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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 2010 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.Node;
import com.google.javascript.rhino.Token;

import java.util.HashMap;
import java.util.Map;

/**
 * Filters warnings based on in-code {@code @suppress} annotations.
 *
 *  Works by looking at the AST node associated with the warning, and looking
 * at parents of the node until it finds a function or a script.
 * For this reason, it doesn't work for warnings without an associated AST node,
 * eg, the ones in parsing/IRFactory. They can be turned off with jscomp_off.
 *
 * @author [email protected] (Nick Santos)
 */
class SuppressDocWarningsGuard extends WarningsGuard {
  private static final long serialVersionUID = 1L;

  /** Warnings guards for each suppressible warnings group, indexed by name. */
  private final Map suppressors =
       new HashMap<>();

  /**
   * The suppressible groups, indexed by name.
   */
  SuppressDocWarningsGuard(Map suppressibleGroups) {
    for (Map.Entry entry : suppressibleGroups.entrySet()) {
      suppressors.put(
          entry.getKey(),
          new DiagnosticGroupWarningsGuard(
              entry.getValue(),
              CheckLevel.OFF));
    }

    // Hack: Allow "@suppress {missingRequire}" to mean
    // "@suppress {strictMissingRequire}".
    // TODO(tbreisacher): Delete this hack when strictMissingRequire is
    // renamed to missingRequire.
    suppressors.put(
        "missingRequire",
        new DiagnosticGroupWarningsGuard(DiagnosticGroups.STRICT_MISSING_REQUIRE, CheckLevel.OFF));
  }

  @Override
  public CheckLevel level(JSError error) {
    Node node = error.node;
    if (node != null) {
      boolean visitedFunction = false;
      for (Node current = node;
           current != null;
           current = current.getParent()) {
        Token type = current.getToken();
        JSDocInfo info = null;

        if (type == Token.FUNCTION) {
          info = NodeUtil.getBestJSDocInfo(current);
          visitedFunction = true;
        } else if (type == Token.SCRIPT) {
          info = current.getJSDocInfo();
        } else if (current.isVar() || current.isAssign()) {
          // There's one edge case we're worried about:
          // if the warning points to an assignment to a function, we
          // want the suppressions on that function to apply.
          // It's OK if we double-count some cases.
          Node rhs = NodeUtil.getRValueOfLValue(current.getFirstChild());
          if (rhs != null) {
            if (rhs.isCast()) {
              rhs = rhs.getFirstChild();
            }

            if (rhs.isFunction() && !visitedFunction) {
              info = NodeUtil.getBestJSDocInfo(current);
            }
          }
        }

        if (info != null) {
          for (String suppressor : info.getSuppressions()) {
            WarningsGuard guard = suppressors.get(suppressor);

            // Some @suppress tags are for other tools, and
            // may not have a warnings guard.
            if (guard != null) {
              CheckLevel newLevel = guard.level(error);
              if (newLevel != null) {
                return newLevel;
              }
            }
          }
        }
      }
    }
    return null;
  }

  @Override
  public int getPriority() {
    // Happens after path-based filtering, but before other times
    // of filtering.
    return WarningsGuard.Priority.SUPPRESS_DOC.value;
  }
}