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/*
* Copyright (C) 2009 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.android.inputmethod.latin;
import android.view.inputmethod.ExtractedText;
import android.view.inputmethod.ExtractedTextRequest;
import android.view.inputmethod.InputConnection;
import java.util.regex.Pattern;
/**
* Utility methods to deal with editing text through an InputConnection.
*/
public class EditingUtils {
/**
* Number of characters we want to look back in order to identify the previous word
*/
// Provision for a long word pair and a separator
private static final int LOOKBACK_CHARACTER_NUM = BinaryDictionary.MAX_WORD_LENGTH * 2 + 1;
private static final int INVALID_CURSOR_POSITION = -1;
private EditingUtils() {
// Unintentional empty constructor for singleton.
}
private static int getCursorPosition(InputConnection connection) {
if (null == connection) return INVALID_CURSOR_POSITION;
final ExtractedText extracted = connection.getExtractedText(new ExtractedTextRequest(), 0);
if (extracted == null) {
return INVALID_CURSOR_POSITION;
}
return extracted.startOffset + extracted.selectionStart;
}
/**
* @param connection connection to the current text field.
* @param separators characters which may separate words
* @return the word that surrounds the cursor, including up to one trailing
* separator. For example, if the field contains "he|llo world", where |
* represents the cursor, then "hello " will be returned.
*/
public static String getWordAtCursor(InputConnection connection, String separators) {
// getWordRangeAtCursor returns null if the connection is null
Range r = getWordRangeAtCursor(connection, separators);
return (r == null) ? null : r.mWord;
}
/**
* Represents a range of text, relative to the current cursor position.
*/
public static class Range {
/** Characters before selection start */
public final int mCharsBefore;
/**
* Characters after selection start, including one trailing word
* separator.
*/
public final int mCharsAfter;
/** The actual characters that make up a word */
public final String mWord;
public Range(int charsBefore, int charsAfter, String word) {
if (charsBefore < 0 || charsAfter < 0) {
throw new IndexOutOfBoundsException();
}
this.mCharsBefore = charsBefore;
this.mCharsAfter = charsAfter;
this.mWord = word;
}
}
private static Range getWordRangeAtCursor(InputConnection connection, String sep) {
if (connection == null || sep == null) {
return null;
}
CharSequence before = connection.getTextBeforeCursor(1000, 0);
CharSequence after = connection.getTextAfterCursor(1000, 0);
if (before == null || after == null) {
return null;
}
// Find first word separator before the cursor
int start = before.length();
while (start > 0 && !isWhitespace(before.charAt(start - 1), sep)) start--;
// Find last word separator after the cursor
int end = -1;
while (++end < after.length() && !isWhitespace(after.charAt(end), sep)) {
// Nothing to do here.
}
int cursor = getCursorPosition(connection);
if (start >= 0 && cursor + end <= after.length() + before.length()) {
String word = before.toString().substring(start, before.length())
+ after.toString().substring(0, end);
return new Range(before.length() - start, end, word);
}
return null;
}
private static boolean isWhitespace(int code, String whitespace) {
return whitespace.contains(String.valueOf((char) code));
}
private static final Pattern spaceRegex = Pattern.compile("\\s+");
public static CharSequence getPreviousWord(InputConnection connection,
String sentenceSeperators) {
//TODO: Should fix this. This could be slow!
if (null == connection) return null;
CharSequence prev = connection.getTextBeforeCursor(LOOKBACK_CHARACTER_NUM, 0);
return getPreviousWord(prev, sentenceSeperators);
}
// Get the word before the whitespace preceding the non-whitespace preceding the cursor.
// Also, it won't return words that end in a separator.
// Example :
// "abc def|" -> abc
// "abc def |" -> abc
// "abc def. |" -> abc
// "abc def . |" -> def
// "abc|" -> null
// "abc |" -> null
// "abc. def|" -> null
public static CharSequence getPreviousWord(CharSequence prev, String sentenceSeperators) {
if (prev == null) return null;
String[] w = spaceRegex.split(prev);
// If we can't find two words, or we found an empty word, return null.
if (w.length < 2 || w[w.length - 2].length() <= 0) return null;
// If ends in a separator, return null
char lastChar = w[w.length - 2].charAt(w[w.length - 2].length() - 1);
if (sentenceSeperators.contains(String.valueOf(lastChar))) return null;
return w[w.length - 2];
}
public static CharSequence getThisWord(InputConnection connection, String sentenceSeperators) {
if (null == connection) return null;
final CharSequence prev = connection.getTextBeforeCursor(LOOKBACK_CHARACTER_NUM, 0);
return getThisWord(prev, sentenceSeperators);
}
// Get the word immediately before the cursor, even if there is whitespace between it and
// the cursor - but not if there is punctuation.
// Example :
// "abc def|" -> def
// "abc def |" -> def
// "abc def. |" -> null
// "abc def . |" -> null
public static CharSequence getThisWord(CharSequence prev, String sentenceSeperators) {
if (prev == null) return null;
String[] w = spaceRegex.split(prev);
// No word : return null
if (w.length < 1 || w[w.length - 1].length() <= 0) return null;
// If ends in a separator, return null
char lastChar = w[w.length - 1].charAt(w[w.length - 1].length() - 1);
if (sentenceSeperators.contains(String.valueOf(lastChar))) return null;
return w[w.length - 1];
}
}
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