command: Fix replace to be able to insert '$' (#2954)

* command: Fix replace to be able to insert '$'

* help: commands: Precise the documentation of `replace`

* help: commands: Further improvement suggested within the review

Co-authored-by: Beni Cherniavsky-Paskin <cben@redhat.com>

* Fix replace with '$' in a more kosher way

On top of JoeKar's fix.

---------

Co-authored-by: Beni Cherniavsky-Paskin <cben@redhat.com>
Co-authored-by: Dmytro Maluka <dmitrymaluka@gmail.com>

internal/action/command.go

@@ -820,7 +820,7 @@ func (h *BufPane) ReplaceCmd(args []string) {
 		end = h.Cursor.CurSelection[1]
 	}
 	if all {
-		nreplaced, _ = h.Buf.ReplaceRegex(start, end, regex, replace)
+		nreplaced, _ = h.Buf.ReplaceRegex(start, end, regex, replace, !noRegex)
 	} else {
 		inRange := func(l buffer.Loc) bool {
 			return l.GreaterEqual(start) && l.LessEqual(end)
@@ -850,7 +850,7 @@ func (h *BufPane) ReplaceCmd(args []string) {
 
 			InfoBar.YNPrompt("Perform replacement (y,n,esc)", func(yes, canceled bool) {
 				if !canceled && yes {
-					_, nrunes := h.Buf.ReplaceRegex(locs[0], locs[1], regex, replace)
+					_, nrunes := h.Buf.ReplaceRegex(locs[0], locs[1], regex, replace, !noRegex)
 
 					searchLoc = locs[0]
 					searchLoc.X += nrunes + locs[0].Diff(locs[1], h.Buf)

internal/buffer/search.go

@@ -148,7 +148,7 @@ func (b *Buffer) FindNext(s string, start, end, from Loc, down bool, useRegex bo
 // ReplaceRegex replaces all occurrences of 'search' with 'replace' in the given area
 // and returns the number of replacements made and the number of runes
 // added or removed on the last line of the range
-func (b *Buffer) ReplaceRegex(start, end Loc, search *regexp.Regexp, replace []byte) (int, int) {
+func (b *Buffer) ReplaceRegex(start, end Loc, search *regexp.Regexp, replace []byte, captureGroups bool) (int, int) {
 	if start.GreaterThan(end) {
 		start, end = end, start
 	}
@@ -172,9 +172,13 @@ func (b *Buffer) ReplaceRegex(start, end Loc, search *regexp.Regexp, replace []b
 			l = util.SliceStart(l, end.X)
 		}
 		newText := search.ReplaceAllFunc(l, func(in []byte) []byte {
-			result := []byte{}
-			for _, submatches := range search.FindAllSubmatchIndex(in, -1) {
-				result = search.Expand(result, replace, in, submatches)
+			var result []byte
+			if captureGroups {
+				for _, submatches := range search.FindAllSubmatchIndex(in, -1) {
+					result = search.Expand(result, replace, in, submatches)
+				}
+			} else {
+				result = replace
 			}
 			found++
 			if i == end.Y {

runtime/help/commands.md

@@ -43,6 +43,12 @@ quotes here but these are not necessary when entering the command in micro.
    Note that `search` must be a valid regex (unless `-l` is passed). If one 
    of the arguments does not have any spaces in it, you may omit the quotes.
 
+   In case the search is done non-literal (without `-l`), the 'value'
+   is interpreted as a template:
+   * `$3` or `${3}` substitutes the submatch of the 3rd (capturing group)
+   * `$foo` or `${foo}` substitutes the submatch of the (?P<foo>named group)
+   * You have to write `$$` to substitute a literal dollar.
+
 * `replaceall 'search' 'value'`: this will replace all occurrences of `search`
    with `value` without user confirmation.