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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. This binary checks for style issues such as incorrect or missing JSDoc usage, and missing goog.require() statements. It does not do more advanced checks such as typechecking.

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/*
 * Copyright 2013 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.newtypes;

import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * A builder for {@link FunctionType} and {@link DeclaredFunctionType}.
 *
 * The builder is called during both JSDoc parsing and type inference, and
 * these parts use different warning systems, so expect the context to handle
 * the exception appropriately.
 *
 * @author [email protected] (Ben Lickly)
 * @author [email protected] (Dimitris Vardoulakis)
 */
public final class FunctionTypeBuilder {
  static class WrongParameterOrderException extends RuntimeException {
    WrongParameterOrderException(String message) {
      super(message);
    }
  }

  private final List requiredFormals = new ArrayList<>();
  private final List optionalFormals = new ArrayList<>();
  private final Map outerVars = new LinkedHashMap<>();
  private JSType restFormals = null;
  private JSType returnType = null;
  private boolean loose = false;
  private boolean isAbstract = false;
  private JSType nominalType;
  // Only used to build DeclaredFunctionType for prototype methods
  private JSType receiverType;
  // Non-empty iff this function has an @template annotation
  private ImmutableList typeParameters = ImmutableList.of();

  private final JSTypes commonTypes;

  public FunctionTypeBuilder(JSTypes commonTypes) {
    this.commonTypes = Preconditions.checkNotNull(commonTypes);
  }

  /**
   * Used when the order of required/optional/rest formals in a function jsdoc is wrong.
   */
  public FunctionTypeBuilder addPlaceholderFormal() {
    if (restFormals != null) {
      // Nothing to do here, since there is no way to add a placeholder.
    } else if (!optionalFormals.isEmpty()) {
      optionalFormals.add(this.commonTypes.UNKNOWN);
    } else {
      requiredFormals.add(this.commonTypes.UNKNOWN);
    }
    return this;
  }

  public FunctionTypeBuilder addReqFormal(JSType t) {
    if (!optionalFormals.isEmpty() || restFormals != null) {
      throw new WrongParameterOrderException(
          "Cannot add required formal after optional or rest args");
    }
    requiredFormals.add(t);
    return this;
  }

  public FunctionTypeBuilder addOptFormal(JSType t) {
    if (restFormals != null) {
      throw new WrongParameterOrderException(
          "Cannot add optional formal after rest args");
    }
    if (t == null) {
      optionalFormals.add(null);
    } else {
      Preconditions.checkArgument(!t.isBottom());
      optionalFormals.add(JSType.join(t, this.commonTypes.UNDEFINED));
    }
    return this;
  }

  public FunctionTypeBuilder addOuterVarPrecondition(String name, JSType t) {
    outerVars.put(name, t);
    return this;
  }

  public FunctionTypeBuilder addRestFormals(JSType t) {
    Preconditions.checkState(restFormals == null);
    restFormals = t;
    return this;
  }

  public FunctionTypeBuilder addRetType(JSType t) {
    Preconditions.checkState(returnType == null);
    returnType = t;
    return this;
  }

  public FunctionTypeBuilder addLoose() {
    loose = true;
    return this;
  }

  public FunctionTypeBuilder addAbstract(boolean isAbstract) {
    this.isAbstract = isAbstract;
    return this;
  }

  public FunctionTypeBuilder addNominalType(JSType t) {
    Preconditions.checkState(this.nominalType == null);
    this.nominalType = t;
    return this;
  }

  public FunctionTypeBuilder addTypeParameters(ImmutableList typeParameters) {
    Preconditions.checkNotNull(typeParameters);
    Preconditions.checkState(this.typeParameters.isEmpty());
    this.typeParameters = typeParameters;
    return this;
  }

  public FunctionTypeBuilder appendTypeParameters(ImmutableList typeParameters) {
    Preconditions.checkNotNull(typeParameters);
    ImmutableList.Builder newTypeParams = ImmutableList.builder();
    newTypeParams.addAll(this.typeParameters);
    newTypeParams.addAll(typeParameters);
    this.typeParameters = newTypeParams.build();
    return this;
  }

  public FunctionTypeBuilder addReceiverType(JSType t) {
    // this.receiverType is not always null here, because of prototype methods
    // with an explicit @this annotation
    this.receiverType = t;
    return this;
  }

  public DeclaredFunctionType buildDeclaration() {
    Preconditions.checkState(!loose);
    Preconditions.checkState(outerVars.isEmpty());
    return DeclaredFunctionType.make(
        this.commonTypes,
        requiredFormals, optionalFormals, restFormals, returnType,
        nominalType, receiverType, typeParameters, isAbstract);
  }

  public FunctionType buildFunction() {
    // qmarkFunctionBuilder().buildDeclaration creates a non-loose function,
    // we change that here to have a unique representation in FunctionType.
    if (this.requiredFormals.isEmpty()
        && this.optionalFormals.isEmpty()
        && this.restFormals != null && this.restFormals.isUnknown()
        && this.returnType != null && this.returnType.isUnknown()
        && this.nominalType == null
        && this.receiverType == null
        && this.typeParameters.isEmpty()
        && this.outerVars.isEmpty()) {
      return this.commonTypes.QMARK_FUNCTION;
    }
    return FunctionType.normalized(
        this.commonTypes,
        requiredFormals, optionalFormals, restFormals, returnType,
        nominalType, receiverType, outerVars, typeParameters, loose, isAbstract);
  }
}