| /* |
| ******************************************************************************* |
| * Copyright (C) 1996-2008, International Business Machines Corporation and * |
| * others. All Rights Reserved. * |
| ******************************************************************************* |
| */ |
| |
| package com.ibm.icu.text; |
| |
| import java.text.CharacterIterator; |
| import java.text.StringCharacterIterator; |
| import java.util.Locale; |
| |
| import com.ibm.icu.util.ULocale; |
| |
| /** |
| * A class that locates boundaries in text. This class defines a protocol for |
| * objects that break up a piece of natural-language text according to a set |
| * of criteria. Instances or subclasses of BreakIterator can be provided, for |
| * example, to break a piece of text into words, sentences, or logical characters |
| * according to the conventions of some language or group of languages. |
| * |
| * We provide five built-in types of BreakIterator: |
| * <ul><li>getTitleInstance() returns a BreakIterator that locates boundaries |
| * between title breaks. |
| * <li>getSentenceInstance() returns a BreakIterator that locates boundaries |
| * between sentences. This is useful for triple-click selection, for example. |
| * <li>getWordInstance() returns a BreakIterator that locates boundaries between |
| * words. This is useful for double-click selection or "find whole words" searches. |
| * This type of BreakIterator makes sure there is a boundary position at the |
| * beginning and end of each legal word. (Numbers count as words, too.) Whitespace |
| * and punctuation are kept separate from real words. |
| * <li>getLineInstance() returns a BreakIterator that locates positions where it is |
| * legal for a text editor to wrap lines. This is similar to word breaking, but |
| * not the same: punctuation and whitespace are generally kept with words (you don't |
| * want a line to start with whitespace, for example), and some special characters |
| * can force a position to be considered a line-break position or prevent a position |
| * from being a line-break position. |
| * <li>getCharacterInstance() returns a BreakIterator that locates boundaries between |
| * logical characters. Because of the structure of the Unicode encoding, a logical |
| * character may be stored internally as more than one Unicode code point. (A with an |
| * umlaut may be stored as an a followed by a separate combining umlaut character, |
| * for example, but the user still thinks of it as one character.) This iterator allows |
| * various processes (especially text editors) to treat as characters the units of text |
| * that a user would think of as characters, rather than the units of text that the |
| * computer sees as "characters".</ul> |
| * |
| * BreakIterator's interface follows an "iterator" model (hence the name), meaning it |
| * has a concept of a "current position" and methods like first(), last(), next(), |
| * and previous() that update the current position. All BreakIterators uphold the |
| * following invariants: |
| * <ul><li>The beginning and end of the text are always treated as boundary positions. |
| * <li>The current position of the iterator is always a boundary position (random- |
| * access methods move the iterator to the nearest boundary position before or |
| * after the specified position, not _to_ the specified position). |
| * <li>DONE is used as a flag to indicate when iteration has stopped. DONE is only |
| * returned when the current position is the end of the text and the user calls next(), |
| * or when the current position is the beginning of the text and the user calls |
| * previous(). |
| * <li>Break positions are numbered by the positions of the characters that follow |
| * them. Thus, under normal circumstances, the position before the first character |
| * is 0, the position after the first character is 1, and the position after the |
| * last character is 1 plus the length of the string. |
| * <li>The client can change the position of an iterator, or the text it analyzes, |
| * at will, but cannot change the behavior. If the user wants different behavior, he |
| * must instantiate a new iterator.</ul> |
| * |
| * BreakIterator accesses the text it analyzes through a CharacterIterator, which makes |
| * it possible to use BreakIterator to analyze text in any text-storage vehicle that |
| * provides a CharacterIterator interface. |
| * |
| * <b>NOTE:</b> Some types of BreakIterator can take a long time to create, and |
| * instances of BreakIterator are not currently cached by the system. For |
| * optimal performance, keep instances of BreakIterator around as long as makes |
| * sense. For example, when word-wrapping a document, don't create and destroy a |
| * new BreakIterator for each line. Create one break iterator for the whole document |
| * (or whatever stretch of text you're wrapping) and use it to do the whole job of |
| * wrapping the text. |
| * |
| * <P> |
| * <strong>Examples</strong>:<P> |
| * Creating and using text boundaries |
| * <blockquote> |
| * <pre> |
