com.google.javascript.jscomp.Es6ConvertSuper Maven / Gradle / Ivy
/*
* Copyright 2014 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.checkState;
import static com.google.javascript.jscomp.Es6ToEs3Util.CANNOT_CONVERT_YET;
import com.google.common.base.Joiner;
import com.google.common.base.Predicate;
import com.google.javascript.jscomp.parsing.parser.FeatureSet;
import com.google.javascript.jscomp.parsing.parser.FeatureSet.Feature;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.jstype.JSType;
/**
* Converts {@code super.method()} calls and adds constructors to any classes that lack them.
*
* This has to run before the main {@link Es6RewriteClass} pass. The super() constructor calls
* are not converted here, but rather in {@link Es6ConvertSuperConstructorCalls}, which runs later.
*/
public final class Es6ConvertSuper extends NodeTraversal.AbstractPostOrderCallback
implements HotSwapCompilerPass {
private final AbstractCompiler compiler;
private final AstFactory astFactory;
private static final FeatureSet transpiledFeatures = FeatureSet.BARE_MINIMUM.with(Feature.SUPER);
public Es6ConvertSuper(AbstractCompiler compiler) {
this.compiler = compiler;
this.astFactory = compiler.createAstFactory();
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (n.isClass()) {
if (NodeUtil.getEs6ClassConstructorMemberFunctionDef(n) == null) {
addSyntheticConstructor(t, n);
}
} else if (n.isSuper()) {
visitSuper(n, parent);
}
}
private void addSyntheticConstructor(NodeTraversal t, Node classNode) {
Node superClass = classNode.getSecondChild();
Node classMembers = classNode.getLastChild();
Node memberDef;
if (superClass.isEmpty()) {
// use the pre-cast type because createEmptyFunction expects a FunctionType
Node function = astFactory.createEmptyFunction(getTypeBeforeCast(classNode));
compiler.reportChangeToChangeScope(function);
memberDef = astFactory.createMemberFunctionDef("constructor", function);
} else {
if (!superClass.isQualifiedName()) {
// This will be reported as an error in Es6ToEs3Converter.
return;
}
Node body = IR.block();
// If a class is defined in an externs file or as an interface, it's only a stub, not an
// implementation that should be instantiated.
// A call to super() shouldn't actually exist for these cases and is problematic to
// transpile, so don't generate it.
if (!classNode.isFromExterns() && !isInterface(classNode)) {
// Generate required call to super()
// `super(...arguments);`
// Note that transpilation of spread args must occur after this pass for this to work.
Node exprResult =
IR.exprResult(
astFactory.createConstructorCall(
classNode.getJSType(), // returned type is the subclass
IR.superNode().setJSType(superClass.getJSType()),
IR.iterSpread(astFactory.createArgumentsReference())));
body.addChildToFront(exprResult);
NodeUtil.addFeatureToScript(t.getCurrentScript(), Feature.SUPER, compiler);
NodeUtil.addFeatureToScript(t.getCurrentScript(), Feature.SPREAD_EXPRESSIONS, compiler);
}
Node constructor = astFactory.createFunction("", IR.paramList(), body, classNode.getJSType());
memberDef = astFactory.createMemberFunctionDef("constructor", constructor);
}
memberDef.useSourceInfoIfMissingFromForTree(classNode);
memberDef.makeNonIndexableRecursive();
classMembers.addChildToFront(memberDef);
NodeUtil.addFeatureToScript(t.getCurrentScript(), Feature.MEMBER_DECLARATIONS, compiler);
// report newly created constructor
compiler.reportChangeToChangeScope(memberDef.getOnlyChild());
// report change to scope containing the class
compiler.reportChangeToEnclosingScope(memberDef);
}
/** Returns the node's pre-CAST type, if is has one. Otherwise just returns node.getJSType() */
private static JSType getTypeBeforeCast(Node node) {
JSType typeBeforeCast = node.getJSTypeBeforeCast();
// might still return null if node.getJSType() is null (i.e. typechecking hasn't run)
return typeBeforeCast != null ? typeBeforeCast : node.getJSType();
}
private boolean isInterface(Node classNode) {
JSDocInfo classJsDocInfo = NodeUtil.getBestJSDocInfo(classNode);
return classJsDocInfo != null && classJsDocInfo.isInterface();
}
private void visitSuper(Node node, Node parent) {
checkState(node.isSuper());
Node exprRoot = node;
if (exprRoot.getParent().isGetElem() || exprRoot.getParent().isGetProp()) {
exprRoot = exprRoot.getParent();
}
Node enclosingMemberDef =
NodeUtil.getEnclosingNode(
exprRoot,
new Predicate() {
@Override
public boolean apply(Node n) {
switch (n.getToken()) {
case MEMBER_FUNCTION_DEF:
case GETTER_DEF:
case SETTER_DEF:
case COMPUTED_PROP:
return true;
default:
return false;
}
}
});
if (parent.isCall()) {
// super(...)
