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Diffstat (limited to 'intl/icu/source/i18n/unicode/stsearch.h')
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diff --git a/intl/icu/source/i18n/unicode/stsearch.h b/intl/icu/source/i18n/unicode/stsearch.h new file mode 100644 index 0000000000..b916aebf24 --- /dev/null +++ b/intl/icu/source/i18n/unicode/stsearch.h @@ -0,0 +1,509 @@ +// © 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +********************************************************************** +* Copyright (C) 2001-2014 IBM and others. All rights reserved. +********************************************************************** +* Date Name Description +* 03/22/2000 helena Creation. +********************************************************************** +*/ + +#ifndef STSEARCH_H +#define STSEARCH_H + +#include "unicode/utypes.h" + +#if U_SHOW_CPLUSPLUS_API + +/** + * \file + * \brief C++ API: Service for searching text based on RuleBasedCollator. + */ + +#if !UCONFIG_NO_COLLATION && !UCONFIG_NO_BREAK_ITERATION + +#include "unicode/tblcoll.h" +#include "unicode/coleitr.h" +#include "unicode/search.h" + +U_NAMESPACE_BEGIN + +/** + * + * <tt>StringSearch</tt> is a <tt>SearchIterator</tt> that provides + * language-sensitive text searching based on the comparison rules defined + * in a {@link RuleBasedCollator} object. + * StringSearch ensures that language eccentricity can be + * handled, e.g. for the German collator, characters ß and SS will be matched + * if case is chosen to be ignored. + * See the <a href="https://htmlpreview.github.io/?https://github.com/unicode-org/icu-docs/blob/main/design/collation/ICU_collation_design.htm"> + * "ICU Collation Design Document"</a> for more information. + * <p> + * There are 2 match options for selection:<br> + * Let S' be the sub-string of a text string S between the offsets start and + * end [start, end]. + * <br> + * A pattern string P matches a text string S at the offsets [start, end] + * if + * <pre> + * option 1. Some canonical equivalent of P matches some canonical equivalent + * of S' + * option 2. P matches S' and if P starts or ends with a combining mark, + * there exists no non-ignorable combining mark before or after S? + * in S respectively. + * </pre> + * Option 2. will be the default. + * <p> + * This search has APIs similar to that of other text iteration mechanisms + * such as the break iterators in <tt>BreakIterator</tt>. Using these + * APIs, it is easy to scan through text looking for all occurrences of + * a given pattern. This search iterator allows changing of direction by + * calling a <tt>reset</tt> followed by a <tt>next</tt> or <tt>previous</tt>. + * Though a direction change can occur without calling <tt>reset</tt> first, + * this operation comes with some speed penalty. + * Match results in the forward direction will match the result matches in + * the backwards direction in the reverse order + * <p> + * <tt>SearchIterator</tt> provides APIs to specify the starting position + * within the text string to be searched, e.g. <tt>setOffset</tt>, + * <tt>preceding</tt> and <tt>following</tt>. Since the + * starting position will be set as it is specified, please take note that + * there are some danger points which the search may render incorrect + * results: + * <ul> + * <li> The midst of a substring that requires normalization. + * <li> If the following match is to be found, the position should not be the + * second character which requires to be swapped with the preceding + * character. Vice versa, if the preceding match is to be found, + * position to search from should not be the first character which + * requires to be swapped with the next character. E.g certain Thai and + * Lao characters require swapping. + * <li> If a following pattern match is to be found, any position within a + * contracting sequence except the first will fail. Vice versa if a + * preceding pattern match is to be found, a invalid starting point + * would be any character within a contracting sequence except the last. + * </ul> + * <p> + * A <tt>BreakIterator</tt> can be used if only matches at logical breaks are desired. + * Using a <tt>BreakIterator</tt> will only give you results that exactly matches the + * boundaries given by the breakiterator. For instance the pattern "e" will + * not be found in the string "\u00e9" if a character break iterator is used. + * <p> + * Options are provided to handle overlapping matches. + * E.g. In English, overlapping matches produces the result 0 and 2 + * for the pattern "abab" in the text "ababab", where else mutually + * exclusive matches only produce the result of 0. + * <p> + * Though collator attributes will be taken into consideration while + * performing matches, there are no APIs here for setting and getting the + * attributes. These attributes can be set by getting the collator + * from <tt>getCollator</tt> and using the APIs in <tt>coll.h</tt>. + * Lastly to update <tt>StringSearch</tt> to the new collator attributes, + * <tt>reset</tt> has