| * public static void main(String args[]) { |
| * if (args.length == 1) { |
| * String stringToExamine = args[0]; |
| * //print each word in order |
| * BreakIterator boundary = BreakIterator.getWordInstance(); |
| * boundary.setText(stringToExamine); |
| * printEachForward(boundary, stringToExamine); |
| * //print each sentence in reverse order |
| * boundary = BreakIterator.getSentenceInstance(Locale.US); |
| * boundary.setText(stringToExamine); |
| * printEachBackward(boundary, stringToExamine); |
| * printFirst(boundary, stringToExamine); |
| * printLast(boundary, stringToExamine); |
| * } |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Print each element in order |
| * <blockquote> |
| * <pre> |
| * public static void printEachForward(BreakIterator boundary, String source) { |
| * int start = boundary.first(); |
| * for (int end = boundary.next(); |
| * end != BreakIterator.DONE; |
| * start = end, end = boundary.next()) { |
| * System.out.println(source.substring(start,end)); |
| * } |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Print each element in reverse order |
| * <blockquote> |
| * <pre> |
| * public static void printEachBackward(BreakIterator boundary, String source) { |
| * int end = boundary.last(); |
| * for (int start = boundary.previous(); |
| * start != BreakIterator.DONE; |
| * end = start, start = boundary.previous()) { |
| * System.out.println(source.substring(start,end)); |
| * } |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Print first element |
| * <blockquote> |
| * <pre> |
| * public static void printFirst(BreakIterator boundary, String source) { |
| * int start = boundary.first(); |
| * int end = boundary.next(); |
| * System.out.println(source.substring(start,end)); |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Print last element |
| * <blockquote> |
| * <pre> |
| * public static void printLast(BreakIterator boundary, String source) { |
| * int end = boundary.last(); |
| * int start = boundary.previous(); |
| * System.out.println(source.substring(start,end)); |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Print the element at a specified position |
| * <blockquote> |
| * <pre> |
| * public static void printAt(BreakIterator boundary, int pos, String source) { |
| * int end = boundary.following(pos); |
| * int start = boundary.previous(); |
| * System.out.println(source.substring(start,end)); |
| * } |
| * </pre> |
| * </blockquote> |
| * |
| * Find the next word |
| * <blockquote> |
| * <pre> |
| * public static int nextWordStartAfter(int pos, String text) { |
| * BreakIterator wb = BreakIterator.getWordInstance(); |
| * wb.setText(text); |
| * int last = wb.following(pos); |
| * int current = wb.next(); |
| * while (current != BreakIterator.DONE) { |
| * for (int p = last; p < current; p++) { |
| * if (Character.isLetter(text.charAt(p)) |
| * return last; |
| * } |
| * last = current; |
| * current = wb.next(); |
| * } |
| * return BreakIterator.DONE; |
| * } |
| * </pre> |
| * (The iterator returned by BreakIterator.getWordInstance() is unique in that |
| * the break positions it returns don't represent both the start and end of the |
| * thing being iterated over. That is, a sentence-break iterator returns breaks |
| * that each represent the end of one sentence and the beginning of the next. |
| * With the word-break iterator, the characters between two boundaries might be a |
| * word, or they might be the punctuation or whitespace between two words. The |
| * above code uses a simple heuristic to determine which boundary is the beginning |
| * of a word: If the characters between this boundary and the next boundary |
| * include at least one letter (this can be an alphabetical letter, a CJK ideograph, |
| * a Hangul syllable, a Kana character, etc.), then the text between this boundary |
| * and the next is a word; otherwise, it's the material between words.) |
| * </blockquote> |
| * |
| * @see CharacterIterator |
| * @stable ICU 2.0 |
| * |
| */ |
| public abstract class BreakIterator implements Cloneable { |
| |
| protected BreakIterator() { |
| } |
| |
| /** |
| * Create a copy of this iterator |
| * @return A copy of this |
| */ |
| public Object clone() { |
| // this is here for subclass use. we must override it ourselves, though. |
| try { |
| return super.clone(); |
| } |
| catch (CloneNotSupportedException e) { |
| throw new InternalError(); |
| } |
| } |
| |
| /** |
| * DONE is returned by previous() and next() after all valid |
| * boundaries have been returned. |
| * @stable ICU 2.0 |
| */ |
| public static final int DONE = -1; |
| |
| /** |
| * Return the first boundary position. This is always the beginning |
| * index of the text this iterator iterates over. For example, if |
| * the iterator iterates over a whole string, this function will |
| * always return 0. This function also updates the iteration position |
| * to point to the beginning of the text. |
| * @return The character offset of the beginning of the stretch of text |
| * being broken. |
| * @stable ICU 2.0 |
| */ |
| public abstract int first(); |
| |
| /** |
