Provided by: tcl8.5-doc_8.5.15-2ubuntu1_all bug

NAME

       Tcl_RegExpMatch, Tcl_RegExpCompile, Tcl_RegExpExec, Tcl_RegExpRange, Tcl_GetRegExpFromObj,
       Tcl_RegExpMatchObj, Tcl_RegExpExecObj, Tcl_RegExpGetInfo - Pattern matching  with  regular
       expressions

SYNOPSIS

       #include <tcl.h>

       int
       Tcl_RegExpMatchObj(interp, textObj, patObj)

       int
       Tcl_RegExpMatch(interp, text, pattern)

       Tcl_RegExp
       Tcl_RegExpCompile(interp, pattern)

       int
       Tcl_RegExpExec(interp, regexp, text, start)

       void
       Tcl_RegExpRange(regexp, index, startPtr, endPtr)

       Tcl_RegExp
       Tcl_GetRegExpFromObj(interp, patObj, cflags)

       int
       Tcl_RegExpExecObj(interp, regexp, textObj, offset, nmatches, eflags)

       void
       Tcl_RegExpGetInfo(regexp, infoPtr)

ARGUMENTS

       Tcl_Interp *interp (in)              Tcl  interpreter  to  use  for  error reporting.  The
                                            interpreter may be NULL  if  no  error  reporting  is
                                            desired.

       Tcl_Obj *textObj (in/out)            Refers  to  the  object from which to get the text to
                                            search.  The internal representation  of  the  object
                                            may  be  converted  to a form that can be efficiently
                                            searched.

       Tcl_Obj *patObj (in/out)             Refers to the object from  which  to  get  a  regular
                                            expression. The compiled regular expression is cached
                                            in the object.

       char *text (in)                      Text to search for a match with a regular expression.

       const char *pattern (in)             String in the form of a regular expression pattern.

       Tcl_RegExp regexp (in)               Compiled regular expression.  Must have been returned
                                            previously       by      Tcl_GetRegExpFromObj      or
                                            Tcl_RegExpCompile.

       char *start (in)                     If text is just a portion of some other string,  this
                                            argument  identifies  the  beginning  of  the  larger
                                            string.  If it is not the same as text, then  no  “^”
                                            matches will be allowed.

       int index (in)                       Specifies  which range is desired:  0 means the range
                                            of the entire match, 1 or  greater  means  the  range
                                            that matched a parenthesized sub-expression.

       const char **startPtr (out)          The  address  of  the first character in the range is
                                            stored here, or NULL if there is no such range.

       const char **endPtr (out)            The address of the character just after the last  one
                                            in  the  range is stored here, or NULL if there is no
                                            such range.

       int cflags (in)                      OR-ed   combination   of   the   compilation    flags
                                            TCL_REG_ADVANCED,   TCL_REG_EXTENDED,  TCL_REG_BASIC,
                                            TCL_REG_EXPANDED,   TCL_REG_QUOTE,    TCL_REG_NOCASE,
                                            TCL_REG_NEWLINE,    TCL_REG_NLSTOP,   TCL_REG_NLANCH,
                                            TCL_REG_NOSUB, and TCL_REG_CANMATCH.  See  below  for
                                            more information.

       int offset (in)                      The  character  offset  into  the text where matching
                                            should begin.  The value of the offset has no  impact
                                            on ^ matches.  This behavior is controlled by eflags.

       int nmatches (in)                    The  number of matching subexpressions that should be
                                            remembered for later use.  If this value is  0,  then
                                            no  subexpression match information will be computed.
                                            If  the  value  is  -1,  then  all  of  the  matching
                                            subexpressions  will  be remembered.  Any other value
                                            will be taken as the maximum number of subexpressions
                                            to remember.

       int eflags (in)                      OR-ed    combination    of    the   execution   flags
                                            TCL_REG_NOTBOL and TCL_REG_NOTEOL. See below for more
                                            information.

       Tcl_RegExpInfo *infoPtr (out)        The address of the location where information about a
                                            previous match should be stored by Tcl_RegExpGetInfo.
_________________________________________________________________

DESCRIPTION

       Tcl_RegExpMatch determines whether its pattern argument matches regexp,  where  regexp  is
       interpreted  as  a regular expression using the rules in the re_syntax reference page.  If
       there  is  a  match  then  Tcl_RegExpMatch  returns  1.   If  there  is  no   match   then
       Tcl_RegExpMatch  returns  0.   If an error occurs in the matching process (e.g. pattern is
       not a valid regular expression) then  Tcl_RegExpMatch  returns  -1  and  leaves  an  error
       message  in  the  interpreter  result.   Tcl_RegExpMatchObj  is similar to Tcl_RegExpMatch
       except it operates on  the  Tcl  objects  textObj  and  patObj  instead  of  UTF  strings.
       Tcl_RegExpMatchObj  is  generally  more  efficient  than  Tcl_RegExpMatch,  so  it  is the
       preferred interface.

