From 073f231b890cb0abd43a00e3dda5c435bbb4d614 Mon Sep 17 00:00:00 2001
From: Aadhavan Srinivasan <aadhavan@twomorecents.org>
Date: Mon, 10 Feb 2025 21:35:51 -0500
Subject: [PATCH] Added function and examples for ReplaceAllFunc()

---
 regex/example_test.go | 11 ++++++++++-
 regex/matching.go     | 23 +++++++++++++++++++++++
 2 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/regex/example_test.go b/regex/example_test.go
index 94b4998..9438cd9 100644
--- a/regex/example_test.go
+++ b/regex/example_test.go
@@ -2,6 +2,7 @@ package regex_test
 
 import (
 	"fmt"
+	"strings"
 
 	"gitea.twomorecents.org/Rockingcool/kleingrep/regex"
 )
@@ -167,6 +168,14 @@ func ExampleReg_ReplaceAllLiteral() {
 	regexStr := `fox|dog`
 	inputStr := "the quick brown fox jumped over the lazy dog"
 	regexComp := regex.MustCompile(regexStr)
-	fmt.Println(regexComp.ReplaceAll(inputStr, `duck`))
+	fmt.Println(regexComp.ReplaceAllLiteral(inputStr, `duck`))
 	// Output: the quick brown duck jumped over the lazy duck
 }
+
+func ExampleReg_ReplaceAllFunc() {
+	regexStr := `\w{5,}`
+	inputStr := `all five or more letter words in this string are capitalized`
+	regexComp := regex.MustCompile(regexStr)
+	fmt.Println(regexComp.ReplaceAllFunc(inputStr, strings.ToUpper))
+	// Output: all five or more LETTER WORDS in this STRING are CAPITALIZED
+}
diff --git a/regex/matching.go b/regex/matching.go
index 80c5cc6..a344a40 100644
--- a/regex/matching.go
+++ b/regex/matching.go
@@ -428,6 +428,7 @@ func (re Reg) ReplaceAllLiteral(src string, repl string) string {
 		if currentMatch < len(zerogroups) && i == zerogroups[currentMatch].StartIdx {
 			dst += repl
 			i = zerogroups[currentMatch].EndIdx
+			currentMatch += 1
 		} else {
 			dst += string(src[i])
 			i++
@@ -435,3 +436,25 @@ func (re Reg) ReplaceAllLiteral(src string, repl string) string {
 	}
 	return dst
 }
+
+// ReplaceAllFunc replaces every match of the expression in src, with the return value of the function replFunc.
+// replFunc takes in the matched string. The return value is substituted in directly without expasion.
+func (re Reg) ReplaceAllFunc(src string, replFunc func(string) string) string {
+	zerogroups := re.FindAll(src)
+	currentMatch := 0
+	i := 0
+	dst := ""
+
+	for i < len(src) {
+		if currentMatch < len(zerogroups) && i == zerogroups[currentMatch].StartIdx {
+			dst += replFunc(src[zerogroups[currentMatch].StartIdx:zerogroups[currentMatch].EndIdx])
+			i = zerogroups[currentMatch].EndIdx
+			currentMatch += 1
+		} else {
+			dst += string(src[i])
+			i++
+		}
+	}
+	return dst
+
+}