RegexMatcher Class Reference

class RegexMatcher bundles together a reular expression pattern and input text to which the expression can be applied. More...

#include <regex.h>

Inheritance diagram for RegexMatcher:
UObject UMemory

Public Member Functions

 RegexMatcher (const UnicodeString &regexp, uint32_t flags, UErrorCode &status)
 Construct a RegexMatcher for a regular expression.
 RegexMatcher (const UnicodeString &regexp, const UnicodeString &input, uint32_t flags, UErrorCode &status)
 Construct a RegexMatcher for a regular expression.
virtual ~RegexMatcher ()
 Destructor.
virtual UBool matches (UErrorCode &status)
 Attempts to match the entire input region against the pattern.
virtual UBool matches (int32_t startIndex, UErrorCode &status)
 Resets the matcher, then attempts to match the input beginning at the specified startIndex, and extending to the end of the input.
virtual UBool lookingAt (UErrorCode &status)
 Attempts to match the input string, starting from the beginning of the region, against the pattern.
virtual UBool lookingAt (int32_t startIndex, UErrorCode &status)
 Attempts to match the input string, starting from the specified index, against the pattern.
virtual UBool find ()
 Find the next pattern match in the input string.
virtual UBool find (int32_t start, UErrorCode &status)
 Resets this RegexMatcher and then attempts to find the next substring of the input string that matches the pattern, starting at the specified index.
virtual UnicodeString group (UErrorCode &status) const
 Returns a string containing the text matched by the previous match.
virtual UnicodeString group (int32_t groupNum, UErrorCode &status) const
 Returns a string containing the text captured by the given group during the previous match operation.
virtual int32_t groupCount () const
 Returns the number of capturing groups in this matcher's pattern.
virtual int32_t start (UErrorCode &status) const
 Returns the index in the input string of the start of the text matched during the previous match operation.
virtual int32_t start (int32_t group, UErrorCode &status) const
 Returns the index in the input string of the start of the text matched by the specified capture group during the previous match operation.
virtual int32_t end (UErrorCode &status) const
 Returns the index in the input string of the first character following the text matched during the previous match operation.
virtual int32_t end (int32_t group, UErrorCode &status) const
 Returns the index in the input string of the character following the text matched by the specified capture group during the previous match operation.
virtual RegexMatcherreset ()
 Resets this matcher.
virtual RegexMatcherreset (int32_t index, UErrorCode &status)
 Resets this matcher, and set the current input position.
virtual RegexMatcherreset (const UnicodeString &input)
 Resets this matcher with a new input string.
virtual const UnicodeStringinput () const
 Returns the input string being matched.
virtual RegexMatcherregion (int32_t start, int32_t limit, UErrorCode &status)
 Sets the limits of this matcher's region.
virtual int32_t regionStart () const
 Reports the start index of this matcher's region.
virtual int32_t regionEnd () const
 Reports the end (limit) index (exclusive) of this matcher's region.
virtual UBool hasTransparentBounds () const
 Queries the transparency of region bounds for this matcher.
virtual RegexMatcheruseTransparentBounds (UBool b)
 Sets the transparency of region bounds for this matcher.
virtual UBool hasAnchoringBounds () const
 Return true if this matcher is using anchoring bounds.
virtual RegexMatcheruseAnchoringBounds (UBool b)
 Set whether this matcher is using Anchoring Bounds for its region.
virtual UBool hitEnd () const
 Return TRUE if the most recent matching operation touched the end of the text being processed.
virtual UBool requireEnd () const
 Return TRUE the most recent match succeeded and additional input could cause it to fail.
virtual const RegexPatternpattern () const
 Returns the pattern that is interpreted by this matcher.
virtual UnicodeString replaceAll (const UnicodeString &replacement, UErrorCode &status)
 Replaces every substring of the input that matches the pattern with the given replacement string.
virtual UnicodeString replaceFirst (const UnicodeString &replacement, UErrorCode &status)
 Replaces the first substring of the input that matches the pattern with the replacement string.
virtual RegexMatcherappendReplacement (UnicodeString &dest, const UnicodeString &replacement, UErrorCode &status)
 Implements a replace operation intended to be used as part of an incremental find-and-replace.
virtual UnicodeStringappendTail (UnicodeString &dest)
 As the final step in a find-and-replace operation, append the remainder of the input string, starting at the position following the last appendReplacement(), to the destination string.
virtual int32_t split (const UnicodeString &input, UnicodeString dest[], int32_t destCapacity, UErrorCode &status)
 Split a string into fields.
virtual void setTimeLimit (int32_t limit, UErrorCode &status)
 Set a processing time limit for match operations with this Matcher.
virtual int32_t getTimeLimit () const
 Get the time limit, if any, for match operations made with this Matcher.
virtual void setStackLimit (int32_t limit, UErrorCode &status)
 Set the amount of heap storage avaliable for use by the match backtracking stack.
virtual int32_t getStackLimit () const
 Get the size of the heap storage available for use by the back tracking stack.
virtual void setMatchCallback (URegexMatchCallback *callback, const void *context, UErrorCode &status)
 Set a callback function for use with this Matcher.
virtual void getMatchCallback (URegexMatchCallback *&callback, const void *&context, UErrorCode &status)
 Get the callback function for this URegularExpression.
void setTrace (UBool state)
 setTrace Debug function, enable/disable tracing of the matching engine.
virtual UClassID getDynamicClassID () const
 ICU "poor man's RTTI", returns a UClassID for the actual class.
void resetPreserveRegion ()