       Tcl_RegExpCompile, Tcl_RegExpExec, and Tcl_RegExpRange provide lower-level access  to  the
       regular  expression  pattern  matcher.   Tcl_RegExpCompile  compiles  a regular expression
       string into the internal form used for efficient pattern matching.  The return value is  a
       token  for  this compiled form, which can be used in subsequent calls to Tcl_RegExpExec or
       Tcl_RegExpRange.   If  an  error  occurs  while  compiling  the  regular  expression  then
       Tcl_RegExpCompile  returns  NULL  and  leaves  an error message in the interpreter result.
       Note:  the return value from Tcl_RegExpCompile is only  valid  up  to  the  next  call  to
       Tcl_RegExpCompile;  it is not safe to retain these values for long periods of time.

       Tcl_RegExpExec  executes  the  regular  expression  pattern matcher.  It returns 1 if text
       contains a range of characters that match regexp, 0 if no match is found,  and  -1  if  an
       error  occurs.   In  the  case  of an error, Tcl_RegExpExec leaves an error message in the
       interpreter result.  When searching a string for multiple matches  of  a  pattern,  it  is
       important  to  distinguish  between  the start of the original string and the start of the
       current search.  For example, when searching for the second occurrence  of  a  match,  the
       text  argument  might  point  to the character just after the first match;  however, it is
       important for the pattern matcher to know that this is not the start of the entire string,
       so  that it does not allow “^” atoms in the pattern to match.  The start argument provides
       this information by pointing to the start of the overall string  containing  text.   Start
       will  be  less  than  or equal to text;  if it is less than text then no ^ matches will be
       allowed.

       Tcl_RegExpRange may  be  invoked  after  Tcl_RegExpExec  returns;   it  provides  detailed
       information  about  what  ranges  of  the  string  matched  what  parts  of  the  pattern.
       Tcl_RegExpRange returns a pair of pointers in *startPtr and *endPtr that identify a  range
       of  characters  in  the  source  string for the most recent call to Tcl_RegExpExec.  Index
       indicates which of several ranges is desired: if index is 0, information is returned about
       the  overall  range of characters that matched the entire pattern;  otherwise, information
       is returned about  the  range  of  characters  that  matched  the  index'th  parenthesized
       subexpression  within  the pattern.  If there is no range corresponding to index then NULL
       is stored in *startPtr and *endPtr.

       Tcl_GetRegExpFromObj, Tcl_RegExpExecObj, and Tcl_RegExpGetInfo are object interfaces  that
       provide  the most direct control of Henry Spencer's regular expression library.  For users
       that need to modify compilation and execution options directly, it is recommended that you
       use  these  interfaces instead of calling the internal regexp functions.  These interfaces
       handle the  details  of  UTF  to  Unicode  translations  as  well  as  providing  improved
       performance through caching in the pattern and string objects.

       Tcl_GetRegExpFromObj attempts to return a compiled regular expression from the patObj.  If
       the object does not already contain a compiled  regular  expression  it  will  attempt  to
       create  one  from the string in the object and assign it to the internal representation of
       the patObj.  The return value of this function is of type Tcl_RegExp.  The return value is
       a token for this compiled form, which can be used in subsequent calls to Tcl_RegExpExecObj
       or Tcl_RegExpGetInfo.  If an error occurs while  compiling  the  regular  expression  then
       Tcl_GetRegExpFromObj  returns  NULL and leaves an error message in the interpreter result.
       The regular expression token can be used as long as the internal representation of  patObj
       refers  to the compiled form.  The cflags argument is a bit-wise OR of zero or more of the
       following flags that control the compilation of patObj:

         TCL_REG_ADVANCED
                Compile advanced regular expressions (“ARE”s).   This  mode  corresponds  to  the
                normal regular expression syntax accepted by the Tcl regexp and regsub commands.

         TCL_REG_EXTENDED
                Compile  extended  regular  expressions  (“ERE”s).   This mode corresponds to the
                regular expression syntax recognized by Tcl 8.0 and earlier versions.

         TCL_REG_BASIC
                Compile basic regular expressions (“BRE”s).  This mode corresponds to the regular
                expression syntax recognized by common Unix utilities like sed and grep.  This is
                the default if no flags are specified.

         TCL_REG_EXPANDED
                Compile the regular expression (basic, extended, or advanced) using  an  expanded
                syntax  that  allows  comments  and whitespace.  This mode causes non-backslashed
                non-bracket-expression white space and #-to-end-of-line comments to be ignored.

         TCL_REG_QUOTE
                Compile a literal string, with all characters treated as ordinary characters.

         TCL_REG_NOCASE
                Compile for matching that ignores upper/lower case distinctions.

