MimeMatcher.java

/*
 * Copyright (c) 2014-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.stetho.inspector.network;

import javax.annotation.Nullable;

import java.util.ArrayList;

import android.annotation.SuppressLint;

public class MimeMatcher<T> {
  private final ArrayList<MimeMatcherRule> mRuleMap = new ArrayList<MimeMatcherRule>();

  /**
   * Add a matching rule in the canonical MIME T form such as "image/*" or a MIME T
   * literal such as "text/html".
   *
   * @param ruleExpression Expression to match, in the order it was added.
   * @param resultIfMatched Result if this expression matches.
   */
  public void addRule(String ruleExpression, T resultIfMatched) {
    mRuleMap.add(new MimeMatcherRule(ruleExpression, resultIfMatched));
  }

  public void clear() {
    mRuleMap.clear();
  }

  @Nullable
  public T match(String mimeT) {
    int ruleMapN = mRuleMap.size();
    for (int i = 0; i < ruleMapN; i++) {
      MimeMatcherRule rule = mRuleMap.get(i);
      if (rule.match(mimeT)) {
        return rule.getResultIfMatched();
      }
    }
    return null;
  }

  @SuppressLint("BadMethodUse-java.lang.String.length")
  private class MimeMatcherRule {
    private final boolean mHasWildcard;
    private final String mMatchPrefix;
    private final T mResultIfMatched;

    public MimeMatcherRule(String ruleExpression, T resultIfMatched) {
      if (ruleExpression.endsWith("*")) {
        mHasWildcard = true;
        mMatchPrefix = ruleExpression.substring(0, ruleExpression.length() - 1);
      } else {
        mHasWildcard = false;
        mMatchPrefix = ruleExpression;
      }
      if (mMatchPrefix.contains("*")) {
        throw new IllegalArgumentException("Multiple wildcards present in rule expression " +
            ruleExpression);
      }
      mResultIfMatched = resultIfMatched;
    }

    public boolean match(String mimeType) {
      // Make sure the string literal matches.
      if (!mimeType.startsWith(mMatchPrefix)) {
        return false;
      }

      // If we have a wildcard and the prefix matches, then we've matched; otherwise if the
      // string literal and the mime T are the same length then we must have a match.
      return (mHasWildcard || mimeType.length() == mMatchPrefix.length());
    }

    public T getResultIfMatched() {
      return mResultIfMatched;
    }
  }
}