package net.sf.saxon.sort;
import net.sf.saxon.Configuration;
import net.sf.saxon.om.FastStringBuffer;
import java.text.CollationElementIterator;
import java.text.RuleBasedCollator;
/**
* This class wraps a RuleBasedCollator to provide a SubstringMatcher. This
* users the facilities offered by the RuleBasedCollator to implement the XPath
* functions contains(), starts-with(), ends-with(), substring-before(), and
* substring-after().
*/
public class RuleBasedSubstringMatcher implements SubstringMatcher {
private RuleBasedCollator collator;
/**
* Create a RuleBasedSubstringMatcher
* @param collator the collation to be used
*/
public RuleBasedSubstringMatcher(RuleBasedCollator collator) {
this.collator = collator;
}
/**
* Test whether one string is equal to another, according to the rules
* of the XPath compare() function. The result is true if and only if the
* compare() method returns zero: but the implementation may be more efficient
* than calling compare and testing the result for zero
*
* @param s1 the first string
* @param s2 the second string
* @return true iff s1 equals s2
*/
public boolean comparesEqual(String s1, String s2) {
return collator.compare(s1, s2) == 0;
}
/**
* Test whether one string contains another, according to the rules
* of the XPath contains() function
*
* @param s1 the containing string
* @param s2 the contained string
* @return true iff s1 contains s2
*/
public boolean contains(String s1, String s2) {
CollationElementIterator iter1 = collator.getCollationElementIterator(s1);
CollationElementIterator iter2 = collator.getCollationElementIterator(s2);
return collationContains(iter1, iter2, null, false);
}
/**
* Test whether one string ends with another, according to the rules
* of the XPath ends-with() function
*
* @param s1 the containing string
* @param s2 the contained string
* @return true iff s1 ends with s2
*/
public boolean endsWith(String s1, String s2) {
CollationElementIterator iter1 = collator.getCollationElementIterator(s1);
CollationElementIterator iter2 = collator.getCollationElementIterator(s2);
return collationContains(iter1, iter2, null, true);
}
/**
* Test whether one string starts with another, according to the rules
* of the XPath starts-with() function
*
* @param s1 the containing string
* @param s2 the contained string
* @return true iff s1 starts with s2
*/
public boolean startsWith(String s1, String s2) {
CollationElementIterator iter1 = collator.getCollationElementIterator(s1);
CollationElementIterator iter2 = collator.getCollationElementIterator(s2);
return collationStartsWith(iter1, iter2);
}
/**
* Return the part of a string after a given substring, according to the rules
* of the XPath substring-after() function
*
* @param s1 the containing string
* @param s2 the contained string
* @return the part of s1 that follows the first occurrence of s2
*/
public String substringAfter(String s1, String s2) {
CollationElementIterator iter1 = collator.getCollationElementIterator(s1);
CollationElementIterator iter2 = collator.getCollationElementIterator(s2);
int[] ia = new int[2];
boolean ba = collationContains(iter1, iter2, ia, false);
if (ba) {
return s1.substring(ia[1]);
} else {
return "";
}
}
/**
* Return the part of a string before a given substring, according to the rules
* of the XPath substring-before() function
*
* @param s1 the containing string
* @param s2 the contained string
* @return the part of s1 that precedes the first occurrence of s2
*/
public String substringBefore(String s1, String s2) {
CollationElementIterator iter1 = collator.getCollationElementIterator(s1);
CollationElementIterator iter2 = collator.getCollationElementIterator(s2);
int[] ib = new int[2];
boolean bb = collationContains(iter1, iter2, ib, false);
if (bb) {
return s1.substring(0, ib[0]);
} else {
return "";
}
}
/**
* Determine whether one string starts with another, under the terms of a given
* collating sequence.