Static Public Member Functions

static UClassID getStaticClassID ()
 ICU "poor man's RTTI", returns a UClassID for this class.

Friends

class RegexPattern
class RegexCImpl

Detailed Description

class RegexMatcher bundles together a reular expression pattern and input text to which the expression can be applied.

It includes methods for testing for matches, and for find and replace operations.

Class RegexMatcher is not intended to be subclassed.

Stable:
ICU 2.4

Definition at line 452 of file regex.h.


Constructor & Destructor Documentation

RegexMatcher::RegexMatcher ( const UnicodeString regexp,
uint32_t  flags,
UErrorCode status 
)

Construct a RegexMatcher for a regular expression.

This is a convenience method that avoids the need to explicitly create a RegexPattern object. Note that if several RegexMatchers need to be created for the same expression, it will be more efficient to separately create and cache a RegexPattern object, and use its matcher() method to create the RegexMatcher objects.

Parameters:
regexp The Regular Expression to be compiled.
flags Regular expression options, such as case insensitive matching.
See also:
UREGEX_CASE_INSENSITIVE
Parameters:
status Any errors are reported by setting this UErrorCode variable.
Stable:
ICU 2.6
RegexMatcher::RegexMatcher ( const UnicodeString regexp,
const UnicodeString input,
uint32_t  flags,
UErrorCode status 
)

Construct a RegexMatcher for a regular expression.

This is a convenience method that avoids the need to explicitly create a RegexPattern object. Note that if several RegexMatchers need to be created for the same expression, it will be more efficient to separately create and cache a RegexPattern object, and use its matcher() method to create the RegexMatcher objects.

The matcher will retain a reference to the supplied input string, and all regexp pattern matching operations happen directly on the original string. It is critical that the string not be altered or deleted before use by the regular expression operations is complete.

Parameters:
regexp The Regular Expression to be compiled.
input The string to match. The matcher retains a reference to the caller's string; mo copy is made.
flags Regular expression options, such as case insensitive matching.
See also:
UREGEX_CASE_INSENSITIVE
Parameters:
status Any errors are reported by setting this UErrorCode variable.
Stable:
ICU 2.6
virtual RegexMatcher::~RegexMatcher (  )  [virtual]

Destructor.

Stable:
ICU 2.4

Member Function Documentation

virtual RegexMatcher& RegexMatcher::appendReplacement ( UnicodeString dest,
const UnicodeString replacement,
UErrorCode status 
) [virtual]

Implements a replace operation intended to be used as part of an incremental find-and-replace.

The input string, starting from the end of the previous replacement and ending at the start of the current match, is appended to the destination string. Then the replacement string is appended to the output string, including handling any substitutions of captured text.

For simple, prepackaged, non-incremental find-and-replace operations, see replaceFirst() or replaceAll().

Parameters:
dest A UnicodeString to which the results of the find-and-replace are appended.
replacement A UnicodeString that provides the text to be substituted for the input text that matched the regexp pattern. The replacement text may contain references to captured text from the input.
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed, and U_INDEX_OUTOFBOUNDS_ERROR if the replacement text specifies a capture group that does not exist in the pattern.
Returns:
this RegexMatcher
Stable:
ICU 2.4
virtual UnicodeString& RegexMatcher::appendTail ( UnicodeString dest  )  [virtual]

As the final step in a find-and-replace operation, append the remainder of the input string, starting at the position following the last appendReplacement(), to the destination string.

appendTail() is intended to be invoked after one or more invocations of the RegexMatcher::appendReplacement().

