/* * Copyright (c) 1999, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved * (C) Copyright IBM Corp. 1996 - 2002 - All Rights Reserved * * The original version of this source code and documentation * is copyrighted and owned by Taligent, Inc., a wholly-owned * subsidiary of IBM. These materials are provided under terms * of a License Agreement between Taligent and Sun. This technology * is protected by multiple US and International patents. * * This notice and attribution to Taligent may not be removed. * Taligent is a registered trademark of Taligent, Inc. */ package java.text; import java.io.BufferedInputStream; import java.io.IOException; import java.security.AccessController; import java.security.PrivilegedActionException; import java.security.PrivilegedExceptionAction; import java.util.Vector; import java.util.Stack; import java.util.Hashtable; import java.util.Enumeration; import java.util.MissingResourceException; import java.text.CharacterIterator; import java.text.StringCharacterIterator; import sun.text.CompactByteArray; import sun.text.SupplementaryCharacterData; /** *

A subclass of BreakIterator whose behavior is specified using a list of rules.

* *

There are two kinds of rules, which are separated by semicolons: substitutions * and regular expressions.

* *

A substitution rule defines a name that can be used in place of an expression. It * consists of a name, which is a string of characters contained in angle brackets, an equals * sign, and an expression. (There can be no whitespace on either side of the equals sign.) * To keep its syntactic meaning intact, the expression must be enclosed in parentheses or * square brackets. A substitution is visible after its definition, and is filled in using * simple textual substitution. Substitution definitions can contain other substitutions, as * long as those substitutions have been defined first. Substitutions are generally used to * make the regular expressions (which can get quite complex) shorted and easier to read. * They typically define either character categories or commonly-used subexpressions.

* *

There is one special substitution.  If the description defines a substitution * called "<ignore>", the expression must be a [] expression, and the * expression defines a set of characters (the "ignore characters") that * will be transparent to the BreakIterator.  A sequence of characters will break the * same way it would if any ignore characters it contains are taken out.  Break * positions never occur befoer ignore characters.

* *

A regular expression uses a subset of the normal Unix regular-expression syntax, and * defines a sequence of characters to be kept together. With one significant exception, the * iterator uses a longest-possible-match algorithm when matching text to regular * expressions. The iterator also treats descriptions containing multiple regular expressions * as if they were ORed together (i.e., as if they were separated by |).

* *

The special characters recognized by the regular-expression parser are as follows:

* *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
*Specifies that the expression preceding the asterisk may occur any number * of times (including not at all).
{}Encloses a sequence of characters that is optional.
()Encloses a sequence of characters.  If followed by *, the sequence * repeats.  Otherwise, the parentheses are just a grouping device and a way to delimit * the ends of expressions containing |.
|Separates two alternative sequences of characters.  Either one * sequence or the other, but not both, matches this expression.  The | character can * only occur inside ().
.Matches any character.
*?Specifies a non-greedy asterisk.  *? works the same way as *, except * when there is overlap between the last group of characters in the expression preceding the * * and the first group of characters following the *.  When there is this kind of * overlap, * will match the longest sequence of characters that match the expression before * the *, and *? will match the shortest sequence of characters matching the expression * before the *?.  For example, if you have "xxyxyyyxyxyxxyxyxyy" in the text, * "x[xy]*x" will match through to the last x (i.e., "xxyxyyyxyxyxxyxyxyy", * but "x[xy]*?x" will only match the first two xes ("xxyxyyyxyxyxxyxyxyy").
[]Specifies a group of alternative characters.  A [] expression will * match any single character that is specified in the [] expression.  For more on the * syntax of [] expressions, see below.
/Specifies where the break position should go if text matches this * expression.  (e.g., "[a-z]*/[:Zs:]*[1-0]" will match if the iterator sees a run * of letters, followed by a run of whitespace, followed by a digit, but the break position * will actually go before the whitespace).  Expressions that don't contain / put the * break position at the end of the matching text.
\Escape character.  The \ itself is ignored, but causes the next * character to be treated as literal character.  This has no effect for many * characters, but for the characters listed above, this deprives them of their special * meaning.  (There are no special escape sequences for Unicode characters, or tabs and * newlines; these are all handled by a higher-level protocol.  In a Java string, * "\n" will be converted to a literal newline character by the time the * regular-expression parser sees it.  Of course, this means that \ sequences that are * visible to the regexp parser must be written as \\ when inside a Java string.)  All * characters in the ASCII range except for letters, digits, and control characters are * reserved characters to the parser and must be preceded by \ even if they currently don't * mean anything.
!If ! appears at the beginning of a regular expression, it tells the regexp * parser that this expression specifies the backwards-iteration behavior of the iterator, * and not its normal iteration behavior.  This is generally only used in situations * where the automatically-generated backwards-iteration brhavior doesn't produce * satisfactory results and must be supplemented with extra client-specified rules.
(all others)All other characters are treated as literal characters, which must match * the corresponding character(s) in the text exactly.
*
* *

