Move the diff-copy helper out of the explorer controller

The next commit deletes the controller this lives in, while the helper
itself is still wanted: it is what makes a copied selection paste
straight into code. Move it first, so that the deletion is a deletion.

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

pkg/gui/controllers/diff_copy.go

@@ -0,0 +1,43 @@
+package controllers
+
+import (
+	"strings"
+
+	"github.com/samber/lo"
+)
+
+// Removes '+' or '-' from the beginning of each line in the diff string, except
+// when both '+' and '-' lines are present, or diff header lines, in which case
+// the diff is returned unchanged. This is useful for copying parts of diffs to
+// the clipboard in order to paste them into code.
+func dropDiffPrefix(diff string) string {
+	lines := strings.Split(strings.TrimRight(diff, "\n"), "\n")
+
+	const (
+		PLUS int = iota
+		MINUS
+		CONTEXT
+		OTHER
+	)
+
+	linesByType := lo.GroupBy(lines, func(line string) int {
+		switch {
+		case strings.HasPrefix(line, "+"):
+			return PLUS
+		case strings.HasPrefix(line, "-"):
+			return MINUS
+		case strings.HasPrefix(line, " "):
+			return CONTEXT
+		}
+		return OTHER
+	})
+
+	hasLinesOfType := func(lineType int) bool { return len(linesByType[lineType]) > 0 }
+
+	keepPrefix := hasLinesOfType(OTHER) || (hasLinesOfType(PLUS) && hasLinesOfType(MINUS))
+	if keepPrefix {
+		return diff
+	}
+
+	return strings.Join(lo.Map(lines, func(line string, _ int) string { return line[1:] + "\n" }), "")
+}

pkg/gui/controllers/patch_explorer_controller.go

@@ -1,12 +1,9 @@
 package controllers
 
 import (
-	"strings"
-
 	"github.com/jesseduffield/lazygit/pkg/gocui"
 	"github.com/jesseduffield/lazygit/pkg/gui/controllers/helpers"
 	"github.com/jesseduffield/lazygit/pkg/gui/types"
-	"github.com/samber/lo"
 )
 
 type PatchExplorerControllerFactory struct {
@@ -351,42 +348,6 @@ func (self *PatchExplorerController) CopySelectedToClipboard() error {
 	return nil
 }
 
-// Removes '+' or '-' from the beginning of each line in the diff string, except
-// when both '+' and '-' lines are present, or diff header lines, in which case
-// the diff is returned unchanged. This is useful for copying parts of diffs to
-// the clipboard in order to paste them into code.
-func dropDiffPrefix(diff string) string {
-	lines := strings.Split(strings.TrimRight(diff, "\n"), "\n")
-
-	const (
-		PLUS int = iota
-		MINUS
-		CONTEXT
-		OTHER
-	)
-
-	linesByType := lo.GroupBy(lines, func(line string) int {
-		switch {
-		case strings.HasPrefix(line, "+"):
-			return PLUS
-		case strings.HasPrefix(line, "-"):
-			return MINUS
-		case strings.HasPrefix(line, " "):
-			return CONTEXT
-		}
-		return OTHER
-	})
-
-	hasLinesOfType := func(lineType int) bool { return len(linesByType[lineType]) > 0 }
-
-	keepPrefix := hasLinesOfType(OTHER) || (hasLinesOfType(PLUS) && hasLinesOfType(MINUS))
-	if keepPrefix {
-		return diff
-	}
-
-	return strings.Join(lo.Map(lines, func(line string, _ int) string { return line[1:] + "\n" }), "")
-}
-
 func (self *PatchExplorerController) isFocused() bool {
 	return self.c.Context().Current().GetKey() == self.context.GetKey()
 }