295 lines
12 KiB
C++
295 lines
12 KiB
C++
/*
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* Copyright © {1999}, International Business Machines 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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#ifndef RBT_RULE_H
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#define RBT_RULE_H
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#include "unicode/unistr.h"
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class Replaceable;
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class TransliterationRuleData;
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class UnicodeFilter;
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/**
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* A transliteration rule used by
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* <code>RuleBasedTransliterator</code>.
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* <code>TransliterationRule</code> is an immutable object.
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*
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* <p>A rule consists of an input pattern and an output string. When
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* the input pattern is matched, the output string is emitted. The
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* input pattern consists of zero or more characters which are matched
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* exactly (the key) and optional context. Context must match if it
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* is specified. Context may be specified before the key, after the
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* key, or both. The key, preceding context, and following context
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* may contain variables. Variables represent a set of Unicode
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* characters, such as the letters <i>a</i> through <i>z</i>.
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* Variables are detected by looking up each character in a supplied
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* variable list to see if it has been so defined.
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*
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* @author Alan Liu
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*/
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class TransliterationRule {
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public:
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/**
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* Constants returned by <code>getMatchDegree()</code> indicating
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* the degree of match between the text and this rule.
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* @see #getMatchDegree
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*/
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enum {
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/**
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* Constant returned by <code>getMatchDegree()</code>
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* indicating a mismatch between the text and this rule. One
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* or more characters of the context or key do not match the
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* text.
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*/
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MISMATCH,
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/**
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* Constant returned by <code>getMatchDegree()</code>
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* indicating a partial match between the text and this rule.
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* All characters of the text match the corresponding context
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* or key, but more characters are required for a complete
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* match. There are some key or context characters at the end
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* of the pattern that remain unmatched because the text isn't
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* long enough.
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*/
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PARTIAL_MATCH,
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/**
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* Constant returned by <code>getMatchDegree()</code>
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* indicating a complete match between the text and this rule.
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* The text matches all context and key characters.
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*/
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FULL_MATCH
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};
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private:
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/**
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* The string that must be matched, consisting of the anteContext, key,
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* and postContext, concatenated together, in that order. Some components
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* may be empty (zero length).
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* @see anteContextLength
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* @see keyLength
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*/
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UnicodeString pattern;
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/**
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* The string that is emitted if the key, anteContext, and postContext
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* are matched.
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*/
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UnicodeString output;
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/**
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* The length of the string that must match before the key. If
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* zero, then there is no matching requirement before the key.
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* Substring [0,anteContextLength) of pattern is the anteContext.
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*/
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int32_t anteContextLength;
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/**
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* The length of the key. Substring [anteContextLength,
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* anteContextLength + keyLength) is the key.
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*/
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int32_t keyLength;
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/**
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* The position of the cursor after emitting the output string, from 0 to
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* output.length(). For most rules with no special cursor specification,
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* the cursorPos is output.length().
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*/
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int32_t cursorPos;
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public:
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/**
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* Construct a new rule with the given input, output text, and other
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* attributes. A cursor position may be specified for the output text.
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* @param input input string, including key and optional ante and
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* post context
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* @param anteContextPos offset into input to end of ante context, or -1 if
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* none. Must be <= input.length() if not -1.
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* @param postContextPos offset into input to start of post context, or -1
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* if none. Must be <= input.length() if not -1, and must be >=
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* anteContextPos.
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* @param output output string
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* @param cursorPos offset into output at which cursor is located, or -1 if
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* none. If less than zero, then the cursor is placed after the
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* <code>output</code>; that is, -1 is equivalent to
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* <code>output.length()</code>. If greater than
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* <code>output.length()</code> then an exception is thrown.
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*/
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TransliterationRule(const UnicodeString& input,
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int32_t anteContextPos, int32_t postContextPos,
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const UnicodeString& output,
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int32_t cursorPos,
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UErrorCode& status);
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/**
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* Destructor.
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*/
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virtual ~TransliterationRule();
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/**
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* Return the length of the key. Equivalent to <code>getKey().length()</code>.