Parameters:
dest A UnicodeString to which the results of the find-and-replace are appended.
Returns:
the destination string.
Stable:
ICU 2.4
virtual int32_t RegexMatcher::end ( int32_t  group,
UErrorCode status 
) const [virtual]

Returns the index in the input string of the character following the text matched by the specified capture group during the previous match operation.

Parameters:
group the capture group number
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed and U_INDEX_OUTOFBOUNDS_ERROR for a bad capture group number
Returns:
the index of the first character following the text captured by the specifed group during the previous match operation. Return -1 if the capture group exists in the pattern but was not part of the match.
Stable:
ICU 2.4
virtual int32_t RegexMatcher::end ( UErrorCode status  )  const [virtual]

Returns the index in the input string of the first character following the text matched during the previous match operation.

Parameters:
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed.
Returns:
the index of the last character matched, plus one.
Stable:
ICU 2.4
virtual UBool RegexMatcher::find ( int32_t  start,
UErrorCode status 
) [virtual]

Resets this RegexMatcher and then attempts to find the next substring of the input string that matches the pattern, starting at the specified index.

Parameters:
start the position in the input string to begin the search
status A reference to a UErrorCode to receive any errors.
Returns:
TRUE if a match is found.
Stable:
ICU 2.4
virtual UBool RegexMatcher::find (  )  [virtual]

Find the next pattern match in the input string.

The find begins searching the input at the location following the end of the previous match, or at the start of the string if there is no previous match. If a match is found, start(), end() and group() will provide more information regarding the match.

Note that if the input string is changed by the application, use find(startPos, status) instead of find(), because the saved starting position may not be valid with the altered input string.

Returns:
TRUE if a match is found.
Stable:
ICU 2.4
virtual UClassID RegexMatcher::getDynamicClassID (  )  const [virtual]

ICU "poor man's RTTI", returns a UClassID for the actual class.

Stable:
ICU 2.2

Implements UObject.

virtual void RegexMatcher::getMatchCallback ( URegexMatchCallback *&  callback,
const void *&  context,
UErrorCode status 
) [virtual]

Get the callback function for this URegularExpression.

Parameters:
callback Out paramater, receives a pointer to the user-supplied callback function.
context Out parameter, receives the user context pointer that was set when uregex_setMatchCallback() was called.
status A reference to a UErrorCode to receive any errors.
Stable:
ICU 4.0
virtual int32_t RegexMatcher::getStackLimit (  )  const [virtual]

Get the size of the heap storage available for use by the back tracking stack.

Returns:
the maximum backtracking stack size, in bytes, or zero if the stack size is unlimited.
Stable:
ICU 4.0
static UClassID RegexMatcher::getStaticClassID (  )  [static]

ICU "poor man's RTTI", returns a UClassID for this class.

Stable:
ICU 2.2
virtual int32_t RegexMatcher::getTimeLimit (  )  const [virtual]

Get the time limit, if any, for match operations made with this Matcher.

Returns:
the maximum allowed time for a match, in units of processing steps.
Stable:
ICU 4.0
virtual UnicodeString RegexMatcher::group ( int32_t  groupNum,
UErrorCode status 
) const [virtual]

Returns a string containing the text captured by the given group during the previous match operation.

Group(0) is the entire match.

Parameters:
groupNum the capture group number
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed and U_INDEX_OUTOFBOUNDS_ERROR for a bad capture group number.
Returns:
the captured text
Stable:
ICU 2.4
virtual UnicodeString RegexMatcher::group ( UErrorCode status  )  const [virtual]

Returns a string containing the text matched by the previous match.

If the pattern can match an empty string, an empty string may be returned.

Parameters:
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed.
Returns:
a string containing the matched input text.
Stable:
ICU 2.4
virtual int32_t RegexMatcher::groupCount (  )  const [virtual]

Returns the number of capturing groups in this matcher's pattern.

Returns:
the number of capture groups
Stable:
ICU 2.4
virtual UBool RegexMatcher::hasAnchoringBounds (  )  const [virtual]

Return true if this matcher is using anchoring bounds.

By default, matchers use anchoring region boounds.

