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-rw-r--r--parse.go76
-rw-r--r--parse_test.go32
-rw-r--r--usage.go25
3 files changed, 84 insertions, 49 deletions
diff --git a/parse.go b/parse.go
index 6e7f4bd..119efbd 100644
--- a/parse.go
+++ b/parse.go
@@ -1,8 +1,11 @@
package arg
import (
+ "errors"
"fmt"
+ "io"
"os"
+ "path/filepath"
"reflect"
"strconv"
"strings"
@@ -20,48 +23,74 @@ type spec struct {
wasPresent bool
}
+// Parse returns this value to indicate that -h or --help were provided
+var ErrHelp = errors.New("help requested by user")
+
// MustParse processes command line arguments and exits upon failure.
func MustParse(dest ...interface{}) {
- err := Parse(dest...)
+ p, err := NewParser(dest...)
+ if err != nil {
+ fmt.Println(err)
+ os.Exit(1)
+ }
+ err = p.Parse(os.Args[1:])
if err != nil {
fmt.Println(err)
+ writeUsage(os.Stdout, filepath.Base(os.Args[0]), p.spec)
os.Exit(1)
}
}
-// Parse processes command line arguments and stores the result in args.
+// Parse processes command line arguments and stores them in dest.
func Parse(dest ...interface{}) error {
- return ParseFrom(os.Args[1:], dest...)
+ p, err := NewParser(dest...)
+ if err != nil {
+ fmt.Println(err)
+ os.Exit(1)
+ }
+ return p.Parse(os.Args[1:])
}
-// ParseFrom processes command line arguments and stores the result in args.
-func ParseFrom(args []string, dest ...interface{}) error {
- // Add the help option if one is not already defined
- var internal struct {
- Help bool `arg:"-h,help:print this help message"`
- }
+// Parser represents a set of command line options with destination values
+type Parser struct {
+ spec []*spec
+}
- // Parse the spec
- dest = append(dest, &internal)
+// NewParser constructs a parser from a list of destination structs
+func NewParser(dest ...interface{}) (*Parser, error) {
spec, err := extractSpec(dest...)
if err != nil {
- return err
+ return nil, err
}
+ return &Parser{spec: spec}, nil
+}
- // Process args
- err = processArgs(spec, args)
- if err != nil {
- return err
+// Parse processes the given command line option, storing the results in the field
+// of the structs from which NewParser was constructed
+func (p *Parser) Parse(args []string) error {
+ // If -h or --help were specified then print usage
+ for _, arg := range args {
+ if arg == "-h" || arg == "--help" {
+ return ErrHelp
+ }
+ if arg == "--" {
+ break
+ }
}
- // If -h or --help were specified then print help
- if internal.Help {
- writeUsage(os.Stdout, spec)
- os.Exit(0)
+ // Process all command line arguments
+ err := process(p.spec, args)
+ if err != nil {
+ return err
}
// Validate
- return validate(spec)
+ return validate(p.spec)
+}
+
+// WriteUsage writes usage information to the given writer
+func (p *Parser) WriteUsage(w io.Writer) {
+ writeUsage(w, filepath.Base(os.Args[0]), p.spec)
}
// extractSpec gets specifications for each argument from the tags in a struct
@@ -143,8 +172,9 @@ func extractSpec(dests ...interface{}) ([]*spec, error) {
return specs, nil
}
-// processArgs processes arguments using a pre-constructed spec
-func processArgs(specs []*spec, args []string) error {
+// process goes through arguments the arguments one-by-one, parses them, and assigns the result to
+// the underlying struct field
+func process(specs []*spec, args []string) error {
// construct a map from --option to spec
optionMap := make(map[string]*spec)
for _, spec := range specs {
diff --git a/parse_test.go b/parse_test.go
index 9ad5944..4037ef5 100644
--- a/parse_test.go
+++ b/parse_test.go
@@ -8,15 +8,19 @@ import (
"github.com/stretchr/testify/require"
)
-func split(s string) []string {
- return strings.Split(s, " ")
+func parse(cmdline string, dest interface{}) error {
+ p, err := NewParser(dest)
+ if err != nil {
+ return err
+ }
+ return p.Parse(strings.Split(cmdline, " "))
}
func TestStringSingle(t *testing.T) {
var args struct {
Foo string
}
- err := ParseFrom(split("--foo bar"), &args)
+ err := parse("--foo bar", &args)
require.NoError(t, err)
assert.Equal(t, "bar", args.Foo)
}
