1/*
2 * Copyright (c) 2017, Daniel Gultsch All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without modification,
5 * are permitted provided that the following conditions are met:
6 *
7 * 1. Redistributions of source code must retain the above copyright notice, this
8 * list of conditions and the following disclaimer.
9 *
10 * 2. Redistributions in binary form must reproduce the above copyright notice,
11 * this list of conditions and the following disclaimer in the documentation and/or
12 * other materials provided with the distribution.
13 *
14 * 3. Neither the name of the copyright holder nor the names of its contributors
15 * may be used to endorse or promote products derived from this software without
16 * specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
20 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
21 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
22 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
24 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
25 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
27 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30package eu.siacs.conversations.utils;
31
32import java.util.ArrayList;
33import java.util.Arrays;
34import java.util.List;
35
36public class ImStyleParser {
37
38 final static List<Character> KEYWORDS = Arrays.asList('*', '_', '~', '`');
39 final static List<Character> NO_SUB_PARSING_KEYWORDS = Arrays.asList('`');
40 final static boolean ALLOW_EMPTY = false;
41
42 public static List<Style> parse(CharSequence text) {
43 return parse(text, 0, text.length() - 1);
44 }
45
46 public static List<Style> parse(CharSequence text, int start, int end) {
47 List<Style> styles = new ArrayList<>();
48 for (int i = start; i <= end; ++i) {
49 char c = text.charAt(i);
50 if (KEYWORDS.contains(c) && precededByWhiteSpace(text, i, start) && !followedByWhitespace(text, i, end)) {
51 int to = seekEnd(text, c, i + 1, end);
52 if (to != -1 && (to != i + 1 || ALLOW_EMPTY)) {
53 styles.add(new Style(c, i, to));
54 if (!NO_SUB_PARSING_KEYWORDS.contains(c)) {
55 styles.addAll(parse(text, i + 1, to - 1));
56 }
57 i = to;
58 }
59 }
60 }
61 return styles;
62 }
63
64 private static boolean precededByWhiteSpace(CharSequence text, int index, int start) {
65 return index == start || Character.isWhitespace(text.charAt(index - 1));
66 }
67
68 private static boolean followedByWhitespace(CharSequence text, int index, int end) {
69 return index >= end || Character.isWhitespace(text.charAt(index + 1));
70 }
71
72 private static int seekEnd(CharSequence text, char needle, int start, int end) {
73 for (int i = start; i <= end; ++i) {
74 char c = text.charAt(i);
75 if (c == needle) {
76 return i;
77 } else if (c == '\n') {
78 return -1;
79 }
80 }
81 return -1;
82 }
83
84 public static class Style {
85
86 private final char c;
87 private final int start;
88 private final int end;
89
90 public Style(char c, int start, int end) {
91 this.c = c;
92 this.start = start;
93 this.end = end;
94 }
95
96 public char getCharacter() {
97 return c;
98 }
99
100 public int getStart() {
101 return start;
102 }
103
104 public int getEnd() {
105 return end;
106 }
107 }
108}