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

Go to download
/*
 * Copyright 2018 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.JSDocInfo;
import com.google.javascript.rhino.JSDocInfo.Visibility;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.jstype.JSType;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

/**
 * This pass looks for properties that are not modified and ensures they use the @const annotation.
 * Can run with or without typechecking but will find more if typechecking is enabled.
 */
class CheckConstPrivateProperties extends NodeTraversal.AbstractPostOrderCallback
    implements HotSwapCompilerPass {

  static final DiagnosticType MISSING_CONST_PROPERTY =
      DiagnosticType.disabled(
          "JSC_MISSING_CONST_PROPERTY",
          "Private property {0} is never modified, use the @const annotation");

  private final AbstractCompiler compiler;
  private final List candidates = new ArrayList<>();
  private final Set modified = new HashSet<>();

  CheckConstPrivateProperties(AbstractCompiler compiler) {
    this.compiler = compiler;
  }

  @Override
  public void process(Node externs, Node root) {
    NodeTraversal.traverse(compiler, root, this);
  }

  @Override
  public void hotSwapScript(Node scriptRoot, Node originalRoot) {
    NodeTraversal.traverse(compiler, scriptRoot, this);
  }

  /** Reports the property definitions that should use the @const annotation. */
  private void reportMissingConst(NodeTraversal t) {
    for (Node n : candidates) {
      String propName = n.getLastChild().getString();
      if (!modified.contains(propName)) {
        t.report(n, MISSING_CONST_PROPERTY, propName);
      }
    }
    candidates.clear();
    modified.clear();
  }

  @Override
  public void visit(NodeTraversal t, Node n, Node parent) {
    switch (n.getToken()) {
      case SCRIPT:
        // Exiting the script, report any non-const privates not modified in the file.
        reportMissingConst(t);
        break;

      case GETELEM:
      case GETPROP:
        // GETELEM is anytime a property is accessed on an object using the '["${key}"]' syntax.
        // GETPROP is anytime a property is accessed on an object using the '.' syntax.
        Node lastChild = n.getLastChild();
        if (!lastChild.isString()) {
          return;
        }
        String propName = lastChild.getString();

        // Only consider non-const @private class properties as candidates
        if (isCandidatePropertyDefinition(n)) {
          candidates.add(n);
        } else if (isModificationOp(n)) {
          // Mark any other modification operation as a modified property, to deal with lambdas, etc
          modified.add(propName);
        }
        break;

      default:
        break;
    }
  }

  /**
   * @return Whether the given node is a @private property declaration that is not marked constant.
   */
  private boolean isCandidatePropertyDefinition(Node n) {
    if (!NodeUtil.isLhsOfAssign(n)) {
      return false;
    }

    Node target = n.getFirstChild();
    // Check whether the given property access is on 'this' or a static property on a class.
    if (!(target.isThis() || isConstructor(target))) {
      return false;
    }

    JSDocInfo info = NodeUtil.getBestJSDocInfo(n);
    return info != null
        && info.getVisibility() == Visibility.PRIVATE
        && !info.isConstant()
        && !info.hasTypedefType()
        && !info.hasEnumParameterType()
        && !info.isInterface()
        && !isFunctionProperty(n);
  }

  /** @return Whether the given property declaration is assigned to a function. */
  private boolean isFunctionProperty(Node n) {
    // TODO(dylandavidson): getAssignedValue does not support GETELEM.
    if (n.isGetElem()) {
      return false;
    }
    Node assignedValue = NodeUtil.getAssignedValue(n);
    return assignedValue != null && assignedValue.isFunction();
  }

  /**
   * @return Whether the given property is modified in any way (assignment, increment/decrement, or
   *     'delete' property).
   */
  private boolean isModificationOp(Node n) {
    Node parent = n.getParent();

    if (n != parent.getFirstChild()) {
      return false;
    }

    return NodeUtil.isAssignmentOp(parent)
        || parent.isInc()
        || parent.isDec()
        || parent.isDelProp();
  }

  private boolean isConstructor(Node n) {
    // If type checking is enabled (not just a per-file lint check),
    // we can check constructor properties too. But it isn't required.
    JSType type = n.getJSType();
    return type != null && (type.isConstructor() || type.isInterface());
  }
}