         TCL_REG_NEWLINE
                Compile for newline-sensitive matching.  By  default,  newline  is  a  completely
                ordinary  character  with  no  special  meaning  in either regular expressions or
                strings.  With this flag, “[^” bracket expressions and “.”  never match  newline,
                “^” matches an empty string after any newline in addition to its normal function,
                and “$” matches an empty string before any newline  in  addition  to  its  normal
                function.  REG_NEWLINE is the bit-wise OR of REG_NLSTOP and REG_NLANCH.

         TCL_REG_NLSTOP
                Compile for partial newline-sensitive matching, with the behavior of “[^” bracket
                expressions and “.”  affected, but not the behavior of  “^”  and  “$”.   In  this
                mode, “[^” bracket expressions and “.”  never match newline.

         TCL_REG_NLANCH
                Compile  for inverse partial newline-sensitive matching, with the behavior of “^”
                and  “$”  (the  “anchors”)  affected,  but  not  the  behavior  of  “[^”  bracket
                expressions  and “.”.  In this mode “^” matches an empty string after any newline
                in addition to its normal function, and “$” matches an empty  string  before  any
                newline in addition to its normal function.

         TCL_REG_NOSUB
                Compile  for matching that reports only success or failure, not what was matched.
                This reduces compile overhead and may improve performance.  Subsequent  calls  to
                Tcl_RegExpGetInfo or Tcl_RegExpRange will not report any match information.

         TCL_REG_CANMATCH
                Compile for matching that reports the potential to complete a partial match given
                more text (see below).

       Only one of TCL_REG_EXTENDED, TCL_REG_ADVANCED, TCL_REG_BASIC, and  TCL_REG_QUOTE  may  be
       specified.

       Tcl_RegExpExecObj executes the regular expression pattern matcher.  It returns 1 if objPtr
       contains a range of characters that match regexp, 0 if no match is found,  and  -1  if  an
       error  occurs.   In the case of an error, Tcl_RegExpExecObj leaves an error message in the
       interpreter result.  The nmatches value indicates to the matcher how  many  subexpressions
       are  of  interest.  If nmatches is 0, then no subexpression match information is recorded,
       which may allow the matcher to make various optimizations.  If the value is -1,  then  all
       of  the subexpressions in the pattern are remembered.  If the value is a positive integer,
       then only that number of subexpressions  will  be  remembered.   Matching  begins  at  the
       specified Unicode character index given by offset.  Unlike Tcl_RegExpExec, the behavior of
       anchors is not affected by the offset value.  Instead  the  behavior  of  the  anchors  is
       explicitly  controlled  by  the eflags argument, which is a bit-wise OR of zero or more of
       the following flags:

         TCL_REG_NOTBOL
                The starting character will not be treated as the beginning  of  a  line  or  the
                beginning of the string, so “^” will not match there.  Note that this flag has no
                effect on how “\A” matches.

         TCL_REG_NOTEOL
                The last character in the string will not be treated as the end of a line or  the
                end  of  the  string,  so  “$”  will not match there.  Note that this flag has no
                effect on how “\Z” matches.

       Tcl_RegExpGetInfo retrieves information about  the  last  match  performed  with  a  given
       regular expression regexp.  The infoPtr argument contains a pointer to a structure that is
       defined as follows:

              typedef struct Tcl_RegExpInfo {
                      int nsubs;
                      Tcl_RegExpIndices *matches;
                      long extendStart;
              } Tcl_RegExpInfo;

       The nsubs field contains a count of the number of parenthesized subexpressions within  the
       regular  expression.   If  the  TCL_REG_NOSUB was used, then this value will be zero.  The
       matches field points to an array of nsubs+1  values  that  indicate  the  bounds  of  each
       subexpression  matched.  The first element in the array refers to the range matched by the
       entire  regular  expression,  and  subsequent  elements   refer   to   the   parenthesized
       subexpressions  in the order that they appear in the pattern.  Each element is a structure
       that is defined as follows:

              typedef struct Tcl_RegExpIndices {
                      long start;
                      long end;
              } Tcl_RegExpIndices;

       The start and end values are Unicode character indices relative  to  the  offset  location
       within objPtr where matching began.  The start index identifies the first character of the
       matched subexpression.  The end index identifies the first  character  after  the  matched
       subexpression.   If the subexpression matched the empty string, then start and end will be
       equal.  If the subexpression did not participate in the match, then start and end will  be
       set to -1.

       The extendStart field in Tcl_RegExpInfo is only set if the TCL_REG_CANMATCH flag was used.
       It indicates the first character in the string where a match could occur.  If a match  was
       found,  this  will  be  the  same  as the beginning of the current match.  If no match was
       found, then it indicates the earliest point at which a match  might  occur  if  additional
       text  is  appended  to  the string.  If it is no match is possible even with further text,
       this field will be set to -1.

SEE ALSO

       re_syntax(3tcl)

KEYWORDS

       match,   pattern,   regular   expression,   string,   subexpression,    Tcl_RegExpIndices,
       Tcl_RegExpInfo