235 lines
8.7 KiB
C++
235 lines
8.7 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 "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 "rep.h"
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void RuleBasedTransliterator::_construct(const UnicodeString& rules,
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Direction direction,
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UErrorCode& status) {
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data = 0;
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isDataOwned = TRUE;
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if (U_SUCCESS(status)) {
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data = TransliterationRuleParser::parse(rules, direction);
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if (data == 0) {
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status = U_ILLEGAL_ARGUMENT_ERROR;
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}
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}
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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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/**
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* Copy constructor. Since the data object is immutable, we can share
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* it with other objects -- no need to clone it.
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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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// TODO: Finish this -- implement with correct data ownership handling
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}
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/**
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* Destructor. We do NOT own the data object, so we do not delete it.
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*/
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RuleBasedTransliterator::~RuleBasedTransliterator() {
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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() const {
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return new RuleBasedTransliterator(*this);
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}
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/**
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* Transliterates a segment of a string. <code>Transliterator</code> API.
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* @param text the string to be transliterated
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* @param start the beginning index, inclusive; <code>0 <= start
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* <= limit</code>.
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* @param limit the ending index, exclusive; <code>start <= limit
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* <= text.length()</code>.
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* @param result buffer to receive the transliterated text; previous
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* contents are discarded
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*/
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void RuleBasedTransliterator::transliterate(const UnicodeString& text,
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int32_t start, int32_t limit,
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UnicodeString& result) const {
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/* In the following loop there is a virtual buffer consisting of the
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* text transliterated so far followed by the untransliterated text. There is
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* also a cursor, which may be in the already transliterated buffer or just
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* before the untransliterated text.
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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 start - no match, copy e to tranlated buffer
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* [e]|abcd match rule 1 - copy output & adjust cursor
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* [ex|y]cd match rule 2 - copy output & adjust cursor
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* [exz]|d no match, copy d to transliterated buffer
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* [exzd]| done
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*
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* cursor: an index into the virtual buffer, 0..result.length()-1.
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* Matches take place at the cursor. If there is no match, the cursor
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* is advanced, and one character is moved from the source text to the
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* result buffer.
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*
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* start, limit: these designate the substring of the source text which
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* has not been processed yet. The range of offsets is start..limit-1.
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* At any moment the virtual buffer consists of result +
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* text.substring(start, limit).
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*/
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int32_t cursor = 0;
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result.remove();
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while (start < limit || cursor < result.length()) {
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TransliterationRule* r = data->ruleSet.findMatch(text, start, limit,
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result,
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cursor,
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*data,
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getFilter());
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if (r == 0) {
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if (cursor == result.length()) {
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result.append(text.charAt(start++));
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}
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++cursor;
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} else {
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// At this point we have a match of one or more
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// characters. The characters cover the range [cursor,
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// cursor + r->getKeyLength()) - a half-open interval.
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// The index values refer to a virtual buffer with result
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// holding [0, result.length()) and text holding
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// [result.length(),...).
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// First, figure out the range of result being replaced.
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int32_t rfirst = cursor;
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int32_t rlimit = icu_min(result.length(),
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cursor + r->getKeyLength());
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// resultPad is length of result to right of cursor; >= 0
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int32_t resultPad = result.length() - cursor;
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if (r->getKeyLength() > resultPad) {
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start += r->getKeyLength() - resultPad;
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}
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result.replaceBetween(rfirst, rlimit,
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r->getOutput());
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cursor += r->getCursorPos();
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}
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}
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}
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/**
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* Transliterates a segment of a string. <code>Transliterator</code> API.
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* @param text the string to be transliterated
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* @param start the beginning index, inclusive; <code>0 <= start
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* <= limit</code>.
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* @param limit the ending index, exclusive; <code>start <= limit
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* <= text.length()</code>.
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* @return The new limit index
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*/
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int32_t RuleBasedTransliterator::transliterate(Replaceable& text,
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int32_t start,
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int32_t limit) const {
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/* When using Replaceable, the algorithm is simpler, since we don't have
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* two separate buffers. We keep start and limit fixed the entire time,
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* relative to the text -- limit may move numerically if text is
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* inserted or removed. The cursor moves from start to limit, with
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* 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 start - no match, advance cursor
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* e|abcd match rule 1 - change text & adjust cursor
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* ex|ycd match rule 2 - change text & adjust cursor
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* exz|d no match, advance cursor
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* exzd| done
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*/
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int32_t cursor = start;
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while (cursor < limit) {
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TransliterationRule* r =
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data->ruleSet.findMatch(text, start, limit,
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cursor, *data,
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getFilter());
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if (r == 0) {
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++cursor;
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} else {
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text.handleReplaceBetween(cursor, cursor + r->getKeyLength(),
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r->getOutput());
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limit += r->getOutput().length() - r->getKeyLength();
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cursor += r->getCursorPos();
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}
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}
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return limit;
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}
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/**
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* Implements {@link Transliterator#handleKeyboardTransliterate}.
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*/
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void
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RuleBasedTransliterator::handleKeyboardTransliterate(Replaceable& text,
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int32_t index[3]) const {
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int32_t start = index[START];
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int32_t limit = index[LIMIT];
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int32_t cursor = index[CURSOR];
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bool_t isPartial;
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while (cursor < limit) {
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TransliterationRule* r = data->ruleSet.findIncrementalMatch(
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text, start, limit, cursor,
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*data, isPartial,
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getFilter());
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/* If we match a rule then apply it by replacing the key
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* with the rule output and repositioning the cursor
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* appropriately. If we get a partial match, then we
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* can't do anything without more text; return with the
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* cursor at the current position. If we get null, then
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* there is no match at this position, and we can advance
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* the cursor.
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*/
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if (r == 0) {
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if (isPartial) {
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break;
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} else {
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++cursor;
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}
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} else {
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text.handleReplaceBetween(cursor, cursor + r->getKeyLength(),
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r->getOutput());
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limit += r->getOutput().length() - r->getKeyLength();
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cursor += r->getCursorPos();
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}
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}
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index[LIMIT] = limit;
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index[CURSOR] = cursor;
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}
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/**
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* Returns the length of the longest context required by this transliterator.
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* This is <em>preceding</em> context.
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* @return Maximum number of preceding context characters this
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* transliterator needs to examine
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*/
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int32_t RuleBasedTransliterator::getMaximumContextLength() const {
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return data->ruleSet.getMaximumContextLength();
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}
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