All Downloads are FREE. Search and download functionalities are using the official Maven repository.

com.google.javascript.jscomp.TranspilationPasses Maven / Gradle / Ivy

Go to download

Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.

There is a newer version: v20240317
Show newest version
/*
 * 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;


import com.google.javascript.jscomp.Es6RewriteDestructuring.ObjectDestructuringRewriteMode;
import com.google.javascript.jscomp.parsing.parser.FeatureSet;
import com.google.javascript.jscomp.parsing.parser.FeatureSet.Feature;
import com.google.javascript.rhino.Node;

/** Provides a single place to manage transpilation passes. */
public class TranspilationPasses {
  private TranspilationPasses() {}

  public static void addEs6ModulePass(
      PassListBuilder passes,
      final PreprocessorSymbolTable.CachedInstanceFactory preprocessorTableFactory) {
    passes.maybeAdd(
        PassFactory.builder()
            .setName("es6RewriteModule")
            .setInternalFactory(
                (compiler) -> {
                  preprocessorTableFactory.maybeInitialize(compiler);
                  return new Es6RewriteModules(
                      compiler,
                      compiler.getModuleMetadataMap(),
                      compiler.getModuleMap(),
                      preprocessorTableFactory.getInstanceOrNull(),
                      compiler.getTopScope(),
                      compiler.getOptions().getChunkOutputType());
                })
            .build());
  }

  public static void addTranspilationRuntimeLibraries(PassListBuilder passes) {
    // Inject runtime libraries needed for the transpilation we will have to do. Should run before
    // typechecking.
    passes.maybeAdd(injectTranspilationRuntimeLibraries);
  }

  public static void addEs6ModuleToCjsPass(PassListBuilder passes) {
    passes.maybeAdd(es6RewriteModuleToCjs);
  }

  public static void addEs6RewriteImportPathPass(PassListBuilder passes) {
    passes.maybeAdd(es6RelativizeImportPaths);
  }

  /** Adds transpilation passes that should run at the beginning of the optimization phase */
  public static void addEarlyOptimizationTranspilationPasses(
      PassListBuilder passes, CompilerOptions options) {

    // Note that we detect feature by feature rather than by yearly languages
    // in order to handle FeatureSet.BROWSER_2020, which is ES2019 without the new RegExp features.
    // However, RegExp features are not transpiled, and this does not imply that we allow arbitrary
    // selection of features to transpile.  They still must be done in chronological order based on.
    // This greatly simplifies testing and the requirements for the transpilation passes.

    if (options.needsTranspilationOf(Feature.REGEXP_FLAG_D)) {
      passes.maybeAdd(
          createFeatureRemovalPass(
              "markEs2022FeaturesNotRequiringTranspilationAsRemoved", Feature.REGEXP_FLAG_D));
    }

    if (options.needsTranspilationOf(Feature.PUBLIC_CLASS_FIELDS)
        || options.needsTranspilationOf(Feature.CLASS_STATIC_BLOCK)) {
      passes.maybeAdd(rewriteClassMembers);
    }

    if (options.needsTranspilationOf(Feature.NUMERIC_SEPARATOR)) {
      // Numeric separators are flagged as present by the parser,
      // but never actually represented in the AST.
      // The only thing we need to do is mark them as not present in the AST.
      passes.maybeAdd(
          createFeatureRemovalPass("markNumericSeparatorsRemoved", Feature.NUMERIC_SEPARATOR));
    }

    if (options.needsTranspilationOf(Feature.LOGICAL_ASSIGNMENT)) {
      passes.maybeAdd(rewriteLogicalAssignmentOperatorsPass);
    }

    if (options.needsTranspilationOf(Feature.OPTIONAL_CHAINING)) {
      passes.maybeAdd(rewriteOptionalChainingOperator);
    }

    if (options.needsTranspilationOf(Feature.BIGINT)) {
      passes.maybeAdd(reportBigIntLiteralTranspilationUnsupported);
    }

    if (options.needsTranspilationOf(Feature.NULL_COALESCE_OP)) {
      passes.maybeAdd(rewriteNullishCoalesceOperator);
    }

