SearchIterator Class Reference

SearchIterator is an abstract base class that provides methods to search for a pattern within a text string. More...

#include <search.h>

Inheritance diagram for SearchIterator:
UObject UMemory StringSearch

Public Member Functions

 SearchIterator (const SearchIterator &other)
 Copy constructor that creates a SearchIterator instance with the same behavior, and iterating over the same text.
virtual ~SearchIterator ()
 Destructor.
virtual void setOffset (int32_t position, UErrorCode &status)=0
 Sets the index to point to the given position, and clears any state that's affected.
virtual int32_t getOffset (void) const =0
 Return the current index in the text being searched.
void setAttribute (USearchAttribute attribute, USearchAttributeValue value, UErrorCode &status)
 Sets the text searching attributes located in the enum USearchAttribute with values from the enum USearchAttributeValue.
USearchAttributeValue getAttribute (USearchAttribute attribute) const
 Gets the text searching attributes.
int32_t getMatchedStart (void) const
 Returns the index to the match in the text string that was searched.
int32_t getMatchedLength (void) const
 Returns the length of text in the string which matches the search pattern.
void getMatchedText (UnicodeString &result) const
 Returns the text that was matched by the most recent call to first, next, previous, or last.
void setBreakIterator (BreakIterator *breakiter, UErrorCode &status)
 Set the BreakIterator that will be used to restrict the points at which matches are detected.
const BreakIteratorgetBreakIterator (void) const
 Returns the BreakIterator that is used to restrict the points at which matches are detected.
virtual void setText (const UnicodeString &text, UErrorCode &status)
 Set the string text to be searched.
virtual void setText (CharacterIterator &text, UErrorCode &status)
 Set the string text to be searched.
const UnicodeStringgetText (void) const
 Return the string text to be searched.
virtual UBool operator== (const SearchIterator &that) const
 Equality operator.
UBool operator!= (const SearchIterator &that) const
 Not-equal operator.
virtual SearchIteratorsafeClone (void) const =0
 Returns a copy of SearchIterator with the same behavior, and iterating over the same text, as this one.
int32_t first (UErrorCode &status)
 Returns the first index at which the string text matches the search pattern.
int32_t following (int32_t position, UErrorCode &status)
 Returns the first index greater than position at which the string text matches the search pattern.
int32_t last (UErrorCode &status)
 Returns the last index in the target text at which it matches the search pattern.
int32_t preceding (int32_t position, UErrorCode &status)
 Returns the first index less than position at which the string text matches the search pattern.
int32_t next (UErrorCode &status)
 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.
int32_t previous (UErrorCode &status)
 Returns the index of the previous point at which the string text matches the search pattern, starting at the current position.
virtual void reset ()
 Resets the iteration.

Protected Member Functions

 SearchIterator ()
 Default constructor.
 SearchIterator (const UnicodeString &text, BreakIterator *breakiter=NULL)
 Constructor for use by subclasses.
 SearchIterator (CharacterIterator &text, BreakIterator *breakiter=NULL)
 Constructor for use by subclasses.
SearchIteratoroperator= (const SearchIterator &that)
 Assignment operator.
virtual int32_t handleNext (int32_t position, UErrorCode &status)=0
 Abstract method which subclasses override to provide the mechanism for finding the next match in the target text.
virtual int32_t handlePrev (int32_t position, UErrorCode &status)=0
 Abstract method which subclasses override to provide the mechanism for finding the previous match in the target text.
virtual void setMatchLength (int32_t length)
 Sets the length of the currently matched string in the text string to be searched.
virtual void setMatchStart (int32_t position)
 Sets the offset of the currently matched string in the text string to be searched.
void setMatchNotFound ()
 sets match not found

Protected Attributes

USearchm_search_
 C search data struct.
BreakIteratorm_breakiterator_
 Break iterator.
UnicodeString m_text_
 Unicode string version of the search text.

Detailed Description

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 occurances 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.getMatchLength());
 }
 
See also:
StringSearch
RuleBasedCollator

Definition at line 79 of file search.h.


Constructor & Destructor Documentation

SearchIterator::SearchIterator ( const SearchIterator other  ) 

Copy constructor that creates a SearchIterator instance with the same behavior, and iterating over the same text.

Parameters:
other the SearchIterator instance to be copied.
Stable:
ICU 2.0
virtual SearchIterator::~SearchIterator (  )  [virtual]

Destructor.

