156 lines
5.0 KiB
C++
156 lines
5.0 KiB
C++
/*
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**********************************************************************
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* Copyright (C) 1999, International Business Machines
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* Corporation and others. All Rights Reserved.
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**********************************************************************
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* Date Name Description
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* 11/17/99 aliu Creation.
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**********************************************************************
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*/
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#include "unicode/rbt.h"
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#include "rbt_pars.h"
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#include "rbt_data.h"
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#include "rbt_rule.h"
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#include "unicode/rep.h"
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U_NAMESPACE_BEGIN
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const char RuleBasedTransliterator::fgClassID = 0; // Value is irrelevant
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void RuleBasedTransliterator::_construct(const UnicodeString& rules,
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UTransDirection direction,
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UParseError& parseError,
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UErrorCode& status) {
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data = 0;
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isDataOwned = TRUE;
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if (U_FAILURE(status)) {
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return;
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}
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TransliteratorParser parser;
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parser.parse(rules, direction, parseError, status);
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if (U_FAILURE(status)) {
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return;
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}
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if (parser.idBlock.length() != 0 ||
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parser.compoundFilter != NULL) {
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status = U_INVALID_RBT_SYNTAX; // ::ID blocks disallowed in RBT
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return;
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}
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data = parser.orphanData();
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setMaximumContextLength(data->ruleSet.getMaximumContextLength());
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}
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RuleBasedTransliterator::RuleBasedTransliterator(const UnicodeString& id,
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const TransliterationRuleData* theData,
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UnicodeFilter* adoptedFilter) :
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Transliterator(id, adoptedFilter),
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data((TransliterationRuleData*)theData), // cast away const
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isDataOwned(FALSE) {
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setMaximumContextLength(data->ruleSet.getMaximumContextLength());
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}
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/**
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* Internal constructor.
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*/
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RuleBasedTransliterator::RuleBasedTransliterator(const UnicodeString& id,
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TransliterationRuleData* theData,
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UBool isDataAdopted) :
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Transliterator(id, 0),
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data(theData),
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isDataOwned(isDataAdopted) {
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setMaximumContextLength(data->ruleSet.getMaximumContextLength());
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}
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/**
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* Copy constructor.
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*/
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RuleBasedTransliterator::RuleBasedTransliterator(
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const RuleBasedTransliterator& other) :
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Transliterator(other), data(other.data),
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isDataOwned(other.isDataOwned) {
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// The data object may or may not be owned. If it is not owned we
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// share it; it is invariant. If it is owned, it's still
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// invariant, but we need to copy it to prevent double-deletion.
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// If this becomes a performance issue (if people do a lot of RBT
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// copying -- unlikely) we can reference count the data object.
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// Only do a deep copy if this is owned data, that is, data that
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// will be later deleted. System transliterators contain
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// non-owned data.
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if (isDataOwned) {
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data = new TransliterationRuleData(*other.data);
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}
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}
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/**
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* Destructor.
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*/
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RuleBasedTransliterator::~RuleBasedTransliterator() {
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// Delete the data object only if we own it.
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if (isDataOwned) {
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delete data;
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}
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}
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Transliterator* // Covariant return NOT ALLOWED (for portability)
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RuleBasedTransliterator::clone(void) const {
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return new RuleBasedTransliterator(*this);
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}
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/**
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* Implements {@link Transliterator#handleTransliterate}.
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*/
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void
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RuleBasedTransliterator::handleTransliterate(Replaceable& text, UTransPosition& index,
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UBool isIncremental) const {
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/* We keep contextStart and contextLimit fixed the entire time,
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* relative to the text -- contextLimit may move numerically if
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* text is inserted or removed. The start offset moves toward
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* limit, with replacements happening under it.
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*
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* Example: rules 1. ab>x|y
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* 2. yc>z
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*
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* |eabcd begin - no match, advance start
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* e|abcd match rule 1 - change text & adjust start
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* ex|ycd match rule 2 - change text & adjust start
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* exz|d no match, advance start
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* exzd| done
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*/
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/* A rule like
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* a>b|a
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* creates an infinite loop. To prevent that, we put an arbitrary
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* limit on the number of iterations that we take, one that is
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* high enough that any reasonable rules are ok, but low enough to
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* prevent a server from hanging. The limit is 16 times the
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* number of characters n, unless n is so large that 16n exceeds a
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* uint32_t.
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*/
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uint32_t loopCount = 0;
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uint32_t loopLimit = index.limit - index.start;
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if (loopLimit >= 0x10000000) {
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loopLimit = 0xFFFFFFFF;
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} else {
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loopLimit <<= 4;
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}
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while (index.start < index.limit &&
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loopCount <= loopLimit &&
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data->ruleSet.transliterate(text, index, isIncremental)) {
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++loopCount;
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}
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}
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UnicodeString& RuleBasedTransliterator::toRules(UnicodeString& rulesSource,
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UBool escapeUnprintable) const {
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return data->ruleSet.toRules(rulesSource, escapeUnprintable);
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}
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U_NAMESPACE_END
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