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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 2015 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.rhino.ErrorReporter;
import com.google.javascript.rhino.JSDocInfo;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.StaticSourceFile;
import com.google.javascript.rhino.jstype.JSType;
import com.google.javascript.rhino.jstype.StaticTypedRef;
import com.google.javascript.rhino.jstype.StaticTypedSlot;

/**
 * Several methods in this class, such as {@code isVar} throw an exception when called, and several
 * methods are currently identical to the ones in Var. The reason for this is that we want to shadow
 * methods from the parent class, to avoid calling them accidentally.
 */
public class TypedVar extends Var implements StaticTypedSlot, StaticTypedRef {

  final TypedScope scope;
  private JSType type;
  // The next two fields and the associated methods are only used by
  // TypeInference.java. Maybe there is a way to avoid having them in all typed variable instances.
  private boolean markedEscaped = false;
  private boolean markedAssignedExactlyOnce = false;

  /**
   * Whether the variable's type has been inferred or is declared. An inferred
   * type may change over time (as more code is discovered), whereas a
   * declared type is a static contract that must be matched.
   */
  private final boolean typeInferred;

  TypedVar(boolean inferred, String name, Node nameNode, JSType type,
      TypedScope scope, int index, CompilerInput input) {
    super(name, nameNode, scope, index, input);
    this.type = type;
    this.scope = scope;
    this.typeInferred = inferred;
  }

  @Override
  public String getName() {
    return name;
  }

  @Override
  public Node getNode() {
    return nameNode;
  }

  @Override
  CompilerInput getInput() {
    return input;
  }

  @Override
  public StaticSourceFile getSourceFile() {
    return nameNode.getStaticSourceFile();
  }

  @Override
  public TypedVar getSymbol() {
    return this;
  }

  @Override
  public TypedVar getDeclaration() {
    return nameNode == null ? null : this;
  }

  @Override
  public Node getParentNode() {
    return nameNode == null ? null : nameNode.getParent();
  }

  @Override
  public boolean isBleedingFunction() {
    throw new IllegalStateException(
        "Method isBleedingFunction cannot be called on typed variables.");
  }

  @Override
  public TypedScope getScope() {
    return scope;
  }

  @Override
  public boolean isGlobal() {
    return scope.isGlobal();
  }

  @Override
  public boolean isLocal() {
    return scope.isLocal();
  }

  @Override
  boolean isExtern() {
    return input == null || input.isExtern();
  }

  @Override
  public boolean isInferredConst() {
    throw new IllegalStateException("Method isInferredConst cannot be called on typed variables.");
  }

  @Override
  public boolean isDefine() {
    throw new IllegalStateException("Method isDefine cannot be called on typed variables.");
  }

  @Override
  public Node getInitialValue() {
    return NodeUtil.getRValueOfLValue(nameNode);
  }

  @Override
  public Node getNameNode() {
    return nameNode;
  }

  @Override
  public JSDocInfo getJSDocInfo() {
    return nameNode == null ? null : NodeUtil.getBestJSDocInfo(nameNode);
  }

  /**
   * Gets this variable's type. To know whether this type has been inferred,
   * see {@code #isTypeInferred()}.
   */
  @Override
  public JSType getType() {
    return type;
  }

  void setType(JSType type) {
    this.type = type;
  }

  void resolveType(ErrorReporter errorReporter) {
    if (type != null) {
      type = type.resolve(errorReporter, scope);
    }
  }

  /**
   * Returns whether this variable's type is inferred. To get the variable's
   * type, see {@link #getType()}.
   */
  @Override
  public boolean isTypeInferred() {
    return typeInferred;
  }

  public String getInputName() {
    if (input == null) {
      return "";
    }
    return input.getName();
  }

  @Override
  public boolean equals(Object other) {
    if (!(other instanceof TypedVar)) {
      return false;
    }
    return ((TypedVar) other).nameNode == nameNode;
  }

  @Override
  public int hashCode() {
    return nameNode.hashCode();
  }

  @Override
  public String toString() {
    return "Var " + name + "{" + type + "}";
  }

  void markEscaped() {
    markedEscaped = true;
  }

  boolean isMarkedEscaped() {
    return markedEscaped;
  }

  void markAssignedExactlyOnce() {
    markedAssignedExactlyOnce = true;
  }

  boolean isMarkedAssignedExactlyOnce() {
    return markedAssignedExactlyOnce;
  }

  @Override
  boolean isVar() {
    throw new IllegalStateException("Method isVar cannot be called on typed variables.");
  }

  @Override
  boolean isLet() {
    throw new IllegalStateException("Method isLet cannot be called on typed variables.");
  }

  @Override
  boolean isConst() {
    throw new IllegalStateException("Method isConst cannot be called on typed variables.");
  }

  @Override
  boolean isParam() {
    throw new IllegalStateException("Method isParam cannot be called on typed variables.");
  }
}