From 200e51835642e161edbba724d809676d6a42040f Mon Sep 17 00:00:00 2001
From: Jun Nishimura <n.junjun0303@gmail.com>
Date: Sat, 22 Jul 2023 14:55:03 +0900
Subject: [PATCH] parse lflags

---
 command.go | 89 +++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 88 insertions(+), 1 deletion(-)

diff --git a/command.go b/command.go
index a683acd6..8bd403c1 100644
--- a/command.go
+++ b/command.go
@@ -1767,6 +1767,91 @@ func (c *Command) persistentFlag(name string) (flag *flag.Flag) {
 	return
 }
 
+func (c *Command) parseLongArgs(s string, args []string) (passedArgs, restArgs []string) {
+	restArgs = args
+
+	split := strings.SplitN(s[2:], "=", 2)
+	name := split[0]
+	searchedFlag := c.lflags.Lookup(name)
+
+	if searchedFlag == nil {
+		// a flag not registered in c.lflags should be registered in c.flags
+		c.flags.VisitAll(func(f *flag.Flag) {
+			if name == f.Name {
+				if len(split) == 1 && f.NoOptDefVal == "" && len(args) > 0 {
+					// '--flag arg'
+					restArgs = args[1:]
+				}
+				return
+			}
+		})
+	}
+
+	passedArgs = append(passedArgs, fmt.Sprintf("--%s", name))
+	if len(split) == 1 && searchedFlag.NoOptDefVal == "" && len(args) > 0 {
+		passedArgs = append(passedArgs, args[0])
+		restArgs = args[1:]
+	}
+
+	return
+}
+
+func (c *Command) parseShortArgs(s string, args []string) (passedArgs []string, restArgs []string) {
+	restArgs = args
+
+	shorthands := s[1:]
+	shorthand := string(s[1])
+
+	searchedFlag := c.lflags.ShorthandLookup(shorthand)
+	if searchedFlag == nil {
+		// a flag not registered in c.lflags should be registered in c.flags
+		c.flags.VisitAll(func(f *flag.Flag) {
+			if shorthand == f.Shorthand {
+				if len(shorthands) == 1 && f.NoOptDefVal == "" && len(args) > 0 {
+					// '-f arg'
+					restArgs = args[1:]
+				}
+			}
+		})
+		return
+	}
+
+	passedArgs = append(passedArgs, s)
+	if len(shorthands) == 1 && searchedFlag.NoOptDefVal == "" && len(args) > 0 {
+		// '-f arg'
+		passedArgs = append(passedArgs, args[0])
+		restArgs = args[1:]
+	}
+
+	return
+}
+
+func (c *Command) removeParentPersistentArgs(args []string) []string {
+	var newArgs []string
+
+	for len(args) > 0 {
+		s := args[0]
+		args = args[1:]
+		if s[0] != '-' {
+			newArgs = append(newArgs, s)
+			continue
+		}
+
+		var passedArgs, restArgs []string
+		if s[1] == '-' {
+			passedArgs, restArgs = c.parseLongArgs(s, args)
+		} else {
+			passedArgs, restArgs = c.parseShortArgs(s, args)
+		}
+		if len(passedArgs) > 0 {
+			newArgs = append(newArgs, passedArgs...)
+		}
+		args = restArgs
+	}
+
+	return newArgs
+}
+
 // ParseFlags parses persistent flag tree and local flags.
 func (c *Command) ParseFlags(args []string) error {
 	if c.DisableFlagParsing {
@@ -1790,7 +1875,9 @@ func (c *Command) ParseFlags(args []string) error {
 	}
 
 	// parse Local Flags
-	err = c.LocalFlags().Parse(args)
+	c.LocalFlags()                                  // need to execute LocalFlags() to set the value in c.lflags before executing removeParentPersistentArgs
+	localArgs := c.removeParentPersistentArgs(args) // get only arguments related to c.lflags
+	err = c.lflags.Parse(localArgs)
 	// Print warnings if they occurred (e.g. deprecated flag messages).
 	if c.flagErrorBuf.Len()-beforeErrorBufLen > 0 && err == nil {
 		c.Print(c.flagErrorBuf.String())