Cleans up the search iterator data struct.

Stable:
ICU 2.0
SearchIterator::SearchIterator (  )  [protected]

Default constructor.

Initializes data to the default values.

Stable:
ICU 2.0
SearchIterator::SearchIterator ( const UnicodeString text,
BreakIterator breakiter = NULL 
) [protected]

Constructor for use by subclasses.

Parameters:
text The target text to be searched.
breakiter A BreakIterator that is used to restrict the points at which matches are detected. If 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 NULL, no break detection is attempted.
See also:
handleNext
handlePrev
Stable:
ICU 2.0
SearchIterator::SearchIterator ( CharacterIterator text,
BreakIterator breakiter = NULL 
) [protected]

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.

Parameters:
text The target text to be searched.
breakiter A BreakIterator that is used to restrict the points at which matches are detected. If 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 NULL, no break detection is attempted.
See also:
handleNext
handlePrev
Stable:
ICU 2.0

Member Function Documentation

int32_t SearchIterator::first ( UErrorCode status  ) 

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

Parameters:
status for errors if it occurs
Returns:
The character index of the first match, or USEARCH_DONE if there are no matches.
See also:
getOffset
Stable:
ICU 2.0
int32_t SearchIterator::following ( int32_t  position,
UErrorCode status 
)

Returns the first index 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

Parameters:
position where search if to start from. If position is less than or greater than the text range for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
status for errors if it occurs
Returns:
The character index of the first match following position, or USEARCH_DONE if there are no matches.
See also:
getOffset
Stable:
ICU 2.0
USearchAttributeValue SearchIterator::getAttribute ( USearchAttribute  attribute  )  const

Gets the text searching attributes.

Parameters:
attribute text attribute (enum USearchAttribute) to be retrieve
Returns:
text attribute value
Stable:
ICU 2.0
const BreakIterator* SearchIterator::getBreakIterator ( void   )  const

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 NULL is a legal value; it means that break detection should not be attempted.

Returns:
BreakIterator used to restrict matchings.
See also:
setBreakIterator
Stable:
ICU 2.0
int32_t SearchIterator::getMatchedLength ( void   )  const

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 length of the match in the target text, or 0 if there is no match currently.
See also:
first
next
previous
last
Stable:
ICU 2.0
int32_t SearchIterator::getMatchedStart ( void   )  const

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:
index of a substring within the text string that is being searched.
See also:
first
next
previous
last
Stable:
ICU 2.0
void SearchIterator::getMatchedText ( UnicodeString result  )  const

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.

Parameters:
result stores the matched string or an empty string if a match is not found.
See also:
first
next
previous
last
Stable:
ICU 2.0
virtual int32_t SearchIterator::getOffset ( void   )  const [pure virtual]

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.

Returns:
current index in the text being searched.
Stable:
ICU 2.0

Implemented in StringSearch.

const UnicodeString& SearchIterator::getText ( void   )  const

Return the string text to be searched.

Returns:
text string to be searched.
Stable:
ICU 2.0
virtual int32_t SearchIterator::handleNext ( int32_t  position,
UErrorCode status 
) [protected, pure virtual]

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.

Parameters:
position The index in the target text at which the search should start.
status for error codes if it occurs.
Returns:
index at which the match starts, else if match is not found USEARCH_DONE is returned
See also:
setMatchLength
Stable:
ICU 2.0

Implemented in StringSearch.

virtual int32_t SearchIterator::handlePrev ( int32_t  position,
UErrorCode status 
) [protected, pure virtual]

Abstract 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.

Parameters:
position The index in the target text at which the search should start.
status for error codes if it occurs.
Returns:
index at which the match starts, else if match is not found USEARCH_DONE is returned
See also:
setMatchLength
Stable:
ICU 2.0

Implemented in StringSearch.

int32_t 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.

Parameters:
status for errors if it occurs
Returns:
The index of the first match, or USEARCH_DONE if there are no matches.
See also:
getOffset
Stable:
ICU 2.0
int32_t SearchIterator::next ( UErrorCode status  ) 

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.

Parameters:
status for errors if it occurs
Returns:
The index of the next match after the current position, or USEARCH_DONE if there are no more matches.
See also:
getOffset
Stable:
ICU 2.0
UBool SearchIterator::operator!= ( const SearchIterator that  )  const [inline]

Not-equal operator.

