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/*
* Copyright 2008 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.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import com.google.common.annotations.VisibleForTesting;
import com.google.javascript.jscomp.AnalyzePrototypeProperties.ClassMemberFunction;
import com.google.javascript.jscomp.AnalyzePrototypeProperties.NameInfo;
import com.google.javascript.jscomp.AnalyzePrototypeProperties.Property;
import com.google.javascript.jscomp.AnalyzePrototypeProperties.PrototypeProperty;
import com.google.javascript.jscomp.AnalyzePrototypeProperties.Symbol;
import com.google.javascript.rhino.Node;
import java.util.Collection;
import java.util.Iterator;
/** Move prototype methods into later chunks. */
public class CrossChunkMethodMotion implements CompilerPass {
// Internal errors
static final DiagnosticType NULL_COMMON_MODULE_ERROR = DiagnosticType.error(
"JSC_INTERNAL_ERROR_MODULE_DEPEND",
"null deepest common module");
private final AbstractCompiler compiler;
private final IdGenerator idGenerator;
private final AnalyzePrototypeProperties analyzer;
private final JSModuleGraph moduleGraph;
private final boolean noStubFunctions;
private final AstFactory astFactory;
static final String STUB_METHOD_NAME = "JSCompiler_stubMethod";
static final String UNSTUB_METHOD_NAME = "JSCompiler_unstubMethod";
@VisibleForTesting
public static final String STUB_DECLARATIONS =
"var JSCompiler_stubMap = [];"
+ "function JSCompiler_stubMethod(JSCompiler_stubMethod_id) {"
+ " return function() {"
+ " return JSCompiler_stubMap[JSCompiler_stubMethod_id].apply("
+ " this, arguments);"
+ " };"
+ "}"
+ "function JSCompiler_unstubMethod("
+ " JSCompiler_unstubMethod_id, JSCompiler_unstubMethod_body) {"
+ " return JSCompiler_stubMap[JSCompiler_unstubMethod_id] = "
+ " JSCompiler_unstubMethod_body;"
+ "}";
/**
* Creates a new pass for moving prototype properties.
*
* @param compiler The compiler.
* @param idGenerator An id generator for method stubs.
* @param canModifyExterns If true, then we can move prototype properties that are declared in the
* externs file.
* @param noStubFunctions if true, we can move methods without stub functions in the parent
* chunk.
*/
CrossChunkMethodMotion(
AbstractCompiler compiler,
IdGenerator idGenerator,
boolean canModifyExterns,
boolean noStubFunctions) {
this.compiler = compiler;
this.idGenerator = idGenerator;
this.moduleGraph = compiler.getModuleGraph();
this.analyzer =
new AnalyzePrototypeProperties(
compiler, moduleGraph, canModifyExterns, false /* anchorUnusedVars */, noStubFunctions);
this.noStubFunctions = noStubFunctions;
this.astFactory = compiler.createAstFactory();
}
@Override
public void process(Node externRoot, Node root) {
// If there are < 2 chunks, then we will never move anything,
// so we're done.
if (moduleGraph.getModuleCount() > 1) {
analyzer.process(externRoot, root);
moveMethods(analyzer.getAllNameInfo());
}
}
/**
* Move methods deeper in the chunk graph when possible.
*/
private void moveMethods(Collection allNameInfo) {
boolean hasStubDeclaration = idGenerator.hasGeneratedAnyIds();
for (NameInfo nameInfo : allNameInfo) {
if (!nameInfo.isReferenced()) {
// The code below can't do anything with unreferenced name
// infos. They should be skipped to avoid NPE since their
// deepestCommonModuleRef is null.
continue;
}
if (nameInfo.readsClosureVariables()) {
continue;
}
JSModule deepestCommonModuleRef = nameInfo.getDeepestCommonModuleRef();
if (deepestCommonModuleRef == null) {
compiler.report(JSError.make(NULL_COMMON_MODULE_ERROR));
continue;
}
Iterator declarations =
nameInfo.getDeclarations().descendingIterator();
while (declarations.hasNext()) {
Symbol symbol = declarations.next();
if (symbol instanceof PrototypeProperty) {
tryToMovePrototypeMethod(nameInfo, deepestCommonModuleRef, (PrototypeProperty) symbol);
} else if (symbol instanceof ClassMemberFunction) {
tryToMoveMemberFunction(nameInfo, deepestCommonModuleRef, (ClassMemberFunction) symbol);
} // else it's a variable definition, and we don't move those.
}
}
if (!noStubFunctions && !hasStubDeclaration && idGenerator
.hasGeneratedAnyIds()) {
// Declare stub functions in the top-most chunk.
