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# word.tcl --
#
# This file defines various procedures for computing word boundaries in
# strings. This file is primarily needed so Tk text and entry widgets behave
# properly for different platforms.
#
# Copyright (c) 1996 Sun Microsystems, Inc.
# Copyright (c) 1998 Scritpics Corporation.
#
# See the file "license.terms" for information on usage and redistribution
# of this file, and for a DISCLAIMER OF ALL WARRANTIES.
# The following variables are used to determine which characters are
# interpreted as white space.
if {$::tcl_platform(platform) eq "windows"} {
# Windows style - any but a unicode space char
if {![info exists ::tcl_wordchars]} {
set ::tcl_wordchars {\S}
}
if {![info exists ::tcl_nonwordchars]} {
set ::tcl_nonwordchars {\s}
}
} else {
# Motif style - any unicode word char (number, letter, or underscore)
if {![info exists ::tcl_wordchars]} {
set ::tcl_wordchars {\w}
}
if {![info exists ::tcl_nonwordchars]} {
set ::tcl_nonwordchars {\W}
}
}
# Arrange for caches of the real matcher REs to be kept, which enables the REs
# themselves to be cached for greater performance (and somewhat greater
# clarity too).
namespace eval ::tcl {
variable WordBreakRE
array set WordBreakRE {}
proc UpdateWordBreakREs args {
# Ignores the arguments
global tcl_wordchars tcl_nonwordchars
variable WordBreakRE
# To keep the RE strings short...
set letter $tcl_wordchars
set space $tcl_nonwordchars
set WordBreakRE(after) "$letter$space|$space$letter"
set WordBreakRE(before) "^.*($letter$space|$space$letter)"
set WordBreakRE(end) "$space*$letter+$space"
set WordBreakRE(next) "$letter*$space+$letter"
set WordBreakRE(previous) "$space*($letter+)$space*\$"
}
# Initialize the cache
UpdateWordBreakREs
trace add variable ::tcl_wordchars write ::tcl::UpdateWordBreakREs
trace add variable ::tcl_nonwordchars write ::tcl::UpdateWordBreakREs
}
# tcl_wordBreakAfter --
#
# This procedure returns the index of the first word boundary after the
# starting point in the given string, or -1 if there are no more boundaries in
# the given string. The index returned refers to the first character of the
# pair that comprises a boundary.
#
# Arguments:
# str - String to search.
# start - Index into string specifying starting point.
proc tcl_wordBreakAfter {str start} {
variable ::tcl::WordBreakRE
set result {-1 -1}
regexp -indices -start $start -- $WordBreakRE(after) $str result
return [lindex $result 1]
}
# tcl_wordBreakBefore --
#
# This procedure returns the index of the first word boundary before the
# starting point in the given string, or -1 if there are no more boundaries in
# the given string. The index returned refers to the second character of the
# pair that comprises a boundary.
#
# Arguments:
# str - String to search.
# start - Index into string specifying starting point.
proc tcl_wordBreakBefore {str start} {
variable ::tcl::WordBreakRE
set result {-1 -1}
regexp -indices -- $WordBreakRE(before) [string range $str 0 $start] result
return [lindex $result 1]
}
# tcl_endOfWord --
#
# This procedure returns the index of the first end-of-word location after a
# starting index in the given string. An end-of-word location is defined to be
# the first whitespace character following the first non-whitespace character
# after the starting point. Returns -1 if there are no more words after the
# starting point.
#
# Arguments:
# str - String to search.
# start - Index into string specifying starting point.
proc tcl_endOfWord {str start} {
variable ::tcl::WordBreakRE
set result {-1 -1}
regexp -indices -start $start -- $WordBreakRE(end) $str result
return [lindex $result 1]
}
# tcl_startOfNextWord --
#
# This procedure returns the index of the first start-of-word location after a
# starting index in the given string. A start-of-word location is defined to
# be a non-whitespace character following a whitespace character. Returns -1
# if there are no more start-of-word locations after the starting point.
#
# Arguments:
# str - String to search.
# start - Index into string specifying starting point.
proc tcl_startOfNextWord {str start} {
variable ::tcl::WordBreakRE
set result {-1 -1}
regexp -indices -start $start -- $WordBreakRE(next) $str result
return [lindex $result 1]
}
# tcl_startOfPreviousWord --
#
# This procedure returns the index of the first start-of-word location before
# a starting index in the given string.
#
# Arguments:
# str - String to search.
# start - Index into string specifying starting point.
proc tcl_startOfPreviousWord {str start} {
variable ::tcl::WordBreakRE
set word {-1 -1}
if {$start > 0} {
regexp -indices -- $WordBreakRE(previous) [string range $str 0 $start-1] \
result word
}
return [lindex $word 0]
}
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