Add support for time.Time flags

Author: max-frank

time.go

@@ -0,0 +1,120 @@
+package pflag
+
+import (
+	"fmt"
+	"strings"
+	"time"
+)
+
+// TimeValue adapts time.Time for use as a flag.
+type TimeValue struct {
+	*time.Time
+	formats []string
+}
+
+func newTimeValue(val time.Time, p *time.Time, formats []string) *TimeValue {
+	*p = val
+	return &TimeValue{
+		Time:    p,
+		formats: formats,
+	}
+}
+
+// Set time.Time value from string based on accepted formats.
+func (d *TimeValue) Set(s string) error {
+	s = strings.TrimSpace(s)
+	for _, f := range d.formats {
+		v, err := time.Parse(f, s)
+		if err != nil {
+			continue
+		}
+		*d.Time = v
+		return nil
+	}
+
+	formatsString := ""
+	for i, f := range d.formats {
+		if i > 0 {
+			formatsString += ", "
+		}
+		formatsString += fmt.Sprintf("`%s`", f)
+	}
+
+	return fmt.Errorf("invalid time format `%s` must be one of: %s", s, formatsString)
+}
+
+// Type name for time.Time flags.
+func (d *TimeValue) Type() string {
+	return "time"
+}
+
+func (d *TimeValue) String() string { return d.Time.Format(time.RFC3339Nano) }
+
+// GetTime return the time value of a flag with the given name
+func (f *FlagSet) GetTime(name string) (time.Time, error) {
+	flag := f.Lookup(name)
+	if flag == nil {
+		err := fmt.Errorf("flag accessed but not defined: %s", name)
+		return time.Time{}, err
+	}
+
+	if flag.Value.Type() != "time" {
+		err := fmt.Errorf("trying to get %s value of flag of type %s", "time", flag.Value.Type())
+		return time.Time{}, err
+	}
+
+	val, ok := flag.Value.(*TimeValue)
+	if !ok {
+		return time.Time{}, fmt.Errorf("value %s is not a time", flag.Value)
+	}
+
+	return *val.Time, nil
+}
+
+// TimeVar defines a time.Time flag with specified name, default value, and usage string.
+// The argument p points to a time.Time variable in which to store the value of the flag.
+func (f *FlagSet) TimeVar(p *time.Time, name string, value time.Time, formats []string, usage string) {
+	f.VarP(newTimeValue(value, p, formats), name, "", usage)
+}
+
+// TimeVarP is like TimeVar, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) TimeVarP(p *time.Time, name, shorthand string, value time.Time, formats []string, usage string) {
+	f.VarP(newTimeValue(value, p, formats), name, shorthand, usage)
+}
+
+// TimeVar defines a time.Time flag with specified name, default value, and usage string.
+// The argument p points to a time.Time variable in which to store the value of the flag.
+func TimeVar(p *time.Time, name string, value time.Time, formats []string, usage string) {
+	CommandLine.VarP(newTimeValue(value, p, formats), name, "", usage)
+}
+
+// TimeVarP is like TimeVar, but accepts a shorthand letter that can be used after a single dash.
+func TimeVarP(p *time.Time, name, shorthand string, value time.Time, formats []string, usage string) {
+	CommandLine.VarP(newTimeValue(value, p, formats), name, shorthand, usage)
+}
+
+// Time defines a time.Time flag with specified name, default value, and usage string.
+// The return value is the address of a time.Time variable that stores the value of the flag.
+func (f *FlagSet) Time(name string, value time.Time, formats []string, usage string) *time.Time {
+	p := new(time.Time)
+	f.TimeVarP(p, name, "", value, formats, usage)
+	return p
+}
+
+// TimeP is like Time, but accepts a shorthand letter that can be used after a single dash.
+func (f *FlagSet) TimeP(name, shorthand string, value time.Time, formats []string, usage string) *time.Time {
+	p := new(time.Time)
+	f.TimeVarP(p, name, shorthand, value, formats, usage)
+	return p
+}
+
+// Time defines a time.Time flag with specified name, default value, and usage string.
+// The return value is the address of a time.Time variable that stores the value of the flag.
+func Time(name string, value time.Time, formats []string, usage string) *time.Time {
+	return CommandLine.TimeP(name, "", value, formats, usage)
+}
+
+// TimeP is like Time, but accepts a shorthand letter that can be used after a single dash.
+func TimeP(name, shorthand string, value time.Time, formats []string, usage string) *time.Time {
+	return CommandLine.TimeP(name, shorthand, value, formats, usage)
+}

time_test.go

@@ -0,0 +1,65 @@
+package pflag
+
+import (
+	"fmt"
+	"os"
+	"testing"
+	"time"
+)
+
+func setUpTime(t *time.Time, formats []string) *FlagSet {
+	f := NewFlagSet("test", ContinueOnError)
+	f.TimeVar(t, "time", time.Time{}, formats, "Time")
+	return f
+}
+
+func TestTime(t *testing.T) {
+	testCases := []struct {
+		input    string
+		success  bool
+		expected string
+	}{
+		{"2022-01-01T01:01:01+00:00", true, "2022-01-01T01:01:01Z"},
+		{" 2022-01-01T01:01:01+00:00", true, "2022-01-01T01:01:01Z"},
+		{"2022-01-01T01:01:01+00:00 ", true, "2022-01-01T01:01:01Z"},
+		{"2022-01-01T01:01:01+02:00", true, "2022-01-01T01:01:01+02:00"},
+		{"2022-01-01T01:01:01.01+02:00", true, "2022-01-01T01:01:01.01+02:00"},
+		{"Sat, 01 Jan 2022 01:01:01 +0000", true, "2022-01-01T01:01:01Z"},
+		{"Sat, 01 Jan 2022 01:01:01 +0200", true, "2022-01-01T01:01:01+02:00"},
+		{"Sat, 01 Jan 2022 01:01:01 +0000", true, "2022-01-01T01:01:01Z"},
+		{"", false, ""},
+		{"not a date", false, ""},
+		{"2022-01-01 01:01:01", false, ""},
+		{"2022-01-01T01:01:01", false, ""},
+		{"01 Jan 2022 01:01:01 +0000", false, ""},
+		{"Sat, 01 Jan 2022 01:01:01", false, ""},
+	}
+
+	devnull, _ := os.Open(os.DevNull)
+	os.Stderr = devnull
+	for i := range testCases {
+		var timeVar time.Time
+		formats := []string{time.RFC3339Nano, time.RFC1123Z}
+		f := setUpTime(&timeVar, formats)
+
+		tc := &testCases[i]
+
+		arg := fmt.Sprintf("--time=%s", tc.input)
+		err := f.Parse([]string{arg})
+		if err != nil && tc.success == true {
+			t.Errorf("expected success, got %q", err)
+			continue
+		} else if err == nil && tc.success == false {
+			t.Errorf("expected failure")
+			continue
+		} else if tc.success {
+			timeResult, err := f.GetTime("time")
+			if err != nil {
+				t.Errorf("Got error trying to fetch the Time flag: %v", err)
+			}
+			if timeResult.Format(time.RFC3339Nano) != tc.expected {
+				t.Errorf("expected %q, got %q", tc.expected, timeVar.Format(time.RFC3339Nano))
+			}
+		}
+	}
+}