@@ -30,7 +34,7 @@ func TestMixed(t *testing.T) {
Spam float32
}
args.Bar = 3
- err := ParseFrom(split("123 -spam=1.2 -ham -f xyz"), &args)
+ err := parse("123 -spam=1.2 -ham -f xyz", &args)
require.NoError(t, err)
assert.Equal(t, "xyz", args.Foo)
assert.Equal(t, 3, args.Bar)
@@ -43,7 +47,7 @@ func TestRequired(t *testing.T) {
var args struct {
Foo string `arg:"required"`
}
- err := ParseFrom(nil, &args)
+ err := parse("", &args)
require.Error(t, err, "--foo is required")
}
@@ -52,15 +56,15 @@ func TestShortFlag(t *testing.T) {
Foo string `arg:"-f"`
}
- err := ParseFrom(split("-f xyz"), &args)
+ err := parse("-f xyz", &args)
require.NoError(t, err)
assert.Equal(t, "xyz", args.Foo)
- err = ParseFrom(split("-foo xyz"), &args)
+ err = parse("-foo xyz", &args)
require.NoError(t, err)
assert.Equal(t, "xyz", args.Foo)
- err = ParseFrom(split("--foo xyz"), &args)
+ err = parse("--foo xyz", &args)
require.NoError(t, err)
assert.Equal(t, "xyz", args.Foo)
}
@@ -71,7 +75,7 @@ func TestCaseSensitive(t *testing.T) {
Upper bool `arg:"-V"`
}
- err := ParseFrom(split("-v"), &args)
+ err := parse("-v", &args)
require.NoError(t, err)
assert.True(t, args.Lower)
assert.False(t, args.Upper)
@@ -83,7 +87,7 @@ func TestCaseSensitive2(t *testing.T) {
Upper bool `arg:"-V"`
}
- err := ParseFrom(split("-V"), &args)
+ err := parse("-V", &args)
require.NoError(t, err)
assert.False(t, args.Lower)
assert.True(t, args.Upper)
@@ -94,7 +98,7 @@ func TestPositional(t *testing.T) {
Input string `arg:"positional"`
Output string `arg:"positional"`
}
- err := ParseFrom(split("foo"), &args)
+ err := parse("foo", &args)
require.NoError(t, err)
assert.Equal(t, "foo", args.Input)
assert.Equal(t, "", args.Output)
@@ -105,7 +109,7 @@ func TestRequiredPositional(t *testing.T) {
Input string `arg:"positional"`
Output string `arg:"positional,required"`
}
- err := ParseFrom(split("foo"), &args)
+ err := parse("foo", &args)
assert.Error(t, err)
}
@@ -114,7 +118,7 @@ func TestTooManyPositional(t *testing.T) {
Input string `arg:"positional"`
Output string `arg:"positional"`
}
- err := ParseFrom(split("foo bar baz"), &args)
+ err := parse("foo bar baz", &args)
assert.Error(t, err)
}
@@ -123,7 +127,7 @@ func TestMultiple(t *testing.T) {
Foo []int
Bar []string
}
- err := ParseFrom(split("--foo 1 2 3 --bar x y z"), &args)
+ err := parse("--foo 1 2 3 --bar x y z", &args)
require.NoError(t, err)
assert.Equal(t, []int{1, 2, 3}, args.Foo)
assert.Equal(t, []string{"x", "y", "z"}, args.Bar)
diff --git a/usage.go b/usage.go
index 5155d82..fdc2248 100644
--- a/usage.go
+++ b/usage.go
@@ -4,11 +4,12 @@ import (
"fmt"
"io"
"os"
+ "path/filepath"
"reflect"
"strings"
)
-// Usage prints usage information to stdout information and exits with status zero
+// Usage prints usage information to stdout and exits with status zero
func Usage(dest ...interface{}) {
if err := WriteUsage(os.Stdout, dest...); err != nil {
fmt.Println(err)
@@ -31,20 +32,12 @@ func WriteUsage(w io.Writer, dest ...interface{}) error {
if err != nil {
return err
}
- writeUsage(w, spec)
+ writeUsage(w, filepath.Base(os.Args[0]), spec)
return nil
}
-func synopsis(spec *spec, form string) string {
- if spec.dest.Kind() == reflect.Bool {
- return form
- } else {
- return form + " " + strings.ToUpper(spec.long)
- }
-}
-
// writeUsage writes usage information to the given writer
-func writeUsage(w io.Writer, specs []*spec) {
+func writeUsage(w io.Writer, cmd string, specs []*spec) {
var positionals, options []*spec
for _, spec := range specs {
if spec.positional {
@@ -54,7 +47,7 @@ func writeUsage(w io.Writer, specs []*spec) {
}
}
- fmt.Fprint(w, "usage: ")
+ fmt.Fprint(w, "usage: %s ", cmd)
// write the option component of the one-line usage message
for _, spec := range options {
@@ -110,3 +103,11 @@ func writeUsage(w io.Writer, specs []*spec) {
}
}
}
+
+func synopsis(spec *spec, form string) string {
+ if spec.dest.Kind() == reflect.Bool {
+ return form
+ } else {
+ return form + " " + strings.ToUpper(spec.long)
+ }
+}
generated by cgit v1.2.3 (git 2.51.0) at 2025-11-20 05:29:10 +0000