'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\" Copyright (c) 2000 Scriptics Corporation.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: regsub.n,v 1.1.1.1 2007/07/10 15:04:23 duncan Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
'\"	or "in/out" to describe whether procedure reads or modifies arg,
'\"	and indent is equivalent to second arg of .IP (shouldn't ever be
'\"	needed;  use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\"	Give maximum sizes of arguments for setting tab stops.  Type and
'\"	name are examples of largest possible arguments that will be passed
'\"	to .AP later.  If args are omitted, default tab stops are used.
'\"
'\" .BS
'\"	Start box enclosure.  From here until next .BE, everything will be
'\"	enclosed in one large box.
'\"
'\" .BE
'\"	End of box enclosure.
'\"
'\" .CS
'\"	Begin code excerpt.
'\"
'\" .CE
'\"	End code excerpt.
'\"
'\" .VS ?version? ?br?
'\"	Begin vertical sidebar, for use in marking newly-changed parts
'\"	of man pages.  The first argument is ignored and used for recording
'\"	the version when the .VS was added, so that the sidebars can be
'\"	found and removed when they reach a certain age.  If another argument
'\"	is present, then a line break is forced before starting the sidebar.
'\"
'\" .VE
'\"	End of vertical sidebar.
'\"
'\" .DS
'\"	Begin an indented unfilled display.
'\"
'\" .DE
'\"	End of indented unfilled display.
'\"
'\" .SO
'\"	Start of list of standard options for a Tk widget.  The
'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
'\"
'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\"	Start of description of a specific option.  cmdName gives the
'\"	option's name as specified in the class command, dbName gives
'\"	the option's name in the option database, and dbClass gives
'\"	the option's class in the option database.
'\"
'\" .UL arg1 arg2
'\"	Print arg1 underlined, then print arg2 normally.
'\"
'\" RCS: @(#) $Id: man.macros,v 1.1.1.1 2007/07/10 15:04:23 duncan Exp $
'\"
'\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
'\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1	\\fI\\$2\\fP	(\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
'\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
'\"	# BS - start boxed text
'\"	# ^y = starting y location
'\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
'\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
'\"	# VS - start vertical sidebar
'\"	# ^Y = starting y location
'\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
'\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
'\"	# Special macro to handle page bottom:  finish off current
'\"	# box/sidebar if in box/sidebar mode, then invoked standard
'\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
'\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
'\"	# DE - end display
.de DE
.fi
.RE
.sp
..
'\"	# SO - start of list of standard options
.de SO
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
'\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\fBoptions\\fR manual entry for details on the standard options.
..
'\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
'\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
'\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.de UL
\\$1\l'|0\(ul'\\$2
..
.TH regsub n 8.3 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
regsub \- Perform substitutions based on regular expression pattern matching
.SH SYNOPSIS
.VS 8.4
\fBregsub \fR?\fIswitches\fR? \fIexp string subSpec \fR?\fIvarName\fR?
.VE 8.4
.BE