| * Return the last boundary position. This is always the "past-the-end" |
| * index of the text this iterator iterates over. For example, if the |
| * iterator iterates over a whole string (call it "text"), this function |
| * will always return text.length(). This function also updated the |
| * iteration position to point to the end of the text. |
| * @return The character offset of the end of the stretch of text |
| * being broken. |
| * @stable ICU 2.0 |
| */ |
| public abstract int last(); |
| |
| /** |
| * Advances the specified number of steps forward in the text (a negative |
| * number, therefore, advances backwards). If this causes the iterator |
| * to advance off either end of the text, this function returns DONE; |
| * otherwise, this function returns the position of the appropriate |
| * boundary. Calling this function is equivalent to calling next() or |
| * previous() n times. |
| * @param n The number of boundaries to advance over (if positive, moves |
| * forward; if negative, moves backwards). |
| * @return The position of the boundary n boundaries from the current |
| * iteration position, or DONE if moving n boundaries causes the iterator |
| * to advance off either end of the text. |
| * @stable ICU 2.0 |
| */ |
| public abstract int next(int n); |
| |
| /** |
| * Advances the iterator forward one boundary. The current iteration |
| * position is updated to point to the next boundary position after the |
| * current position, and this is also the value that is returned. If |
| * the current position is equal to the value returned by last(), or to |
| * DONE, this function returns DONE and sets the current position to |
| * DONE. |
| * @return The position of the first boundary position following the |
| * iteration position. |
| * @stable ICU 2.0 |
| */ |
| public abstract int next(); |
| |
| /** |
| * Advances the iterator backward one boundary. The current iteration |
| * position is updated to point to the last boundary position before |
| * the current position, and this is also the value that is returned. If |
| * the current position is equal to the value returned by first(), or to |
| * DONE, this function returns DONE and sets the current position to |
| * DONE. |
| * @return The position of the last boundary position preceding the |
| * iteration position. |
| * @stable ICU 2.0 |
| */ |
| public abstract int previous(); |
| |
| /** |
| * Sets the iterator's current iteration position to be the first |
| * boundary position following the specified position. (Whether the |
| * specified position is itself a boundary position or not doesn't |
| * matter-- this function always moves the iteration position to the |
| * first boundary after the specified position.) If the specified |
| * position is the past-the-end position, returns DONE. |
| * @param offset The character position to start searching from. |
| * @return The position of the first boundary position following |
| * "offset" (whether or not "offset" itself is a boundary position), |
| * or DONE if "offset" is the past-the-end offset. |
| * @stable ICU 2.0 |
| */ |
| public abstract int following(int offset); |
| |
| /** |
| * Sets the iterator's current iteration position to be the last |
| * boundary position preceding the specified position. (Whether the |
| * specified position is itself a boundary position or not doesn't |
| * matter-- this function always moves the iteration position to the |
| * last boundary before the specified position.) If the specified |
| * position is the starting position, returns DONE. |
| * @param offset The character position to start searching from. |
| * @return The position of the last boundary position preceding |
| * "offset" (whether of not "offset" itself is a boundary position), |
| * or DONE if "offset" is the starting offset of the iterator. |
| * @stable ICU 2.0 |
| */ |
| public int preceding(int offset) { |
| int pos = following(offset); |
| while (pos >= offset && pos != DONE) { |
| pos = previous(); |
| } |
| return pos; |
| } |
| |
| /** |
| * Return true if the specfied position is a boundary position. If the |
| * function returns true, the current iteration position is set to the |
| * specified position; if the function returns false, the current |
| * iteration position is set as though following() had been called. |
| * @param offset the offset to check. |
| * @return True if "offset" is a boundary position. |
| * @stable ICU 2.0 |
| */ |
| public boolean isBoundary(int offset) { |
| return offset == 0 || following(offset - 1) == offset; |
| } |
| |
| /** |
| * Return the iterator's current position. |
| * @return The iterator's current position. |
| * @stable ICU 2.0 |
| */ |
| public abstract int current(); |
| |
| /** |
| * Returns a CharacterIterator over the text being analyzed. |
| * For at least some subclasses of BreakIterator, this is a reference |
| * to the <b>actual iterator being used</b> by the BreakIterator, |
| * and therefore, this function's return value should be treated as |
| * <tt>const</tt>. No guarantees are made about the current position |
