Java example source code file (CharSet.java)
The CharSet.java Java example source code/*
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*
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*
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/*
* (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 build.tools.generatebreakiteratordata;
import java.util.Arrays;
import java.util.Hashtable;
/**
* An object representing a set of characters. (This is a "set" in the
* mathematical sense: an unduplicated list of characters on which set
* operations such as union and intersection can be performed.) The
* set information is stored in compressed, optimized form: The object
* contains an integer array with an even number of characters. Each
* pair of characters represents a range of characters contained in the set
* (a pair of the same character represents a single character). The
* characters are sorted in increasing order.
*/
class CharSet {
/**
* The structure containing the set information. The characters
* in this array are organized into pairs, each pair representing
* a range of characters contained in the set
*/
private int[] chars;
//==========================================================================
// parseString() and associated routines
//==========================================================================
/**
* A cache which is used to speed up parseString() whenever it is
* used to parse a description that has been parsed before
*/
private static Hashtable<String, CharSet> expressionCache = null;
/**
* Builds a CharSet based on a textual description. For the syntax of
* the description, see the documentation of RuleBasedBreakIterator.
* @see java.text.RuleBasedBreakIterator
*/
public static CharSet parseString(String s) {
CharSet result = null;
// if "s" is in the expression cache, pull the result out
// of the expresison cache
if (expressionCache != null) {
result = expressionCache.get(s);
}
// otherwise, use doParseString() to actually parse the string,
// and then add a corresponding entry to the expression cache
if (result == null) {
result = doParseString(s);
if (expressionCache == null) {
expressionCache = new Hashtable<>();
}
expressionCache.put(s, result);
}
result = (CharSet)(result.clone());
return result;
}
/**
* This function is used by parseString() to actually parse the string
*/
private static CharSet doParseString(String s) {
CharSet result = new CharSet();
int p = 0;
boolean haveDash = false;
boolean haveTilde = false;
boolean wIsReal = false;
int w = 0x0000;
// for each character in the description...
while (p < s.length()) {
int c = s.codePointAt(p);
// if it's an opening bracket...
if (c == '[') {
// flush the single-character cache
if (wIsReal) {
result.internalUnion(new CharSet(w));
}
// locate the matching closing bracket
int bracketLevel = 1;
int q = p + 1;
while (bracketLevel != 0) {
// if no matching bracket by end of string then...
if (q >= s.length()) {
throw new IllegalArgumentException("Parse error at position " + p + " in " + s);
}
int ch = s.codePointAt(q);
switch (ch) {
case '\\': // need to step over next character
ch = s.codePointAt(++q);
break;
case '[':
++bracketLevel;
break;
case ']':
--bracketLevel;
break;
}
q += Character.charCount(ch);
}
--q;
// call parseString() recursively to parse the text inside
// the brackets, then either add or subtract the result from
// our running result depending on whether or not the []
// expresison was preceded by a ^
if (!haveTilde) {
result.internalUnion(CharSet.parseString(s.substring(p + 1, q)));
}
else {
result.internalDifference(CharSet.parseString(s.substring(p + 1, q)));
}
haveTilde = false;
haveDash = false;
wIsReal = false;
p = q + 1;
}
// if the character is a colon...
else if (c == ':') {
// flush the single-character cache
if (wIsReal) {
result.internalUnion(new CharSet(w));
}
// locate the matching colon (and throw an error if there
// isn't one)
int q = s.indexOf(':', p + 1);
if (q == -1) {
throw new IllegalArgumentException("Parse error at position " + p + " in " + s);
}
// use charSetForCategory() to parse the text in the colons,
// and either add or substract the result from our running
// result depending on whether the :: expression was
// preceded by a ^
if (!haveTilde) {
result.internalUnion(charSetForCategory(s.substring(p + 1, q)));
}
else {
result.internalDifference(charSetForCategory(s.substring(p + 1, q)));
}
// reset everything and advance to the next character
haveTilde = false;
haveDash = false;
wIsReal = false;
p = q + 1;
}
// if the character is a dash, set an appropriate flag
else if (c == '-') {
if (wIsReal) {
haveDash = true;
}
++p;
}
// if the character is a caret, flush the single-character
// cache and set an appropriate flag. If the set is empty
// (i.e., if the expression begins with ^), invert the set
// (i.e., set it to include everything). The idea here is
// that a set that includes nothing but ^ expressions
// means "everything but these things".
else if (c == '^') {
if (wIsReal) {
result.internalUnion(new CharSet(w));
wIsReal = false;
}
haveTilde = true;
++p;
if (result.empty()) {
result.internalComplement();
}
}
// throw an exception on an illegal character
else if (c >= ' ' && c < '\u007f' && !Character.isLetter((char)c)
&& !Character.isDigit((char)c) && c != '\\') {
throw new IllegalArgumentException("Parse error at position " + p + " in " + s);
}
// otherwise, we end up here...