visitSuperCall(node, parent, enclosingMemberDef);
} else if (parent.isGetProp() || parent.isGetElem()) {
if (parent.getFirstChild() == node) {
if (parent.getParent().isCall() && NodeUtil.isInvocationTarget(parent)) {
// super.something(...) or super['something'](..)
visitSuperPropertyCall(node, parent, enclosingMemberDef);
} else {
// super.something or super['something']
visitSuperPropertyAccess(node, parent, enclosingMemberDef);
}
} else {
// super.something used in some other way
compiler.report(
JSError.make(
node,
CANNOT_CONVERT_YET,
"Only calls to super or to a method of super are supported."));
}
} else if (parent.isNew()) {
throw new IllegalStateException("This should never happen. Did Es6SuperCheck fail to run?");
} else {
// some other use of super we don't support yet
compiler.report(
JSError.make(
node,
CANNOT_CONVERT_YET,
"Only calls to super or to a method of super are supported."));
}
}
private void visitSuperCall(Node node, Node parent, Node enclosingMemberDef) {
checkState(parent.isCall(), parent);
checkState(node.isSuper(), node);
Node clazz = NodeUtil.getEnclosingClass(node);
Node superName = clazz.getSecondChild();
if (!superName.isQualifiedName()) {
// This will be reported as an error in Es6ToEs3Converter.
return;
}
if (NodeUtil.isEs6ConstructorMemberFunctionDef(enclosingMemberDef)) {
// Calls to super() constructors will be transpiled by Es6ConvertSuperConstructorCalls later.
if (node.isFromExterns() || isInterface(clazz)) {
// If a class is defined in an externs file or as an interface, it's only a stub, not an
// implementation that should be instantiated.
// A call to super() shouldn't actually exist for these cases and is problematic to
// transpile, so just drop it.
Node enclosingStatement = NodeUtil.getEnclosingStatement(node);
Node enclosingStatementParent = enclosingStatement.getParent();
enclosingStatement.detach();
compiler.reportChangeToEnclosingScope(enclosingStatementParent);
}
// Calls to super() constructors will be transpiled by Es6ConvertSuperConstructorCalls
// later.
return;
} else {
// super can only be directly called in a constructor
throw new IllegalStateException("This should never happen. Did Es6SuperCheck fail to run?");
}
}
private void visitSuperPropertyCall(Node node, Node parent, Node enclosingMemberDef) {
checkState(parent.isGetProp() || parent.isGetElem(), parent);
checkState(node.isSuper(), node);
Node grandparent = parent.getParent();
checkState(grandparent.isCall());
Node clazz = NodeUtil.getEnclosingClass(node);
Node superName = clazz.getSecondChild();
if (!superName.isQualifiedName()) {
// This will be reported as an error in Es6ToEs3Converter.
return;
}
Node callTarget = parent;
Node callNode = IR.string("call");
callNode.makeNonIndexable();
if (enclosingMemberDef.isStaticMember()) {
Node expandedSuper = superName.cloneTree().useSourceInfoFromForTree(node);
expandedSuper.setOriginalName("super");
callTarget.replaceChild(node, expandedSuper);
callTarget = astFactory.createGetProp(callTarget.detach(), "call");
grandparent.addChildToFront(callTarget);
Node thisNode = astFactory.createThis(clazz.getJSType());
thisNode.makeNonIndexable(); // no direct correlation with original source
grandparent.addChildAfter(thisNode, callTarget);
grandparent.useSourceInfoIfMissingFromForTree(parent);
} else {
// Replace super node to give
// super.method(...) -> SuperClass.prototype.method(...)
