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/*
* Copyright (c) 2017, Daniel Gultsch All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation and/or
* other materials provided with the distribution.
*
* 3. Neither the name of the copyright holder nor the names of its contributors
* may be used to endorse or promote products derived from this software without
* specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
* ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
* ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package de.pixart.messenger.utils;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
public class ImStyleParser {
private final static List<Character> KEYWORDS = Arrays.asList('*', '_', '~', '`');
private final static List<Character> NO_SUB_PARSING_KEYWORDS = Arrays.asList('`');
private final static List<Character> BLOCK_KEYWORDS = Arrays.asList('`');
private final static boolean ALLOW_EMPTY = false;
private final static boolean PARSE_HIGHER_ORDER_END = true;
public static List<Style> parse(CharSequence text) {
return parse(text, 0, text.length() - 1);
}
public static List<Style> parse(CharSequence text, int start, int end) {
List<Style> styles = new ArrayList<>();
for (int i = start; i <= end; ++i) {
char c = text.charAt(i);
if (KEYWORDS.contains(c) && precededByWhiteSpace(text, i, start) && !followedByWhitespace(text, i, end)) {
if (BLOCK_KEYWORDS.contains(c) && isCharRepeatedTwoTimes(text, c, i + 1, end)) {
int to = seekEndBlock(text, c, i + 3, end);
if (to != -1 && (to != i + 5 || ALLOW_EMPTY)) {
String keyword = String.valueOf(c) + String.valueOf(c) + String.valueOf(c);
styles.add(new Style(keyword, i, to));
i = to;
continue;
}
}
int to = seekEnd(text, c, i + 1, end);
if (to != -1 && (to != i + 1 || ALLOW_EMPTY)) {
styles.add(new Style(c, i, to));
if (!NO_SUB_PARSING_KEYWORDS.contains(c)) {
styles.addAll(parse(text, i + 1, to - 1));
}
i = to;
}
}
}
return styles;
}
private static boolean isCharRepeatedTwoTimes(CharSequence text, char c, int index, int end) {
return index + 1 <= end && text.charAt(index) == c && text.charAt(index + 1) == c;
}
private static boolean precededByWhiteSpace(CharSequence text, int index, int start) {
return index == start || Character.isWhitespace(text.charAt(index - 1));
}
private static boolean followedByWhitespace(CharSequence text, int index, int end) {
return index >= end || Character.isWhitespace(text.charAt(index + 1));
}
private static int seekEnd(CharSequence text, char needle, int start, int end) {
for (int i = start; i <= end; ++i) {
char c = text.charAt(i);
if (c == needle && !Character.isWhitespace(text.charAt(i - 1))) {
if (!PARSE_HIGHER_ORDER_END || followedByWhitespace(text, i, end)) {
return i;
} else {
int higherOrder = seekHigherOrderEndWithoutNewBeginning(text, needle, i + 1, end);
if (higherOrder != -1) {
return higherOrder;
}
return i;
}
} else if (c == '\n') {
return -1;
}
}
return -1;
}
private static int seekHigherOrderEndWithoutNewBeginning(CharSequence text, char needle, int start, int end) {
for (int i = start; i <= end; ++i) {
char c = text.charAt(i);
if (c == needle && precededByWhiteSpace(text, i, start) && !followedByWhitespace(text, i, end)) {
return -1; // new beginning
} else if (c == needle && !Character.isWhitespace(text.charAt(i - 1)) && followedByWhitespace(text, i, end)) {
return i;
} else if (c == '\n') {
return -1;
}
}
return -1;
}
private static int seekEndBlock(CharSequence text, char needle, int start, int end) {
for (int i = start; i <= end; ++i) {
char c = text.charAt(i);
if (c == needle && isCharRepeatedTwoTimes(text, needle, i + 1, end)) {
return i + 2;
}
}
return -1;
}
public static class Style {
private final String keyword;
private final int start;
private final int end;
public Style(char character, int start, int end) {
this(String.valueOf(character), start, end);
}
public Style(String keyword, int start, int end) {
this.keyword = keyword;
this.start = start;
this.end = end;
}
public String getKeyword() {
return keyword;
}
public int getStart() {
return start;
}
public int getEnd() {
return end;
}
}
}
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