From 6a0425cafe807ec69149614c54879888d3bf20bc Mon Sep 17 00:00:00 2001
From: Thomas Lindop <thomas16256@gmail.com>
Date: Tue, 27 May 2025 23:05:35 +0100
Subject: [PATCH] >> add support for POSIX portable runeset

---
 main.go | 21 +++++++++++++++++----
 1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/main.go b/main.go
index 1069800..57aa034 100644
--- a/main.go
+++ b/main.go
@@ -47,6 +47,7 @@ type context struct {
 	Strategy string
 	DoHelp bool
 	DoVersion bool
+	Rset runeset
 }
 
 
@@ -74,6 +75,15 @@ var FAT_RUNESET = runeset{
 	{ 0x7d, MAX_CODE_POINT},
 }
 
+var POSIX_PORTABLE_RUNESET = runeset{
+	{ 0x2d, 0x2d },
+	{ 0x2e, 0x2e },
+	{ 0x5f, 0x5f },
+	{ 0x30, 0x39 },
+	{ 0x41, 0x5a },
+	{ 0x61, 0x7a },
+}
+
 /// MAIN FUNCTIONS
 /**
  * Compares paths so that all files come before the directories that contain 
@@ -145,8 +155,8 @@ func (ctx *context) parseFileList() ([]string, map[string]bool, error) {
 	}
 }
 
-func isFatValid(r rune) bool {
-	for _, runeRange := range FAT_RUNESET {
+func inRuneset(r rune, rset runeset) bool {
+	for _, runeRange := range rset {
 		if runeRange[0] <= r && r <= runeRange[1] {
 			return true
 		}
@@ -159,13 +169,13 @@ func (ctx *context) restrictRuneset(s string) string {
 	toValidSubs := make(map[rune]string)
 	if ctx.Strategy == "remove" {
 		for _, r := range result {
-			if !isFatValid(r) {
+			if !inRuneset(r, ctx.Rset) {
 				toValidSubs[r] = ""
 			}
 		}
 	} else {
 		for _, r := range result {
-			if !isFatValid(r) {
+			if !inRuneset(r, ctx.Rset) {
 				toValidSubs[r] = fmt.Sprintf("_U%X_", r)
 			}
 		}
@@ -200,6 +210,7 @@ func parseCLIArgs(args []string) (context, error) {
 		Strategy: "represent",
 		DoHelp: false,
 		DoVersion: false,
+		Rset: FAT_RUNESET,
 	}
 	index := 1
 	isFlag := func(arg string) bool {
@@ -215,6 +226,8 @@ func parseCLIArgs(args []string) (context, error) {
 		case "-s", "--strategy":
 			index++
 			result.Strategy = args[index]
+		case "-p", "--portable":
+			result.Rset = POSIX_PORTABLE_RUNESET
 		case "-h", "--help":
 			result.DoHelp = true
 		case "-v", "--version":