com.google.javascript.jscomp.transpile.BaseTranspiler Maven / Gradle / Ivy
/*
* Copyright 2016 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.transpile;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.base.Strings;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.javascript.jscomp.CheckLevel;
import com.google.javascript.jscomp.Compiler;
import com.google.javascript.jscomp.CompilerOptions;
import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
import com.google.javascript.jscomp.DiagnosticGroup;
import com.google.javascript.jscomp.DiagnosticType;
import com.google.javascript.jscomp.Es6RewriteModulesToCommonJsModules;
import com.google.javascript.jscomp.PropertyRenamingPolicy;
import com.google.javascript.jscomp.Result;
import com.google.javascript.jscomp.SourceFile;
import com.google.javascript.jscomp.SourceMap;
import com.google.javascript.jscomp.VariableRenamingPolicy;
import com.google.javascript.jscomp.bundle.TranspilationException;
import com.google.javascript.jscomp.deps.ModuleLoader;
import com.google.javascript.jscomp.deps.ModuleLoader.PathEscaper;
import com.google.javascript.jscomp.deps.ModuleLoader.ResolutionMode;
import com.google.javascript.rhino.Node;
import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
/**
* Basic Transpiler implementation for outputting ES5 code.
*/
public final class BaseTranspiler implements Transpiler {
private final CompilerSupplier compilerSupplier;
private final String runtimeLibraryName;
public BaseTranspiler(CompilerSupplier compilerSupplier, String runtimeLibraryName) {
this.compilerSupplier = checkNotNull(compilerSupplier);
this.runtimeLibraryName = checkNotNull(runtimeLibraryName);
}
@Override
public TranspileResult transpile(URI path, String code) {
CompileResult result = compilerSupplier.compile(path, code);
if (!result.transpiled) {
return new TranspileResult(path, code, code, "");
}
return new TranspileResult(path, code, result.source, result.sourceMap);
}
@Override
public String runtime() {
StringBuilder sb = new StringBuilder();
if (!Strings.isNullOrEmpty(runtimeLibraryName)) {
sb.append(compilerSupplier.runtime(runtimeLibraryName));
}
sb.append(compilerSupplier.runtime("modules"));
return sb.toString();
}
public static final BaseTranspiler ES5_TRANSPILER = new BaseTranspiler(
new CompilerSupplier(), "es6_runtime");
public static final BaseTranspiler ES_MODULE_TO_CJS_TRANSPILER =
new BaseTranspiler(new EsmToCjsCompilerSupplier(), "");
/**
* Wraps the Compiler into a more relevant interface, making it
* easy to test the Transpiler without depending on implementation
* details of the Compiler itself. Also works around the fact
* that the Compiler is not thread-safe (since we may do multiple
* transpiles concurrently), so we supply a fresh instance each
* time when we're in single-file mode.
*/
public static class CompilerSupplier {
protected final ResolutionMode moduleResolution;
protected final ImmutableList moduleRoots;
protected final ImmutableMap prefixReplacements;
public CompilerSupplier() {
// Use the default resolution mode
this(new CompilerOptions().getModuleResolutionMode(), ImmutableList.of(), ImmutableMap.of());
}
/**
* Accepts commonly overridden options for ES6 modules to avoid needed to subclass.
*
* @param moduleResolution module resolution for resolving import paths
* @param prefixReplacements prefix replacements for when moduleResolution is {@link
* ModuleLoader.ResolutionMode#BROWSER_WITH_TRANSFORMED_PREFIXES}
*/
public CompilerSupplier(
ModuleLoader.ResolutionMode moduleResolution,
ImmutableList moduleRoots,
ImmutableMap prefixReplacements) {
this.moduleResolution = moduleResolution;
this.moduleRoots = moduleRoots;
this.prefixReplacements = prefixReplacements;
}
public CompileResult compile(URI path, String code) {
Compiler compiler = compiler();
Result result =
compiler.compile(EXTERNS, SourceFile.fromCode(path.toString(), code), options());
String source = compiler.toSource();
StringBuilder sourceMap = new StringBuilder();
if (result.sourceMap != null) {
try {
result.sourceMap.appendTo(sourceMap, path.toString());
} catch (IOException e) {
// impossible, and not a big deal even if it did happen.
