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Liferay Frontend JS Minifier
/*
* Copyright 2011 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 com.google.common.annotations.VisibleForTesting;
import com.google.javascript.jscomp.NodeTraversal.AbstractPostOrderCallback;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
import java.util.Collections;
import java.util.Iterator;
/**
* Rewrites an AMD module https://github.com/amdjs/amdjs-api/wiki/AMD to a
* CommonJS module. See {@link ProcessCommonJSModules} for follow up processing
* step.
*/
public final class TransformAMDToCJSModule implements CompilerPass {
@VisibleForTesting
static final DiagnosticType UNSUPPORTED_DEFINE_SIGNATURE_ERROR =
DiagnosticType.error(
"UNSUPPORTED_DEFINE_SIGNATURE",
"Only define(function() ...), define(OBJECT_LITERAL) and define("
+ "['dep', 'dep1'], function(d0, d2, [exports, module]) ...) forms "
+ "are currently supported.");
static final DiagnosticType NON_TOP_LEVEL_STATEMENT_DEFINE_ERROR =
DiagnosticType.error(
"NON_TOP_LEVEL_STATEMENT_DEFINE",
"The define function must be called as a top-level statement.");
static final DiagnosticType REQUIREJS_PLUGINS_NOT_SUPPORTED_WARNING =
DiagnosticType.warning(
"REQUIREJS_PLUGINS_NOT_SUPPORTED",
"Plugins in define requirements are not supported: {0}");
static final String VAR_RENAME_SUFFIX = "__alias";
private final AbstractCompiler compiler;
private int renameIndex = 0;
public TransformAMDToCJSModule(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void process(Node externs, Node root) {
NodeTraversal.traverseEs6(compiler, root, new TransformAMDModulesCallback());
}
private static void unsupportedDefineError(NodeTraversal t, Node n) {
t.report(n, UNSUPPORTED_DEFINE_SIGNATURE_ERROR);
}
/**
* The modules "exports", "require" and "module" are virtual in terms of
* existing implicitly in CommonJS.
*/
private static boolean isVirtualModuleName(String moduleName) {
return "exports".equals(moduleName) || "require".equals(moduleName) ||
"module".equals(moduleName);
}
/**
* Rewrites calls to define which has to be in void context just below the
* current script node.
*/
private class TransformAMDModulesCallback extends AbstractPostOrderCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isCall() && n.getFirstChild() != null &&
n.getFirstChild().isName() &&
"define".equals(n.getFirstChild().getString())) {
Var define = t.getScope().getVar(n.getFirstChild().
getString());
if (define != null && !define.isGlobal()) {
// Ignore non-global define.
return;
}
if (!(parent.isExprResult() && parent.getParent().isScript())) {
t.report(n, NON_TOP_LEVEL_STATEMENT_DEFINE_ERROR);
return;
}
Node script = parent.getParent();
Node requiresNode = null;
Node callback = null;
int defineArity = n.getChildCount() - 1;
if (defineArity == 0) {
unsupportedDefineError(t, n);
return;
} else if (defineArity == 1) {
callback = n.getSecondChild();
if (callback.isObjectLit()) {
handleDefineObjectLiteral(t, parent, callback, script);
return;
}
} else if (defineArity == 2) {
requiresNode = n.getSecondChild();
callback = n.getChildAtIndex(2);
} else if (defineArity >= 3) {
unsupportedDefineError(t, n);
return;
}
if (!callback.isFunction() ||
(requiresNode != null && !requiresNode.isArrayLit())) {
unsupportedDefineError(t, n);
return;
}
handleRequiresAndParamList(t, n, script, requiresNode, callback);
Node callbackBlock = callback.getChildAtIndex(2);
NodeTraversal.traverseEs6(compiler, callbackBlock,
new DefineCallbackReturnCallback());
moveCallbackContentToTopLevel(parent, script, callbackBlock);
t.reportCodeChange();
}
}
/**
* When define is called with an object literal, assign it to module.exports and
* we're done.