else {
// on a backslash, advance to the next character
if (c == '\\') {
++p;
}
// if the preceding character was a dash, this character
// defines the end of a range. Add or subtract that range
// from the running result depending on whether or not it
// was preceded by a ^
if (haveDash) {
if (s.codePointAt(p) < w) {
throw new IllegalArgumentException("U+" +
Integer.toHexString(s.codePointAt(p))
+ " is less than U+" + Integer.toHexString(w) + ". Dash expressions "
+ "can't have their endpoints in reverse order.");
}
int ch = s.codePointAt(p);
if (!haveTilde) {
result.internalUnion(new CharSet(w, ch));
}
else {
result.internalDifference(new CharSet(w, ch));
}
p += Character.charCount(ch);
haveDash = false;
haveTilde = false;
wIsReal = false;
}
// if the preceding character was a caret, remove this character
// from the running result
else if (haveTilde) {
w = s.codePointAt(p);
result.internalDifference(new CharSet(w));
p += Character.charCount(w);
haveTilde = false;
wIsReal = false;
}
// otherwise, flush the single-character cache and then
// put this character into the cache
else if (wIsReal) {
result.internalUnion(new CharSet(w));
w = s.codePointAt(p);
p += Character.charCount(w);
wIsReal = true;
} else {
w = s.codePointAt(p);
p += Character.charCount(w);
wIsReal = true;
}
}
}
// finally, flush the single-character cache one last time
if (wIsReal) {
result.internalUnion(new CharSet(w));
}
return result;
}
/**
* Creates a CharSet containing all the characters in a particular
* Unicode category. The text is either a two-character code from
* the Unicode database or a single character that begins one or more
* two-character codes.
*/
private static CharSet charSetForCategory(String category) {
// throw an exception if we have anything other than one or two
// characters inside the colons
if (category.length() == 0 || category.length() >= 3) {
throw new IllegalArgumentException("Invalid character category: " + category);
}
// if we have two characters, search the category map for that code
// and either construct and return a CharSet from the data in the
// category map or throw an exception
if (category.length() == 2) {
for (int i = 0; i < CharacterCategory.categoryNames.length; i++) {
if (CharacterCategory.categoryNames[i].equals(category)) {
return new CharSet(CharacterCategory.getCategoryMap(i));
}
}
throw new IllegalArgumentException("Invalid character category: " + category);
}
// if we have one character, search the category map for codes beginning
// with that letter, and union together all of the matching sets that
// we find (or throw an exception if there are no matches)
else if (category.length() == 1) {
CharSet result = new CharSet();
for (int i = 0; i < CharacterCategory.categoryNames.length; i++) {
if (CharacterCategory.categoryNames[i].startsWith(category)) {
result = result.union(new CharSet(CharacterCategory.getCategoryMap(i)));
}
}
if (result.empty()) {
throw new IllegalArgumentException("Invalid character category: " + category);
}
else {
return result;
}
}
return new CharSet(); // should never get here, but to make the compiler happy...
}
/**
* Returns a copy of CharSet's expression cache and sets CharSet's
* expression cache to empty.
*/
public static Hashtable<String, CharSet> releaseExpressionCache() {
Hashtable<String, CharSet> result = expressionCache;
expressionCache = null;
return result;
}
//==========================================================================
// CharSet manipulation
//==========================================================================
/**
* Creates an empty CharSet.
*/
public CharSet() {
chars = new int[0];
}
/**
* Creates a CharSet containing a single character.
* @param c The character to put into the CharSet
*/
public CharSet(int c) {
chars = new int[2];
chars[0] = c;
chars[1] = c;
}
/**
* Creates a CharSet containing a range of characters.
* @param lo The lowest-numbered character to include in the range
* @param hi The highest-numbered character to include in the range
*/
public CharSet(int lo, int hi) {
chars = new int[2];
if (lo <= hi) {
chars[0] = lo;
chars[1] = hi;
}
else {
chars[0] = hi;
chars[1] = lo;
}
}
/**
* Creates a CharSet, initializing it from the internal storage
* of another CharSet (this function performs no error checking
* on "chars", so if it's malformed, undefined behavior will result)
*/
private CharSet(int[] chars) {
this.chars = chars;
}
/**
* Returns a CharSet representing the union of two CharSets.