    if (options.needsTranspilationOf(Feature.OPTIONAL_CATCH_BINDING)) {
      passes.maybeAdd(rewriteCatchWithNoBinding);
    }

    if (options.needsTranspilationOf(Feature.FOR_AWAIT_OF)
        || options.needsTranspilationOf(Feature.ASYNC_GENERATORS)) {
      passes.maybeAdd(rewriteAsyncIteration);
    }

    if (options.needsTranspilationOf(Feature.OBJECT_LITERALS_WITH_SPREAD)
        || options.needsTranspilationOf(Feature.OBJECT_PATTERN_REST)) {
      passes.maybeAdd(rewriteObjectSpread);
      if (!options.needsTranspilationOf(Feature.OBJECT_DESTRUCTURING)
          && options.needsTranspilationOf(Feature.OBJECT_PATTERN_REST)) {
        // We only need to transpile away object destructuring that uses `...`, rather than
        // all destructuring.
        // For this to work correctly for object destructuring in parameter lists and variable
        // declarations, we need to normalize them a bit first.
        passes.maybeAdd(es6RenameVariablesInParamLists);
        passes.maybeAdd(es6SplitVariableDeclarations);
        passes.maybeAdd(
            getEs6RewriteDestructuring(ObjectDestructuringRewriteMode.REWRITE_OBJECT_REST));
      }
    }

    if (options.needsTranspilationOf(Feature.TRAILING_COMMA_IN_PARAM_LIST)) {
      passes.maybeAdd(removeTrailingCommaFromParamList);
    }

    if (options.needsTranspilationOf(Feature.ASYNC_FUNCTIONS)) {
      passes.maybeAdd(rewriteAsyncFunctions);
    }

    if (options.needsTranspilationOf(Feature.EXPONENT_OP)) {
      passes.maybeAdd(rewriteExponentialOperator);
    }

    if (options.needsTranspilationFrom(
        FeatureSet.BARE_MINIMUM.with(
            Feature.BINARY_LITERALS,
            Feature.OCTAL_LITERALS,
            Feature.REGEXP_FLAG_U,
            Feature.REGEXP_FLAG_Y))) {
      // Binary and octal literals are effectively transpiled by the parser.
      // There's no transpilation we can do for the new regexp flags.
      passes.maybeAdd(
          createFeatureRemovalPass(
              "markEs6FeaturesNotRequiringTranspilationAsRemoved",
              Feature.BINARY_LITERALS,
              Feature.OCTAL_LITERALS,
              Feature.REGEXP_FLAG_U,
              Feature.REGEXP_FLAG_Y));
    }

    if (options.needsTranspilationOf(Feature.EXTENDED_OBJECT_LITERALS)) {
      passes.maybeAdd(es6NormalizeShorthandProperties);
    }
    if (options.needsTranspilationOf(Feature.CLASSES)) {
      passes.maybeAdd(es6RewriteClassExtends);
      passes.maybeAdd(es6ConvertSuper);
    }
    if (options.needsTranspilationFrom(
        FeatureSet.BARE_MINIMUM.with(Feature.ARRAY_DESTRUCTURING, Feature.OBJECT_DESTRUCTURING))) {
      passes.maybeAdd(es6RenameVariablesInParamLists);
      passes.maybeAdd(es6SplitVariableDeclarations);
      passes.maybeAdd(
          getEs6RewriteDestructuring(ObjectDestructuringRewriteMode.REWRITE_ALL_OBJECT_PATTERNS));
    }
    if (options.needsTranspilationOf(Feature.NEW_TARGET)) {
      passes.maybeAdd(rewriteNewDotTarget);
    }
    if (options.needsTranspilationOf(Feature.ARROW_FUNCTIONS)) {
      passes.maybeAdd(es6RewriteArrowFunction);
    }
    if (options.needsTranspilationOf(Feature.CLASSES)) {
      passes.maybeAdd(es6ExtractClasses);
      passes.maybeAdd(es6RewriteClass);
    }
    if (options.needsTranspilationFrom(
        FeatureSet.BARE_MINIMUM.with(Feature.REST_PARAMETERS, Feature.SPREAD_EXPRESSIONS))) {
      passes.maybeAdd(es6RewriteRestAndSpread);
    }
    if (options.needsTranspilationFrom(
        FeatureSet.BARE_MINIMUM.with(
            Feature.COMPUTED_PROPERTIES, Feature.MEMBER_DECLARATIONS, Feature.TEMPLATE_LITERALS))) {
      passes.maybeAdd(lateConvertEs6ToEs3);
    }
    if (options.needsTranspilationOf(Feature.FOR_OF)) {
      passes.maybeAdd(es6ForOf);
    }
    if (options.needsTranspilationOf(Feature.BLOCK_SCOPED_FUNCTION_DECLARATION)) {
      passes.maybeAdd(rewriteBlockScopedFunctionDeclaration);
    }
    if (options.needsTranspilationFrom(
        FeatureSet.BARE_MINIMUM.with(Feature.LET_DECLARATIONS, Feature.CONST_DECLARATIONS))) {
      passes.maybeAdd(rewriteBlockScopedDeclaration);
    }
    if (options.needsTranspilationOf(Feature.GENERATORS)) {
      passes.maybeAdd(rewriteGenerators);
    }
  }

