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| | # Replace all occurrences of a regular expression in a scalar variable.
# The variable is modified directly. Respects the setting of the option
# RE_MATCH_PCRE, but otherwise sets the zsh emulation mode.
#
# Arguments:
#
# 1. *name* (not contents) of variable or more generally any lvalue;
# expected to be scalar.
#
# 2. regular expression
#
# 3. replacement string. This can contain all forms of
# $ and backtick substitutions; in particular, $MATCH will be
# replaced by the portion of the string matched by the regular
# expression. Parsing errors are fatal to the shell process.
if (( $# < 2 || $# > 3 )); then
setopt localoptions functionargzero
print -ru2 "Usage: $0 <varname> <regexp> [<replacement>]"
return 2
fi
# ensure variable exists in the caller's scope before referencing it
# to make sure we don't end up referencing one of our own.
typeset -g -- "$1" || return 2
typeset -nu -- var=$1 || return 2
local -i use_pcre=0
[[ -o re_match_pcre ]] && use_pcre=1
emulate -L zsh
local regexp=$2 replacement=$3 result MATCH MBEGIN MEND
local -a match mbegin mend
if (( use_pcre )); then
# if using pcre, we're using pcre_match and a running offset
# That's needed for ^, \A, \b, and look-behind operators to work
# properly.
zmodload zsh/pcre || return 2
pcre_compile -- "$regexp" && pcre_study || return 2
local -i offset=0 start stop
local new ZPCRE_OP
local -a finds
while pcre_match -b -n $offset -- "$var"; do
# we need to perform the evaluation in a scalar assignment so that
# if it generates an array, the elements are converted to string (by
# joining with the first chararacter of $IFS as usual)
new=${(Xe)replacement}
finds+=( ${(s[ ])ZPCRE_OP} "$new" )
# for 0-width matches, increase offset by 1 to avoid
# infinite loop
(( offset = finds[-2] + (finds[-3] == finds[-2]) ))
done
(( $#finds )) || return # no match
unsetopt multibyte
offset=1
for start stop new in "$finds[@]"; do
result+=${var[offset,start]}$new
(( offset = stop + 1 ))
done
result+=${var[offset,-1]}
else # no PCRE
# in ERE, we can't use an offset so ^, (and \<, \b, \B, [[:<:]] where
# available) won't work properly.
local subject=$var
local -i ok
while [[ $subject =~ $regexp ]]; do
# append initial part and substituted match
result+=$subject[1,MBEGIN-1]${(Xe)replacement}
# truncate remaining string
if (( MEND < MBEGIN )); then
# zero-width match, skip one character for the next match
(( MEND++ ))
result+=$subject[MBEGIN]
fi
subject=$subject[MEND+1,-1]
ok=1
[[ -n $subject ]] && break
done
(( ok )) || return
result+=$subject
fi
var=$result
|