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Diffstat (limited to 'intl/icu/source/i18n/rbt_rule.h')
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diff --git a/intl/icu/source/i18n/rbt_rule.h b/intl/icu/source/i18n/rbt_rule.h new file mode 100644 index 0000000000..c6f5151d4c --- /dev/null +++ b/intl/icu/source/i18n/rbt_rule.h @@ -0,0 +1,310 @@ +// © 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +* Copyright (C) {1999-2001}, International Business Machines Corporation and others. All Rights Reserved. +********************************************************************** +* Date Name Description +* 11/17/99 aliu Creation. +********************************************************************** +*/ +#ifndef RBT_RULE_H +#define RBT_RULE_H + +#include "unicode/utypes.h" + +#if !UCONFIG_NO_TRANSLITERATION + +#include "unicode/uobject.h" +#include "unicode/unistr.h" +#include "unicode/utrans.h" +#include "unicode/unimatch.h" + +U_NAMESPACE_BEGIN + +class Replaceable; +class TransliterationRuleData; +class StringMatcher; +class UnicodeFunctor; + +/** + * A transliteration rule used by + * <code>RuleBasedTransliterator</code>. + * <code>TransliterationRule</code> is an immutable object. + * + * <p>A rule consists of an input pattern and an output string. When + * the input pattern is matched, the output string is emitted. The + * input pattern consists of zero or more characters which are matched + * exactly (the key) and optional context. Context must match if it + * is specified. Context may be specified before the key, after the + * key, or both. The key, preceding context, and following context + * may contain variables. Variables represent a set of Unicode + * characters, such as the letters <i>a</i> through <i>z</i>. + * Variables are detected by looking up each character in a supplied + * variable list to see if it has been so defined. + * + * <p>A rule may contain segments in its input string and segment + * references in its output string. A segment is a substring of the + * input pattern, indicated by an offset and limit. The segment may + * be in the preceding or following context. It may not span a + * context boundary. A segment reference is a special character in + * the output string that causes a segment of the input string (not + * the input pattern) to be copied to the output string. The range of + * special characters that represent segment references is defined by + * RuleBasedTransliterator.Data. + * + * @author Alan Liu + */ +class TransliterationRule : public UMemory { + +private: + + // TODO Eliminate the pattern and keyLength data members. They + // are used only by masks() and getIndexValue() which are called + // only during build time, not during run-time. Perhaps these + // methods and pattern/keyLength can be isolated into a separate + // object. + + /** + * The match that must occur before the key, or null if there is no + * preceding context. + */ + StringMatcher *anteContext; + + /** + * The matcher object for the key. If null, then the key is empty. + */ + StringMatcher *key; + + /** + * The match that must occur after the key, or null if there is no + * following context. + */ + StringMatcher *postContext; + + /** + * The object that performs the replacement if the key, + * anteContext, and postContext are matched. Never null. + */ + UnicodeFunctor* output; + + /** + * The string that must be matched, consisting of the anteContext, key, + * and postContext, concatenated together, in that order. Some components + * may be empty (zero length). + * @see anteContextLength + * @see keyLength + */ + UnicodeString pattern; + + /** + * An array of matcher objects corresponding to the input pattern + * segments. If there are no segments this is null. N.B. This is + * a UnicodeMatcher for generality, but in practice it is always a + * StringMatcher. In the future we may generalize this, but for + * now we sometimes cast down to StringMatcher. + * + * The array is owned, but the pointers within it are not. + */ + UnicodeFunctor** segments; + + /** + * The number of elements in segments[] or zero if segments is nullptr. + */ + int32_t segmentsCount; + + /** + * The length of the string that must match before the key. If + * zero, then there is no matching requirement before the key. + * Substring [0,anteContextLength) of pattern is the anteContext. + */ + int32_t anteContextLength; + + /** + * The length of the key. Substring [anteContextLength, + * anteContextLength + keyLength) is the key. + + */ + int32_t keyLength; + + /** + * Miscellaneous attributes. + */ + int8_t flags; + + /** + * Flag attributes. + */ + enum { + ANCHOR_START = 1, + ANCHOR_END = 2 + }; + + /** + * An alias pointer to the data for this rule. The data provides + * lookup services for matchers and segments. + */ + const TransliterationRuleData* data; + +public: + + /** + * Construct a new rule with the given input, output text, and other + * attributes. A cursor position may be specified for the output text. + * @param input input string, including key and optional ante and + * post context. + * @param anteContextPos offset into input to end of ante context, or -1 if + * none. Must be <= input.length() if not -1. + * @param postContextPos offset into input to start of post context, or -1 + * if none. Must be <= input.length() if not -1, and must be >= + * anteContextPos. + * @param outputStr output string. + * @param cursorPosition offset into output at which cursor is located, or -1 if + * none. If less than