Feat: Add flags list

flagmap.go

@@ -26,6 +26,7 @@ package grumble
 
 import (
 	"fmt"
+	"strings"
 	"time"
 )
 
@@ -161,3 +162,29 @@ func (f FlagMap) Duration(long string) time.Duration {
 	}
 	return v
 }
+
+// List returns the given flag value as a slice of strings.
+// Panics if not present. Flags must be registered.
+// List returns the given flag value as a slice of key-value pairs.
+// Panics if not present. Flags must be registered.
+func (f FlagMap) List(long string) map[string]string {
+	i := f[long]
+	if i == nil {
+		panic(fmt.Errorf("missing flag value: flag '%s' not registered", long))
+	}
+	val, ok := i.Value.([]string)
+	if !ok {
+		panic(fmt.Errorf("failed to assert flag '%s' to []string", long))
+	}
+
+	result := make(map[string]string)
+	for _, item := range val {
+		parts := strings.SplitN(item, "=", 2)
+		if len(parts) == 2 {
+			key := strings.TrimSpace(parts[0])
+			value := strings.TrimSpace(parts[1])
+			result[key] = value
+		}
+	}
+	return result
+}

flags.go

@@ -486,3 +486,43 @@ func trimQuotes(s string) string {
 	}
 	return s
 }
+
+func (f *Flags) ListL(long string, defaultValue []string, help string) {
+	f.List("", long, defaultValue, help)
+}
+
+func (f *Flags) List(short, long string, defaultValue []string, help string) {
+	f.register(short, long, help, "list", true, defaultValue,
+		func(res FlagMap) {
+			res[long] = &FlagMapItem{
+				Value:     defaultValue,
+				IsDefault: true,
+			}
+		},
+		func(flag, equalVal string, args []string, res FlagMap) ([]string, bool, error) {
+			if !f.match(flag, short, long) {
+				return args, false, nil
+			}
+
+			if len(equalVal) > 0 {
+				values := strings.Split(equalVal, ",")
+				res[long] = &FlagMapItem{
+					Value:     values,
+					IsDefault: false,
+				}
+				return args, true, nil
+			}
+
+			if len(args) == 0 {
+				return args, false, fmt.Errorf("missing list values for flag: %s", flag)
+			}
+
+			values := strings.Split(args[0], ",")
+			res[long] = &FlagMapItem{
+				Value:     values,
+				IsDefault: false,
+			}
+			args = args[1:]
+			return args, true, nil
+		})
+}