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* @return the length of the match key.
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*/
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virtual int32_t getKeyLength(void) const;
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/**
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* Return the output string.
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* @return the output string.
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*/
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virtual const UnicodeString& getOutput(void) const;
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/**
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* Return the position of the cursor within the output string.
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* @return a value from 0 to <code>getOutput().length()</code>, inclusive.
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*/
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virtual int32_t getCursorPos(void) const;
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/**
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* Return the preceding context length. This method is needed to
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* support the <code>Transliterator</code> method
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* <code>getMaximumContextLength()</code>.
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*/
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virtual int32_t getAnteContextLength(void) const;
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/**
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* Internal method. Returns 8-bit index value for this rule.
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* This is the low byte of the first character of the key,
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* unless the first character of the key is a set. If it's a
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* set, or otherwise can match multiple keys, the index value is -1.
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*/
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int16_t getIndexValue(const TransliterationRuleData& data);
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/**
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* Internal method. Returns true if this rule matches the given
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* index value. The index value is an 8-bit integer, 0..255,
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* representing the low byte of the first character of the key.
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* It matches this rule if it matches the first character of the
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* key, or if the first character of the key is a set, and the set
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* contains any character with a low byte equal to the index
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* value. If the rule contains only ante context, as in foo)>bar,
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* then it will match any key.
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*/
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UBool matchesIndexValue(uint8_t v,
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const TransliterationRuleData& data);
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/**
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* Return true if this rule masks another rule. If r1 masks r2 then
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* r1 matches any input string that r2 matches. If r1 masks r2 and r2 masks
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* r1 then r1 == r2. Examples: "a>x" masks "ab>y". "a>x" masks "a[b]>y".
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* "[c]a>x" masks "[dc]a>y".
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*/
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virtual UBool masks(const TransliterationRule& r2) const;
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/**
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* Return true if this rule matches the given 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 filter the filter. Any character for which
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* <tt>filter.isIn()</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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*/
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virtual UBool matches(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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/**
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* Return the degree of match between this rule and the given text. The
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* degree of match may be mismatch, a partial match, or a full match. A
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* mismatch means at least one character of the text does not match the
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* context or key. A partial match means some context and key characters
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* match, but the text is not long enough to match all of them. A full
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* match means all context and key characters match.
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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 filter the filter. Any character for which
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* <tt>filter.isIn()</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 one of <code>MISMATCH</code>, <code>PARTIAL_MATCH</code>, or
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* <code>FULL_MATCH</code>.
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* @see #MISMATCH
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* @see #PARTIAL_MATCH
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* @see #FULL_MATCH
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*/
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virtual int32_t getMatchDegree(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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/**
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* Return the number of characters of the text that match this rule. If
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* there is a mismatch, return -1. If the text is not long enough to match
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* any characters, return 0.
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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 templ the text to match against. All characters must match.
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* @param data a dictionary of variables mapping <code>Character</code>
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* to <code>UnicodeSet</code>
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* @param filter the filter. Any character for which
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* <tt>filter.isIn()</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 -1 if there is a mismatch, 0 if the text is not long enough to
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* match any characters, otherwise the number of characters of text that
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* match this rule.
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*/
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virtual int32_t getRegionMatchLength(const Replaceable& text, int32_t start,
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int32_t limit, int32_t cursor,
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const UnicodeString& templ,
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const TransliterationRuleData& data,
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const UnicodeFilter* filter) const;
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/**
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* Return true if the given key matches the given text. This method
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* accounts for the fact that the key character may represent a character
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* set. Note that the key and text characters may not be interchanged
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* without altering the results.
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* @param keyChar a character in the match key
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* @param textChar a character in the text being transliterated
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* @param data a dictionary of variables mapping <code>Character</code>
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* to <code>UnicodeSet</code>
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* @param filter the filter. Any character for which
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* <tt>filter.isIn()</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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*/
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virtual UBool charMatches(UChar keyChar, UChar textChar,
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const TransliterationRuleData& data,
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const UnicodeFilter* filter) const;
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};
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#endif
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