new: added FindFirstArg function (#33)

Author: sttk

find.go

@@ -0,0 +1,30 @@
+// Copyright (C) 2023 Takayuki Sato. All Rights Reserved.
+// This program is free software under MIT License.
+// See the file LICENSE in this distribution for more details.
+
+package cliargs
+
+import (
+	"strings"
+)
+
+// FindFirstArg is a function which returns an index, a name, a existent flag
+// of first non option-format element in a specified string array.
+// If non option-format element is found, a existent flag is true, but if
+// the element is not found, the flag is false.
+func FindFirstArg(osArgs []string) (index int, arg string, exists bool) {
+	isNonOpt := false
+	if len(osArgs) > 0 {
+		for i, a := range osArgs[1:] {
+			if isNonOpt {
+				return i + 1, a, true
+			} else if a == "--" {
+				isNonOpt = true
+				continue
+			} else if !strings.HasPrefix(a, "-") {
+				return i + 1, a, true
+			}
+		}
+	}
+	return -1, "", false
+}

find_test.go

@@ -0,0 +1,61 @@
+package cliargs_test
+
+import (
+	"github.com/stretchr/testify/assert"
+	"github.com/sttk-go/cliargs"
+	"testing"
+)
+
+func TestFindFirstArg_findAtFirstIndex(t *testing.T) {
+	osArgs := []string{"app", "foo-bar", "-a", "--baz", "--bcd"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, 1)
+	assert.Equal(t, arg, "foo-bar")
+	assert.True(t, exists)
+}
+
+func TestFindFirstArg_findAtMiddleIndex(t *testing.T) {
+	osArgs := []string{"app", "--corge", "foo-bar", "-a", "--baz", "--bcd"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, 2)
+	assert.Equal(t, arg, "foo-bar")
+	assert.True(t, exists)
+}
+
+func TestFindFirstArg_findAtLastIndex(t *testing.T) {
+	osArgs := []string{"app", "--corge", "--foo-bar", "-a", "baz"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, 4)
+	assert.Equal(t, arg, "baz")
+	assert.True(t, exists)
+}
+
+func TestFindFirstArg_returnFoundFirst(t *testing.T) {
+	osArgs := []string{"app", "--corge", "foo-bar", "-a", "baz", "--bcd"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, 2)
+	assert.Equal(t, arg, "foo-bar")
+	assert.True(t, exists)
+}
+
+func TestFindFirstArg_notFound(t *testing.T) {
+	osArgs := []string{"app", "--corge", "--foo-bar", "-a", "-baz", "--bcd"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, -1)
+	assert.Equal(t, arg, "")
+	assert.False(t, exists)
+}
+
+func TestFindFirstArg_supportDoubleHyphens(t *testing.T) {
+	osArgs := []string{"app", "--", "--foo-bar", "-a", "-baz", "--bcd"}
+
+	i, arg, exists := cliargs.FindFirstArg(osArgs)
+	assert.Equal(t, i, 2)
+	assert.Equal(t, arg, "--foo-bar")
+	assert.True(t, exists)
+}