Returns:
TRUE if this matcher is using anchoring bounds.
Stable:
ICU 4.0
virtual UBool RegexMatcher::hasTransparentBounds (  )  const [virtual]

Queries the transparency of region bounds for this matcher.

See useTransparentBounds for a description of transparent and opaque bounds. By default, a matcher uses opaque region boundaries.

Returns:
TRUE if this matcher is using opaque bounds, false if it is not.
Stable:
ICU 4.0
virtual UBool RegexMatcher::hitEnd (  )  const [virtual]

Return TRUE if the most recent matching operation touched the end of the text being processed.

In this case, additional input text could change the results of that match.

hitEnd() is defined for both successful and unsuccessful matches. In either case hitEnd() will return TRUE if if the end of the text was reached at any point during the matching process.

Returns:
TRUE if the most recent match hit the end of input
Stable:
ICU 4.0
virtual const UnicodeString& RegexMatcher::input (  )  const [virtual]

Returns the input string being matched.

The returned string is not a copy, but the live input string. It should not be altered or deleted.

Returns:
the input string
Stable:
ICU 2.4
virtual UBool RegexMatcher::lookingAt ( int32_t  startIndex,
UErrorCode status 
) [virtual]

Attempts to match the input string, starting from the specified index, against the pattern.

The match may be of any length, and is not required to extend to the end of the input string. Contrast with match().

If the match succeeds then more information can be obtained via the start(), end(), and group() functions.

Parameters:
startIndex The input string index at which to begin matching.
status A reference to a UErrorCode to receive any errors.
Returns:
TRUE if there is a match.
Stable:
ICU 2.8
virtual UBool RegexMatcher::lookingAt ( UErrorCode status  )  [virtual]

Attempts to match the input string, starting from the beginning of the region, against the pattern.

Like the matches() method, this function always starts at the beginning of the input region; unlike that function, it does not require that the entire region be matched.

If the match succeeds then more information can be obtained via the start(), end(), and group() functions.

Parameters:
status A reference to a UErrorCode to receive any errors.
Returns:
TRUE if there is a match at the start of the input string.
Stable:
ICU 2.4
virtual UBool RegexMatcher::matches ( int32_t  startIndex,
UErrorCode status 
) [virtual]

Resets the matcher, then attempts to match the input beginning at the specified startIndex, and extending to the end of the input.

The input region is reset to include the entire input string. A successful match must extend to the end of the input.

Parameters:
startIndex The input string index at which to begin matching.
status A reference to a UErrorCode to receive any errors.
Returns:
TRUE if there is a match
Stable:
ICU 2.8
virtual UBool RegexMatcher::matches ( UErrorCode status  )  [virtual]

Attempts to match the entire input region against the pattern.

Parameters:
status A reference to a UErrorCode to receive any errors.
Returns:
TRUE if there is a match
Stable:
ICU 2.4
virtual const RegexPattern& RegexMatcher::pattern (  )  const [virtual]

Returns the pattern that is interpreted by this matcher.

Returns:
the RegexPattern for this RegexMatcher
Stable:
ICU 2.4
virtual RegexMatcher& RegexMatcher::region ( int32_t  start,
int32_t  limit,
UErrorCode status 
) [virtual]

Sets the limits of this matcher's region.

The region is the part of the input string that will be searched to find a match. Invoking this method resets the matcher, and then sets the region to start at the index specified by the start parameter and end at the index specified by the end parameter.

Depending on the transparency and anchoring being used (see useTransparentBounds and useAnchoringBounds), certain constructs such as anchors may behave differently at or around the boundaries of the region

The function will fail if start is greater than limit, or if either index is less than zero or greater than the length of the string being matched.

Parameters:
start The index to begin searches at.
limit The index to end searches at (exclusive).
status A reference to a UErrorCode to receive any errors.
Stable:
ICU 4.0
virtual int32_t RegexMatcher::regionEnd (  )  const [virtual]

Reports the end (limit) index (exclusive) of this matcher's region.

The searches this matcher conducts are limited to finding matches within regionStart (inclusive) and regionEnd (exclusive).

Returns:
The ending point of this matcher's region.
Stable:
ICU 4.0
virtual int32_t RegexMatcher::regionStart (  )  const [virtual]

Reports the start index of this matcher's region.

The searches this matcher conducts are limited to finding matches within regionStart (inclusive) and regionEnd (exclusive).