to be called. + * <p> + * Restriction: <br> + * Currently there are no composite characters that consists of a + * character with combining class > 0 before a character with combining + * class == 0. However, if such a character exists in the future, + * <tt>StringSearch</tt> does not guarantee the results for option 1. + * <p> + * Consult the <tt>SearchIterator</tt> documentation for information on + * and examples of how to use instances of this class to implement text + * searching. + * <pre><code> + * UnicodeString target("The quick brown fox jumps over the lazy dog."); + * UnicodeString pattern("fox"); + * + * UErrorCode error = U_ZERO_ERROR; + * StringSearch iter(pattern, target, Locale::getUS(), nullptr, status); + * for (int pos = iter.first(error); + * pos != USEARCH_DONE; + * pos = iter.next(error)) + * { + * printf("Found match at %d pos, length is %d\n", pos, iter.getMatchedLength()); + * } + * </code></pre> + * <p> + * Note, <tt>StringSearch</tt> is not to be subclassed. + * </p> + * @see SearchIterator + * @see RuleBasedCollator + * @since ICU 2.0 + */ + +class U_I18N_API StringSearch final : public SearchIterator +{ +public: + + // public constructors and destructors -------------------------------- + + /** + * Creating a <tt>StringSearch</tt> instance using the argument locale + * language rule set. A collator will be created in the process, which + * will be owned by this instance and will be deleted during + * destruction + * @param pattern The text for which this object will search. + * @param text The text in which to search for the pattern. + * @param locale A locale which defines the language-sensitive + * comparison rules used to determine whether text in the + * pattern and target matches. + * @param breakiter A <tt>BreakIterator</tt> object used to constrain + * the matches that are found. Matches whose start and end + * indices in the target text are not boundaries as + * determined by the <tt>BreakIterator</tt> are + * ignored. If this behavior is not desired, + * <tt>nullptr</tt> can be passed in instead. + * @param status for errors if any. If pattern or text is nullptr, or if + * either the length of pattern or text is 0 then an + * U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + StringSearch(const UnicodeString &pattern, const UnicodeString &text, + const Locale &locale, + BreakIterator *breakiter, + UErrorCode &status); + + /** + * Creating a <tt>StringSearch</tt> instance using the argument collator + * language rule set. Note, user retains the ownership of this collator, + * it does not get destroyed during this instance's destruction. + * @param pattern The text for which this object will search. + * @param text The text in which to search for the pattern. + * @param coll A <tt>RuleBasedCollator</tt> object which defines + * the language-sensitive comparison rules used to + * determine whether text in the pattern and target + * matches. User is responsible for the clearing of this + * object. + * @param breakiter A <tt>BreakIterator</tt> object used to constrain + * the matches that are found. Matches whose start and end + * indices in the target text are not boundaries as + * determined by the <tt>BreakIterator</tt> are + * ignored. If this behavior is not desired, + * <tt>nullptr</tt> can be passed in instead. + * @param status for errors if any. If either the length of pattern or + * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + StringSearch(const UnicodeString &pattern, + const UnicodeString &text, + RuleBasedCollator *coll, + BreakIterator *breakiter, + UErrorCode &status); + + /** + * Creating a <tt>StringSearch</tt> instance using the argument locale + * language rule set. A collator will be created in the process, which + * will be owned by this instance and will be deleted during + * destruction + * <p> + * Note: No parsing of the text within the <tt>CharacterIterator</tt> + * will be done during searching for this version. The block of text + * in <tt>CharacterIterator</tt> will be used as it is. + * @param pattern The text for which this object will search. + * @param text The text iterator in which to search for the pattern. + * @param locale A locale which defines the language-sensitive + * comparison rules used to determine whether text in the + * pattern and target matches. User is responsible for + * the clearing of this object. + * @param breakiter A <tt>BreakIterator</tt> object used to constrain + * the matches that are found. Matches whose start and end + * indices in the target text are not boundaries as + * determined by the <tt>BreakIterator</tt> are + * ignored. If this behavior is not desired, + * <tt>nullptr</tt> can be passed in instead. + * @param status for errors if any. If either the length of pattern or + * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + StringSearch(const UnicodeString &pattern, CharacterIterator &text, + const Locale &locale, + BreakIterator *breakiter, + UErrorCode &status); + + /** + * Creating a <tt>StringSearch</tt> instance using the