com.google.javascript.jscomp.LateEs6ToEs3Converter Maven / Gradle / Ivy
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/*
* 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.javascript.jscomp.Es6ToEs3Util.createType;
import static com.google.javascript.jscomp.Es6ToEs3Util.withType;
import com.google.common.base.Preconditions;
import com.google.common.collect.Lists;
import com.google.javascript.jscomp.AbstractCompiler.MostRecentTypechecker;
import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
import com.google.javascript.jscomp.parsing.parser.FeatureSet;
import com.google.javascript.rhino.IR;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.ObjectTypeI;
import com.google.javascript.rhino.Token;
import com.google.javascript.rhino.TypeI;
import com.google.javascript.rhino.TypeIRegistry;
import com.google.javascript.rhino.jstype.JSTypeNative;
import java.util.ArrayList;
import java.util.List;
/**
* Converts ES6 code to valid ES5 code. This class does most of the transpilation, and
* https://github.com/google/closure-compiler/wiki/ECMAScript6 lists which ES6 features are
* supported. Other classes that start with "Es6" do other parts of the transpilation.
*
* In most cases, the output is valid as ES3 (hence the class name) but in some cases, if
* the output language is set to ES5, we rely on ES5 features such as getters, setters,
* and Object.defineProperties.
*
* @author [email protected] (Tyler Breisacher)
*/
// TODO(tbreisacher): This class does too many things. Break it into smaller passes.
public final class LateEs6ToEs3Converter implements NodeTraversal.Callback, HotSwapCompilerPass {
private final AbstractCompiler compiler;
private static final FeatureSet transpiledFeatures = FeatureSet.ES6.without(FeatureSet.ES5);
// addTypes indicates whether we should add type information when transpiling.
private final boolean addTypes;
private final TypeIRegistry registry;
private final TypeI unknownType;
private final TypeI stringType;
private final TypeI booleanType;
private static final String FRESH_COMP_PROP_VAR = "$jscomp$compprop";
private static final String ITER_BASE = "$jscomp$iter$";
private static final String ITER_RESULT = "$jscomp$key$";
public LateEs6ToEs3Converter(AbstractCompiler compiler) {
this.compiler = compiler;
// Only add type information if NTI has been run.
this.addTypes = MostRecentTypechecker.NTI.equals(compiler.getMostRecentTypechecker());
this.registry = compiler.getTypeIRegistry();
this.unknownType = createType(addTypes, registry, JSTypeNative.UNKNOWN_TYPE);
this.stringType = createType(addTypes, registry, JSTypeNative.STRING_TYPE);
this.booleanType = createType(addTypes, registry, JSTypeNative.BOOLEAN_TYPE);
}
@Override
public void process(Node externs, Node root) {
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);
}
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case GETTER_DEF:
case SETTER_DEF:
if (compiler.getOptions().getLanguageOut() == LanguageMode.ECMASCRIPT3) {
Es6ToEs3Util.cannotConvert(
compiler, n, "ES5 getters/setters (consider using --language_out=ES5)");
return false;
}
break;
case FUNCTION:
if (n.isAsyncFunction()) {
throw new IllegalStateException("async functions should have already been converted");
}
break;
default:
break;
}
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case OBJECTLIT:
visitObject(n);
break;
case MEMBER_FUNCTION_DEF:
if (parent.isObjectLit()) {
visitMemberFunctionDefInObjectLit(n, parent);
}
break;
case FOR_OF:
visitForOf(t, n, parent);
break;
case TAGGED_TEMPLATELIT:
Es6TemplateLiterals.visitTaggedTemplateLiteral(t, n, addTypes);
break;
case TEMPLATELIT:
if (!parent.isTaggedTemplateLit()) {
Es6TemplateLiterals.visitTemplateLiteral(t, n, addTypes);
}
break;
default:
break;
}
}
/**
* Converts a member definition in an object literal to an ES3 key/value pair.
* Member definitions in classes are handled in {@link Es6RewriteClass}.