  /** Adds the pass to inject ES2015 polyfills, which goes after the late ES2015 passes. */
  public static void addRewritePolyfillPass(PassListBuilder passes) {
    passes.maybeAdd(rewritePolyfills);
  }

  /** Rewrites ES6 modules */
  private static final PassFactory es6RewriteModuleToCjs =
      PassFactory.builder()
          .setName("es6RewriteModuleToCjs")
          .setInternalFactory(Es6RewriteModulesToCommonJsModules::new)
          .build();

  /** Rewrites ES6 modules import paths to be browser compliant */
  private static final PassFactory es6RelativizeImportPaths =
      PassFactory.builder()
          .setName("es6RelativizeImportPaths")
          .setInternalFactory(Es6RelativizeImportPaths::new)
          .build();

  private static final PassFactory rewriteAsyncFunctions =
      PassFactory.builder()
          .setName("rewriteAsyncFunctions")
          .setInternalFactory(RewriteAsyncFunctions::create)
          .build();

  private static final PassFactory rewriteAsyncIteration =
      PassFactory.builder()
          .setName("rewriteAsyncIteration")
          .setInternalFactory(RewriteAsyncIteration::create)
          .build();

  private static final PassFactory rewriteObjectSpread =
      PassFactory.builder()
          .setName("rewriteObjectSpread")
          .setInternalFactory(RewriteObjectSpread::new)
          .build();

  private static final PassFactory rewriteCatchWithNoBinding =
      PassFactory.builder()
          .setName("rewriteCatchWithNoBinding")
          .setInternalFactory(RewriteCatchWithNoBinding::new)
          .build();

  private static final PassFactory rewriteNewDotTarget =
      PassFactory.builder()
          .setName("rewriteNewDotTarget")
          .setInternalFactory(RewriteNewDotTarget::new)
          .build();

  private static final PassFactory removeTrailingCommaFromParamList =
      PassFactory.builder()
          .setName("removeTrailingCommaFromParamList")
          .setInternalFactory(RemoveTrailingCommaFromParamList::new)
          .build();

  private static final PassFactory reportBigIntLiteralTranspilationUnsupported =
      PassFactory.builder()
          .setName("reportBigIntTranspilationUnsupported")
          .setInternalFactory(ReportBigIntLiteralTranspilationUnsupported::new)
          .build();

  private static final PassFactory rewriteExponentialOperator =
      PassFactory.builder()
          .setName("rewriteExponentialOperator")
          .setInternalFactory(Es7RewriteExponentialOperator::new)
          .build();

  private static final PassFactory es6NormalizeShorthandProperties =
      PassFactory.builder()
          .setName("es6NormalizeShorthandProperties")
          .setInternalFactory(Es6NormalizeShorthandProperties::new)
          .build();

  static final PassFactory es6RewriteClassExtends =
      PassFactory.builder()
          .setName(PassNames.ES6_REWRITE_CLASS_EXTENDS)
          .setInternalFactory(Es6RewriteClassExtendsExpressions::new)
          .build();

