275 lines
11 KiB
C++
275 lines
11 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_set.h"
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#include "rbt_rule.h"
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#include "unicode/unistr.h"
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/* Note: There was an old implementation that indexed by first letter of
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* key. Problem with this is that key may not have a meaningful first
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* letter; e.g., {Lu}>*. One solution is to keep a separate vector of all
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* rules whose intial key letter is a category variable. However, the
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* problem is that they must be kept in order with respect to other rules.
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* One solution -- add a sequence number to each rule. Do the usual
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* first-letter lookup, and also a lookup from the spare bin with rules like
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* {Lu}>*. Take the lower sequence number. This seems complex and not
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* worth the trouble, but we may revisit this later. For documentation (or
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* possible resurrection) the old code is included below, commented out
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* with the remark "// OLD INDEXED IMPLEMENTATION". Under the old
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* implementation, <code>rules</code> is a Hashtable, not a Vector.
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*/
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/**
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* Construct a new empty rule set.
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*/
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TransliterationRuleSet::TransliterationRuleSet() {
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maxContextLength = 0;
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ruleVector = new UVector();
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rules = NULL;
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}
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/**
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* Destructor.
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*/
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TransliterationRuleSet::~TransliterationRuleSet() {
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delete ruleVector;
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delete[] rules;
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}
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/**
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* Return the maximum context length.
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* @return the length of the longest preceding context.
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*/
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int32_t TransliterationRuleSet::getMaximumContextLength(void) const {
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return maxContextLength;
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}
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/**
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* Add a rule to this set. Rules are added in order, and order is
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* significant.
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*
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* <p>Once freeze() is called, this method must not be called.
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* @param adoptedRule the rule to add
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*/
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void TransliterationRuleSet::addRule(TransliterationRule* adoptedRule,
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UErrorCode& status) {
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if (U_FAILURE(status)) {
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delete adoptedRule;
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return;
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}
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if (ruleVector == NULL) {
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// throw new IllegalArgumentException("Cannot add rules after freezing");
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status = U_ILLEGAL_ARGUMENT_ERROR;
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delete adoptedRule;
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return;
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}
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ruleVector->addElement(adoptedRule);
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int32_t len;
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if ((len = adoptedRule->getAnteContextLength()) > maxContextLength) {
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maxContextLength = len;
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}
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}
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/**
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* Close this rule set to further additions, check it for masked rules,
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* and index it to optimize performance. Once this method is called,
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* addRule() can no longer be called.
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* @exception IllegalArgumentException if some rules are masked
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*/
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void TransliterationRuleSet::freeze(const TransliterationRuleData& data,
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UErrorCode& status) {
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if (U_FAILURE(status)) {
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return;
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}
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/* Construct the rule array and index table. We reorder the
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* rules by sorting them into 256 bins. Each bin contains all
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* rules matching the index value for that bin. A rule
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* matches an index value if string whose first key character
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* has a low byte equal to the index value can match the rule.
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*
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* Each bin contains zero or more rules, in the same order
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* they were found originally. However, the total rules in
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* the bins may exceed the number in the original vector,
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* since rules that have a variable as their first key
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* character will generally fall into more than one bin.
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*
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* That is, each bin contains all rules that either have that
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* first index value as their first key character, or have
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* a set containing the index value as their first character.
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*/
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int32_t n = ruleVector->size();
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int32_t j;
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int16_t x;
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UVector v(2*n); // heuristic; adjust as needed
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/* Precompute the index values. This saves a LOT of time.
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*/
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int16_t* indexValue = new int16_t[n];
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for (j=0; j<n; ++j) {
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TransliterationRule* r = (TransliterationRule*) ruleVector->elementAt(j);
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indexValue[j] = r->getIndexValue(data);
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}
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for (x=0; x<256; ++x) {
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index[x] = v.size();
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for (j=0; j<n; ++j) {
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if (indexValue[j] >= 0) {
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if (indexValue[j] == x) {
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v.addElement(ruleVector->elementAt(j));
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}
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} else {
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// If the indexValue is < 0, then the first key character is
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// a set, and we must use the more time-consuming
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// matchesIndexValue check. In practice this happens
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// rarely, so we seldom tread this code path.
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TransliterationRule* r = (TransliterationRule*) ruleVector->elementAt(j);
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if (r->matchesIndexValue((uint8_t)x, data)) {
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v.addElement(r);
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}
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}
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}
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}
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delete[] indexValue;
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index[256] = v.size();
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/* Freeze things into an array.