*/
private void visitMemberFunctionDefInObjectLit(Node n, Node parent) {
String name = n.getString();
Node nameNode = n.getFirstFirstChild();
Node stringKey = withType(IR.stringKey(name, n.getFirstChild().detach()), n.getTypeI());
stringKey.setJSDocInfo(n.getJSDocInfo());
parent.replaceChild(n, stringKey);
stringKey.useSourceInfoFrom(nameNode);
compiler.reportChangeToEnclosingScope(stringKey);
}
private void visitForOf(NodeTraversal t, Node node, Node parent) {
Node variable = node.removeFirstChild();
Node iterable = node.removeFirstChild();
Node body = node.removeFirstChild();
TypeI typeParam = unknownType;
if (addTypes) {
// TODO(sdh): This is going to be null if the iterable is nullable or unknown. We might want
// to consider some way of unifying rather than simply looking at the nominal type.
ObjectTypeI iterableType = iterable.getTypeI().autobox().toMaybeObjectType();
if (iterableType != null) {
TypeIRegistry registry = compiler.getTypeIRegistry();
TypeI iterableBaseType = registry.getNativeType(JSTypeNative.ITERABLE_TYPE);
typeParam = iterableType.getInstantiatedTypeArgument(iterableBaseType);
}
}
TypeI iteratorType = createGenericType(JSTypeNative.ITERATOR_TYPE, typeParam);
TypeI iIterableResultType = createGenericType(JSTypeNative.I_ITERABLE_RESULT_TYPE, typeParam);
TypeI iteratorNextType =
addTypes ? iteratorType.toMaybeObjectType().getPropertyType("next") : null;
JSDocInfo varJSDocInfo = variable.getJSDocInfo();
Node iterName =
withType(IR.name(ITER_BASE + compiler.getUniqueNameIdSupplier().get()), iteratorType);
iterName.makeNonIndexable();
Node getNext =
withType(
IR.call(
withType(
IR.getprop(iterName.cloneTree(), withStringType(IR.string("next"))),
iteratorNextType)),
iIterableResultType);
String variableName;
Token declType;
if (variable.isName()) {
declType = Token.NAME;
variableName = variable.getQualifiedName();
} else {
Preconditions.checkState(NodeUtil.isNameDeclaration(variable),
"Expected var, let, or const. Got %s", variable);
declType = variable.getToken();
variableName = variable.getFirstChild().getQualifiedName();
}
Node iterResult = withType(IR.name(ITER_RESULT + variableName), iIterableResultType);
iterResult.makeNonIndexable();
Node call = Es6ToEs3Util.makeIterator(compiler, iterable);
if (addTypes) {
TypeI jscompType = t.getScope().getVar("$jscomp").getNode().getTypeI();
TypeI makeIteratorType = jscompType.toMaybeObjectType().getPropertyType("makeIterator");
call.getFirstChild().setTypeI(makeIteratorType);
call.getFirstFirstChild().setTypeI(jscompType);
}
Node init = IR.var(iterName.cloneTree(), withType(call, iteratorType));
Node initIterResult = iterResult.cloneTree();
initIterResult.addChildToFront(getNext.cloneTree());
init.addChildToBack(initIterResult);
Node cond =
withBooleanType(
IR.not(
withBooleanType(
IR.getprop(iterResult.cloneTree(), withStringType(IR.string("done"))))));
Node incr =
withType(IR.assign(iterResult.cloneTree(), getNext.cloneTree()), iIterableResultType);
Node declarationOrAssign;
if (declType == Token.NAME) {
declarationOrAssign =
withType(
IR.assign(
withType(IR.name(variableName).useSourceInfoFrom(variable), typeParam),
withType(
IR.getprop(iterResult.cloneTree(), withStringType(IR.string("value"))),
typeParam)),
typeParam);
declarationOrAssign.setJSDocInfo(varJSDocInfo);
declarationOrAssign = IR.exprResult(declarationOrAssign);
} else {
declarationOrAssign = new Node(
declType,
withType(IR.name(variableName).useSourceInfoFrom(variable.getFirstChild()), typeParam));
declarationOrAssign.getFirstChild().addChildToBack(
withType(
IR.getprop(iterResult.cloneTree(), withStringType(IR.string("value"))),
typeParam));
declarationOrAssign.setJSDocInfo(varJSDocInfo);
}
Node newBody = IR.block(declarationOrAssign, body).useSourceInfoFrom(body);
Node newFor = IR.forNode(init, cond, incr, newBody);
newFor.useSourceInfoIfMissingFromForTree(node);
parent.replaceChild(node, newFor);
compiler.reportChangeToEnclosingScope(newFor);
}
private void visitObject(Node obj) {
for (Node child : obj.children()) {
if (child.isComputedProp()) {
visitObjectWithComputedProperty(obj);
return;
}
}
}
/**
* Transpiles an object node with computed property,
* and add type information to the new nodes if this pass ran after type checking.