Within a [] expression, a number of other special characters can be used to specify * groups of characters:

* *
* * * * * * * * * * * * * * * * * * * * * *
-Specifies a range of matching characters.  For example * "[a-p]" matches all lowercase Latin letters from a to p (inclusive).  The - * sign specifies ranges of continuous Unicode numeric values, not ranges of characters in a * language's alphabetical order: "[a-z]" doesn't include capital letters, nor does * it include accented letters such as a-umlaut.
::A pair of colons containing a one- or two-letter code matches all * characters in the corresponding Unicode category.  The two-letter codes are the same * as the two-letter codes in the Unicode database (for example, "[:Sc::Sm:]" * matches all currency symbols and all math symbols).  Specifying a one-letter code is * the same as specifying all two-letter codes that begin with that letter (for example, * "[:L:]" matches all letters, and is equivalent to * "[:Lu::Ll::Lo::Lm::Lt:]").  Anything other than a valid two-letter Unicode * category code or a single letter that begins a Unicode category code is illegal within * colons.
[][] expressions can nest.  This has no effect, except when used in * conjunction with the ^ token.
^Excludes the character (or the characters in the [] expression) following * it from the group of characters.  For example, "[a-z^p]" matches all Latin * lowercase letters except p.  "[:L:^[\u4e00-\u9fff]]" matches all letters * except the Han ideographs.
(all others)All other characters are treated as literal characters.  (For * example, "[aeiou]" specifies just the letters a, e, i, o, and u.)
*
* *

For a more complete explanation, see http://www.ibm.com/java/education/boundaries/boundaries.html. *   For examples, see the resource data (which is annotated).

* * @author Richard Gillam */ class RuleBasedBreakIterator extends BreakIterator { /** * A token used as a character-category value to identify ignore characters */ protected static final byte IGNORE = -1; /** * The state number of the starting state */ private static final short START_STATE = 1; /** * The state-transition value indicating "stop" */ private static final short STOP_STATE = 0; /** * Magic number for the BreakIterator data file format. */ static final byte[] LABEL = { (byte)'B', (byte)'I', (byte)'d', (byte)'a', (byte)'t', (byte)'a', (byte)'\0' }; static final int LABEL_LENGTH = LABEL.length; /** * Version number of the dictionary that was read in. */ static final byte supportedVersion = 1; /** * Header size in byte count */ private static final int HEADER_LENGTH = 36; /** * An array length of indices for BMP characters */ private static final int BMP_INDICES_LENGTH = 512; /** * Tables that indexes from character values to character category numbers */ private CompactByteArray charCategoryTable = null; private SupplementaryCharacterData supplementaryCharCategoryTable = null; /** * The table of state transitions used for forward iteration */ private short[] stateTable = null; /** * The table of state transitions used to sync up the iterator with the * text in backwards and random-access iteration */ private short[] backwardsStateTable = null; /** * A list of flags indicating which states in the state table are accepting * ("end") states */ private boolean[] endStates = null; /** * A list of flags indicating which states in the state table are * lookahead states (states which turn lookahead on and off) */ private boolean[] lookaheadStates = null; /** * A table for additional data. May be used by a subclass of * RuleBasedBreakIterator. */ private byte[] additionalData = null; /** * The number of character categories (and, thus, the number of columns in * the state tables) */ private int numCategories; /** * The character iterator through which this BreakIterator accesses the text */ private CharacterIterator text = null; /** * A CRC32 value of all data in datafile */ private long checksum; //======================================================================= // constructors //======================================================================= /** * Constructs a RuleBasedBreakIterator according to the datafile * provided. */ public RuleBasedBreakIterator(String datafile) throws IOException, MissingResourceException { readTables(datafile); } /** * Read datafile. The datafile's format is as follows: *
     *   BreakIteratorData {
     *       u1           magic[7];
     *       u1           version;
     *       u4           totalDataSize;
     *       header_info  header;
     *       body         value;
     *   }
     * 
* totalDataSize is the summation of the size of * header_info and body in byte count. *

* In header, each field except for checksum implies the * length of each field. Since BMPdataLength is a fixed-length * data(512 entries), its length isn't included in header. * checksum is a CRC32 value of all in body. *

     *   header_info {
     *       u4           stateTableLength;
     *       u4           backwardsStateTableLength;
     *       u4           endStatesLength;
     *       u4           lookaheadStatesLength;
     *       u4           BMPdataLength;
     *       u4           nonBMPdataLength;
     *       u4           additionalDataLength;
     *       u8           checksum;
     *   }
     * 
*

* * Finally, BMPindices and BMPdata are set to * charCategoryTable. nonBMPdata is set to * supplementaryCharCategoryTable. *

     *   body {
     *       u2           stateTable[stateTableLength];
     *       u2           backwardsStateTable[backwardsStateTableLength];
     *       u1           endStates[endStatesLength];
     *       u1           lookaheadStates[lookaheadStatesLength];
     *       u2           BMPindices[512];
     *       u1           BMPdata[BMPdataLength];
     *       u4           nonBMPdata[numNonBMPdataLength];
     *       u1           additionalData[additionalDataLength];
     *   }
     * 
*/ protected void readTables(String datafile) throws IOException, MissingResourceException { byte[] buffer = readFile(datafile); /* Read header_info. */ int stateTableLength = BreakIterator.getInt(buffer, 0); int backwardsStateTableLength = BreakIterator.getInt(buffer, 4); int endStatesLength = BreakIterator.getInt(buffer, 8); int lookaheadStatesLength = BreakIterator.getInt(buffer, 12); int BMPdataLength = BreakIterator.getInt(buffer, 16); int nonBMPdataLength = BreakIterator.getInt(buffer, 20); int additionalDataLength = BreakIterator.getInt(buffer, 24); checksum = BreakIterator.getLong(buffer, 28); /* Read stateTable[numCategories * numRows] */ stateTable = new short[stateTableLength]; int offset = HEADER_LENGTH; for (int i = 0; i < stateTableLength; i++, offset+=2) { stateTable[i] = BreakIterator.getShort(buffer, offset); } /* Read backwardsStateTable[numCategories * numRows] */ backwardsStateTable = new short[backwardsStateTableLength]; for (int i = 0; i < backwardsStateTableLength; i++, offset+=2) { backwardsStateTable[i] = BreakIterator.getShort(buffer, offset); } /* Read endStates[numRows] */ endStates = new boolean[endStatesLength]; for (int i = 0; i < endStatesLength; i++, offset++) { endStates[i] = buffer[offset] == 1; } /* Read lookaheadStates[numRows] */ lookaheadStates = new boolean[lookaheadStatesLength]; for (int i = 0; i < lookaheadStatesLength; i++, offset++) { lookaheadStates[i] = buffer[offset] == 1; } /* Read a category table and indices for BMP characters. */ short[] temp1 = new short[BMP_INDICES_LENGTH]; // BMPindices for (int i = 0; i < BMP_INDICES_LENGTH; i++, offset+=2) { temp1[i] = BreakIterator.getShort(buffer, offset); } byte[] temp2 = new byte[BMPdataLength]; // BMPdata System.arraycopy(buffer, offset, temp2, 0, BMPdataLength); offset += BMPdataLength; charCategoryTable = new CompactByteArray(temp1, temp2); /* Read a category table for non-BMP characters. */ int[] temp3 = new int[nonBMPdataLength]; for (int i = 0; i < nonBMPdataLength; i++, offset+=4) { temp3[i] = BreakIterator.getInt(buffer, offset); } supplementaryCharCategoryTable = new SupplementaryCharacterData(temp3); /* Read additional data */ if (additionalDataLength > 0) { additionalData = new byte[additionalDataLength]; System.arraycopy(buffer, offset, additionalData, 0, additionalDataLength); } /* Set numCategories */ numCategories = stateTable.length / endStates.length; } protected byte[] readFile(final String datafile) throws IOException, MissingResourceException { BufferedInputStream is; try { is = (BufferedInputStream)AccessController.doPrivileged( new PrivilegedExceptionAction() { public Object run() throws Exception { return new BufferedInputStream(getClass().getResourceAsStream("/sun/text/resources/" + datafile)); } } ); } catch (PrivilegedActionException e) { throw new InternalError(e.toString()); } int offset = 0; /* First, read magic, version, and header_info. */ int len = LABEL_LENGTH + 5; byte[] buf = new byte[len]; if (is.read(buf) != len) { throw new MissingResourceException("Wrong header length", datafile, ""); } /* Validate the magic number. */ for (int i = 0; i < LABEL_LENGTH; i++, offset++) { if (buf[offset] != LABEL[offset]) { throw