*/
public CharSet union(CharSet that) {
return new CharSet(doUnion(that.chars));
}
/**
* Adds the characters in "that" to this CharSet
*/
private void internalUnion(CharSet that) {
chars = doUnion(that.chars);
}
/**
* The actual implementation of the union functions
*/
private int[] doUnion(int[] c2) {
int[] result = new int[chars.length+c2.length];
int i = 0;
int j = 0;
int index = 0;
// consider all the characters in both strings
while (i < chars.length && j < c2.length) {
int ub;
// the first character in the result is the lower of the
// starting characters of the two strings, and "ub" gets
// set to the upper bound of that range
if (chars[i] < c2[j]) {
result[index++] = chars[i];
ub = chars[++i];
}
else {
result[index++] = c2[j];
ub = c2[++j];
}
// for as long as one of our two pointers is pointing to a range's
// end point, or i is pointing to a character that is less than
// "ub" plus one (the "plus one" stitches touching ranges together)...
while (i % 2 == 1 ||
j % 2 == 1 ||
(i < chars.length && chars[i] <= ub + 1)) {
// advance i to the first character that is greater than
// "ub" plus one
while (i < chars.length && chars[i] <= ub + 1) {
++i;
}
// if i points to the endpoint of a range, update "ub"
// to that character, or if i points to the start of
// a range and the endpoint of the preceding range is
// greater than "ub", update "up" to _that_ character
if (i % 2 == 1) {
ub = chars[i];
}
else if (i > 0 && chars[i - 1] > ub) {
ub = chars[i - 1];
}
// now advance j to the first character that is greater
// that "ub" plus one
while (j < c2.length && c2[j] <= ub + 1) {
++j;
}
// if j points to the endpoint of a range, update "ub"
// to that character, or if j points to the start of
// a range and the endpoint of the preceding range is
// greater than "ub", update "up" to _that_ character
if (j % 2 == 1) {
ub = c2[j];
}
else if (j > 0 && c2[j - 1] > ub) {
ub = c2[j - 1];
}
}
// when we finally fall out of this loop, we will have stitched
// together a series of ranges that overlap or touch, i and j
// will both point to starting points of ranges, and "ub" will
// be the endpoint of the range we're working on. Write "ub"
// to the result
result[index++] = ub;
// loop back around to create the next range in the result
}
// we fall out to here when we've exhausted all the characters in
// one of the operands. We can append all of the remaining characters
// in the other operand without doing any extra work.
if (i < chars.length) {
for (int k = i; k < chars.length; k++) {
result[index++] = chars[k];
}
}
if (j < c2.length) {
for (int k = j; k < c2.length; k++) {
result[index++] = c2[k];
}
}
if (result.length > index) {
int[] tmpbuf = new int[index];
System.arraycopy(result, 0, tmpbuf, 0, index);
return tmpbuf;
}
return result;
}
/**
* Returns the intersection of two CharSets.
*/
public CharSet intersection(CharSet that) {
return new CharSet(doIntersection(that.chars));
}
/**
* Removes from this CharSet any characters that aren't also in "that"
*/
private void internalIntersection(CharSet that) {
chars = doIntersection(that.chars);
}
/**
* The internal implementation of the two intersection functions
*/
private int[] doIntersection(int[] c2) {
int[] result = new int[chars.length+c2.length];
int i = 0;
int j = 0;
int oldI;
int oldJ;
int index = 0;
// iterate until we've exhausted one of the operands
while (i < chars.length && j < c2.length) {
// advance j until it points to a character that is larger than
// the one i points to. If this is the beginning of a one-
// character range, advance j to point to the end
if (i < chars.length && i % 2 == 0) {
while (j < c2.length && c2[j] < chars[i]) {
++j;
}
if (j < c2.length && j % 2 == 0 && c2[j] == chars[i]) {
++j;
}
}
// if j points to the endpoint of a range, save the current
// value of i, then advance i until it reaches a character
// which is larger than the character pointed at
// by j. All of the characters we've advanced over (except
// the one currently pointed to by i) are added to the result
oldI = i;
while (j % 2 == 1 && i < chars.length && chars[i] <= c2[j]) {
++i;
}
for (int k = oldI; k < i; k++) {
result[index++] = chars[k];
}
// if i points to the endpoint of a range, save the current
// value of j, then advance j until it reaches a character
// which is larger than the character pointed at
// by i. All of the characters we've advanced over (except
// the one currently pointed to by i) are added to the result
oldJ = j;
while (i % 2 == 1 && j < c2.length && c2[j] <= chars[i]) {
++j;
}
for (int k = oldJ; k < j; k++) {
result[index++] = c2[k];
}
// advance i until it points to a character larger than j
// If it points at the beginning of a one-character range,
// advance it to the end of that range
if (j < c2.length && j % 2 == 0) {
while (i < chars.length && chars[i] < c2[j]) {
++i;
}
if (i < chars.length && i % 2 == 0 && c2[j] == chars[i]) {
++i;
}
}
}
if (result.length > index) {
int[] tmpbuf = new int[index];
System.arraycopy(result, 0, tmpbuf, 0, index);
return tmpbuf;
}
return result;
}
/**
* Returns a CharSet containing all the characters in "this" that
* aren't also in "that"
*/
public CharSet difference(CharSet that) {
return new CharSet(doIntersection(that.doComplement()));
}
/**
* Removes from "this" all the characters that are also in "that"
*/
private void internalDifference(CharSet that) {
chars = doIntersection(that.doComplement());
}
/**
* Returns a CharSet containing all the characters which are not
* in "this"
*/
public CharSet complement() {
return new CharSet(doComplement());
}
/**
* Complements "this". All the characters it contains are removed,
* and all the characters it doesn't contain are added.