  static final PassFactory es6ExtractClasses =
      PassFactory.builder()
          .setName(PassNames.ES6_EXTRACT_CLASSES)
          .setInternalFactory(Es6ExtractClasses::new)
          .build();

  static final PassFactory rewriteClassMembers =
      PassFactory.builder()
          .setName("RewriteClassMembers")
          .setInternalFactory(RewriteClassMembers::new)
          .build();

  static final PassFactory es6RewriteClass =
      PassFactory.builder()
          .setName("Es6RewriteClass")
          .setInternalFactory(Es6RewriteClass::new)
          .build();

  static final PassFactory getEs6RewriteDestructuring(ObjectDestructuringRewriteMode rewriteMode) {
    return PassFactory.builder()
        .setName("Es6RewriteDestructuring")
        .setInternalFactory(
            (compiler) ->
                new Es6RewriteDestructuring.Builder(compiler)
                    .setDestructuringRewriteMode(rewriteMode)
                    .build())
        .build();
  }

  static final PassFactory es6RenameVariablesInParamLists =
      PassFactory.builder()
          .setName("Es6RenameVariablesInParamLists")
          .setInternalFactory(Es6RenameVariablesInParamLists::new)
          .build();

  static final PassFactory es6RewriteArrowFunction =
      PassFactory.builder()
          .setName("Es6RewriteArrowFunction")
          .setInternalFactory(Es6RewriteArrowFunction::new)
          .build();

  static final PassFactory rewritePolyfills =
      PassFactory.builder()
          .setName("RewritePolyfills")
          .setInternalFactory(
              (compiler) ->
                  new RewritePolyfills(
                      compiler,
                      compiler.getOptions().getRewritePolyfills(),
                      compiler.getOptions().getIsolatePolyfills()))
          .build();

  static final PassFactory es6SplitVariableDeclarations =
      PassFactory.builder()
          .setName("Es6SplitVariableDeclarations")
          .setInternalFactory(Es6SplitVariableDeclarations::new)
          .build();

  static final PassFactory es6ConvertSuper =
      PassFactory.builder()
          .setName("es6ConvertSuper")
          .setInternalFactory(Es6ConvertSuper::new)
          .build();

  /** Injects runtime library code needed for transpiled ES2015+ code. */
  static final PassFactory injectTranspilationRuntimeLibraries =
      PassFactory.builder()
          .setName("es6InjectRuntimeLibraries")
          .setInternalFactory(InjectTranspilationRuntimeLibraries::new)
          .build();

  /** Transpiles REST parameters and SPREAD in both array literals and function calls. */
  static final PassFactory es6RewriteRestAndSpread =
      PassFactory.builder()
          .setName("es6RewriteRestAndSpread")
          .setInternalFactory(Es6RewriteRestAndSpread::new)
          .build();

  /**
   * Does the main ES2015 to ES3 conversion. There are a few other passes which run before this one,
   * to convert constructs which are not converted by this pass.
   */
  static final PassFactory lateConvertEs6ToEs3 =
      PassFactory.builder()
          .setName("lateConvertEs6")
          .setInternalFactory(LateEs6ToEs3Converter::new)
          .build();

  static final PassFactory es6ForOf =
      PassFactory.builder().setName("es6ForOf").setInternalFactory(Es6ForOfConverter::new).build();

  static final PassFactory rewriteBlockScopedFunctionDeclaration =
      PassFactory.builder()
          .setName("Es6RewriteBlockScopedFunctionDeclaration")
          .setInternalFactory(Es6RewriteBlockScopedFunctionDeclaration::new)
          .build();

  static final PassFactory rewriteBlockScopedDeclaration =
      PassFactory.builder()
          .setName("Es6RewriteBlockScopedDeclaration")
          .setInternalFactory(Es6RewriteBlockScopedDeclaration::new)
          .build();

  static final PassFactory rewriteGenerators =
      PassFactory.builder()
          .setName("rewriteGenerators")
          .setInternalFactory(Es6RewriteGenerators::new)
          .build();

  static final PassFactory rewriteLogicalAssignmentOperatorsPass =
      PassFactory.builder()
          .setName("rewriteLogicalAssignmentOperatorsPass")
          .setInternalFactory(RewriteLogicalAssignmentOperatorsPass::new)
          .build();

  static final PassFactory rewriteOptionalChainingOperator =
      PassFactory.builder()
          .setName("rewriteOptionalChainingOperator")
          .setInternalFactory(RewriteOptionalChainingOperator::new)
          .build();

  static final PassFactory rewriteNullishCoalesceOperator =
      PassFactory.builder()
          .setName("rewriteNullishCoalesceOperator")
          .setInternalFactory(RewriteNullishCoalesceOperator::new)
          .build();