new MissingResourceException("Wrong magic number", datafile, ""); } } /* Validate the version number. */ if (buf[offset] != supportedVersion) { throw new MissingResourceException("Unsupported version(" + buf[offset] + ")", datafile, ""); } /* Read data: totalDataSize + 8(for checksum) */ len = BreakIterator.getInt(buf, ++offset); buf = new byte[len]; if (is.read(buf) != len) { throw new MissingResourceException("Wrong data length", datafile, ""); } is.close(); return buf; } byte[] getAdditionalData() { return additionalData; } void setAdditionalData(byte[] b) { additionalData = b; } //======================================================================= // boilerplate //======================================================================= /** * Clones this iterator. * @return A newly-constructed RuleBasedBreakIterator with the same * behavior as this one. */ public Object clone() { RuleBasedBreakIterator result = (RuleBasedBreakIterator) super.clone(); if (text != null) { result.text = (CharacterIterator) text.clone(); } return result; } /** * Returns true if both BreakIterators are of the same class, have the same * rules, and iterate over the same text. */ public boolean equals(Object that) { try { if (that == null) { return false; } RuleBasedBreakIterator other = (RuleBasedBreakIterator) that; if (checksum != other.checksum) { return false; } if (text == null) { return other.text == null; } else { return text.equals(other.text); } } catch(ClassCastException e) { return false; } } /** * Returns text */ public String toString() { StringBuffer sb = new StringBuffer(); sb.append('['); sb.append("checksum=0x" + Long.toHexString(checksum)); sb.append(']'); return sb.toString(); } /** * Compute a hashcode for this BreakIterator * @return A hash code */ public int hashCode() { return (int)checksum; } //======================================================================= // BreakIterator overrides //======================================================================= /** * Sets the current iteration position to the beginning of the text. * (i.e., the CharacterIterator's starting offset). * @return The offset of the beginning of the text. */ public int first() { CharacterIterator t = getText(); t.first(); return t.getIndex(); } /** * Sets the current iteration position to the end of the text. * (i.e., the CharacterIterator's ending offset). * @return The text's past-the-end offset. */ public int last() { CharacterIterator t = getText(); // I'm not sure why, but t.last() returns the offset of the last character, // rather than the past-the-end offset t.setIndex(t.getEndIndex()); return t.getIndex(); } /** * Advances the iterator either forward or backward the specified number of steps. * Negative values move backward, and positive values move forward. This is * equivalent to repeatedly calling next() or previous(). * @param n The number of steps to move. The sign indicates the direction * (negative is backwards, and positive is forwards). * @return The character offset of the boundary position n boundaries away from * the current one. */ public int next(int n) { int result = current(); while (n > 0) { result = handleNext(); --n; } while (n < 0) { result = previous(); ++n; } return result; } /** * Advances the iterator to the next boundary position. * @return The position of the first boundary after this one. */ public int next() { return handleNext(); } private int cachedLastKnownBreak = BreakIterator.DONE; /** * Advances the iterator backwards, to the last boundary preceding this one. * @return The position of the last boundary position preceding this one. */ public int previous() { // if we're already sitting at the beginning of the text, return DONE CharacterIterator text = getText(); if (current() == text.getBeginIndex()) { return BreakIterator.DONE; } // set things up. handlePrevious() will back us up to some valid // break position before the current position (we back our internal // iterator up one step to prevent handlePrevious() from returning // the current position), but not necessarily the last one before // where we started int start = current(); int lastResult = cachedLastKnownBreak; if (lastResult >= start || lastResult <= BreakIterator.DONE) { getPrevious(); lastResult = handlePrevious(); } else { //it might be better to check if handlePrevious() give us closer //safe value but handlePrevious() is slow too //So, this has to be