Fix backrefs in lineinfile or line mode

Author: mblaschke

main.go

@@ -103,7 +103,14 @@ func applyChangesetsToFile(fileitem fileitem, changesets []changeset) (string, b
     if opts.ModeIsLineInFile {
         for _, changeset := range changesets {
             if !changeset.MatchFound {
-                buffer.WriteString(changeset.Replace + "\n")
+                line = changeset.Replace + "\n"
+
+                // remove backrefs (no match)
+                if opts.RegexBackref {
+                    line = regexp.MustCompile("\\$[0-9]+").ReplaceAllLiteralString(line, "")
+                }
+
+                buffer.WriteString(line)
                 writeBufferToFile = true
             }
         }
@@ -165,8 +172,16 @@ func applyChangesetsToLine(line string, changesets []changeset) (string, bool, b
             if searchMatch(line, changeset) {
                 // --mode=line or --mode=lineinfile
                 if opts.ModeIsReplaceLine || opts.ModeIsLineInFile {
-                    // replace whole line with replace term
-                    line = changeset.Replace
+                    if opts.RegexBackref {
+                        // get match
+                        line = string(changeset.Search.Find([]byte(line)))
+
+                        // replace regex backrefs in match
+                        line = changeset.Search.ReplaceAllString(line, changeset.Replace)
+                    } else {
+                        // replace whole line with replace term
+                        line = changeset.Replace
+                    }
                 } else {
                     // replace only term inside line
                     line = replaceText(line, changeset)

tests/main.test

@@ -141,6 +141,34 @@ Testing replace mode with regex:
   this is the second line
   this is the third ___bar line
   this is the last line
+  $ goreplace --regex --regex-backrefs -s 'not-existing-line' -r '___$1' test.txt
+  $ cat test.txt
+  this is a testline
+  this is the second line
+  this is the third ___bar line
+  this is the last line
+
+Testing lineinfile mode with regex:
+
+  $ cat > test.txt <<EOF
+  > this is a testline
+  > this is the second line
+  > this is the third foobar line
+  > this is the last line
+  > EOF
+  $ goreplace --mode=lineinfile --regex --regex-backrefs -s 'f[o]+(b[a]*r)' -r '___$1' test.txt
+  $ cat test.txt
+  this is a testline
+  this is the second line
+  ___bar
+  this is the last line
+  $ goreplace  --mode=lineinfile --regex --regex-backrefs -s 'not-existing-line' -r '___$1' test.txt
+  $ cat test.txt
+  this is a testline
+  this is the second line
+  ___bar
+  this is the last line
+  ___
 
 Testing replace mode with regex and case-insensitive: