com.google.javascript.jscomp.Es6SplitVariableDeclarations 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 com.google.javascript.rhino.IR;
import com.google.javascript.rhino.Node;
/**
* Splits variable declarations that declare multiple variables into
* separate declarations, if at least one of the declarations is a
* destructuring declaration. For example
*
* var [a, b] = foo(), c = bar();}
*
* becomes
*
* var [a, b] = foo();
* var c = bar();
*
*
* This runs before the main ES6 transpilation step, to simplify
* the transpilation of destructuring syntax.
*
* @author [email protected] (Tyler Breisacher)
*/
public final class Es6SplitVariableDeclarations extends
NodeTraversal.AbstractPostOrderCallback implements HotSwapCompilerPass {
private final AbstractCompiler compiler;
public Es6SplitVariableDeclarations(AbstractCompiler compiler) {
this.compiler = compiler;
}
@Override
public void process(Node externs, Node root) {
TranspilationPasses.processTranspile(compiler, root, this);
}
@Override
public void hotSwapScript(Node scriptRoot, Node originalRoot) {
TranspilationPasses.hotSwapTranspile(compiler, scriptRoot, this);
}
@Override
public void visit(NodeTraversal t, Node n, Node parent) {
if (NodeUtil.isDestructuringDeclaration(n)) {
splitDeclaration(n, parent);
}
}
public void splitDeclaration(Node n, Node parent) {
while (n.getFirstChild() != n.getLastChild()) {
Node child = n.getLastChild().detach();
Node newVar = IR.declaration(child, n.getToken()).srcref(n);
parent.addChildAfter(newVar, n);
compiler.reportCodeChange();
}
}
}