done carefully text.setIndex(lastResult); } int result = lastResult; // iterate forward from the known break position until we pass our // starting point. The last break position before the starting // point is our return value while (result != BreakIterator.DONE && result < start) { lastResult = result; result = handleNext(); } // set the current iteration position to be the last break position // before where we started, and then return that value text.setIndex(lastResult); cachedLastKnownBreak = lastResult; return lastResult; } /** * Returns previous character */ private int getPrevious() { char c2 = text.previous(); if (Character.isLowSurrogate(c2) && text.getIndex() > text.getBeginIndex()) { char c1 = text.previous(); if (Character.isHighSurrogate(c1)) { return Character.toCodePoint(c1, c2); } else { text.next(); } } return (int)c2; } /** * Returns current character */ int getCurrent() { char c1 = text.current(); if (Character.isHighSurrogate(c1) && text.getIndex() < text.getEndIndex()) { char c2 = text.next(); text.previous(); if (Character.isLowSurrogate(c2)) { return Character.toCodePoint(c1, c2); } } return (int)c1; } /** * Returns the count of next character. */ private int getCurrentCodePointCount() { char c1 = text.current(); if (Character.isHighSurrogate(c1) && text.getIndex() < text.getEndIndex()) { char c2 = text.next(); text.previous(); if (Character.isLowSurrogate(c2)) { return 2; } } return 1; } /** * Returns next character */ int getNext() { int index = text.getIndex(); int endIndex = text.getEndIndex(); if (index == endIndex || (index = index + getCurrentCodePointCount()) >= endIndex) { return CharacterIterator.DONE; } text.setIndex(index); return getCurrent(); } /** * Returns the position of next character. */ private int getNextIndex() { int index = text.getIndex() + getCurrentCodePointCount(); int endIndex = text.getEndIndex(); if (index > endIndex) { return endIndex; } else { return index; } } /** * Throw IllegalArgumentException unless begin <= offset < end. */ protected static final void checkOffset(int offset, CharacterIterator text) { if (offset < text.getBeginIndex() || offset > text.getEndIndex()) { throw new IllegalArgumentException("offset out of bounds"); } } /** * Sets the iterator to refer to the first boundary position following * the specified position. * @offset The position from which to begin searching for a break position. * @return The position of the first break after the current position. */ public int following(int offset) { CharacterIterator text = getText(); checkOffset(offset, text); // Set our internal iteration position (temporarily) // to the position passed in. If this is the _beginning_ position, // then we can just use next() to get our return value text.setIndex(offset); if (offset == text.getBeginIndex()) { cachedLastKnownBreak = handleNext(); return cachedLastKnownBreak; } // otherwise, we have to sync up first. Use handlePrevious() to back // us up to a known break position before the specified position (if // we can determine that the specified position is a break position, // we don't back up at all). This may or may not be the last break // position at or before our starting position. Advance forward // from here until we've passed the starting position. The position // we stop on will be the first break position after the specified one. int result = cachedLastKnownBreak; if (result >= offset || result <= BreakIterator.DONE) { result = handlePrevious(); } else { //it might be better to check if handlePrevious() give us closer //safe value but handlePrevious() is slow too //So, this has to be done carefully text.setIndex(result); } while (result != BreakIterator.DONE && result <= offset) { result = handleNext(); } cachedLastKnownBreak = result; return result; } /** * Sets the iterator to refer to the last boundary position before the * specified position. * @offset The position to begin searching for a break from. * @return The position of the last boundary before the starting position. */ public int preceding(int offset) { // if we start by updating the current iteration position to the // position specified by the caller, we can just use previous() // to carry out this operation CharacterIterator text = getText(); checkOffset(offset, text); text.setIndex(offset); return previous(); } /** * Returns true if the specfied position is a boundary position. As a side * effect, leaves the iterator pointing