Node declarations = compiler.parseSyntheticCode(STUB_DECLARATIONS);
NodeUtil.markNewScopesChanged(declarations, compiler);
Node firstScript = compiler.getNodeForCodeInsertion(null);
firstScript.addChildrenToFront(declarations.removeChildren());
compiler.reportChangeToEnclosingScope(firstScript);
}
}
private void tryToMovePrototypeMethod(
NameInfo nameInfo, JSModule deepestCommonModuleRef, PrototypeProperty prop) {
// We should only move a property across chunks if:
// 1) We can move it deeper in the chunk graph, and
// 2) it's a function, and
// 3) it is not a GETTER_DEF or a SETTER_DEF, and
// 4) it does not refer to `super`
// 5) the class is available in the global scope.
//
// #1 should be obvious. #2 is more subtle. It's possible
// to copy off of a prototype, as in the code:
// for (var k in Foo.prototype) {
// doSomethingWith(Foo.prototype[k]);
// }
// This is a common way to implement pseudo-multiple inheritance in JS.
//
// So if we move a prototype method into a deeper chunk, we must
// replace it with a stub function so that it preserves its original
// behavior.
if (prop.getRootVar() == null || !prop.getRootVar().isGlobal()) {
return;
}
if (nameInfo.referencesSuper()) {
// It is illegal to move `super` outside of a member function def.
return;
}
Node value = prop.getValue();
Node valueParent = value.getParent();
// Only attempt to move normal functions.
if (!value.isFunction()
// A GET or SET can't be deferred like a normal
// FUNCTION property definition as a mix-in would get the result
// of a GET instead of the function itself.
|| valueParent.isGetterDef()
|| valueParent.isSetterDef()) {
return;
}
if (moduleGraph.dependsOn(deepestCommonModuleRef, prop.getModule())) {
if (hasUnmovableRedeclaration(nameInfo, prop)) {
// If it has been redeclared on the same object, skip it.
return;
}
Node destParent = compiler.getNodeForCodeInsertion(deepestCommonModuleRef);
if (valueParent.isMemberFunctionDef()) {
movePrototypeObjectLiteralMethodShorthand(nameInfo.name, destParent, value);
} else if (valueParent.isStringKey()) {
movePrototypeObjectLiteralProperty(nameInfo.name, destParent, value);
} else {
// Note that computed properties should have been filtered out by
// AnalyzePrototypeProperties, because they don't have a recognizable property name.
// Getters and setters are filtered out by the code above
checkState(valueParent.isAssign(), valueParent);
movePrototypeDotMethodAssignment(destParent, value);
}
}
}
/**
* Move a property defined by object literal assigned to `.prototype`.
*
*
*/
private void movePrototypeDotMethodAssignment(Node destParent, Node functionNode) {
checkState(functionNode.isFunction(), functionNode);
Node assignNode = functionNode.getParent();
checkState(assignNode.isAssign() && functionNode.isSecondChildOf(assignNode), assignNode);
Node definitionStatement = assignNode.getParent();
checkState(definitionStatement.isExprResult(), assignNode);
if (noStubFunctions) {
// Remove the definition statement from its current location
Node assignStatementParent = definitionStatement.getParent();
definitionStatement.detach();
compiler.reportChangeToEnclosingScope(assignStatementParent);
// Prepend definition to new chunk
// Foo.prototype.propName = function() {};
destParent.addChildToFront(definitionStatement);
compiler.reportChangeToEnclosingScope(destParent);
} else {
int stubId = idGenerator.newId();
// replace function definition with temporary placeholder so we can clone the whole
// assignment statement without cloning the function definition itself.
Node originalDefinitionPlaceholder = astFactory.createEmpty();
functionNode.replaceWith(originalDefinitionPlaceholder);
Node newDefinitionStatement = definitionStatement.cloneTree();
Node newDefinitionPlaceholder =
newDefinitionStatement // EXPR_RESULT
.getOnlyChild() // ASSIGN
.getLastChild(); // EMPTY RHS node
// convert original assignment statement to
// owner.prototype.propName = JSCompiler_stubMethod(0);
Node stubCall = createStubCall(functionNode, stubId);
originalDefinitionPlaceholder.replaceWith(stubCall);
compiler.reportChangeToEnclosingScope(definitionStatement);
// Prepend new definition to new chunk
// Foo.prototype.propName = JSCompiler_unstubMethod(0, function() {});
Node unstubCall = createUnstubCall(functionNode, stubId);
newDefinitionPlaceholder.replaceWith(unstubCall);
destParent.addChildToFront(newDefinitionStatement);
compiler.reportChangeToEnclosingScope(destParent);
}
}
/**
* Move a property defined by assignment to `.prototype` or `.prototype.propName`.