* For example,
{@code
* var obj = {a: 1, [i++]: 2}
* is transpiled to
* var $jscomp$compprop0 = {};
* var obj = ($jscomp$compprop0.a = 1, ($jscomp$compprop0[i++] = 2, $jscomp$compprop0));
* }
* Note that when adding type information to the nodes, the NAME node $jscomp$compprop0
* would always be assigned the type of the entire object (in the above example {a: number}).
* This is because we do not have sufficient type information during transpilation to know,
* for example, $jscomp$compprop0 has type Object{} in the expression $jscomp$compprop0.a = 1
*/
private void visitObjectWithComputedProperty(Node obj) {
checkArgument(obj.isObjectLit());
List props = new ArrayList<>();
Node currElement = obj.getFirstChild();
TypeI objectType = obj.getTypeI();
while (currElement != null) {
if (currElement.getBooleanProp(Node.COMPUTED_PROP_GETTER)
|| currElement.getBooleanProp(Node.COMPUTED_PROP_SETTER)) {
Es6ToEs3Util.cannotConvertYet(
compiler, currElement, "computed getter/setter in an object literal");
return;
} else if (currElement.isGetterDef() || currElement.isSetterDef()) {
currElement = currElement.getNext();
} else {
Node nextNode = currElement.getNext();
obj.removeChild(currElement);
props.add(currElement);
currElement = nextNode;
}
}
String objName = FRESH_COMP_PROP_VAR + compiler.getUniqueNameIdSupplier().get();
props = Lists.reverse(props);
Node result = withType(IR.name(objName), objectType);
for (Node propdef : props) {
if (propdef.isComputedProp()) {
Node propertyExpression = propdef.removeFirstChild();
Node value = propdef.removeFirstChild();
TypeI valueType = value.getTypeI();
result =
withType(
IR.comma(
withType(
IR.assign(
withUnknownType(
IR.getelem(
withType(IR.name(objName), objectType), propertyExpression)),
value),
valueType),
result),
objectType);
} else {
Node val = propdef.removeFirstChild();
TypeI valueType = val.getTypeI();
propdef.setToken(Token.STRING);
propdef.setTypeI(null);
Token token = propdef.isQuotedString() ? Token.GETELEM : Token.GETPROP;
Node access =
withType(new Node(token, withType(IR.name(objName), objectType), propdef), valueType);
result =
withType(IR.comma(withType(IR.assign(access, val), valueType), result), objectType);
}
}
Node statement = obj;
while (!NodeUtil.isStatement(statement)) {
statement = statement.getParent();
}
result.useSourceInfoIfMissingFromForTree(obj);
obj.replaceWith(result);
TypeI simpleObjectType = createType(addTypes, registry, JSTypeNative.EMPTY_OBJECT_LITERAL_TYPE);
Node var = IR.var(withType(IR.name(objName), objectType), withType(obj, simpleObjectType));
var.useSourceInfoIfMissingFromForTree(statement);
statement.getParent().addChildBefore(var, statement);
compiler.reportChangeToEnclosingScope(var);
}
private TypeI createGenericType(JSTypeNative typeName, TypeI typeArg) {
return Es6ToEs3Util.createGenericType(addTypes, registry, typeName, typeArg);
}
private Node withStringType(Node n) {
return withType(n, stringType);
}
private Node withBooleanType(Node n) {
return withType(n, booleanType);
}
private Node withUnknownType(Node n) {
return withType(n, unknownType);
}
}