Feature: Add xand tag (#442)

* Feat: Add xand group and check for missing

* Fix: Split and combine err in TestMultiand for consistency

* Feat: Check missing required flags in xand groups

* Feat: Handle combined xor and xand

* Docs: Add info about combined xand and required use

* Docs: Fix language error in xand description

Co-authored-by: Stautis <thkrst@gmail.com>

* Feat: Rename xand to and

* Refactor: Switch from fmt.Sprintf to err.Error

* Refactor: Get requiredAndGroup map in separate function

---------

Co-authored-by: Stautis <thkrst@gmail.com>

README.md

@@ -554,7 +554,7 @@ Tags can be in two forms:
 Both can coexist with standard Tag parsing.
 
 | Tag                  | Description                                                                                                                                                                                                                                                                                                                    |
-| -------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
+|----------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
 | `cmd:""`             | If present, struct is a command.                                                                                                                                                                                                                                                                                               |
 | `arg:""`             | If present, field is an argument. Required by default.                                                                                                                                                                                                                                                                         |
 | `env:"X,Y,..."`      | Specify envars to use for default value. The envs are resolved in the declared order. The first value found is used.                                                                                                                                                                                                           |
@@ -566,7 +566,7 @@ Both can coexist with standard Tag parsing.
 | `default:"1"`        | On a command, make it the default.                                                                                                                                                                                                                                                                                             |
 | `default:"withargs"` | On a command, make it the default and allow args/flags from that command                                                                                                                                                                                                                                                       |
 | `short:"X"`          | Short name, if flag.                                                                                                                                                                                                                                                                                                           |
-| `aliases:"X,Y"`      | One or more aliases (for cmd or flag).                                                                                                                                                                                                                                                                                                 |
+| `aliases:"X,Y"`      | One or more aliases (for cmd or flag).                                                                                                                                                                                                                                                                                         |
 | `required:""`        | If present, flag/arg is required.                                                                                                                                                                                                                                                                                              |
 | `optional:""`        | If present, flag/arg is optional.                                                                                                                                                                                                                                                                                              |
 | `hidden:""`          | If present, command or flag is hidden.                                                                                                                                                                                                                                                                                         |
@@ -577,6 +577,7 @@ Both can coexist with standard Tag parsing.
 | `enum:"X,Y,..."`     | Set of valid values allowed for this flag. An enum field must be `required` or have a valid `default`.                                                                                                                                                                                                                         |
 | `group:"X"`          | Logical group for a flag or command.                                                                                                                                                                                                                                                                                           |
 | `xor:"X,Y,..."`      | Exclusive OR groups for flags. Only one flag in the group can be used which is restricted within the same command. When combined with `required`, at least one of the `xor` group will be required.                                                                                                                            |
+| `and:"X,Y,..."`      | Exclsuive AND groups for flags. All flags in the group must be used in the same command. When combined with `required`, all flags in the group will be required.                                                                                                                                                               |
 | `prefix:"X"`         | Prefix for all sub-flags.                                                                                                                                                                                                                                                                                                      |
 | `envprefix:"X"`      | Envar prefix for all sub-flags.                                                                                                                                                                                                                                                                                                |
 | `set:"K=V"`          | Set a variable for expansion by child elements. Multiples can occur.                                                                                                                                                                                                                                                           |

build.go

@@ -323,6 +323,7 @@ func buildField(k *Kong, node *Node, v reflect.Value, ft reflect.StructField, fv
 			Envs:        tag.Envs,
 			Group:       buildGroupForKey(k, tag.Group),
 			Xor:         tag.Xor,
+			And:         tag.And,
 			Hidden:      tag.Hidden,
 		}
 		value.Flag = flag

context.go

@@ -259,7 +259,7 @@ func (c *Context) Validate() error { //nolint: gocyclo
 	if err := checkMissingPositionals(positionals, node.Positional); err != nil {
 		return err
 	}
-	if err := checkXorDuplicates(c.Path); err != nil {
+	if err := checkXorDuplicatedAndAndMissing(c.Path); err != nil {
 		return err
 	}
 