Parameters:
that SearchIterator instance to be compared.
Returns:
FALSE if operator== returns TRUE, and vice versa.
Stable:
ICU 2.0

Definition at line 560 of file search.h.

References operator==().

SearchIterator& SearchIterator::operator= ( const SearchIterator that  )  [protected]

Assignment operator.

Sets this iterator to have the same behavior, and iterate over the same text, as the one passed in.

Parameters:
that instance to be copied.
Stable:
ICU 2.0

Reimplemented in StringSearch.

virtual UBool SearchIterator::operator== ( const SearchIterator that  )  const [virtual]

Equality operator.

Parameters:
that SearchIterator instance to be compared.
Returns:
TRUE if both BreakIterators are of the same class, have the same behavior, terates over the same text and have the same attributes. FALSE otherwise.
Stable:
ICU 2.0

Referenced by operator!=().

int32_t 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

Parameters:
position where search is to start from. If position is less than or greater than the text range for searching, an U_INDEX_OUTOFBOUNDS_ERROR will be returned
status for errors if it occurs
Returns:
The character index of the first match preceding position, or USEARCH_DONE if there are no matches.
See also:
getOffset
Stable:
ICU 2.0
int32_t SearchIterator::previous ( UErrorCode status  ) 

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

Parameters:
status for errors if it occurs
Returns:
The index of the previous match before the current position, or USEARCH_DONE if there are no more matches.
See also:
getOffset
Stable:
ICU 2.0
virtual void SearchIterator::reset (  )  [virtual]

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.

Stable:
ICU 2.0

Reimplemented in StringSearch.

virtual SearchIterator* SearchIterator::safeClone ( void   )  const [pure virtual]

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.

Returns:
cloned object
Stable:
ICU 2.0

Implemented in StringSearch.

void SearchIterator::setAttribute ( USearchAttribute  attribute,
USearchAttributeValue  value,
UErrorCode status 
)

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.

Parameters:
attribute text attribute (enum USearchAttribute) to be set
value text attribute value
status for errors if it occurs
Stable:
ICU 2.0
void SearchIterator::setBreakIterator ( BreakIterator breakiter,
UErrorCode status 
)

Set the BreakIterator that will be used to restrict the points at which matches are detected.

The user is responsible for deleting the breakiterator.

Parameters:
breakiter A BreakIterator that will be used to restrict the points at which matches are detected. If a match is found, but the match's start or end index is not a boundary as determined by the BreakIterator, the match will be rejected and another will be searched for. If this parameter is NULL, no break detection is attempted.
status for errors if it occurs
See also:
BreakIterator
Stable:
ICU 2.0
virtual void SearchIterator::setMatchLength ( int32_t  length  )  [protected, virtual]

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.

Parameters:
length length of the matched text.
See also:
handleNext
handlePrev
Stable:
ICU 2.0
void SearchIterator::setMatchNotFound (  )  [protected]

sets match not found

Stable:
ICU 2.0
virtual void SearchIterator::setMatchStart ( int32_t  position  )  [protected, virtual]

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.

Parameters:
position start offset of the matched text.
See also:
handleNext
handlePrev
Stable:
ICU 2.0
virtual void SearchIterator::setOffset ( int32_t  position,
UErrorCode status 
) [pure virtual]

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.

Parameters:
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
status for errors if it occurs
Stable:
ICU 2.0

Implemented in StringSearch.

virtual void SearchIterator::setText ( CharacterIterator text,
UErrorCode status 
) [virtual]

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.

Parameters:
text string iterator to be searched.
status for errors if any. If the text length is 0 then an U_ILLEGAL_ARGUMENT_ERROR is returned.
Stable:
ICU 2.0

Reimplemented in StringSearch.

virtual void SearchIterator::setText ( const UnicodeString text,
UErrorCode status 
) [virtual]

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.

Parameters:
text string to be searched.
status for errors. If the text length is 0, an U_ILLEGAL_ARGUMENT_ERROR is returned.
Stable:
ICU 2.0

Reimplemented in StringSearch.


Field Documentation

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.

Stable:
ICU 2.0

Definition at line 419 of file search.h.

C search data struct.

Stable:
ICU 2.0

Definition at line 409 of file search.h.

Unicode string version of the search text.

Stable:
ICU 2.0

Definition at line 425 of file search.h.


The documentation for this class was generated from the following file:
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Generated on Sat Jan 23 15:17:44 2010 for ICU 4.3.4 by  doxygen 1.6.1