* @param s0 iterator over the collation elements of the containing string
* @param s1 iterator over the collation elements of the contained string
* @return true if the first string starts with the second
*/
private boolean collationStartsWith(CollationElementIterator s0,
CollationElementIterator s1) {
while (true) {
int e0, e1;
do {
e1 = s1.next();
} while (e1 == 0);
if (e1 == -1) {
return true;
}
do {
e0 = s0.next();
} while (e0 == 0);
if (e0 != e1) {
return false;
}
}
}
/**
* Determine whether one string contains another, under the terms of a given
* collating sequence. If matchAtEnd=true, the match must be at the end of the first
* string.
* @param s0 iterator over the collation elements of the containing string
* @param s1 iterator over the collation elements of the contained string
* @param offsets may be null, but if it is supplied, it must be an array of two
* integers which, if the function returns true, will contain the start position of the
* first matching substring, and the offset of the first character after the first
* matching substring. This is not available for matchAtEnd=true
* @param matchAtEnd true if the match is required to be at the end of the string
* @return true if the first string contains the second
*/
private boolean collationContains(CollationElementIterator s0,
CollationElementIterator s1,
int[] offsets,
boolean matchAtEnd) {
int e0, e1;
do {
e1 = s1.next();
} while (e1 == 0);
if (e1 == -1) {
return true;
}
e0 = -1;
while (true) {
// scan the first string to find a matching character
while (e0 != e1) {
do {
e0 = s0.next();
} while (e0 == 0);
if (e0 == -1) {
// hit the end, no match
return false;
}
}
// matched first character, note the position of the possible match
int start = s0.getOffset();
if (collationStartsWith(s0, s1)) {
if (matchAtEnd) {
do {
e0 = s0.next();
} while (e0 == 0);
if (e0 == -1) {
// the match is at the end
return true;
}
// else ignore this match and keep looking
} else {
if (offsets != null) {
offsets[0] = start-1;
offsets[1] = s0.getOffset();
}
return true;
}
}
// reset the position and try again
s0.setOffset(start);
// workaround for a difference between JDK 1.4.0 and JDK 1.4.1
if (s0.getOffset() != start) {
// JDK 1.4.0 takes this path
s0.next();
}
s1.reset();
e0 = -1;
do {
e1 = s1.next();
} while (e1 == 0);
// loop round to try again
}
}
/**
* Compare two strings
*
* @param o1 the first string
* @param o2 the second string
* @return 0 if the strings are considered equal, a negative integer if the first string is less than the second,
* a positive integer if the first string is greater than the second
*/
public int compareStrings(String o1, String o2) {
return collator.compare(o1, o2);
}
/**
* Get a collation key for two Strings. The essential property of collation keys
* is that if two values are equal under the collation, then the collation keys are
* compare correctly under the equals() method.
*/
public Object getCollationKey(String s) {
return null; //AUTO
}
/**
* Test program to output the sequence of collation element iterators for a given input string
* @param args command line arguments (collationURI, test-string)
*/
public static void main(String[] args) {
Configuration config = new Configuration();
StringCollator collator = StandardCollationURIResolver.getInstance().resolve(args[0], args[0], config);
FastStringBuffer sb = new FastStringBuffer(100);
if (collator instanceof RuleBasedCollator) {
CollationElementIterator iter = ((RuleBasedCollator)collator).getCollationElementIterator(args[1]);
while (true) {
int e = iter.next();
if (e==-1) {
break;
}
sb.append(e+" ");
}
System.err.println(sb.toString());
}
}
}
//
// The contents of this file are subject to the Mozilla Public License Version 1.0 (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.mozilla.org/MPL/
//
// Software distributed under the License is distributed on an "AS IS" basis,
// WITHOUT WARRANTY OF ANY KIND, either express or implied.
// See the License for the specific language governing rights and limitations under the License.
//
// The Original Code is: all this file.
//
// The Initial Developer of the Original Code is Michael H. Kay.
//
// Portions created by (your name) are Copyright (C) (your legal entity). All Rights Reserved.
//
// Contributor(s): none.
//