| * of this iterator when it is returned. If you need to move that |
| * position to examine the text, clone this function's return value first. |
| * @return A CharacterIterator over the text being analyzed. |
| * @stable ICU 2.0 |
| */ |
| public abstract CharacterIterator getText(); |
| |
| /** |
| * Sets the iterator to analyze a new piece of text. The new |
| * piece of text is passed in as a String, and the current |
| * iteration position is reset to the beginning of the string. |
| * (The old text is dropped.) |
| * @param newText A String containing the text to analyze with |
| * this BreakIterator. |
| * @stable ICU 2.0 |
| */ |
| public void setText(String newText) { |
| setText(new StringCharacterIterator(newText)); |
| } |
| |
| /** |
| * Sets the iterator to analyze a new piece of text. The |
| * BreakIterator is passed a CharacterIterator through which |
| * it will access the text itself. The current iteration |
| * position is reset to the CharacterIterator's start index. |
| * (The old iterator is dropped.) |
| * @param newText A CharacterIterator referring to the text |
| * to analyze with this BreakIterator (the iterator's current |
| * position is ignored, but its other state is significant). |
| * @stable ICU 2.0 |
| */ |
| public abstract void setText(CharacterIterator newText); |
| |
| /** @stable ICU 2.4 */ |
| public static final int KIND_CHARACTER = 0; |
| /** @stable ICU 2.4 */ |
| public static final int KIND_WORD = 1; |
| /** @stable ICU 2.4 */ |
| public static final int KIND_LINE = 2; |
| /** @stable ICU 2.4 */ |
| public static final int KIND_SENTENCE = 3; |
| /** @stable ICU 2.4 */ |
| public static final int KIND_TITLE = 4; |
| |
| /** |
| * Returns a new instance of BreakIterator that locates word boundaries. |
| * This function assumes that the text being analyzed is in the default |
| * locale's language. |
| * @return An instance of BreakIterator that locates word boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getWordInstance() { |
| return getWordInstance(Locale.getDefault()); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates word boundaries. |
| * @param where A locale specifying the language of the text to be |
| * analyzed. |
| * @return An instance of BreakIterator that locates word boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getWordInstance(Locale where) { |
| return getBreakInstance(where, KIND_WORD); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates word boundaries. |
| * @param where A locale specifying the language of the text to be |
| * analyzed. |
| * @return An instance of BreakIterator that locates word boundaries. |
| * @stable ICU 3.4.3 |
| */ |
| public static BreakIterator getWordInstance(ULocale where) { |
| return getBreakInstance(where.toLocale(), KIND_WORD); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates legal line- |
| * wrapping positions. This function assumes the text being broken |
| * is in the default locale's language. |
| * @return A new instance of BreakIterator that locates legal |
| * line-wrapping positions. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getLineInstance() { |
| return getLineInstance(Locale.getDefault()); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates legal line- |
| * wrapping positions. |
| * @param where A Locale specifying the language of the text being broken. |
| * @return A new instance of BreakIterator that locates legal |
| * line-wrapping positions. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getLineInstance(Locale where) { |
| return getBreakInstance(where, KIND_LINE); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates legal line- |
| * wrapping positions. |
| * @param where A Locale specifying the language of the text being broken. |
| * @return A new instance of BreakIterator that locates legal |
| * line-wrapping positions. |
| * @stable ICU 3.4.3 |
| */ |
| public static BreakIterator getLineInstance(ULocale where) { |
| return getBreakInstance(where.toLocale(), KIND_LINE); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates logical-character |
| * boundaries. This function assumes that the text being analyzed is |
| * in the default locale's language. |
| * @return A new instance of BreakIterator that locates logical-character |
| * boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getCharacterInstance() { |
| return getCharacterInstance(Locale.getDefault()); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates logical-character |
| * boundaries. |
| * @param where A Locale specifying the language of the text being analyzed. |
| * @return A new instance of BreakIterator that locates logical-character |
| * boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getCharacterInstance(Locale where) { |
| return getBreakInstance(where, KIND_CHARACTER); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates logical-character |
| * boundaries. |
| * @param where A Locale specifying the language of the text being analyzed. |
| * @return A new instance of BreakIterator that locates logical-character |
