com.google.javascript.jscomp.serialization.JSTypeColorIdHasher Maven / Gradle / Ivy

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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.

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/*
 * Copyright 2020 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.serialization;

import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.ImmutableMap.toImmutableMap;
import static java.nio.charset.StandardCharsets.UTF_8;

import com.google.common.collect.ImmutableMap;
import com.google.common.hash.HashFunction;
import com.google.common.hash.Hasher;
import com.google.common.hash.Hashing;
import com.google.javascript.jscomp.colors.ColorId;
import com.google.javascript.jscomp.colors.StandardColors;
import com.google.javascript.rhino.jstype.FunctionType;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.JSTypeNative;
import com.google.javascript.rhino.jstype.JSTypeRegistry;
import com.google.javascript.rhino.jstype.ObjectType;
import java.util.Map;
import org.jspecify.nullness.Nullable;

final class JSTypeColorIdHasher {

  private final ImmutableMap standardColorObjectIds;

  JSTypeColorIdHasher(JSTypeRegistry registry) {
    this.standardColorObjectIds =
        NATIVE_TYPE_TO_ID.entrySet().stream()
            .collect(
                toImmutableMap(
                    (e) -> registry.getNativeObjectType(e.getKey()), Map.Entry::getValue));
  }

  ColorId hashObjectType(ObjectType type) {
    checkState(
        type != null
            && !type.isEnumElementType()
            && !type.isNoResolvedType()
            && !type.isTemplatizedType()
            && !type.isUnknownType()
            && !type.isTemplateType(),
        type);

    ColorId boxId = this.standardColorObjectIds.get(type);
    if (boxId != null) {
      return boxId;
    }

    Hasher hasher = FARM_64.newHasher();

    if (type.isFunctionType()) {
      FunctionType fnType = type.toMaybeFunctionType();
      if (fnType.hasInstanceType()) {
        hasher.putInt(Marker.HAS_INSTANCE_TYPE);
      }
    }

    if (type.hasReferenceName()) {
      this.putReferenceNameType(hasher, type);
    } else {
      for (String prop : type.getOwnPropertyNames()) {
        putUtf8(hasher, prop);
      }
    }

    return ColorId.fromUnsigned(hasher.hash().asLong());
  }

  private void putReferenceNameType(Hasher hasher, ObjectType type) {
    putUtf8(hasher, type.getReferenceName());

    JSType.WithSourceRef sourceRef = sourceRefFor(type);
    if (sourceRef == null) {
      // TODO(b/185519307): This is a hack to work around bugs in the typesystem.
      hasher.putInt(Marker.UNKNOWN_SOURCEREF);
      return;
    }

    String moduleId = sourceRef.getGoogModuleId();
    if (moduleId == null) {
      hasher.putInt(Marker.NO_GOOG_MODULE_ID);
    } else {
      putUtf8(hasher, moduleId);
    }
  }

  private static JSType.@Nullable WithSourceRef sourceRefFor(ObjectType type) {
    if (type.isEnumType()) {
      return type.toMaybeEnumType();
    } else if (type.isEnumElementType()) {
      // EnumElementTypes are proxied to their underlying type when transformed to colors.
      throw new AssertionError(type);
    }

    if (type.isFunctionType()) {
      return type.toMaybeFunctionType();
    } else if (type.isFunctionPrototypeType()) {
      return type.getOwnerFunction();
    } else if (type.getConstructor() != null) {
      return type.getConstructor();
    }

    return null;
  }

  private static final HashFunction FARM_64 = Hashing.farmHashFingerprint64();

  private static void putUtf8(Hasher hasher, String s) {
    hasher.putString(s, UTF_8);
  }

  /**
   * Arbitrary constants that may get hashed into ColorId.
   *
   * Since a hash may end up including combinations of markers, using int values reduces that
   * chance that two combinations will concatenate to the same bit sequence.
   */
  private static final class Marker {
    static final int HAS_INSTANCE_TYPE = 0x8c8b70db;
    static final int NO_GOOG_MODULE_ID = 0x2593c5ff;
    static final int UNKNOWN_SOURCEREF = 0x660be782;
  }

  static final ImmutableMap NATIVE_TYPE_TO_ID =
      ImmutableMap.builder()
          .put(JSTypeNative.ARGUMENTS_TYPE, StandardColors.ARGUMENTS_ID)
          .put(JSTypeNative.ARRAY_TYPE, StandardColors.ARRAY_ID)
          .put(JSTypeNative.READONLY_ARRAY_TYPE, StandardColors.READONLY_ARRAY_ID)
          .put(JSTypeNative.ASYNC_ITERATOR_ITERABLE_TYPE, StandardColors.ASYNC_ITERATOR_ITERABLE_ID)
          .put(JSTypeNative.GENERATOR_TYPE, StandardColors.GENERATOR_ID)
          .put(JSTypeNative.I_TEMPLATE_ARRAY_TYPE, StandardColors.I_TEMPLATE_ARRAY_ID)
          .put(JSTypeNative.ITERATOR_TYPE, StandardColors.ITERATOR_ID)
          .put(JSTypeNative.PROMISE_TYPE, StandardColors.PROMISE_ID)
          .put(JSTypeNative.BIGINT_OBJECT_TYPE, StandardColors.BIGINT_OBJECT_ID)
          .put(JSTypeNative.BOOLEAN_OBJECT_TYPE, StandardColors.BOOLEAN_OBJECT_ID)
          .put(JSTypeNative.NUMBER_OBJECT_TYPE, StandardColors.NUMBER_OBJECT_ID)
          .put(JSTypeNative.STRING_OBJECT_TYPE, StandardColors.STRING_OBJECT_ID)
          .put(JSTypeNative.SYMBOL_OBJECT_TYPE, StandardColors.SYMBOL_OBJECT_ID)
          .buildOrThrow();
}