.SH DESCRIPTION
.PP
This command matches the regular expression \fIexp\fR against
\fIstring\fR,
.VS 8.4
and either copies \fIstring\fR to the variable whose name is
given by \fIvarName\fR or returns \fIstring\fR if \fIvarName\fR is not
present.
.VE 8.4
(Regular expression matching is described in the \fBre_syntax\fR
reference page.)
If there is a match, then while copying \fIstring\fR to \fIvarName\fR
.VS 8.4
(or to the result of this command if \fIvarName\fR is not present)
.VE 8.4
the portion of \fIstring\fR that
matched \fIexp\fR is replaced with \fIsubSpec\fR.
If \fIsubSpec\fR contains a ``&'' or ``\e0'', then it is replaced
in the substitution with the portion of \fIstring\fR that
matched \fIexp\fR.
If \fIsubSpec\fR contains a ``\e\fIn\fR'', where \fIn\fR is a digit
between 1 and 9, then it is replaced in the substitution with
the portion of \fIstring\fR that matched the \fIn\fR-th
parenthesized subexpression of \fIexp\fR.
Additional backslashes may be used in \fIsubSpec\fR to prevent special
interpretation of ``&'' or ``\e0'' or ``\e\fIn\fR'' or
backslash.
The use of backslashes in \fIsubSpec\fR tends to interact badly
with the Tcl parser's use of backslashes, so it's generally
safest to enclose \fIsubSpec\fR in braces if it includes
backslashes.
.LP
If the initial arguments to \fBregsub\fR start with \fB\-\fR then
they are treated as switches.  The following switches are
currently supported:
.TP 10
\fB\-all\fR
All ranges in \fIstring\fR that match \fIexp\fR are found and
substitution is performed for each of these ranges.
Without this switch only the first
matching range is found and substituted.
If \fB\-all\fR is specified, then ``&'' and ``\e\fIn\fR''
sequences are handled for each substitution using the information
from the corresponding match.
.TP 15
\fB\-expanded\fR
Enables use of the expanded regular expression syntax where
whitespace and comments are ignored.  This is the same as specifying
the \fB(?x)\fR embedded option (see the \fBre_syntax\fR manual page).
.TP 15
\fB\-line\fR
Enables newline-sensitive matching.  By default, newline is a
completely ordinary character with no special meaning.  With this
flag, `[^' bracket expressions and `.' never match newline, `^'
matches an empty string after any newline in addition to its normal
function, and `$' matches an empty string before any newline in
addition to its normal function.  This flag is equivalent to
specifying both \fB\-linestop\fR and \fB\-lineanchor\fR, or the
\fB(?n)\fR embedded option (see the \fBre_syntax\fR manual page).
.TP 15
\fB\-linestop\fR
Changes the behavior of `[^' bracket expressions and `.' so that they
stop at newlines.  This is the same as specifying the \fB(?p)\fR
embedded option (see the \fBre_syntax\fR manual page).
.TP 15
\fB\-lineanchor\fR
Changes the behavior of `^' and `$' (the ``anchors'') so they match the
beginning and end of a line respectively.  This is the same as
specifying the \fB(?w)\fR embedded option (see the \fBre_syntax\fR
manual page).
.TP 10
\fB\-nocase\fR
Upper-case characters in \fIstring\fR will be converted to lower-case
before matching against \fIexp\fR;  however, substitutions specified
by \fIsubSpec\fR use the original unconverted form of \fIstring\fR.
.TP 10
\fB\-start\fR \fIindex\fR
Specifies a character index offset into the string to start
matching the regular expression at.  When using this switch, `^'
will not match the beginning of the line, and \\A will still
match the start of the string at \fIindex\fR.
\fIindex\fR will be constrained to the bounds of the input string.
.TP 10
\fB\-\|\-\fR
Marks the end of switches.  The argument following this one will
be treated as \fIexp\fR even if it starts with a \fB\-\fR.
.PP
.VS 8.4
If \fIvarName\fR is supplied, the command returns a count of the
number of matching ranges that were found and replaced, otherwise the
string after replacement is returned.
.VE 8.4
See the manual entry for \fBregexp\fR for details on the interpretation
of regular expressions.
.SH EXAMPLES
Replace (in the string in variable \fIstring\fR) every instance of
\fBfoo\fR which is a word by itself with \fBbar\fR:
.CS
\fBregsub\fR -all {\e<foo\e>} $string bar string
.CE
.PP
Insert double-quotes around the first instance of the word
\fBinteresting\fR, however it is capitalised.
.CS
\fBregsub\fR -nocase {\e<interesting\e>} $string {"&"} string
.CE
.PP
Convert all non-ASCII and Tcl-significant characters into \eu escape
sequences by using \fBregsub\fR and \fBsubst\fR in combination:
.CS
# This RE is just a character class for everything "bad"
set RE {[][{}\e$\es\eu0100-\euffff]}

# We will substitute with a fragment of Tcl script in brackets
set substitution {[format \e\e\e\eu%04x [scan "\e\e&" %c]]}

# Now we apply the substitution to get a subst-string that
# will perform the computational parts of the conversion.
set quoted [subst [\fBregsub\fR -all $RE $string $substitution]]
.CE

.SH "SEE ALSO"
regexp(n), re_syntax(n), subst(n)

.SH KEYWORDS
match, pattern, regular expression, substitute