com.ibm.icu.text.TransliterationRuleSet Maven / Gradle / Ivy
Show all versions of icu4j Show documentation
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 1996-2010, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.text;
import java.util.ArrayList;
import java.util.List;
import com.ibm.icu.impl.UtilityExtensions;
/**
* A set of rules for a RuleBasedTransliterator. This set encodes
* the transliteration in one direction from one set of characters or short
* strings to another. A RuleBasedTransliterator consists of up to
* two such sets, one for the forward direction, and one for the reverse.
*
* A TransliterationRuleSet has one important operation, that of
* finding a matching rule at a given point in the text. This is accomplished
* by the findMatch() method.
*
*
Copyright © IBM Corporation 1999. All rights reserved.
*
* @author Alan Liu
*/
class TransliterationRuleSet {
/**
* Vector of rules, in the order added.
*/
private List ruleVector;
/**
* Length of the longest preceding context
*/
private int maxContextLength;
/**
* Sorted and indexed table of rules. This is created by freeze() from
* the rules in ruleVector. rules.length >= ruleVector.size(), and the
* references in rules[] are aliases of the references in ruleVector.
* A single rule in ruleVector is listed one or more times in rules[].
*/
private TransliterationRule[] rules;
/**
* Index table. For text having a first character c, compute x = c&0xFF.
* Now use rules[index[x]..index[x+1]-1]. This index table is created by
* freeze().
*/
private int[] index;
/**
* Construct a new empty rule set.
*/
public TransliterationRuleSet() {
ruleVector = new ArrayList();
maxContextLength = 0;
}
/**
* Return the maximum context length.
* @return the length of the longest preceding context.
*/
public int getMaximumContextLength() {
return maxContextLength;
}
/**
* Add a rule to this set. Rules are added in order, and order is
* significant.
* @param rule the rule to add
*/
public void addRule(TransliterationRule rule) {
ruleVector.add(rule);
int len;
if ((len = rule.getAnteContextLength()) > maxContextLength) {
maxContextLength = len;
}
rules = null;
}
/**
* Close this rule set to further additions, check it for masked rules,
* and index it to optimize performance.
* @exception IllegalArgumentException if some rules are masked
*/
public void freeze() {
/* Construct the rule array and index table. We reorder the
* rules by sorting them into 256 bins. Each bin contains all
* rules matching the index value for that bin. A rule
* matches an index value if string whose first key character
* has a low byte equal to the index value can match the rule.
*
* Each bin contains zero or more rules, in the same order
* they were found originally. However, the total rules in
* the bins may exceed the number in the original vector,
* since rules that have a variable as their first key
* character will generally fall into more than one bin.
*
* That is, each bin contains all rules that either have that
* first index value as their first key character, or have
* a set containing the index value as their first character.
*/
int n = ruleVector.size();
index = new int[257]; // [sic]
List v = new ArrayList(2*n); // heuristic; adjust as needed
/* Precompute the index values. This saves a LOT of time.
*/
int[] indexValue = new int[n];
for (int j=0; j= 0) {
if (indexValue[j] == x) {
v.add(ruleVector.get(j));
}
} else {
// If the indexValue is < 0, then the first key character is
// a set, and we must use the more time-consuming
// matchesIndexValue check. In practice this happens
// rarely, so we seldom tread this code path.
TransliterationRule r = ruleVector.get(j);
if (r.matchesIndexValue(x)) {
v.add(r);
}
}
}
}
index[256] = v.size();
/* Freeze things into an array.
*/
rules = new TransliterationRule[v.size()];
v.toArray(rules);
StringBuilder errors = null;
/* Check for masking. This is MUCH faster than our old check,
* which was each rule against each following rule, since we
* only have to check for masking within each bin now. It's
* 256*O(n2^2) instead of O(n1^2), where n1 is the total rule
* count, and n2 is the per-bin rule count. But n2< " +
UtilityExtensions.formatInput(text, pos));
}
return true;
case UnicodeMatcher.U_PARTIAL_MATCH:
if (Transliterator.DEBUG) {
System.out.println((incremental ? "Rule.i: partial match ":"Rule: partial match ") +
rules[i].toRule(true) + " => " +
UtilityExtensions.formatInput(text, pos));
}
return false;
default:
if (Transliterator.DEBUG) {
System.out.println("Rule: no match " + rules[i]);
}
}
}
// No match or partial match from any rule
pos.start += UTF16.getCharCount(text.char32At(pos.start));
if (Transliterator.DEBUG) {
System.out.println((incremental ? "Rule.i: no match => ":"Rule: no match => ") +
UtilityExtensions.formatInput(text, pos));
}
return true;
}
/**
* Create rule strings that represents this rule set.
*/
String toRules(boolean escapeUnprintable) {
int i;
int count = ruleVector.size();
StringBuilder ruleSource = new StringBuilder();
for (i=0; i |b ; b > c ;
// TODO Merge into r.addSourceTargetSet, to avoid duplicate testing
void addSourceTargetSet(UnicodeSet filter, UnicodeSet sourceSet, UnicodeSet targetSet) {
UnicodeSet currentFilter = new UnicodeSet(filter);
UnicodeSet revisiting = new UnicodeSet();
int count = ruleVector.size();
for (int i=0; i