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With inspiration from other libraries
// © 2016 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html#License
/*
*******************************************************************************
* Copyright (C) 2001-2016, International Business Machines Corporation and *
* others. All Rights Reserved. *
*******************************************************************************
*/
package com.ibm.icu.text;
/**
* UnicodeMatcher defines a protocol for objects that can
* match a range of characters in a Replaceable string.
* @stable ICU 2.0
*/
public interface UnicodeMatcher {
/**
* Constant returned by matches() indicating a
* mismatch between the text and this matcher. The text contains
* a character which does not match, or the text does not contain
* all desired characters for a non-incremental match.
* @stable ICU 2.0
*/
public static final int U_MISMATCH = 0;
/**
* Constant returned by matches() indicating a
* partial match between the text and this matcher. This value is
* only returned for incremental match operations. All characters
* of the text match, but more characters are required for a
* complete match. Alternatively, for variable-length matchers,
* all characters of the text match, and if more characters were
* supplied at limit, they might also match.
* @stable ICU 2.0
*/
public static final int U_PARTIAL_MATCH = 1;
/**
* Constant returned by matches() indicating a
* complete match between the text and this matcher. For an
* incremental variable-length match, this value is returned if
* the given text matches, and it is known that additional
* characters would not alter the extent of the match.
* @stable ICU 2.0
*/
public static final int U_MATCH = 2;
/**
* The character at index i, where i < contextStart || i >= contextLimit,
* is ETHER. This allows explicit matching by rules and UnicodeSets
* of text outside the context. In traditional terms, this allows anchoring
* at the start and/or end.
* @stable ICU 2.0
*/
static final char ETHER = '\uFFFF';
/**
* Return a UMatchDegree value indicating the degree of match for
* the given text at the given offset. Zero, one, or more
* characters may be matched.
*
* Matching in the forward direction is indicated by limit >
* offset. Characters from offset forwards to limit-1 will be
* considered for matching.
*
* Matching in the reverse direction is indicated by limit <
* offset. Characters from offset backwards to limit+1 will be
* considered for matching.
*
* If limit == offset then the only match possible is a zero
* character match (which subclasses may implement if desired).
*
* If U_MATCH is returned, then as a side effect, advance the
* offset parameter to the limit of the matched substring. In the
* forward direction, this will be the index of the last matched
* character plus one. In the reverse direction, this will be the
* index of the last matched character minus one.
*
* @param text the text to be matched
* @param offset on input, the index into text at which to begin
* matching. On output, the limit of the matched text. The
* number of matched characters is the output value of offset
* minus the input value. Offset should always point to the
* HIGH SURROGATE (leading code unit) of a pair of surrogates,
* both on entry and upon return.
* @param limit the limit index of text to be matched. Greater
* than offset for a forward direction match, less than offset for
* a backward direction match. The last character to be
* considered for matching will be text.charAt(limit-1) in the
* forward direction or text.charAt(limit+1) in the backward
* direction.
* @param incremental if TRUE, then assume further characters may
* be inserted at limit and check for partial matching. Otherwise
* assume the text as given is complete.
* @return a match degree value indicating a full match, a partial
* match, or a mismatch. If incremental is FALSE then
* U_PARTIAL_MATCH should never be returned.
* @stable ICU 2.0
*/
public abstract int matches(Replaceable text,
int[] offset,
int limit,
boolean incremental);
/**
* Returns a string representation of this matcher. If the result of
* calling this function is passed to the appropriate parser, it
* will produce another matcher that is equal to this one.
* @param escapeUnprintable if TRUE then convert unprintable
* character to their hex escape representations, \\uxxxx or
* \\Uxxxxxxxx. Unprintable characters are those other than
* U+000A, U+0020..U+007E.
* @stable ICU 2.0
*/
public abstract String toPattern(boolean escapeUnprintable);
/**
* Returns TRUE if this matcher will match a character c, where c
* & 0xFF == v, at offset, in the forward direction (with limit >
* offset). This is used by RuleBasedTransliterator for
* indexing.
*
* Note: This API uses an int even though the value will be
* restricted to 8 bits in order to avoid complications with
* signedness (bytes convert to ints in the range -128..127).
* @stable ICU 2.0
*/
public abstract boolean matchesIndexValue(int v);
/**
* Union the set of all characters that may be matched by this object
* into the given set.
* @param toUnionTo the set into which to union the source characters
* @stable ICU 2.2
*/
public abstract void addMatchSetTo(UnicodeSet toUnionTo);
}
//eof