27604: substitution using regular expressions

Doc/Zsh/contrib.yo

@@ -1570,14 +1570,14 @@ tindex(replace-string-again)
 tindex(replace-pattern)
 xitem(tt(replace-string), tt(replace-pattern))
 item(tt(replace-string-again), tt(replace-pattern-again))(
-The function tt(replace-string) implements two widgets.
+The function tt(replace-string) implements three widgets.
 If defined under the same name as the function, it prompts for two
 strings; the first (source) string will be replaced by the second
 everywhere it occurs in the line editing buffer.
 
 If the widget name contains the word `tt(pattern)', for example by
 defining the widget using the command `tt(zle -N replace-pattern
-replace-string)', then the replacement is done by pattern matching.  All
+replace-string)', then the matching is performed using zsh patterns.  All
 zsh extended globbing patterns can be used in the source string; note
 that unlike filename generation the pattern does not need to match an
 entire word, nor do glob qualifiers have any effect.  In addition, the
@@ -1588,6 +1588,12 @@ replaced by the var(N)th parenthesised expression matched.  The form
 `tt(\{)var(N)tt(})' may be used to protect the digit from following
 digits.
 
+If the widget instead contains the word `tt(regex)' (or `tt(regexp)'),
+then the matching is performed using regular expressions, respecting
+the setting of the option tt(RE_MATCH_PCRE) (see the description of the
+function tt(regexp-replace) below).  The facilities described
+for pattern matching are also available.
+
 By default the previous source or replacement string will not be offered
 for editing.  However, this feature can be activated by setting the style
 tt(edit-previous) in the context tt(:zle:)var(widget) (for example,
@@ -1595,12 +1601,12 @@ tt(:zle:replace-string)) to tt(true).  In addition, a positive
 numeric argument forces the previous values to be offered, a negative or
 zero argument forces them not to be.
 
-The function tt(replace-string-again) can be used to repeat the
-previous replacement; no prompting is done.  As with tt(replace-string), if
-the name of the widget contains the word `tt(pattern)', pattern matching
-is performed, else a literal string replacement.  Note that the
-previous source and replacement text are the same whether pattern or string
-matching is used.
+The function tt(replace-string-again) can be used to repeat the previous
+replacement; no prompting is done.  As with tt(replace-string), if the name
+of the widget contains the word `tt(pattern)' or `tt(regex)', pattern or
+regular expression matching is performed, else a literal string
+replacement.  Note that the previous source and replacement text are the
+same whether pattern, regular expression or string matching is used.
 
 For example, starting from the line:
 
@@ -2574,6 +2580,25 @@ the context prefix `tt(:completion:nslookup)'.
 
 See also the tt(pager), tt(prompt) and tt(rprompt) styles below.
 )
+findex(regexp-replace)
+item(tt(regexp-replace) var(var) var(regexp) var(replace))(
+Use regular expressions to perform a global search and replace operation
+on a variable.  If the option tt(RE_MATCH_PCRE) is not set, POSIX
+extended regular expressions are used, else Perl-compatible regular
+expressions (this requires the shell to be linked against the tt(pcre)
+library).
+
+var(var) is the name of the variable containing the string to be matched.
+The variable will be modified directly by the function.  The
+variables tt(MATCH), tt(MBEGIN), tt(MEND), tt(match), tt(mbegin), tt(mend)
+should be avoided as these are used by the regular expression code.
+
+var(regexp) is the regular expression to match against the string.
+
+var(replace) is the replacement text.  This can contain parameter, command
+and arithmetic expressions which will be replaced:  in particular, a
+reference to tt($MATCH) will be replaced by the text matched by the pattern.
+)
 findex(run-help)
 item(tt(run-help) var(cmd))(
 This function is designed to be invoked by the tt(run-help) ZLE widget,

Functions/Misc/.distfiles

@@ -10,6 +10,7 @@ is-at-least
 mere
 nslookup
 promptnl
+regexp-replace
 relative
 run-help
 run-help-git

Functions/Misc/regexp-replace

@@ -0,0 +1,35 @@
+# Replace all occurrences of a regular expression in a variable.  The
+# variable is modified directly.  Respects the setting of the
+# option RE_MATCH_PCRE.
+#
+# First argument: *name* (not contents) of variable.
+# Second argument: regular expression
+# Third argument: 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.
+
+integer pcre
+
+[[ -o re_match_pcre ]] && pcre=1
+
+emulate -L zsh
+(( pcre )) && setopt re_match_pcre
+
+# $4 is the string to be matched
+4=${(P)1}
+# $5 is the final string
+5=
+local MATCH MBEGIN MEND
+local -a match mbegin mend
+
+while [[ -n $4 ]]; do
+  if [[ $4 =~ $2 ]]; then
+    5+=${4[1,MBEGIN-1]}${(e)3}
+    4=${4[MEND+1,-1]}
+  else
+    break
+  fi
+done
+5+=$4
+
+eval ${1}=${(q)5}

Functions/Zle/replace-string-again

@@ -13,7 +13,7 @@ if [[ -z $_replace_string_src ]]; then
   return 1
 fi
 
-if [[ $curwidget = *pattern* ]]; then
+if [[ $curwidget = *(pattern|regex)* ]]; then
     local rep2
     # The following horror is so that an & preceded by an even
     # number of backslashes is active, without stripping backslashes,
@@ -38,8 +38,14 @@ if [[ $curwidget = *pattern* ]]; then
 	rep=${match[5]}
     done
     rep2+=$rep
-    LBUFFER=${LBUFFER//(#bm)$~_replace_string_src/${(e)rep2}}
-    RBUFFER=${RBUFFER//(#bm)$~_replace_string_src/${(e)rep2}}
+    if [[ $curwidget = *regex* ]]; then
+      autoload -U regexp-replace
+      regexp-replace LBUFFER $_replace_string_src $rep2
+      regexp-replace RBUFFER $_replace_string_src $rep2
+    else
+      LBUFFER=${LBUFFER//(#bm)$~_replace_string_src/${(e)rep2}}
+      RBUFFER=${RBUFFER//(#bm)$~_replace_string_src/${(e)rep2}}
+    fi
 else
     LBUFFER=${LBUFFER//$_replace_string_src/$_replace_string_rep}
     RBUFFER=${RBUFFER//$_replace_string_src/$_replace_string_rep}