@@ -831,23 +831,35 @@ func (c *Context) PrintUsage(summary bool) error {
 func checkMissingFlags(flags []*Flag) error {
 	xorGroupSet := map[string]bool{}
 	xorGroup := map[string][]string{}
+	andGroupSet := map[string]bool{}
+	andGroup := map[string][]string{}
 	missing := []string{}
+	andGroupRequired := getRequiredAndGroupMap(flags)
 	for _, flag := range flags {
+		for _, and := range flag.And {
+			flag.Required = andGroupRequired[and]
+		}
 		if flag.Set {
 			for _, xor := range flag.Xor {
 				xorGroupSet[xor] = true
 			}
+			for _, and := range flag.And {
+				andGroupSet[and] = true
+			}
 		}
 		if !flag.Required || flag.Set {
 			continue
 		}
-		if len(flag.Xor) > 0 {
+		if len(flag.Xor) > 0 || len(flag.And) > 0 {
 			for _, xor := range flag.Xor {
 				if xorGroupSet[xor] {
 					continue
 				}
 				xorGroup[xor] = append(xorGroup[xor], flag.Summary())
 			}
+			for _, and := range flag.And {
+				andGroup[and] = append(andGroup[and], flag.Summary())
+			}
 		} else {
 			missing = append(missing, flag.Summary())
 		}
@@ -857,6 +869,11 @@ func checkMissingFlags(flags []*Flag) error {
 			missing = append(missing, strings.Join(flags, " or "))
 		}
 	}
+	for _, flags := range andGroup {
+		if len(flags) > 1 {
+			missing = append(missing, strings.Join(flags, " and "))
+		}
+	}
 
 	if len(missing) == 0 {
 		return nil
@@ -867,6 +884,18 @@ func checkMissingFlags(flags []*Flag) error {
 	return fmt.Errorf("missing flags: %s", strings.Join(missing, ", "))
 }
 
+func getRequiredAndGroupMap(flags []*Flag) map[string]bool {
+	andGroupRequired := map[string]bool{}
+	for _, flag := range flags {
+		for _, and := range flag.And {
+			if flag.Required {
+				andGroupRequired[and] = true
+			}
+		}
+	}
+	return andGroupRequired
+}
+
 func checkMissingChildren(node *Node) error {
 	missing := []string{}
 
@@ -977,6 +1006,20 @@ func checkPassthroughArg(target reflect.Value) bool {
 	}
 }
 
+func checkXorDuplicatedAndAndMissing(paths []*Path) error {
+	errs := []string{}
+	if err := checkXorDuplicates(paths); err != nil {
+		errs = append(errs, err.Error())
+	}
+	if err := checkAndMissing(paths); err != nil {
+		errs = append(errs, err.Error())
+	}
+	if len(errs) > 0 {
+		return fmt.Errorf(strings.Join(errs, ", "))
+	}
+	return nil
+}
+
 func checkXorDuplicates(paths []*Path) error {
 	for _, path := range paths {
 		seen := map[string]*Flag{}
@@ -995,6 +1038,38 @@ func checkXorDuplicates(paths []*Path) error {
 	return nil
 }
 
+func checkAndMissing(paths []*Path) error {
+	for _, path := range paths {
+		missingMsgs := []string{}
+		andGroups := map[string][]*Flag{}
+		for _, flag := range path.Flags {
+			for _, and := range flag.And {
+				andGroups[and] = append(andGroups[and], flag)
+			}
+		}
+		for _, flags := range andGroups {
+			oneSet := false
+			notSet := []*Flag{}
+			flagNames := []string{}
+			for _, flag := range flags {
+				flagNames = append(flagNames, flag.Name)
+				if flag.Set {
+					oneSet = true
+				} else {
+					notSet = append(notSet, flag)
+				}
+			}
+			if len(notSet) > 0 && oneSet {
+				missingMsgs = append(missingMsgs, fmt.Sprintf("--%s must be used together", strings.Join(flagNames, " and --")))
+			}
+		}
+		if len(missingMsgs) > 0 {
+			return fmt.Errorf("%s", strings.Join(missingMsgs, ", "))
+		}
+	}
+	return nil
+}
+
 func findPotentialCandidates(needle string, haystack []string, format string, args ...interface{}) error {
 	if len(haystack) == 0 {
 		return fmt.Errorf(format, args...)

