1/*
2 * Copyright (C) 2010 Google Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17package com.google.clearsilver.jsilver.functions.string;
18
19import com.google.clearsilver.jsilver.functions.NonEscapingFunction;
20import com.google.clearsilver.jsilver.values.Value;
21import static com.google.clearsilver.jsilver.values.Value.literalConstant;
22import static com.google.clearsilver.jsilver.values.Value.literalValue;
23
24import static java.lang.Math.max;
25import static java.lang.Math.min;
26
27/**
28 * Returns the string slice starting at start and ending at end, similar to the Python slice
29 * operator.
30 */
31public class SliceFunction extends NonEscapingFunction {
32
33  /**
34   * @param args 1 string values then 2 numeric values (start and end).
35   * @return Sliced string
36   */
37  public Value execute(Value... args) {
38    Value stringValue = args[0];
39    Value startValue = args[1];
40    Value endValue = args[2];
41    String string = stringValue.asString();
42    int start = startValue.asNumber();
43    int end = endValue.asNumber();
44    int length = string.length();
45
46    if (start < 0) {
47      start += max(-start, length);
48      if (end == 0) {
49        end = length;
50      }
51    }
52
53    if (end < 0) {
54      end += length;
55    }
56
57    end = min(end, length);
58
59    if (end < start) {
60      return literalConstant("", args[0]);
61    }
62
63    return literalValue(string.substring(start, end), stringValue.getEscapeMode(), stringValue
64        .isPartiallyEscaped()
65        || startValue.isPartiallyEscaped() || endValue.isPartiallyEscaped());
66  }
67}
68