to the first boundary position at * or after "offset". * @param offset the offset to check. * @return True if "offset" is a boundary position. */ public boolean isBoundary(int offset) { CharacterIterator text = getText(); checkOffset(offset, text); if (offset == text.getBeginIndex()) { return true; } // to check whether this is a boundary, we can use following() on the // position before the specified one and return true if the position we // get back is the one the user specified else { return following(offset - 1) == offset; } } /** * Returns the current iteration position. * @return The current iteration position. */ public int current() { return getText().getIndex(); } /** * Return a CharacterIterator over the text being analyzed. This version * of this method returns the actual CharacterIterator we're using internally. * Changing the state of this iterator can have undefined consequences. If * you need to change it, clone it first. * @return An iterator over the text being analyzed. */ public CharacterIterator getText() { // The iterator is initialized pointing to no text at all, so if this // function is called while we're in that state, we have to fudge an // iterator to return. if (text == null) { text = new StringCharacterIterator(""); } return text; } /** * Set the iterator to analyze a new piece of text. This function resets * the current iteration position to the beginning of the text. * @param newText An iterator over the text to analyze. */ public void setText(CharacterIterator newText) { // Test iterator to see if we need to wrap it in a SafeCharIterator. // The correct behavior for CharacterIterators is to allow the // position to be set to the endpoint of the iterator. Many // CharacterIterators do not uphold this, so this is a workaround // to permit them to use this class. int end = newText.getEndIndex(); boolean goodIterator; try { newText.setIndex(end); // some buggy iterators throw an exception here goodIterator = newText.getIndex() == end; } catch(IllegalArgumentException e) { goodIterator = false; } if (goodIterator) { text = newText; } else { text = new SafeCharIterator(newText); } text.first(); cachedLastKnownBreak = BreakIterator.DONE; } //======================================================================= // implementation //======================================================================= /** * This method is the actual implementation of the next() method. All iteration * vectors through here. This method initializes the state machine to state 1 * and advances through the text character by character until we reach the end * of the text or the state machine transitions to state 0. We update our return * value every time the state machine passes through a possible end state. */ protected int handleNext() { // if we're already at the end of the text, return DONE. CharacterIterator text = getText(); if (text.getIndex() == text.getEndIndex()) { return BreakIterator.DONE; } // no matter what, we always advance at least one character forward int result = getNextIndex(); int lookaheadResult = 0; // begin in state 1 int state = START_STATE; int category; int c = getCurrent(); // loop until we reach the end of the text or transition to state 0 while (c != CharacterIterator.DONE && state != STOP_STATE) { // look up the current character's character category (which tells us // which column in the state table to look at) category = lookupCategory(c); // if the character isn't an ignore character, look up a state // transition in the state table if (category != IGNORE) { state = lookupState(state, category); } // if the state we've just transitioned to is a lookahead state, // (but not also an end state), save its position. If it's // both a lookahead state and an end state, update the break position // to the last saved lookup-state position if (lookaheadStates[state]) { if (endStates[state]) { result = lookaheadResult; } else { lookaheadResult = getNextIndex(); } } // otherwise, if the state we've just transitioned to is an accepting // state, update the break position to be the current iteration position else { if (endStates[state]) { result = getNextIndex(); } } c = getNext(); } // if we've run off the end of the text, and the very last character took us into // a lookahead state, advance the break position to the lookahead position // (the theory here is that if there are no characters at all after the lookahead // position, that