argument collator + * language rule set. Note, user retains the ownership of this collator, + * it does not get destroyed during this instance's destruction. + * <p> + * Note: No parsing of the text within the <tt>CharacterIterator</tt> + * will be done during searching for this version. The block of text + * in <tt>CharacterIterator</tt> will be used as it is. + * @param pattern The text for which this object will search. + * @param text The text in which to search for the pattern. + * @param coll A <tt>RuleBasedCollator</tt> object which defines + * the language-sensitive comparison rules used to + * determine whether text in the pattern and target + * matches. User is responsible for the clearing of this + * object. + * @param breakiter A <tt>BreakIterator</tt> object used to constrain + * the matches that are found. Matches whose start and end + * indices in the target text are not boundaries as + * determined by the <tt>BreakIterator</tt> are + * ignored. If this behavior is not desired, + * <tt>nullptr</tt> can be passed in instead. + * @param status for errors if any. If either the length of pattern or + * text is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + StringSearch(const UnicodeString &pattern, CharacterIterator &text, + RuleBasedCollator *coll, + BreakIterator *breakiter, + UErrorCode &status); + + /** + * Copy constructor that creates a StringSearch instance with the same + * behavior, and iterating over the same text. + * @param that StringSearch instance to be copied. + * @stable ICU 2.0 + */ + StringSearch(const StringSearch &that); + + /** + * Destructor. Cleans up the search iterator data struct. + * If a collator is created in the constructor, it will be destroyed here. + * @stable ICU 2.0 + */ + virtual ~StringSearch(void); + + /** + * Clone this object. + * Clones can be used concurrently in multiple threads. + * If an error occurs, then nullptr is returned. + * The caller must delete the clone. + * + * @return a clone of this object + * + * @see getDynamicClassID + * @stable ICU 2.8 + */ + StringSearch *clone() const; + + // operator overloading --------------------------------------------- + + /** + * Assignment operator. Sets this iterator to have the same behavior, + * and iterate over the same text, as the one passed in. + * @param that instance to be copied. + * @stable ICU 2.0 + */ + StringSearch & operator=(const StringSearch &that); + + /** + * Equality operator. + * @param that instance to be compared. + * @return true if both instances have the same attributes, + * breakiterators, collators and iterate over the same text + * while looking for the same pattern. + * @stable ICU 2.0 + */ + virtual bool operator==(const SearchIterator &that) const override; + + // public get and set methods ---------------------------------------- + + /** + * Sets the index to point to the given position, and clears any state + * that's affected. + * <p> + * This method takes the argument index and sets the position in the text + * string accordingly without checking if the index is pointing to a + * valid starting point to begin searching. + * @param position within the text to be set. If position is less + * than or greater than the text range for searching, + * an U_INDEX_OUTOFBOUNDS_ERROR will be returned + * @param status for errors if it occurs + * @stable ICU 2.0 + */ + virtual void setOffset(int32_t position, UErrorCode &status) override; + + /** + * Return the current index in the text being searched. + * If the iteration has gone past the end of the text + * (or past the beginning for a backwards search), USEARCH_DONE + * is returned. + * @return current index in the text being searched. + * @stable ICU 2.0 + */ + virtual int32_t getOffset(void) const override; + + /** + * Set the target text to be searched. + * Text iteration will hence begin at the start of the text string. + * This method is + * useful if you want to re-use an iterator to search for the same + * pattern within a different body of text. + * @param text text string to be searched + * @param status for errors if any. If the text length is 0 then an + * U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + virtual void setText(const UnicodeString &text, UErrorCode &status) override; + + /** + * Set the target text to be searched. + * Text iteration will hence begin at the start of the text string. + * This method is + * useful if you want to re-use an iterator to search for the same + * pattern within a different body of text. + * Note: No parsing of the text within the <tt>CharacterIterator</tt> + * will be done during searching for this version. The block of text + * in <tt>CharacterIterator</tt> will be used as it is. + * @param text text string to be searched + * @param status for errors if any. If the text length is 0 then an + * U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + virtual void setText(CharacterIterator &text, UErrorCode &status) override; + + /** + * Gets the collator used for the language rules. + * <p> + * Caller may modify but <b>must not</b> delete the <tt>RuleBasedCollator</tt>! + * Modifications to this collator will affect the original collator passed in to + * the <tt>StringSearch></tt> constructor or to setCollator, if any. + * @return collator used for string search + * @stable ICU 2.0 + */ + RuleBasedCollator * getCollator() const; + + /** + * Sets the collator used for the language rules. User retains the + * ownership of this collator, thus the responsibility of deletion lies + * with the user. The iterator's position will not be changed by this method. + * @param coll collator + * @param status for errors if any + * @stable ICU 2.0 + */ + void setCollator(RuleBasedCollator *coll, UErrorCode &status); + + /** + * Sets the pattern used for matching. + * The iterator's position will not be changed by this method. + * @param pattern search pattern to be found + * @param status for errors if any. If the pattern length is 0 then an + * U_ILLEGAL_ARGUMENT_ERROR is returned. + * @stable ICU 2.0 + */ + void setPattern(const UnicodeString &pattern, UErrorCode &status); + + /** + * Gets the search pattern. + * @return pattern used for matching + * @stable ICU 2.0 + */ + const UnicodeString & getPattern() const; + + // public methods ---------------------------------------------------- + + /** + * Reset the iteration. + * Search will begin at the start of the text string if a forward + * iteration is initiated before a backwards iteration. Otherwise if + * a backwards iteration is initiated before a forwards iteration, the + * search will begin at the end of the text string. + * @stable ICU 2.0 + */ + virtual void reset() override; + + /** + * Returns a copy of StringSearch with the same behavior, and + * iterating over the same text, as this one. Note that all data will be + * replicated, except for the user-specified collator and the + * breakiterator. + * @return cloned object + * @stable ICU 2.0 + */ + virtual StringSearch * safeClone() const override; + + /** + * ICU "poor man's RTTI", returns a UClassID for the actual class. + * + * @stable ICU 2.2 + */ + virtual UClassID getDynamicClassID() const override; + + /** + * ICU "poor man's RTTI", returns a UClassID for this class. + * + * @stable ICU 2.2 + */ + static UClassID U_EXPORT2 getStaticClassID(); + +protected: + + // protected method ------------------------------------------------- + + /** + * Search forward for matching text, starting at a given location. + * Clients should not call this method directly; instead they should + * call {@link SearchIterator#next }. + * <p> + * If a match is found, this method returns the index at which the match + * starts and calls {@link SearchIterator#setMatchLength } with the number + * of characters in the target text that make up the match. If no match + * is found, the method returns <tt>USEARCH_DONE</tt>. + * <p> + * The <tt>StringSearch</tt> is adjusted so that its current index + * (as returned by {@link #getOffset }) is the match position if one was + * found. + * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and + * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE. + * @param position The index in the target text at which the search + * starts + * @param status for errors if any occurs + * @return The index at which the matched text in the target starts, or + * USEARCH_DONE if no match was found. + * @stable ICU 2.0 + */ + virtual int32_t handleNext(int32_t position, UErrorCode &status) override; + + /** + * Search backward for matching text, starting at a given location. + * Clients should not call this method directly; instead they should call + * <tt>SearchIterator.previous()</tt>, which this method overrides. + * <p> + * If a match is found, this method returns the index at which the match + * starts and calls {@link SearchIterator#setMatchLength } with the number + * of characters in the target text that make up the match. If no match + * is found, the method returns <tt>USEARCH_DONE</tt>. + * <p> + * The <tt>StringSearch</tt> is adjusted so that its current index + * (as returned by {@link #getOffset }) is the match position if one was + * found. + * If a match is not found, <tt>USEARCH_DONE</tt> will be returned and + * the <tt>StringSearch</tt> will be adjusted to the index USEARCH_DONE. + * @param position The index in the target text at which the search + * starts. + * @param status for errors if any occurs + * @return The index at which the matched text in the target starts, or + * USEARCH_DONE if no match was found. + * @stable ICU 2.0 + */ + virtual int32_t handlePrev(int32_t position, UErrorCode &status) override; + +private : + StringSearch() = delete; // default constructor not implemented + + // private data members ---------------------------------------------- + + /** + * Pattern text + * @stable ICU 2.0 + */ + UnicodeString m_pattern_; + /** + * String search struct data + * @stable ICU 2.0 + */ + UStringSearch *m_strsrch_; + +}; + +U_NAMESPACE_END + +#endif /* #if !UCONFIG_NO_COLLATION */ + +#endif /* U_SHOW_CPLUSPLUS_API */ + +#endif + |