Returns:
The starting index of this matcher's region.
Stable:
ICU 4.0
virtual UnicodeString RegexMatcher::replaceAll ( const UnicodeString replacement,
UErrorCode status 
) [virtual]

Replaces every substring of the input that matches the pattern with the given replacement string.

This is a convenience function that provides a complete find-and-replace-all operation.

This method first resets this matcher. It then scans the input string looking for matches of the pattern. Input that is not part of any match is left unchanged; each match is replaced in the result by the replacement string. The replacement string may contain references to capture groups.

Parameters:
replacement a string containing the replacement text.
status a reference to a UErrorCode to receive any errors.
Returns:
a string containing the results of the find and replace.
Stable:
ICU 2.4
virtual UnicodeString RegexMatcher::replaceFirst ( const UnicodeString replacement,
UErrorCode status 
) [virtual]

Replaces the first substring of the input that matches the pattern with the replacement string.

This is a convenience function that provides a complete find-and-replace operation.

This function first resets this RegexMatcher. It then scans the input string looking for a match of the pattern. Input that is not part of the match is appended directly to the result string; the match is replaced in the result by the replacement string. The replacement string may contain references to captured groups.

The state of the matcher (the position at which a subsequent find() would begin) after completing a replaceFirst() is not specified. The RegexMatcher should be reset before doing additional find() operations.

Parameters:
replacement a string containing the replacement text.
status a reference to a UErrorCode to receive any errors.
Returns:
a string containing the results of the find and replace.
Stable:
ICU 2.4
virtual UBool RegexMatcher::requireEnd (  )  const [virtual]

Return TRUE the most recent match succeeded and additional input could cause it to fail.

If this method returns false and a match was found, then more input might change the match but the match won't be lost. If a match was not found, then requireEnd has no meaning.

Returns:
TRUE if more input could cause the most recent match to no longer match.
Stable:
ICU 4.0
virtual RegexMatcher& RegexMatcher::reset ( const UnicodeString input  )  [virtual]

Resets this matcher with a new input string.

This allows instances of RegexMatcher to be reused, which is more efficient than creating a new RegexMatcher for each input string to be processed.

Parameters:
input The new string on which subsequent pattern matches will operate. The matcher retains a reference to the callers string, and operates directly on that. Ownership of the string remains with the caller. Because no copy of the string is made, it is essential that the caller not delete the string until after regexp operations on it are done.
Returns:
this RegexMatcher.
Stable:
ICU 2.4
virtual RegexMatcher& RegexMatcher::reset ( int32_t  index,
UErrorCode status 
) [virtual]

Resets this matcher, and set the current input position.

The effect is to remove any memory of previous matches, and to cause subsequent find() operations to begin at the specified position in the input string.

The matcher's region is reset to its default, which is the entire input string.

An alternative to this function is to set a match region beginning at the desired index.

Returns:
this RegexMatcher.
Stable:
ICU 2.8
virtual RegexMatcher& RegexMatcher::reset (  )  [virtual]

Resets this matcher.

The effect is to remove any memory of previous matches, and to cause subsequent find() operations to begin at the beginning of the input string.

Returns:
this RegexMatcher.
Stable:
ICU 2.4
void RegexMatcher::resetPreserveRegion (  ) 
Internal:
Do not use. This API is for internal use only.
virtual void RegexMatcher::setMatchCallback ( URegexMatchCallback callback,
const void *  context,
UErrorCode status 
) [virtual]

Set a callback function for use with this Matcher.

During matching operations the function will be called periodically, giving the application the opportunity to terminate a long-running match.

Parameters:
callback A pointer to the user-supplied callback function.
context User context pointer. The value supplied at the time the callback function is set will be saved and passed to the callback each time that it is called.
status A reference to a UErrorCode to receive any errors.
Stable:
ICU 4.0
virtual void RegexMatcher::setStackLimit ( int32_t  limit,
UErrorCode status 
) [virtual]

Set the amount of heap storage avaliable for use by the match backtracking stack.

The matcher is also reset, discarding any results from previous matches.

ICU uses a backtracking regular expression engine, with the backtrack stack maintained on the heap. This function sets the limit to the amount of memory that can be used for this purpose. A backtracking stack overflow will result in an error from the match operation that caused it.

A limit is desirable because a malicious or poorly designed pattern can use excessive memory, potentially crashing the process. A limit is enabled by default.