go.sum

@@ -1,15 +1,5 @@
-github.com/alecthomas/assert/v2 v2.4.1 h1:mwPZod/d35nlaCppr6sFP0rbCL05WH9fIo7lvsf47zo=
-github.com/alecthomas/assert/v2 v2.4.1/go.mod h1:fw5suVxB+wfYJ3291t0hRTqtGzFYdSwstnRQdaQx2DM=
-github.com/alecthomas/assert/v2 v2.5.0 h1:OJKYg53BQx06/bMRBSPDCO49CbCDNiUQXwdoNrt6x5w=
-github.com/alecthomas/assert/v2 v2.5.0/go.mod h1:fw5suVxB+wfYJ3291t0hRTqtGzFYdSwstnRQdaQx2DM=
-github.com/alecthomas/assert/v2 v2.6.0 h1:o3WJwILtexrEUk3cUVal3oiQY2tfgr/FHWiz/v2n4FU=
-github.com/alecthomas/assert/v2 v2.6.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
-github.com/alecthomas/assert/v2 v2.8.1 h1:YCxnYR6jjpfnEK5AK5SysALKdUEBPGH4Y7As6tBnDw0=
-github.com/alecthomas/assert/v2 v2.8.1/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
 github.com/alecthomas/assert/v2 v2.10.0 h1:jjRCHsj6hBJhkmhznrCzoNpbA3zqy0fYiUcYZP/GkPY=
 github.com/alecthomas/assert/v2 v2.10.0/go.mod h1:Bze95FyfUr7x34QZrjL+XP+0qgp/zg8yS+TtBj1WA3k=
-github.com/alecthomas/repr v0.3.0 h1:NeYzUPfjjlqHY4KtzgKJiWd6sVq2eNUPTi34PiFGjY8=
-github.com/alecthomas/repr v0.3.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/alecthomas/repr v0.4.0 h1:GhI2A8MACjfegCPVq9f1FLvIBS+DrQ2KQBFZP1iFzXc=
 github.com/alecthomas/repr v0.4.0/go.mod h1:Fr0507jx4eOXV7AlPV6AVZLYrLIuIeSOWtW57eE/O/4=
 github.com/hexops/gotextdiff v1.0.3 h1:gitA9+qJrrTCsiCl7+kh75nPqQt1cx4ZkudSTLoUqJM=

kong_test.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
+	"sort"
 	"strings"
 	"testing"
 
@@ -919,6 +920,21 @@ func TestXor(t *testing.T) {
 	assert.NoError(t, err)
 }
 
+func TestAnd(t *testing.T) {
+	var cli struct {
+		Hello bool   `and:"another"`
+		One   bool   `and:"group"`
+		Two   string `and:"group"`
+	}
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"--hello", "--one"})
+	assert.EqualError(t, err, "--one and --two must be used together")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--one", "--two=hi", "--hello"})
+	assert.NoError(t, err)
+}
+
 func TestXorChild(t *testing.T) {
 	var cli struct {
 		One bool `xor:"group"`
@@ -936,6 +952,23 @@ func TestXorChild(t *testing.T) {
 	assert.Error(t, err, "--two and --three can't be used together")
 }
 
+func TestAndChild(t *testing.T) {
+	var cli struct {
+		One bool `and:"group"`
+		Cmd struct {
+			Two   string `and:"group"`
+			Three string `and:"group"`
+		} `cmd`
+	}
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"--one", "cmd", "--two=hi", "--three=hello"})
+	assert.NoError(t, err)
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--two=hi", "cmd"})
+	assert.Error(t, err, "--two and --three must be used together")
+}
+
 func TestMultiXor(t *testing.T) {
 	var cli struct {
 		Hello bool   `xor:"one,two"`
@@ -952,6 +985,47 @@ func TestMultiXor(t *testing.T) {
 	assert.EqualError(t, err, "--hello and --two can't be used together")
 }
 