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*/
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rules = new TransliterationRule*[v.size()];
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for (j=0; j<v.size(); ++j) {
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rules[j] = (TransliterationRule*) v.elementAt(j);
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}
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delete ruleVector;
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ruleVector = NULL;
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// TODO Add error reporting that indicates the rules that
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// are being masked.
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//UnicodeString errors;
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/* Check for masking. This is MUCH faster than our old check,
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* which was each rule against each following rule, since we
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* only have to check for masking within each bin now. It's
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* 256*O(n2^2) instead of O(n1^2), where n1 is the total rule
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* count, and n2 is the per-bin rule count. But n2<<n1, so
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* it's a big win.
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*/
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for (x=0; x<256; ++x) {
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for (j=index[x]; j<index[x+1]-1; ++j) {
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TransliterationRule* r1 = rules[j];
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for (int32_t k=j+1; k<index[x+1]; ++k) {
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TransliterationRule* r2 = rules[k];
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if (r1->masks(*r2)) {
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//| if (errors == null) {
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//| errors = new StringBuffer();
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//| } else {
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//| errors.append("\n");
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//| }
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//| errors.append("Rule " + r1 + " masks " + r2);
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status = U_ILLEGAL_ARGUMENT_ERROR;
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return;
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}
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}
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}
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}
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//if (errors != null) {
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// throw new IllegalArgumentException(errors.toString());
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//}
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}
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/**
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* Attempt to find a matching rule at the specified point in the text.
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* @param text the text, both translated and untranslated
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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 cursor position at which to translate next, representing offset
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* into text. This value must be between <code>start</code> and
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* <code>limit</code>.
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* @param data a dictionary mapping variables to the sets they
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* represent (maps <code>Character</code> to <code>UnicodeSet</code>)
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* @param filter the filter. Any character for which
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* <tt>filter.contains()</tt> returns <tt>false</tt> will not be
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* altered by this transliterator. If <tt>filter</tt> is
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* <tt>null</tt> then no filtering is applied.
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* @return the matching rule, or null if none found.
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*/
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TransliterationRule*
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TransliterationRuleSet::findMatch(const Replaceable& text,
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int32_t start, int32_t limit,
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int32_t cursor,
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const TransliterationRuleData& data,
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const UnicodeFilter* filter) const {
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/* We only need to check our indexed bin of the rule table,
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* based on the low byte of the first key character.
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*/
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int16_t x = text.charAt(cursor) & 0xFF;
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for (int32_t i=index[x]; i<index[x+1]; ++i) {
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if (rules[i]->matches(text, start, limit, cursor, data, filter)) {
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return rules[i];
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}
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}
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return NULL;
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}
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/**
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* Attempt to find a matching rule at the specified point in the text.
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* Unlike <code>findMatch()</code>, this method does an incremental match.
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* An incremental match requires that there be no partial matches that might
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* pre-empt the full match that is found. If there are partial matches,
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* then null is returned. A non-null result indicates that a full match has
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* been found, and that it cannot be pre-empted by a partial match
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* regardless of what additional text is added to the translation buffer.
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* @param text the text, both translated and untranslated
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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 cursor position at which to translate next, representing offset
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* into text. This value must be between <code>start</code> and
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* <code>limit</code>.
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* @param data a dictionary mapping variables to the sets they
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* represent (maps <code>Character</code> to <code>UnicodeSet</code>)
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* @param partial output parameter. <code>partial[0]</code> is set to
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* true if a partial match is returned.
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* @param filter the filter. Any character for which
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* <tt>filter.contains()</tt> returns <tt>false</tt> will not be
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* altered by this transliterator. If <tt>filter</tt> is
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* <tt>null</tt> then no filtering is applied.
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* @return the matching rule, or null if none found, or if the text buffer
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* does not have enough text yet to unambiguously match a rule.
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*/
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TransliterationRule*
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TransliterationRuleSet::findIncrementalMatch(const Replaceable& text,
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int32_t start,
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int32_t limit, int32_t cursor,
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const TransliterationRuleData& data,
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bool_t& isPartial,
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const UnicodeFilter* filter) const {
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/* We only need to check our indexed bin of the rule table,
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* based on the low byte of the first key character.
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*/
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isPartial = FALSE;
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int16_t x = text.charAt(cursor) & 0xFF;
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for (int32_t i=index[x]; i<index[x+1]; ++i) {
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int32_t match = rules[i]->getMatchDegree(text, start, limit, cursor,
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data, filter);
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switch (match) {
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case TransliterationRule::FULL_MATCH:
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return rules[i];
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case TransliterationRule::PARTIAL_MATCH:
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isPartial = TRUE;
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return NULL;
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}
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}
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return NULL;
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}
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