SearchIterator is an abstract base class that provides methods to search for a pattern within a text string. More...
#include <search.h>
first, next, previous, or last. More...
position at which the string text matches the search pattern. More...
position at which the string text matches the search pattern. More...
getOffset) is the match position if one was found. More...
SearchIterator is an abstract base class that provides methods to search for a pattern within a text string.
Instances of SearchIterator maintain a current position and scans over the target text, returning the indices the pattern is matched and the length of each match.
SearchIterator defines a protocol for text searching. Subclasses provide concrete implementations of various search algorithms. For example, StringSearch implements language-sensitive pattern matching based on the comparison rules defined in a RuleBasedCollator object.
Other options for searching includes using a BreakIterator to restrict the points at which matches are detected.
SearchIterator provides an API that is similar to that of other text iteration classes such as BreakIterator. Using this class, it is easy to scan through text looking for all occurrences of a given pattern. The following example uses a StringSearch object to find all instances of "fox" in the target string. Any other subclass of SearchIterator can be used in an identical manner.
UnicodeString target("The quick brown fox jumped over the lazy fox");
UnicodeString pattern("fox");
SearchIterator *iter = new StringSearch(pattern, target);
UErrorCode error = U_ZERO_ERROR;
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());
}
Definition at line 82 of file search.h.
◆ SearchIterator() [1/4]Copy constructor that creates a SearchIterator instance with the same behavior, and iterating over the same text.
Destructor.
Cleans up the search iterator data struct.
Default constructor.
Initializes data to the default values.
Constructor for use by subclasses.
handleNext or handlePrev finds a match, but the match's start or end index is not a boundary as determined by the BreakIterator, the match is rejected and handleNext or handlePrev is called again. If this parameter is nullptr, no break detection is attempted.
Constructor for use by subclasses.
Note: No parsing of the text within the CharacterIterator will be done during searching for this version. The block of text in CharacterIterator will be used as it is.
handleNext or handlePrev finds a match, but the match's start or end index is not a boundary as determined by the BreakIterator, the match is rejected and handleNext or handlePrev is called again. If this parameter is nullptr, no break detection is attempted.
Returns the first index at which the string text matches the search pattern.
The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found. If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to the index USEARCH_DONE
USEARCH_DONE if there are no matches.
Returns the first index equal or greater than position at which the string text matches the search pattern.
The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found. If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to the index USEARCH_DONE.
position, or USEARCH_DONE if there are no matches.
Gets the text searching attributes.
Returns the BreakIterator that is used to restrict the points at which matches are detected.
This will be the same object that was passed to the constructor or to setBreakIterator. Note that nullptr is a legal value; it means that break detection should not be attempted.
Returns the length of text in the string which matches the search pattern.
This call returns a valid result only after a successful call to first, next, previous, or last. Just after construction, or after a searching method returns USEARCH_DONE, this method will return 0.
Returns the index to the match in the text string that was searched.
This call returns a valid result only after a successful call to first, next, previous, or last. Just after construction, or after a searching method returns USEARCH_DONE, this method will return USEARCH_DONE.
Use getMatchedLength to get the matched string length.
Returns the text that was matched by the most recent call to first, next, previous, or last.
If the iterator is not pointing at a valid match (e.g. just after construction or after USEARCH_DONE has been returned, returns an empty string.
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.
Implemented in icu::StringSearch.
◆ getText()Return the string text to be searched.
Abstract method which subclasses override to provide the mechanism for finding the next match in the target text.
This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at which the match starts and should call setMatchLength with the number of characters in the target text that make up the match. If no match is found, the method should return USEARCH_DONE.
Implemented in icu::StringSearch.
◆ handlePrev() virtual int32_t icu::SearchIterator::handlePrev ( int32_t position, UErrorCode & status ) protectedpure virtualAbstract method which subclasses override to provide the mechanism for finding the previous match in the target text.
This allows different subclasses to provide different search algorithms.
If a match is found, the implementation should return the index at which the match starts and should call setMatchLength with the number of characters in the target text that make up the match. If no match is found, the method should return USEARCH_DONE.
Implemented in icu::StringSearch.
◆ last() int32_t icu::SearchIterator::last ( UErrorCode & status )Returns the last index in the target text at which it matches the search pattern.
The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found. If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to the index USEARCH_DONE.
USEARCH_DONE if there are no matches.
Returns the index of the next point at which the text matches the search pattern, starting from the current position The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found.
If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to a position after the end of the text string.
USEARCH_DONE if there are no more matches.
Not-equal operator.
Definition at line 569 of file search.h.
References icu::operator==().
◆ operator=()Assignment operator.
Sets this iterator to have the same behavior, and iterate over the same text, as the one passed in.
Equality operator.
Reimplemented in icu::StringSearch.
◆ preceding() int32_t icu::SearchIterator::preceding ( int32_t position, UErrorCode & status )Returns the first index less than position at which the string text matches the search pattern.
The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found. If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to the index USEARCH_DONE
When USEARCH_OVERLAP option is off, the last index of the result match is always less than position. When USERARCH_OVERLAP is on, the result match may span across position.
position, or USEARCH_DONE if there are no matches.
Returns the index of the previous point at which the string text matches the search pattern, starting at the current position.
The iterator is adjusted so that its current index (as returned by getOffset) is the match position if one was found. If a match is not found, USEARCH_DONE will be returned and the iterator will be adjusted to the index USEARCH_DONE
USEARCH_DONE if there are no more matches.
Resets 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.
Reimplemented in icu::StringSearch.
◆ safeClone()Returns a copy of SearchIterator with the same behavior, and iterating over the same text, as this one.
Note that all data will be replicated, except for the text string to be searched.
Implemented in icu::StringSearch.
◆ setAttribute()Sets the text searching attributes located in the enum USearchAttribute with values from the enum USearchAttributeValue.
USEARCH_DEFAULT can be used for all attributes for resetting.
Set the BreakIterator that will be used to restrict the points at which matches are detected.
The user is responsible for deleting the breakiterator.
BreakIterator, the match will be rejected and another will be searched for. If this parameter is nullptr, no break detection is attempted. status for errors if it occurs
Sets the length of the currently matched string in the text string to be searched.
Subclasses' handleNext and handlePrev methods should call this when they find a match in the target text.
sets match not found
Sets the offset of the currently matched string in the text string to be searched.
Subclasses' handleNext and handlePrev methods should call this when they find a match in the target text.
Sets the index to point to the given position, and clears any state that's affected.
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.
Implemented in icu::StringSearch.
◆ setText() [1/2]Set the string 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 CharacterIterator will be done during searching for this version. The block of text in CharacterIterator will be used as it is. The user is responsible for deleting the text.
Reimplemented in icu::StringSearch.
◆ setText() [2/2]Set the string 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. The user is responsible for deleting the text.
Reimplemented in icu::StringSearch.
◆ m_breakiterator_Break iterator.
Currently the C++ breakiterator does not have getRules etc to reproduce another in C. Hence we keep the original around and do the verification at the end of the match. The user is responsible for deleting this break iterator.
Definition at line 428 of file search.h.
◆ m_search_ USearch* icu::SearchIterator::m_search_ protected ◆ m_text_Unicode string version of the search text.
Definition at line 434 of file search.h.
The documentation for this class was generated from the following file:
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