*/
private void internalComplement() {
chars = doComplement();
}
/**
* The internal implementation function for the complement routines
*/
private int[] doComplement() {
// the complement of an empty CharSet is one containing everything
if (empty()) {
int[] result = new int[2];
result[0] = 0x0000;
result[1] = 0x10FFFF;
return result;
}
int[] result = new int[chars.length+2];
int i = 0;
int index = 0;
// the result begins with \u0000 unless the original CharSet does
if (chars[0] != 0x0000) {
result[index++] = 0x0000;
}
// walk through the characters in this CharSet. Append a pair of
// characters the first of which is one less than the first
// character we see and the second of which is one plus the second
// character we see (don't write the first character if it's \u0000,
// and don't write the second character if it's \uffff.
while (i < chars.length) {
if (chars[i] != 0x0000) {
result[index++] = chars[i] - 1;
}
if (chars[i + 1] != 0x10FFFF) {
result[index++] = chars[i + 1] + 1;
}
i += 2;
}
// add 0x10ffff to the end of the result, unless it was in
// the original set
if (chars[i-1] != 0x10FFFF) {
result[index++] = 0x10FFFF;
}
if (result.length > index) {
int[] tmpbuf = new int[index];
System.arraycopy(result, 0, tmpbuf, 0, index);
return tmpbuf;
}
return result;
}
/**
* Returns true if this CharSet contains the specified character
* @param c The character we're testing for set membership
*/
public boolean contains(int c) {
// search for the first range endpoint that is greater than or
// equal to c
int i = 1;
while (i < chars.length && chars[i] < c) {
i += 2;
}
// if we've walked off the end, we don't contain c
if (i == chars.length) {
return false;
}
// otherwise, we contain c if the beginning of the range is less
// than or equal to c
return chars[i - 1] <= c;
}
/**
* Returns true if "that" is another instance of CharSet containing
* the exact same characters as this one
*/
public boolean equals(Object that) {
return (that instanceof CharSet) && Arrays.equals(chars, ((CharSet)that).chars);
}
/**
* Returns the hash code for this set of characters
*/
public int hashCode() {
return Arrays.hashCode(chars);
}
/**
* Creates a new CharSet that is equal to this one
*/
public Object clone() {
return new CharSet(chars);
}
/**
* Returns true if this CharSet contains no characters
*/
public boolean empty() {
return chars.length == 0;
}
/**
* Returns a textual representation of this CharSet. If the result
* of calling this function is passed to CharSet.parseString(), it
* will produce another CharSet that is equal to this one.
*/
public String toString() {
StringBuffer result = new StringBuffer();
// the result begins with an opening bracket
result.append('[');
// iterate through the ranges in the CharSet
for (int i = 0; i < chars.length; i += 2) {
// for a range with the same beginning and ending point,
// output that character
if (chars[i] == chars[i + 1]) {
result.append("0x");
result.append(Integer.toHexString(chars[i]));
}
// otherwise, output the start and end points of the range
// separated by a dash
else {
result.append("0x");
result.append(Integer.toHexString(chars[i]));
result.append("-0x");
result.append(Integer.toHexString(chars[i + 1]));
}
}
// the result ends with a closing bracket
result.append(']');
return result.toString();
}
/**
* Returns an integer array representing the contents of this CharSet
* in the same form in which they're stored internally: as pairs
* of characters representing the start and end points of ranges
*/
public int[] getRanges() {
return chars;
}
/**
* Returns an Enumeration that will return the ranges of characters
* contained in this CharSet one at a time
*/
public Enumeration getChars() {
return new Enumeration(this);
}
//==========================================================================
// CharSet.Enumeration
//==========================================================================
/**
* An Enumeration that can be used to extract the character ranges
* from a CharSet one at a time
*/
public class Enumeration implements java.util.Enumeration<int[]> {
/**
* Initializes a CharSet.Enumeration
*/
Enumeration(CharSet cs) {
this.chars = cs.chars;
p = 0;
}
/**
* Returns true if the enumeration hasn't yet returned
* all the ranges in the CharSet
*/
public boolean hasMoreElements() {
return p < chars.length;
}
/**
* Returns the next range in the CarSet
*/
public int[] nextElement() {
int[] result = new int[2];
result[0] = chars[p++];
result[1] = chars[p++];
return result;
}
int p;
int[] chars;
}
}
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