  /**
   * @param script The SCRIPT node representing a JS file
   * @return If the file has any features not in {@code supportedFeatures}
   */
  static boolean doesScriptHaveUnsupportedFeatures(Node script, FeatureSet supportedFeatures) {
    FeatureSet features = NodeUtil.getFeatureSetOfScript(script);
    return features != null && !supportedFeatures.contains(features);
  }

  /**
   * Process transpilations if the input language needs transpilation from certain features, on any
   * JS file that has features not present in the compiler's output language mode.
   *
   * @param compiler An AbstractCompiler
   * @param combinedRoot The combined root for all JS files.
   * @param featureSet Ignored
   * @param callbacks The callbacks that should be invoked if a file has ES2015 features.
   * @deprecated Please use a regular NodeTraversal object directly, using `shouldTraverse` to skip
   *     SCRIPT node if desired.
   */
  @Deprecated
  static void processTranspile(
      AbstractCompiler compiler,
      Node combinedRoot,
      FeatureSet featureSet,
      NodeTraversal.Callback... callbacks) {
    FeatureSet languageOutFeatures = compiler.getOptions().getOutputFeatureSet();
    for (Node singleRoot = combinedRoot.getFirstChild();
        singleRoot != null;
        singleRoot = singleRoot.getNext()) {

      // Only run the transpilation if this file has features not in the compiler's target output
      // language. For example, if this file is purely ES6 and the output language is ES6, don't
      // run any transpilation passes on it.
      // TODO(lharker): We could save time by being more selective about what files we transpile.
      // e.g. if a file has async functions but not `**`, don't run `**` transpilation on it.
      // Right now we know what features were in a file at parse time, but not what features were
      // added to that file by other transpilation passes.
      if (doesScriptHaveUnsupportedFeatures(singleRoot, languageOutFeatures)) {
        for (NodeTraversal.Callback callback : callbacks) {
          singleRoot.putBooleanProp(Node.TRANSPILED, true);
          NodeTraversal.traverse(compiler, singleRoot, callback);
        }
      }
    }
  }

  static void maybeMarkFeaturesAsTranspiledAway(
      AbstractCompiler compiler, FeatureSet transpiledFeatures) {
    // We don't bother to do this if the compiler has halting errors, which avoids unnecessary
    // warnings from AstValidator warning that the features are still there.
    if (!compiler.hasHaltingErrors()) {
      compiler.setFeatureSet(compiler.getFeatureSet().without(transpiledFeatures));
    }
  }

  static void maybeMarkFeaturesAsTranspiledAway(
      AbstractCompiler compiler, Feature transpiledFeature, Feature... moreTranspiledFeatures) {
    if (!compiler.hasHaltingErrors()) {
      compiler.setFeatureSet(
          compiler.getFeatureSet().without(transpiledFeature, moreTranspiledFeatures));
    }
  }

  /**
   * Returns a pass that just removes features from the AST FeatureSet.
   *
   * 
Doing this indicates that the AST no longer contains uses of the features, or that they are
   * no longer of concern for some other reason.
   */
  private static PassFactory createFeatureRemovalPass(
      String passName, final Feature featureToRemove, final Feature... moreFeaturesToRemove) {
    return PassFactory.builder()
        .setName(passName)
        .setInternalFactory(
            (compiler) ->
                ((Node externs, Node root) ->
                    maybeMarkFeaturesAsTranspiledAway(
                        compiler, featureToRemove, moreFeaturesToRemove)))
        .build();
  }
}




© 2015 - 2024 Weber Informatics LLC | Privacy Policy