*/
private void handleDefineObjectLiteral(NodeTraversal t, Node parent, Node onlyExport,
Node script) {
onlyExport.detach();
script.replaceChild(parent,
IR.exprResult(
IR.assign(
NodeUtil.newQName(compiler, "module.exports"),
onlyExport))
.useSourceInfoIfMissingFromForTree(onlyExport));
t.reportCodeChange();
}
/**
* Rewrites the required modules to
* var nameInParamList = require("nameFromRequireList");
*/
private void handleRequiresAndParamList(NodeTraversal t, Node defineNode,
Node script, Node requiresNode, Node callback) {
Iterator paramList = callback.getSecondChild().children().
iterator();
Iterator requires = requiresNode != null ?
requiresNode.children().iterator() : Collections.emptyIterator();
while (paramList.hasNext() || requires.hasNext()) {
Node aliasNode = paramList.hasNext() ? paramList.next() : null;
Node modNode = requires.hasNext() ? requires.next() : null;
handleRequire(t, defineNode, script, callback, aliasNode, modNode);
}
}
/**
* Rewrite a single require call.
*/
private void handleRequire(NodeTraversal t, Node defineNode, Node script,
Node callback, Node aliasNode, Node modNode) {
String moduleName = null;
if (modNode != null) {
moduleName = handlePlugins(t, script, modNode.getString(), modNode);
}
if (isVirtualModuleName(moduleName)) {
return;
}
String aliasName = aliasNode != null ? aliasNode.getString() : null;
Scope globalScope = t.getScope();
if (aliasName != null &&
globalScope.isDeclared(aliasName, true)) {
while (true) {
String renamed = aliasName + VAR_RENAME_SUFFIX + renameIndex;
if (!globalScope.isDeclared(renamed, true)) {
NodeTraversal.traverseEs6(compiler, callback,
new RenameCallback(aliasName, renamed));
aliasName = renamed;
break;
}
renameIndex++;
}
}
Node requireNode;
if (moduleName != null) {
Node call = IR.call(IR.name("require"), IR.string(moduleName));
call.putBooleanProp(Node.FREE_CALL, true);
if (aliasName != null) {
requireNode = IR.var(IR.name(aliasName), call)
.useSourceInfoIfMissingFromForTree(aliasNode);
} else {
requireNode = IR.exprResult(call).
useSourceInfoIfMissingFromForTree(modNode);
}
} else {
// ignore exports, require and module (because they are implicit
// in CommonJS);
if (isVirtualModuleName(aliasName)) {
return;
}
requireNode = IR.var(IR.name(aliasName), IR.nullNode())
.useSourceInfoIfMissingFromForTree(aliasNode);
}
script.addChildBefore(requireNode,
defineNode.getParent());
}
/**
* Require.js supports a range of plugins that are hard to support
* statically. Generally none are supported right now with the
* exception of a simple hack to support condition loading. This
* was added to make compilation of Dojo work better but will
* probably break, so just don't use them :)
*/
private String handlePlugins(NodeTraversal t, Node script,
String moduleName, Node modNode) {
if (moduleName.contains("!")) {
t.report(modNode, REQUIREJS_PLUGINS_NOT_SUPPORTED_WARNING, moduleName);
int condition = moduleName.indexOf('?');
if (condition > 0) {
if (moduleName.contains(":")) {
return null;
}
return handlePlugins(t, script, moduleName.substring(condition + 1),
modNode);
}
moduleName = null;
}
return moduleName;
}
/**
* Moves the statements in the callback to be direct children of the
* current script.
*/
private void moveCallbackContentToTopLevel(Node defineParent, Node script,
Node callbackBlock) {
int curIndex = script.getIndexOfChild(defineParent);
script.removeChild(defineParent);
NodeUtil.markFunctionsDeleted(defineParent, compiler);
callbackBlock.detach();
Node before = script.getChildAtIndex(curIndex);
if (before != null) {
script.addChildBefore(callbackBlock, before);
}
script.addChildToBack(callbackBlock);
NodeUtil.tryMergeBlock(callbackBlock, false);
}
}
/**
* Rewrites the return statement of the callback to be an assignment to
* module.exports.
*/
private static class DefineCallbackReturnCallback extends
NodeTraversal.AbstractShallowStatementCallback {
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isReturn() && n.hasChildren()) {
Node retVal = n.getFirstChild();
n.removeChild(retVal);
parent.replaceChild(n, IR.exprResult(
IR.assign(
IR.getprop(IR.name("module"), IR.string("exports")), retVal))
.useSourceInfoFromForTree(n));
}
}
}
/**
* Renames names;
*/
private static class RenameCallback extends AbstractPostOrderCallback {
private final String from;
private final String to;
public RenameCallback(String from, String to) {
this.from = from;
this.to = to;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isName() && from.equals(n.getString())) {
n.setString(to);
n.setOriginalName(from);
}
}
}
}