*
*
* Foo.prototype = { propName() {}};
*
*/
private void movePrototypeObjectLiteralMethodShorthand(
String propName, Node destParent, Node functionNode) {
checkState(functionNode.isFunction(), functionNode);
Node memberFunctionDef = functionNode.getParent();
checkState(memberFunctionDef.isMemberFunctionDef(), memberFunctionDef);
Node prototypeObjectLiteral = memberFunctionDef.getParent();
checkState(prototypeObjectLiteral.isObjectLit(), prototypeObjectLiteral);
Node assignNode = prototypeObjectLiteral.getParent();
checkState(
assignNode.isAssign() && prototypeObjectLiteral.isSecondChildOf(assignNode), assignNode);
Node ownerDotPrototypeNode = assignNode.getFirstChild();
checkState(
ownerDotPrototypeNode.isQualifiedName()
&& ownerDotPrototypeNode.getLastChild().getString().equals("prototype"),
ownerDotPrototypeNode);
if (noStubFunctions) {
// Remove the definition from the object literal
memberFunctionDef.detach();
compiler.reportChangeToEnclosingScope(prototypeObjectLiteral);
// Prepend definition to new chunk
// Foo.prototype.propName = function() {};
Node ownerDotPrototypeDotPropName =
astFactory.createGetProp(ownerDotPrototypeNode.cloneTree(), propName);
Node definitionStatement =
astFactory
.createAssignStatement(ownerDotPrototypeDotPropName, functionNode.detach())
.useSourceInfoIfMissingFromForTree(memberFunctionDef);
destParent.addChildToFront(definitionStatement);
compiler.reportChangeToEnclosingScope(destParent);
} else {
int stubId = idGenerator.newId();
// { propName() {} } => { propName: JSCompiler_stubMethod(0) }
Node stubCall = createStubCall(functionNode, stubId);
memberFunctionDef.replaceWith(astFactory.createStringKey(propName, stubCall));
compiler.reportChangeToEnclosingScope(prototypeObjectLiteral);
// Prepend definition to new chunk
// Foo.prototype.propName = function() {};
Node ownerDotPrototypeDotPropName =
astFactory.createGetProp(ownerDotPrototypeNode.cloneTree(), propName);
Node unstubCall = createUnstubCall(functionNode.detach(), stubId);
Node definitionStatement =
astFactory
.createAssignStatement(ownerDotPrototypeDotPropName, unstubCall)
.useSourceInfoIfMissingFromForTree(memberFunctionDef);
destParent.addChildToFront(definitionStatement);
compiler.reportChangeToEnclosingScope(destParent);
}
}
/**
* Returns a new Node to be used as the stub definition for a method.
*
* @param originalDefinition function Node whose definition is being stubbed
* @param stubId ID to use for stubbing and unstubbing
* @return a Node that looks like JSCompiler_stubMethod(0)
*/
private Node createStubCall(Node originalDefinition, int stubId) {
return astFactory
.createCall(
// We can't look up the type of the stub creating method, because we add its
// definition after type checking.
astFactory.createNameWithUnknownType(STUB_METHOD_NAME), astFactory.createNumber(stubId))
.useSourceInfoIfMissingFromForTree(originalDefinition);
}
/**
* Returns a new Node to be used as the stub definition for a method.
*
* @param functionNode actual function definition to be attached. Must be detached now.
* @param stubId ID to use for stubbing and unstubbing
* @return a Node that looks like JSCompiler_unstubMethod(0, function() {})
*/
private Node createUnstubCall(Node functionNode, int stubId) {
return astFactory
.createCall(
// We can't look up the type of the stub creating method, because we add its
// definition after type checking.
astFactory.createNameWithUnknownType(UNSTUB_METHOD_NAME),
astFactory.createNumber(stubId),
functionNode)
.useSourceInfoIfMissingFromForTree(functionNode);
}
/**
* If possible, move a class instance member function definition to the deepest chunk common to
* all uses of the method.
*
* @param nameInfo information about all definitions of the given property name
* @param deepestCommonModuleRef all uses of the method are either in this chunk or in chunks that
* depend on it
* @param classMemberFunction definition of the method within its class body
*/
private void tryToMoveMemberFunction(
NameInfo nameInfo, JSModule deepestCommonModuleRef, ClassMemberFunction classMemberFunction) {
// We should only move a property across chunks if:
// 1) We can move it deeper in the chunk graph,
// 2) and it's a normal member function, and not a GETTER_DEF or a SETTER_DEF, or
// or the class constructor.
// 3) and it does not refer to `super`, which would be invalid outside of the class.
// 4) and the class is available in the global scope.
Var rootVar = classMemberFunction.getRootVar();
if (rootVar == null || !rootVar.isGlobal()) {
return;
}
Node definitionNode = classMemberFunction.getDefinitionNode();
// Only attempt to move normal member functions.