| * boundaries. |
| * @stable ICU 3.2 |
| */ |
| public static BreakIterator getCharacterInstance(ULocale where) { |
| return getBreakInstance(where.toLocale(), KIND_CHARACTER); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates sentence boundaries. |
| * This function assumes the text being analyzed is in the default locale's |
| * language. |
| * @return A new instance of BreakIterator that locates sentence boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getSentenceInstance() { |
| return getSentenceInstance(Locale.getDefault()); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates sentence boundaries. |
| * @param where A Locale specifying the language of the text being analyzed. |
| * @return A new instance of BreakIterator that locates sentence boundaries. |
| * @stable ICU 2.0 |
| */ |
| public static BreakIterator getSentenceInstance(Locale where) { |
| return getBreakInstance(where, KIND_SENTENCE); |
| } |
| |
| /** |
| * Returns a new instance of BreakIterator that locates sentence boundaries. |
| * @param where A Locale specifying the language of the text being analyzed. |
| * @return A new instance of BreakIterator that locates sentence boundaries. |
| * @stable ICU 3.4.3 |
| */ |
| public static BreakIterator getSentenceInstance(ULocale where) { |
| return getBreakInstance(where.toLocale(), KIND_SENTENCE); |
| } |
| |
| private static BreakIterator getBreakInstance(Locale where, int kind) { |
| java.text.BreakIterator br = null; |
| switch(kind) { |
| case KIND_CHARACTER: br = java.text.BreakIterator.getCharacterInstance(where); break; |
| case KIND_WORD: br = java.text.BreakIterator.getWordInstance(where); break; |
| case KIND_LINE: br = java.text.BreakIterator.getLineInstance(where); break; |
| case KIND_SENTENCE: br = java.text.BreakIterator.getSentenceInstance(where); break; |
| case KIND_TITLE: throw new UnsupportedOperationException(); |
| } |
| return new BreakIteratorHandle(br); |
| } |
| |
| /** |
| * Returns a list of locales for which BreakIterators can be used. |
| * @return An array of Locales. All of the locales in the array can |
| * be used when creating a BreakIterator. |
| * @stable ICU 3.4.3 |
| */ |
| public static synchronized Locale[] getAvailableLocales() { |
| return java.text.BreakIterator.getAvailableLocales(); |
| } |
| |
| /** |
| * Returns a list of locales for which BreakIterators can be used. |
| * @return An array of ULocales. All of the locales in the array can |
| * be used when creating a BreakIterator. |
| * @stable ICU 3.4.3 |
| */ |
| public static synchronized ULocale[] getAvailableULocales() { |
| Locale[] locales = java.text.BreakIterator.getAvailableLocales(); |
| ULocale[] ulocales = new ULocale[locales.length]; |
| for (int i = 0; i < locales.length; ++i) { |
| ulocales[i] = ULocale.forLocale(locales[i]); |
| } |
| return ulocales; |
| } |
| |
| // forwarding implementation class |
| static final class BreakIteratorHandle extends BreakIterator { |
| /** |
| * @internal |
| */ |
| public final java.text.BreakIterator breakIterator; |
| |
| /** |
| * @internal |
| * @param delegate the BreakIterator to which to delegate |
| */ |
| public BreakIteratorHandle(java.text.BreakIterator delegate) { |
| this.breakIterator = delegate; |
| } |
| |
| public int first() { |
| return breakIterator.first(); |
| } |
| public int last() { |
| return breakIterator.last(); |
| } |
| public int next(int n) { |
| return breakIterator.next(n); |
| } |
| public int next() { |
| return breakIterator.next(); |
| } |
| public int previous() { |
| return breakIterator.previous(); |
| } |
| public int following(int offset) { |
| return breakIterator.following(offset); |
| } |
| public int preceding(int offset) { |
| return breakIterator.preceding(offset); |
| } |
| public boolean isBoundary(int offset) { |
| return breakIterator.isBoundary(offset); |
| } |
| public int current() { |
| return breakIterator.current(); |
| } |
| public CharacterIterator getText() { |
| return breakIterator.getText(); |
| } |
| public void setText(CharacterIterator newText) { |
| breakIterator.setText(newText); |
| } |
| |
| /** |
| * Return a string suitable for debugging. |
| * @return a string suitable for debugging |
| * @stable ICU 3.4.3 |
| */ |
| public String toString() { |
| return breakIterator.toString(); |
| } |
| |
| /** |
| * Return a clone of this BreakIterator. |
| * @return a clone of this BreakIterator |
| * @stable ICU 3.4.3 |
| */ |
| public Object clone() { |
| return new BreakIteratorHandle((java.text.BreakIterator)breakIterator.clone()); |
| } |
| |
| /** |
| * Return true if rhs is a BreakIterator with the same break behavior as this. |
| * @return true if rhs equals this |
| * @stable ICU 3.4.3 |
| */ |
| public boolean equals(Object rhs) { |
| try { |
| return breakIterator.equals(((BreakIteratorHandle)rhs).breakIterator); |
| } |
| catch (Exception e) { |
| return false; |
| } |
| } |
| |
| /** |
| * Return a hashCode. |
| * @return a hashCode |
| * @stable ICU 3.4.3 |
| */ |
| public int hashCode() { |
| return breakIterator.hashCode(); |
| } |
| } |
| } |
