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.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.javascript.jscomp.AstFactory.type;
import com.google.common.collect.Lists;
import com.google.javascript.jscomp.colors.StandardColors;
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.Node;
import com.google.javascript.rhino.QualifiedName;
import com.google.javascript.rhino.Token;
import java.util.ArrayList;
import java.util.List;
import org.jspecify.nullness.Nullable;
/**
* 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.
*/
// TODO(tbreisacher): This class does too many things. Break it into smaller passes.
public final class LateEs6ToEs3Converter implements NodeTraversal.Callback, CompilerPass {
private final AbstractCompiler compiler;
private final AstFactory astFactory;
private final Es6TemplateLiterals templateLiteralConverter;
private static final FeatureSet transpiledFeatures =
FeatureSet.BARE_MINIMUM.with(
Feature.COMPUTED_PROPERTIES,
Feature.MEMBER_DECLARATIONS,
Feature.TEMPLATE_LITERALS);
// We want to insert the call to `var tagFnFirstArg = $jscomp.createTemplateTagFirstArg...` just
// before this node. For the first script, this node is right after the runtime injected function
// definition as injecting to the top of the script causes runtime errors
// https://github.com/google/closure-compiler/issues/3589. For the subsequent script(s), the call
// is injected to the top of that script.
private @Nullable Node templateLitInsertionPoint = null;
private static final String FRESH_COMP_PROP_VAR = "$jscomp$compprop";
public LateEs6ToEs3Converter(AbstractCompiler compiler) {
this.compiler = compiler;
this.astFactory = compiler.createAstFactory();
this.templateLiteralConverter = new Es6TemplateLiterals(compiler);
}
@Override
public void process(Node externs, Node root) {
TranspilationPasses.processTranspile(compiler, root, transpiledFeatures, this);
TranspilationPasses.maybeMarkFeaturesAsTranspiledAway(compiler, transpiledFeatures);
}
@Override
public boolean shouldTraverse(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case SCRIPT:
// For all scripts, initialize the injection point to be top of the script
templateLitInsertionPoint = n.getFirstChild();
break;
case GETTER_DEF:
case SETTER_DEF:
if (FeatureSet.ES3.contains(compiler.getOptions().getOutputFeatureSet())) {
TranspilationUtil.cannotConvert(
compiler, n, "ES5 getters/setters (consider using --language_out=ES5)");
return false;
}
break;
case FUNCTION:
if (n.isAsyncFunction()) {
throw new IllegalStateException("async functions should have already been converted");
}
break;
default:
break;
}
return true;
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
switch (n.getToken()) {
case ASSIGN:
// Find whether this script contains the `$jscomp.createTemplateTagFirstArgWithRaw =
// function(..) {..}` node. If yes, update the templateLitInsertionPoint.
Node lhs = n.getFirstChild();
Node rhs = n.getSecondChild();
if (lhs.isGetProp() && rhs.isFunction() && lhs.getFirstChild().isName()) {
QualifiedName qName = QualifiedName.of("$jscomp.createTemplateTagFirstArgWithRaw");
if (qName.matches(lhs)) {
checkNotNull(n.getParent(), n);
checkState(n.getParent().isExprResult(), n);
templateLitInsertionPoint = n.getParent().getNext();
}
}
break;
case OBJECTLIT:
visitObject(n);
break;
case MEMBER_FUNCTION_DEF:
if (parent.isObjectLit()) {
visitMemberFunctionDefInObjectLit(n);
}
break;
case TAGGED_TEMPLATELIT:
templateLiteralConverter.visitTaggedTemplateLiteral(t, n, templateLitInsertionPoint);
break;
case TEMPLATELIT:
if (!parent.isTaggedTemplateLit()) {
templateLiteralConverter.visitTemplateLiteral(t, n);
}
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) {
String name = n.getString();
Node nameNode = n.getFirstFirstChild();
Node stringKey = astFactory.createStringKey(name, n.removeFirstChild());
stringKey.setJSDocInfo(n.getJSDocInfo());
n.replaceWith(stringKey);
stringKey.srcref(nameNode);
compiler.reportChangeToEnclosingScope(stringKey);
}
private void visitObject(Node obj) {
for (Node child = obj.getFirstChild(); child != null; child = child.getNext()) {
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();
AstFactory.Type objectType = type(obj);
while (currElement != null) {
if (currElement.getBooleanProp(Node.COMPUTED_PROP_GETTER)
|| currElement.getBooleanProp(Node.COMPUTED_PROP_SETTER)) {
TranspilationUtil.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();
currElement.detach();
props.add(currElement);
currElement = nextNode;
}
}
String objName = FRESH_COMP_PROP_VAR + compiler.getUniqueNameIdSupplier().get();
props = Lists.reverse(props);
Node result = astFactory.createName(objName, objectType);
for (Node propdef : props) {
if (propdef.isComputedProp()) {
Node propertyExpression = propdef.removeFirstChild();
Node value = propdef.removeFirstChild();
result =
astFactory.createComma(
astFactory.createAssign(
astFactory.createGetElem(
astFactory.createName(objName, objectType), propertyExpression),
value),
result);
} else {
Node val = propdef.removeFirstChild();
boolean isQuotedAccess = propdef.isQuotedStringKey();
propdef.setToken(Token.STRINGLIT);
propdef.setColor(StandardColors.STRING);
propdef.putBooleanProp(Node.QUOTED_PROP, false);
Node objNameNode = astFactory.createName(objName, objectType);
Node access =
isQuotedAccess
? astFactory.createGetElem(objNameNode, propdef)
: astFactory.createGetProp(objNameNode, propdef.getString(), type(propdef));
result = astFactory.createComma(astFactory.createAssign(access, val), result);
}
}
Node statement = obj;
while (!NodeUtil.isStatement(statement)) {
statement = statement.getParent();
}
result.srcrefTreeIfMissing(obj);
obj.replaceWith(result);
Node var = IR.var(astFactory.createName(objName, objectType), obj);
var.srcrefTreeIfMissing(statement);
var.insertBefore(statement);
compiler.reportChangeToEnclosingScope(var);
}
}