Move RegexListSearcher out of giant server library into ioutil

Change-Id: I984dc32a38c4bb75e5f25764caebe3c4b072b293

java/com/google/gerrit/server/util/RegexListSearcher.java

@@ -1,100 +0,0 @@
-// Copyright (C) 2014 The Android Open Source Project
-//
-// 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.gerrit.server.util;
-
-import static com.google.common.base.Preconditions.checkNotNull;
-
-import com.google.common.collect.Lists;
-import com.google.common.primitives.Chars;
-import dk.brics.automaton.Automaton;
-import dk.brics.automaton.RegExp;
-import dk.brics.automaton.RunAutomaton;
-import java.util.Collections;
-import java.util.List;
-import java.util.function.Function;
-import java.util.stream.Stream;
-
-/** Helper to search sorted lists for elements matching a {@link RegExp}. */
-public final class RegexListSearcher<T> {
-  public static RegexListSearcher<String> ofStrings(String re) {
-    return new RegexListSearcher<>(re, Function.identity());
-  }
-
-  private final RunAutomaton pattern;
-  private final Function<T, String> toStringFunc;
-
-  private final String prefixBegin;
-  private final String prefixEnd;
-  private final int prefixLen;
-  private final boolean prefixOnly;
-
-  public RegexListSearcher(String re, Function<T, String> toStringFunc) {
-    this.toStringFunc = checkNotNull(toStringFunc);
-
-    if (re.startsWith("^")) {
-      re = re.substring(1);
-    }
-
-    if (re.endsWith("$") && !re.endsWith("\\$")) {
-      re = re.substring(0, re.length() - 1);
-    }
-
-    Automaton automaton = new RegExp(re).toAutomaton();
-    prefixBegin = automaton.getCommonPrefix();
-    prefixLen = prefixBegin.length();
-
-    if (0 < prefixLen) {
-      char max = Chars.checkedCast(prefixBegin.charAt(prefixLen - 1) + 1);
-      prefixEnd = prefixBegin.substring(0, prefixLen - 1) + max;
-      prefixOnly = re.equals(prefixBegin + ".*");
-    } else {
-      prefixEnd = "";
-      prefixOnly = false;
-    }
-
-    pattern = prefixOnly ? null : new RunAutomaton(automaton);
-  }
-
-  public Stream<T> search(List<T> list) {
-    checkNotNull(list);
-    int begin;
-    int end;
-
-    if (0 < prefixLen) {
-      // Assumes many consecutive elements may have the same prefix, so the cost of two binary
-      // searches is less than iterating linearly and running the regexp find the endpoints.
-      List<String> strings = Lists.transform(list, toStringFunc::apply);
-      begin = find(strings, prefixBegin);
-      end = find(strings, prefixEnd);
-    } else {
-      begin = 0;
-      end = list.size();
-    }
-    if (begin >= end) {
-      return Stream.empty();
-    }
-
-    Stream<T> result = list.subList(begin, end).stream();
-    if (!prefixOnly) {
-      result = result.filter(x -> pattern.run(toStringFunc.apply(x)));
-    }
-    return result;
-  }
-
-  private static int find(List<String> list, String p) {
-    int r = Collections.binarySearch(list, p);
-    return r < 0 ? -(r + 1) : r;
-  }
-}