com.google.javascript.jscomp.Es6TemplateLiterals 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.checkState;
import static com.google.javascript.jscomp.AstFactory.type;
import com.google.javascript.jscomp.colors.Color;
import com.google.javascript.jscomp.colors.StandardColors;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticScope;
/**
* Helper class for transpiling ES6 template literals.
*/
class Es6TemplateLiterals {
private static final String TEMPLATELIT_VAR = "$jscomp$templatelit$";
private final AstFactory astFactory;
private final AbstractCompiler compiler;
private final StaticScope namespace;
Es6TemplateLiterals(AbstractCompiler compiler) {
this.compiler = compiler;
this.astFactory = compiler.createAstFactory();
this.namespace = this.compiler.getTranspilationNamespace();
}
/**
* Converts `${a} b ${c} d ${e}` to (a + " b " + c + " d " + e)
*
* @param n A TEMPLATELIT node that is not prefixed with a tag
*/
void visitTemplateLiteral(NodeTraversal t, Node n) {
int length = n.getChildCount();
if (length == 0) {
n.replaceWith(astFactory.createString("\"\""));
} else {
Node first = n.removeFirstChild();
checkState(first.isTemplateLitString() && first.getCookedString() != null);
Node firstStr = astFactory.createString(first.getCookedString());
if (length == 1) {
n.replaceWith(firstStr);
} else {
// Add the first string with the first substitution expression
Node add = astFactory.createAdd(firstStr, n.removeFirstChild().removeFirstChild());
// Process the rest of the template literal
for (int i = 2; i < length; i++) {
Node child = n.removeFirstChild();
if (child.isTemplateLitString()) {
checkState(child.getCookedString() != null);
if (child.getCookedString().isEmpty()) {
continue;
} else if (i == 2 && first.getCookedString().isEmpty()) {
// So that `${hello} world` gets translated into (hello + " world")
// instead of ("" + hello + " world").
add = add.getSecondChild().detach();
}
}
add =
astFactory.createAdd(
add,
child.isTemplateLitString()
? astFactory.createString(child.getCookedString())
: child.removeFirstChild());
}
n.replaceWith(add.srcrefTreeIfMissing(n));
}
}
t.reportCodeChange();
}
/**
* Converts a tagged template into a call to the tag.
*
* If the cooked and raw strings of the template literal are same, this will create a call to
* createtemplatetagfirstarg that simply calls slice() on the cooked array at runtime to make the
* raw array a copy of the cooked array, and returns the cooked array. For example, tag`ab${bar}`
* will change to:
*
*
* // A call to the tagging function:
* tag($jscomp$templatelit$createTemplateTagFirstArg(['ab'], bar);
*
*
*
If the cooked and raw strings of the template literal are not same, this will construct the
* raw strings array, and call {@code createtemplatetagfirstargwithraw} with it, which assigns the
* raw strings array to the property 'raw' of the cooked array at runtime, and returns the cooked
* array. For example, tag`a\tb${bar}` will change to:
*
*
* // A call to the tagging function:
* tag($jscomp$templatelit$createTemplateTagFirstArgWithRaw(['a\tb'] /, ['a\\tb']), bar);
*
*
*
See template_literal_test.js for more examples.
*
* @param n A TAGGED_TEMPLATELIT node
*/
void visitTaggedTemplateLiteral(NodeTraversal t, Node n, Node insertBefore) {
Node templateLit = n.getLastChild();
Node siteObject = createCookedStringArray(templateLit);
// Node holding the function call to the runtime injected function
Node callTemplateTagArgCreator;
if (cookedAndRawStringsSame(templateLit)) {
// The cooked and raw versions of the array are the same, so just call slice() on the
// cooked array at runtime to make the raw array a copy of the cooked array.
callTemplateTagArgCreator =
astFactory.createCall(
astFactory.createQName(this.namespace, "$jscomp.createTemplateTagFirstArg"),
type(siteObject),
siteObject.cloneTree());
} else {
// The raw string array is different, so we need to construct it.
Node raw = createRawStringArray(templateLit);
callTemplateTagArgCreator =
astFactory.createCall(
astFactory.createQName(this.namespace, "$jscomp.createTemplateTagFirstArgWithRaw"),
type(siteObject),
siteObject.cloneTree(),
raw);
}
JSDocInfo.Builder jsDocInfoBuilder = JSDocInfo.builder();
jsDocInfoBuilder.recordNoInline();
JSDocInfo info = jsDocInfoBuilder.build();
CompilerInput input = t.getInput();
String uniqueId = compiler.getUniqueIdSupplier().getUniqueId(input);
// var tagFnFirstArg = $jscomp.createTemplateTagFirstArg...
Node tagFnFirstArgDeclaration =
astFactory
.createSingleVarNameDeclaration(TEMPLATELIT_VAR + uniqueId, callTemplateTagArgCreator)
.setJSDocInfo(info)
.srcrefTreeIfMissing(n);
// For the first script, insertion point 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 any subsequent script(s), the
// call is injected to the top of that script.
tagFnFirstArgDeclaration.insertBefore(insertBefore);
t.reportCodeChange(tagFnFirstArgDeclaration);
// Generate the call expression.
Node tagFnFirstArg = tagFnFirstArgDeclaration.getFirstChild().cloneNode();
Node call = astFactory.createCall(n.removeFirstChild(), type(n), tagFnFirstArg);
for (Node child = templateLit.getFirstChild(); child != null; child = child.getNext()) {
if (!child.isTemplateLitString()) {
call.addChildToBack(child.removeFirstChild());
}
}
call.srcrefTreeIfMissing(templateLit);
call.putBooleanProp(Node.FREE_CALL, !call.getFirstChild().isGetProp());
n.replaceWith(call);
t.reportCodeChange();
}
private Node createRawStringArray(Node n) {
Node array = astFactory.createArraylit();
for (Node child = n.getFirstChild(); child != null; child = child.getNext()) {
if (child.isTemplateLitString()) {
array.addChildToBack(astFactory.createString(child.getRawString()));
}
}
return array;
}
private Node createCookedStringArray(Node n) {
Color templateArrayType =
astFactory.isAddingColors()
? compiler.getColorRegistry().get(StandardColors.I_TEMPLATE_ARRAY_ID)
: null;
Node array =
astFactory
.createArraylit()
.setColor(templateArrayType); // tighten the type from Array to ITemplateArray
for (Node child = n.getFirstChild(); child != null; child = child.getNext()) {
if (child.isTemplateLitString()) {
if (child.getCookedString() != null) {
array.addChildToBack(astFactory.createString(child.getCookedString()));
} else {
// undefined cooked string due to exception in template escapes
array.addChildToBack(astFactory.createVoid(astFactory.createNumber(0)));
}
}
}
return array;
}
private static boolean cookedAndRawStringsSame(Node n) {
for (Node child = n.getFirstChild(); child != null; child = child.getNext()) {
if (!child.isTemplateLitString()) {
continue;
}
// getCookedString() returns null when the template literal has an illegal escape sequence.
if (child.getCookedString() == null
|| !child.getCookedString().equals(child.getRawString())) {
return false;
}
}
return true;
}
}