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A very small Java8 String utility library.
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/*
 * Copyright 2011-present Objectos, Fábrica de Software LTDA.
 *
 * 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 br.com.objectos.core.lang;

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

/**
 * Based on Guava's ArrayBasedCharEscaper
 *
 * @author [email protected] (Marcio Endo)
 */
public class Escaper {

  private final char[][] replacementMap;
  private final int length;

  private Escaper(char[][] map) {
    replacementMap = map;
    length = map.length;
  }

  public static Builder builder() {
    return new Builder();
  }

  public String escape(String string) {
    int length = string.length();
    for (int index = 0; index < length; index++) {
      if (escape(string.charAt(index)) != null) {
        return escapeSlow(string, index);
      }
    }
    return string;
  }

  private char[] escape(char c) {
    if (c < length) {
      char[] chars = replacementMap[c];
      if (chars != null) {
        return chars;
      }
    }
    return null;
  }

  private String escapeSlow(String string, int index) {
    StringBuilder builder = new StringBuilder(string.length() + 16);
    builder.append(string.substring(0, index));

    for (int i = index; i < string.length(); i++) {
      char c = string.charAt(i);
      char[] replacement = escape(c);
      if (replacement == null) {
        builder.append(c);
      } else {
        builder.append(replacement);
      }
    }

    return builder.toString();
  }

  public static class Builder {

    private final Map map = new HashMap<>();
    private char max = Character.MIN_VALUE;

    private Builder() {
    }

    public Builder addEscape(char c, String replacement) {
      map.put(c, replacement);
      if (c > max) {
        max = c;
      }
      return this;
    }

    public Escaper build() {
      char[][] replacementMap = new char[max + 1][];

      map.entrySet()
          .stream()
          .forEach(e -> replacementMap[e.getKey().charValue()] = e.getValue().toCharArray());

      return new Escaper(replacementMap);
    }

  }

}