+func TestMultiAnd(t *testing.T) {
+	var cli struct {
+		Hello bool   `and:"one,two"`
+		One   bool   `and:"one"`
+		Two   string `and:"two"`
+	}
+
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"--hello"})
+	// Split and combine error so messages always will be in the same order
+	// when testing
+	missingMsgs := strings.Split(err.Error(), ", ")
+	sort.Strings(missingMsgs)
+	err = fmt.Errorf("%s", strings.Join(missingMsgs, ", "))
+	assert.EqualError(t, err, "--hello and --one must be used together, --hello and --two must be used together")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--two=foo"})
+	assert.EqualError(t, err, "--hello and --two must be used together")
+}
+
+func TestXorAnd(t *testing.T) {
+	var cli struct {
+		Hello bool   `xor:"one" and:"two"`
+		One   bool   `xor:"one"`
+		Two   string `and:"two"`
+	}
+
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"--hello"})
+	assert.EqualError(t, err, "--hello and --two must be used together")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--one"})
+	assert.NoError(t, err)
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--hello", "--one"})
+	assert.EqualError(t, err, "--hello and --one can't be used together, --hello and --two must be used together")
+}
+
 func TestXorRequired(t *testing.T) {
 	var cli struct {
 		One   bool `xor:"one,two" required:""`
@@ -972,6 +1046,26 @@ func TestXorRequired(t *testing.T) {
 	assert.EqualError(t, err, "missing flags: --four, --one or --three, --one or --two")
 }
 
+func TestAndRequired(t *testing.T) {
+	var cli struct {
+		One   bool `and:"one,two" required:""`
+		Two   bool `and:"one" required:""`
+		Three bool `and:"two"`
+		Four  bool `required:""`
+	}
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{"--one", "--two", "--three"})
+	assert.EqualError(t, err, "missing flags: --four")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--four"})
+	assert.EqualError(t, err, "missing flags: --one and --three, --one and --two")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{})
+	assert.EqualError(t, err, "missing flags: --four, --one and --three, --one and --two")
+}
+
 func TestXorRequiredMany(t *testing.T) {
 	var cli struct {
 		One   bool `xor:"one" required:""`
@@ -991,6 +1085,21 @@ func TestXorRequiredMany(t *testing.T) {
 	assert.EqualError(t, err, "missing flags: --one or --two or --three")
 }
 
+func TestAndRequiredMany(t *testing.T) {
+	var cli struct {
+		One   bool `and:"one" required:""`
+		Two   bool `and:"one" required:""`
+		Three bool `and:"one" required:""`
+	}
+	p := mustNew(t, &cli)
+	_, err := p.Parse([]string{})
+	assert.EqualError(t, err, "missing flags: --one and --two and --three")
+
+	p = mustNew(t, &cli)
+	_, err = p.Parse([]string{"--three"})
+	assert.EqualError(t, err, "missing flags: --one and --two")
+}
+
 func TestEnumSequence(t *testing.T) {
 	var cli struct {
 		State []string `enum:"a,b,c" default:"a"`

model.go

@@ -405,6 +405,7 @@ type Flag struct {
 	*Value
 	Group       *Group // Logical grouping when displaying. May also be used by configuration loaders to group options logically.
 	Xor         []string
+	And         []string
 	PlaceHolder string
 	Envs        []string
 	Aliases     []string

tag.go

@@ -32,6 +32,7 @@ type Tag struct {
 	Enum        string
 	Group       string
 	Xor         []string
+	And         []string
 	Vars        Vars
 	Prefix      string // Optional prefix on anonymous structs. All sub-flags will have this prefix.
 	EnvPrefix   string
@@ -249,6 +250,9 @@ func hydrateTag(t *Tag, typ reflect.Type) error { //nolint: gocyclo
 	for _, xor := range t.GetAll("xor") {
 		t.Xor = append(t.Xor, strings.FieldsFunc(xor, tagSplitFn)...)
 	}
+	for _, and := range t.GetAll("and") {
+		t.And = append(t.And, strings.FieldsFunc(and, tagSplitFn)...)
+	}
 	t.Prefix = t.Get("prefix")
 	t.EnvPrefix = t.Get("envprefix")
 	t.Embed = t.Has("embed")