleBody()) {
node = node.getFirstChild();
}
node.addChildrenToFront(newHeaderNode(traversal, node).removeChildren());
}
traversal.reportCodeChange();
return;
}
// Don't instrument global statements
if (reach == CoverageReach.CONDITIONAL
&& parent != null && parent.isScript()) {
return;
}
// For arrow functions whose body is an expression instead of a block,
// convert it to a block so that it can be instrumented.
if (node.isFunction() && !NodeUtil.getFunctionBody(node).isBlock()) {
Node returnValue = NodeUtil.getFunctionBody(node);
Node body = IR.block(IR.returnNode(returnValue.detach()));
body.useSourceInfoIfMissingFromForTree(returnValue);
node.addChildToBack(body);
}
// Add instrumentation code just before a function block.
// Similarly before other constructs: 'with', 'case', 'default', 'catch'
if (node.isFunction()
|| node.isWith()
|| node.isCase()
|| node.isDefaultCase()
|| node.isCatch()) {
Node codeBlock = node.getLastChild();
codeBlock.addChildToFront(
newInstrumentationNode(traversal, node));
traversal.reportCodeChange();
return;
}
// Add instrumentation code as the first child of a 'try' block.
if (node.isTry()) {
Node firstChild = node.getFirstChild();
firstChild.addChildToFront(
newInstrumentationNode(traversal, node));
traversal.reportCodeChange();
return;
}
// For any other statement, add instrumentation code just before it.
if (parent != null && NodeUtil.isStatementBlock(parent) && !node.isModuleBody()) {
parent.addChildBefore(
newInstrumentationNode(traversal, node),
node);
traversal.reportCodeChange();
return;
}
}
}