always matches the lookahead criteria) if (c == CharacterIterator.DONE && lookaheadResult == text.getEndIndex()) { result = lookaheadResult; } text.setIndex(result); return result; } /** * This method backs the iterator back up to a "safe position" in the text. * This is a position that we know, without any context, must be a break position. * The various calling methods then iterate forward from this safe position to * the appropriate position to return. (For more information, see the description * of buildBackwardsStateTable() in RuleBasedBreakIterator.Builder.) */ protected int handlePrevious() { CharacterIterator text = getText(); int state = START_STATE; int category = 0; int lastCategory = 0; int c = getCurrent(); // loop until we reach the beginning of the text or transition to state 0 while (c != CharacterIterator.DONE && state != STOP_STATE) { // save the last character's category and look up the current // character's category lastCategory = category; category = lookupCategory(c); // if the current character isn't an ignore character, look up a // state transition in the backwards state table if (category != IGNORE) { state = lookupBackwardState(state, category); } // then advance one character backwards c = getPrevious(); } // if we didn't march off the beginning of the text, we're either one or two // positions away from the real break position. (One because of the call to // previous() at the end of the loop above, and another because the character // that takes us into the stop state will always be the character BEFORE // the break position.) if (c != CharacterIterator.DONE) { if (lastCategory != IGNORE) { getNext(); getNext(); } else { getNext(); } } return text.getIndex(); } /** * Looks up a character's category (i.e., its category for breaking purposes, * not its Unicode category) */ protected int lookupCategory(int c) { if (c < Character.MIN_SUPPLEMENTARY_CODE_POINT) { return charCategoryTable.elementAt((char)c); } else { return supplementaryCharCategoryTable.getValue(c); } } /** * Given a current state and a character category, looks up the * next state to transition to in the state table. */ protected int lookupState(int state, int category) { return stateTable[state * numCategories + category]; } /** * Given a current state and a character category, looks up the * next state to transition to in the backwards state table. */ protected int lookupBackwardState(int state, int category) { return backwardsStateTable[state * numCategories + category]; } /* * This class exists to work around a bug in incorrect implementations * of CharacterIterator, which incorrectly handle setIndex(endIndex). * This iterator relies only on base.setIndex(n) where n is less than * endIndex. * * One caveat: if the base iterator's begin and end indices change * the change will not be reflected by this wrapper. Does that matter? */ private static final class SafeCharIterator implements CharacterIterator, Cloneable { private CharacterIterator base; private int rangeStart; private int rangeLimit; private int currentIndex; SafeCharIterator(CharacterIterator base) { this.base = base; this.rangeStart = base.getBeginIndex(); this.rangeLimit = base.getEndIndex(); this.currentIndex = base.getIndex(); } public char first() { return setIndex(rangeStart); } public char last() { return setIndex(rangeLimit - 1); } public char current() { if (currentIndex < rangeStart || currentIndex >= rangeLimit) { return DONE; } else { return base.setIndex(currentIndex); } } public char next() { currentIndex++; if (currentIndex >= rangeLimit) { currentIndex = rangeLimit; return DONE; } else { return base.setIndex(currentIndex); } } public char previous() { currentIndex--; if (currentIndex < rangeStart) { currentIndex = rangeStart; return DONE; } else { return base.setIndex(currentIndex); } } public char setIndex(int i) { if (i < rangeStart || i > rangeLimit) { throw new IllegalArgumentException("Invalid position"); } currentIndex = i; return current(); } public int getBeginIndex() { return rangeStart; } public int getEndIndex() { return rangeLimit; } public int getIndex() { return currentIndex; } public Object clone() { SafeCharIterator copy = null; try { copy = (SafeCharIterator) super.clone(); } catch(CloneNotSupportedException e) { throw new Error("Clone not supported: " + e); } CharacterIterator copyOfBase = (CharacterIterator) base.clone(); copy.base = copyOfBase; return copy; } } }