}
}
boolean transpiled = !result.transpiledFiles.isEmpty();
if (result.errors.length > 0) {
throw new TranspilationException(compiler, result.errors, result.warnings);
}
return new CompileResult(
source,
transpiled,
transpiled ? sourceMap.toString() : "");
}
public String runtime(String library) {
Compiler compiler = compiler();
CompilerOptions options = options();
options.setForceLibraryInjection(ImmutableList.of(library));
compiler.compile(EXTERNS, EMPTY, options);
return compiler.toSource();
}
protected Compiler compiler() {
return new Compiler();
}
protected CompilerOptions options() {
CompilerOptions options = new CompilerOptions();
setOptions(options);
return options;
}
protected void setOptions(CompilerOptions options) {
options.setLanguageIn(LanguageMode.ECMASCRIPT_NEXT);
// TODO(sdh): It would be nice to allow people to output code in
// strict mode. But currently we swallow all the input language
// strictness checks, and there are various tests that are never
// compiled and so are broken when we output 'use strict'. We
// could consider adding some sort of logging/warning/error in
// cases where the input was not strict, though there could still
// be semantic differences even if syntax is strict. Possibly
// the first step would be to allow the option of outputting strict
// and then change the default and see what breaks. b/33005948
options.setLanguageOut(LanguageMode.ECMASCRIPT5);
options.setQuoteKeywordProperties(true);
options.setSkipNonTranspilationPasses(true);
options.setVariableRenaming(VariableRenamingPolicy.OFF);
options.setPropertyRenaming(PropertyRenamingPolicy.OFF);
options.setWrapGoogModulesForWhitespaceOnly(false);
options.setPrettyPrint(true);
options.setWarningLevel(ES5_WARNINGS, CheckLevel.OFF);
options.setTranspileEs6ModulesToCjsModules(true);
options.setModuleResolutionMode(moduleResolution);
options.setModuleRoots(moduleRoots);
options.setBrowserResolverPrefixReplacements(prefixReplacements);
// Don't escape module paths when bundling in the event paths are URLs.
options.setPathEscaper(PathEscaper.CANONICALIZE_ONLY);
options.setSourceMapOutputPath("/dev/null");
options.setSourceMapIncludeSourcesContent(true);
// Make sourcemaps use absolute paths, so that the path is not duplicated if a build tool adds
// a sourceurl. Exception: if the location has a scheme (like http:) then leave the path
// intact. This makes this usable from web servers.
options.setSourceMapLocationMappings(
ImmutableList.of((location) -> {
try {
if (new URI(location).getScheme() != null) {
return location;
}
} catch (URISyntaxException e) {
// Swallow, return the absolute version below.
}
return new SourceMap.PrefixLocationMapping("", "/").map(location);
}));
}
protected static final SourceFile EXTERNS =
SourceFile.fromCode("externs.js", "function Symbol() {}");
protected static final SourceFile EMPTY = SourceFile.fromCode("empty.js", "");
protected static final DiagnosticGroup ES5_WARNINGS = new DiagnosticGroup(
DiagnosticType.error("JSC_CANNOT_CONVERT", ""));
}
/**
* CompilerSupplier that only transforms EcmaScript Modules into a form that can be safely
* transformed on a file by file basis and concatenated.
*/
public static class EsmToCjsCompilerSupplier extends CompilerSupplier {
public EsmToCjsCompilerSupplier() {
super();
}
public EsmToCjsCompilerSupplier(
ModuleLoader.ResolutionMode moduleResolution,
ImmutableList moduleRoots,
ImmutableMap prefixReplacements) {
super(moduleResolution, moduleRoots, prefixReplacements);
}
@Override
public CompileResult compile(URI path, String code) {
CompilerOptions options = new CompilerOptions();
options.setLanguageIn(LanguageMode.ECMASCRIPT_NEXT);
options.setEmitUseStrict(false);
options.setSourceMapOutputPath("/dev/null");
options.setSourceMapIncludeSourcesContent(true);
options.setPrettyPrint(true);
options.setModuleResolutionMode(moduleResolution);
options.setModuleRoots(moduleRoots);
options.setBrowserResolverPrefixReplacements(prefixReplacements);
// Create a compiler and run specifically this one pass on it.
Compiler compiler = compiler();
compiler.init(
ImmutableList.of(),
ImmutableList.of(SourceFile.fromCode(path.toString(), code)),
options);
compiler.parseForCompilation();
boolean transpiled = false;
if (!compiler.hasErrors()
&& compiler.getRoot().getSecondChild().getFirstFirstChild().isModuleBody()
&& !compiler
.getRoot()
.getSecondChild()
.getFirstChild()
.getBooleanProp(Node.GOOG_MODULE)) {
new Es6RewriteModulesToCommonJsModules(compiler)
.process(null, compiler.getRoot().getSecondChild());
compiler.getRoot().getSecondChild().getFirstChild().putBooleanProp(Node.TRANSPILED, true);
transpiled = true;
}
Result result = compiler.getResult();
String source = compiler.toSource();
StringBuilder sourceMap = new StringBuilder();
if (result.sourceMap != null) {
try {
result.sourceMap.appendTo(sourceMap, path.toString());
} catch (IOException e) {
// impossible, and not a big deal even if it did happen.
}
}
if (result.errors.length > 0) {
throw new TranspilationException(compiler, result.errors, result.warnings);
}
return new CompileResult(source, transpiled, transpiled ? sourceMap.toString() : "");
}
}
/**
* The source together with the additional compilation results.
*/
public static class CompileResult {
public final String source;
public final boolean transpiled;
public final String sourceMap;
public CompileResult(String source, boolean transpiled, String sourceMap) {
this.source = checkNotNull(source);
this.transpiled = transpiled;
this.sourceMap = checkNotNull(sourceMap);
}
}
}
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