Parameters:
limit The maximum size, in bytes, of the matching backtrack stack. A value of zero means no limit. The limit must be greater or equal to zero.
status A reference to a UErrorCode to receive any errors.
Stable:
ICU 4.0
virtual void RegexMatcher::setTimeLimit ( int32_t  limit,
UErrorCode status 
) [virtual]

Set a processing time limit for match operations with this Matcher.

Some patterns, when matching certain strings, can run in exponential time. For practical purposes, the match operation may appear to be in an infinite loop. When a limit is set a match operation will fail with an error if the limit is exceeded.

The units of the limit are steps of the match engine. Correspondence with actual processor time will depend on the speed of the processor and the details of the specific pattern, but will typically be on the order of milliseconds.

By default, the matching time is not limited.

Parameters:
limit The limit value, or 0 for no limit.
status A reference to a UErrorCode to receive any errors.
Stable:
ICU 4.0
void RegexMatcher::setTrace ( UBool  state  ) 

setTrace Debug function, enable/disable tracing of the matching engine.

For internal ICU development use only. DO NO USE!!!!

Internal:
Do not use. This API is for internal use only.
virtual int32_t RegexMatcher::split ( const UnicodeString input,
UnicodeString  dest[],
int32_t  destCapacity,
UErrorCode status 
) [virtual]

Split a string into fields.

Somewhat like split() from Perl. The pattern matches identify delimiters that separate the input into fields. The input data between the matches becomes the fields themselves.

Parameters:
input The string to be split into fields. The field delimiters match the pattern (in the "this" object). This matcher will be reset to this input string.
dest An array of UnicodeStrings to receive the results of the split. This is an array of actual UnicodeString objects, not an array of pointers to strings. Local (stack based) arrays can work well here.
destCapacity The number of elements in the destination array. If the number of fields found is less than destCapacity, the extra strings in the destination array are not altered. If the number of destination strings is less than the number of fields, the trailing part of the input string, including any field delimiters, is placed in the last destination string.
status A reference to a UErrorCode to receive any errors.
Returns:
The number of fields into which the input string was split.
Stable:
ICU 2.6
virtual int32_t RegexMatcher::start ( int32_t  group,
UErrorCode status 
) const [virtual]

Returns the index in the input string of the start of the text matched by the specified capture group during the previous match operation.

Return -1 if the capture group exists in the pattern, but was not part of the last match.

Parameters:
group the capture group number
status A reference to a UErrorCode to receive any errors. Possible errors are U_REGEX_INVALID_STATE if no match has been attempted or the last match failed, and U_INDEX_OUTOFBOUNDS_ERROR for a bad capture group number
Returns:
the start position of substring matched by the specified group.
Stable:
ICU 2.4
virtual int32_t RegexMatcher::start ( UErrorCode status  )  const [virtual]

Returns the index in the input string of the start of the text matched during the previous match operation.

Parameters:
status a reference to a UErrorCode to receive any errors.
Returns:
The position in the input string of the start of the last match.
Stable:
ICU 2.4
virtual RegexMatcher& RegexMatcher::useAnchoringBounds ( UBool  b  )  [virtual]

Set whether this matcher is using Anchoring Bounds for its region.

With anchoring bounds, pattern anchors such as ^ and $ will match at the start and end of the region. Without Anchoring Bounds, anchors will only match at the positions they would in the complete text.

Anchoring Bounds are the default for regions.

Parameters:
b TRUE if to enable anchoring bounds; FALSE to disable them.
Returns:
This Matcher
Stable:
ICU 4.0
virtual RegexMatcher& RegexMatcher::useTransparentBounds ( UBool  b  )  [virtual]

Sets the transparency of region bounds for this matcher.

Invoking this function with an argument of true will set this matcher to use transparent bounds. If the boolean argument is false, then opaque bounds will be used.

Using transparent bounds, the boundaries of this matcher's region are transparent to lookahead, lookbehind, and boundary matching constructs. Those constructs can see text beyond the boundaries of the region while checking for a match.

With opaque bounds, no text outside of the matcher's region is visible to lookahead, lookbehind, and boundary matching constructs.

By default, a matcher uses opaque bounds.

Parameters:
b TRUE for transparent bounds; FALSE for opaque bounds
Returns:
This Matcher;
Stable:
ICU 4.0

The documentation for this class was generated from the following file:
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Generated on Sat Jan 23 15:17:43 2010 for ICU 4.3.4 by  doxygen 1.6.1