zero, then the cursor is placed after the + * <code>output</code>; that is, -1 is equivalent to + * <code>output.length()</code>. If greater than + * <code>output.length()</code> then an exception is thrown. + * @param cursorOffset an offset to be added to cursorPos to position the + * cursor either in the ante context, if < 0, or in the post context, if > + * 0. For example, the rule "abc{def} > | @@@ xyz;" changes "def" to + * "xyz" and moves the cursor to before "a". It would have a cursorOffset + * of -3. + * @param segs array of UnicodeMatcher corresponding to input pattern + * segments, or null if there are none. The array itself is adopted, + * but the pointers within it are not. + * @param segsCount number of elements in segs[]. + * @param anchorStart true if the the rule is anchored on the left to + * the context start. + * @param anchorEnd true if the rule is anchored on the right to the + * context limit. + * @param data the rule data. + * @param status Output parameter filled in with success or failure status. + */ + TransliterationRule(const UnicodeString& input, + int32_t anteContextPos, int32_t postContextPos, + const UnicodeString& outputStr, + int32_t cursorPosition, int32_t cursorOffset, + UnicodeFunctor** segs, + int32_t segsCount, + UBool anchorStart, UBool anchorEnd, + const TransliterationRuleData* data, + UErrorCode& status); + + /** + * Copy constructor. + * @param other the object to be copied. + */ + TransliterationRule(TransliterationRule& other); + + /** + * Destructor. + */ + virtual ~TransliterationRule(); + + /** + * Change the data object that this rule belongs to. Used + * internally by the TransliterationRuleData copy constructor. + * @param data the new data value to be set. + */ + void setData(const TransliterationRuleData* data); + + /** + * Return the preceding context length. This method is needed to + * support the <code>Transliterator</code> method + * <code>getMaximumContextLength()</code>. Internally, this is + * implemented as the anteContextLength, optionally plus one if + * there is a start anchor. The one character anchor gap is + * needed to make repeated incremental transliteration with + * anchors work. + * @return the preceding context length. + */ + virtual int32_t getContextLength() const; + + /** + * Internal method. Returns 8-bit index value for this rule. + * This is the low byte of the first character of the key, + * unless the first character of the key is a set. If it's a + * set, or otherwise can match multiple keys, the index value is -1. + * @return 8-bit index value for this rule. + */ + int16_t getIndexValue() const; + + /** + * Internal method. Returns true if this rule matches the given + * index value. The index value is an 8-bit integer, 0..255, + * representing the low byte of the first character of the key. + * It matches this rule if it matches the first character of the + * key, or if the first character of the key is a set, and the set + * contains any character with a low byte equal to the index + * value. If the rule contains only ante context, as in foo)>bar, + * then it will match any key. + * @param v the given index value. + * @return true if this rule matches the given index value. + */ + UBool matchesIndexValue(uint8_t v) const; + + /** + * Return true if this rule masks another rule. If r1 masks r2 then + * r1 matches any input string that r2 matches. If r1 masks r2 and r2 masks + * r1 then r1 == r2. Examples: "a>x" masks "ab>y". "a>x" masks "a[b]>y". + * "[c]a>x" masks "[dc]a>y". + * @param r2 the given rule to be compared with. + * @return true if this rule masks 'r2' + */ + virtual UBool masks(const TransliterationRule& r2) const; + + /** + * Attempt a match and replacement at the given position. Return + * the degree of match between this rule and the given text. The + * degree of match may be mismatch, a partial match, or a full + * match. A mismatch means at least one character of the text + * does not match the context or key. A partial match means some + * context and key characters match, but the text is not long + * enough to match all of them. A full match means all context + * and key characters match. + * + * If a full match is obtained, perform a replacement, update pos, + * and return U_MATCH. Otherwise both text and pos are unchanged. + * + * @param text the text + * @param pos the position indices + * @param incremental if true, test for partial matches that may + * be completed by additional text inserted at pos.limit. + * @return one of <code>U_MISMATCH</code>, + * <code>U_PARTIAL_MATCH</code>, or <code>U_MATCH</code>. If + * incremental is false then U_PARTIAL_MATCH will not be returned. + */ + UMatchDegree matchAndReplace(Replaceable& text, + UTransPosition& pos, + UBool incremental) const; + + /** + * Create a rule string that represents this rule object. Append + * it to the given string. + */ + virtual UnicodeString& toRule(UnicodeString& pat, + UBool escapeUnprintable) const; + + /** + * Union the set of all characters that may be modified by this rule + * into the given set. + */ + void addSourceSetTo(UnicodeSet& toUnionTo) const; + + /** + * Union the set of all characters that may be emitted by this rule + * into the given set. + */ + void addTargetSetTo(UnicodeSet& toUnionTo) const; + + private: + + friend class StringMatcher; + + TransliterationRule &operator=(const TransliterationRule &other); // forbid copying of this class +}; + +U_NAMESPACE_END + +#endif /* #if !UCONFIG_NO_TRANSLITERATION */ + +#endif |