Node expandedSuper =
astFactory
.createGetProp(superName.cloneTree(), "prototype")
.useSourceInfoFromForTree(node);
expandedSuper.setOriginalName("super");
node.replaceWith(expandedSuper);
// Set the 'this' object correctly for the call
// SuperClass.prototype.method(...) -> SuperClass.prototype.method.call(this, ...)
callTarget = astFactory.createGetProp(callTarget.detach(), "call");
grandparent.addChildToFront(callTarget);
JSType thisType = getInstanceTypeForClassNode(clazz);
Node thisNode = astFactory.createThis(thisType);
thisNode.makeNonIndexable(); // no direct correlation with original source
grandparent.addChildAfter(thisNode, callTarget);
grandparent.putBooleanProp(Node.FREE_CALL, false);
grandparent.useSourceInfoIfMissingFromForTree(parent);
}
compiler.reportChangeToEnclosingScope(grandparent);
}
private JSType getInstanceTypeForClassNode(Node classNode) {
checkArgument(classNode.isClass(), classNode);
final JSType constructorType = classNode.getJSType();
final JSType result;
if (constructorType != null) {
checkArgument(constructorType.isConstructor(), classNode);
result = JSType.toMaybeFunctionType(constructorType).getInstanceType();
} else {
result = null;
}
return result;
}
private void visitSuperPropertyAccess(Node node, Node parent, Node enclosingMemberDef) {
checkState(parent.isGetProp() || parent.isGetElem(), parent);
checkState(node.isSuper(), node);
Node grandparent = parent.getParent();
if (NodeUtil.isLValue(parent)) {
// We don't support assigning to a super property
compiler.report(JSError.make(parent, CANNOT_CONVERT_YET, "assigning to a super property"));
return;
}
Node clazz = NodeUtil.getEnclosingClass(node);
Node superName = clazz.getSecondChild();
if (!superName.isQualifiedName()) {
// This will be reported as an error in Es6ToEs3Converter.
return;
}
if (enclosingMemberDef.isStaticMember()) {
// super.prop -> SuperClass.prop
Node expandedSuper = superName.cloneTree().useSourceInfoFromForTree(node);
expandedSuper.setOriginalName("super");
node.replaceWith(expandedSuper);
} else {
if (astFactory.isAddingTypes()) {
// super.prop -> SuperClass.prototype.prop
Node newprop =
astFactory
.createGetProp(superName.cloneTree(), "prototype")
.useSourceInfoFromForTree(node);
newprop.setOriginalName("super");
node.replaceWith(newprop);
} else {
String newPropName = Joiner.on('.').join(superName.getQualifiedName(), "prototype");
// TODO(bradfordcsmith): This is required for Kythe, which doesn't work correctly with
// Node#useSourceInfoIfMissingFromForTree. Fortunately, we only care about Kythe
// if we're not adding types.
// Once this pass is always run after type checking, we can eliminate this branch.
node.replaceWith(
NodeUtil.newQName(compiler, newPropName, node, "super").useSourceInfoFromForTree(node));
}
}
compiler.reportChangeToEnclosingScope(grandparent);
}
@Override
public void process(Node externs, Node root) {
// Might need to synthesize constructors for ambient classes in .d.ts externs
TranspilationPasses.processTranspile(compiler, externs, transpiledFeatures, this);
TranspilationPasses.processTranspile(compiler, root, transpiledFeatures, this);
}
@Override
public void hotSwapScript(Node scriptRoot, Node originalRoot) {
TranspilationPasses.hotSwapTranspile(compiler, scriptRoot, transpiledFeatures, this);
TranspilationPasses.maybeMarkFeaturesAsTranspiledAway(compiler, transpiledFeatures);
}
}