// A getter or setter cannot be as easily defined outside of the class to which it belongs.
if (!definitionNode.isMemberFunctionDef()) {
return;
}
if (NodeUtil.isEs6ConstructorMemberFunctionDef(definitionNode)) {
// Constructor functions cannot be moved.
return;
}
if (nameInfo.referencesSuper()) {
// Do not move methods containing `super`, because it doesn't work outside of a
// class method or object literal method.
return;
}
if (moduleGraph.dependsOn(deepestCommonModuleRef, classMemberFunction.getModule())) {
if (hasUnmovableRedeclaration(nameInfo, classMemberFunction)) {
// If it has been redeclared on the same object, skip it.
return;
}
Node destinationParent = compiler.getNodeForCodeInsertion(deepestCommonModuleRef);
String className = rootVar.getName();
if (noStubFunctions) {
moveClassInstanceMethodWithoutStub(className, definitionNode, destinationParent);
} else {
moveClassInstanceMethodWithStub(className, definitionNode, destinationParent);
}
}
}
private void moveClassInstanceMethodWithoutStub(
String className, Node methodDefinition, Node destinationParent) {
checkArgument(methodDefinition.isMemberFunctionDef(), methodDefinition);
Node classMembers = checkNotNull(methodDefinition.getParent());
checkState(classMembers.isClassMembers(), classMembers);
Node classNode = classMembers.getParent();
checkState(classNode.isClass(), classNode);
methodDefinition.detach();
compiler.reportChangeToEnclosingScope(classMembers);
// ClassName.prototype.propertyName = function() {};
Node classNameDotPrototypeDotPropName =
astFactory.createGetProps(
astFactory.createName(className, classNode.getJSType()),
"prototype",
methodDefinition.getString());
Node functionNode = checkNotNull(methodDefinition.getOnlyChild());
functionNode.detach();
Node definitionStatementNode =
astFactory
.createAssignStatement(classNameDotPrototypeDotPropName, functionNode)
.useSourceInfoIfMissingFromForTree(methodDefinition);
destinationParent.addChildToFront(definitionStatementNode);
compiler.reportChangeToEnclosingScope(destinationParent);
}
private void moveClassInstanceMethodWithStub(
String className, Node methodDefinition, Node destinationParent) {
checkArgument(methodDefinition.isMemberFunctionDef(), methodDefinition);
Node classMembers = checkNotNull(methodDefinition.getParent());
checkState(classMembers.isClassMembers(), classMembers);
Node classNode = classMembers.getParent();
checkState(classNode.isClass(), classNode);
int stubId = idGenerator.newId();
// Put a stub definition after the class
// ClassName.prototype.propertyName = JSCompiler_stubMethod(id);
Node classNameDotPrototypeDotPropName =
astFactory.createGetProps(
astFactory.createName(className, classNode.getJSType()),
"prototype",
methodDefinition.getString());
Node stubCall = createStubCall(methodDefinition, stubId);
Node stubDefinitionStatement =
astFactory
.createAssignStatement(classNameDotPrototypeDotPropName, stubCall)
.useSourceInfoIfMissingFromForTree(methodDefinition);
Node classDefiningStatement = NodeUtil.getEnclosingStatement(classMembers);
classDefiningStatement
.getParent()
.addChildAfter(stubDefinitionStatement, classDefiningStatement);
// remove the definition from the class
methodDefinition.detach();
compiler.reportChangeToEnclosingScope(classMembers);
// Prepend unstub definition to the new location.
// ClassName.prototype.propertyName = JSCompiler_unstubMethod(id, function(...) {...});
Node classNameDotPrototypeDotPropName2 = classNameDotPrototypeDotPropName.cloneTree();
Node functionNode = checkNotNull(methodDefinition.getOnlyChild());
functionNode.detach();
Node unstubCall = createUnstubCall(functionNode, stubId);
Node statementNode =
astFactory
.createAssignStatement(classNameDotPrototypeDotPropName2, unstubCall)
.useSourceInfoIfMissingFromForTree(methodDefinition);
destinationParent.addChildToFront(statementNode);
compiler.reportChangeToEnclosingScope(destinationParent);
}
static boolean hasUnmovableRedeclaration(NameInfo nameInfo, Property prop) {
for (Symbol symbol : nameInfo.getDeclarations()) {
if (symbol instanceof Property) {
Property otherProp = (Property) symbol;
// It is possible to do better here if the dependencies are well defined
// but redefinitions are usually in optional chunks so it isn't likely
// worth the effort to check.
if (prop != otherProp
&& prop.getRootVar() == otherProp.getRootVar()
&& prop.getModule() != otherProp.getModule()) {
return true;
}
}
}
return false;
}
}
