meta,args: add missing Include, add iterator to use normal or Readonly the same way

pkg/meta/meta.go

@@ -3,6 +3,8 @@ package meta
 import (
 	"errors"
 	"fmt"
+	"iter"
+	"sort"
 	"strings"
 
 	"github.com/ipld/go-ipld-prime"
@@ -171,6 +173,36 @@ func (m *Meta) AddEncrypted(key string, val any, encryptionKey []byte) error {
 	return m.Add(key, encrypted)
 }
 
+type Iterator interface {
+	Iter() iter.Seq2[string, ipld.Node]
+}
+
+// Include merges the provided meta into the existing one.
+//
+// If duplicate keys are encountered, the new value is silently dropped
+// without causing an error.
+func (m *Meta) Include(other Iterator) {
+	for key, value := range other.Iter() {
+		if _, ok := m.Values[key]; ok {
+			// don't overwrite
+			continue
+		}
+		m.Values[key] = value
+		m.Keys = append(m.Keys, key)
+	}
+}
+
+// Iter iterates over the meta key/values
+func (m *Meta) Iter() iter.Seq2[string, ipld.Node] {
+	return func(yield func(string, ipld.Node) bool) {
+		for _, key := range m.Keys {
+			if !yield(key, m.Values[key]) {
+				return
+			}
+		}
+	}
+}
+
 // Equals tells if two Meta hold the same key/values.
 func (m *Meta) Equals(other *Meta) bool {
 	if len(m.Keys) != len(other.Keys) {
@@ -188,6 +220,8 @@ func (m *Meta) Equals(other *Meta) bool {
 }
 
 func (m *Meta) String() string {
+	sort.Strings(m.Keys)
+
 	buf := strings.Builder{}
 	buf.WriteString("{")
 
@@ -209,5 +243,18 @@ func (m *Meta) String() string {
 
 // ReadOnly returns a read-only version of Meta.
 func (m *Meta) ReadOnly() ReadOnly {
-	return ReadOnly{m: m}
+	return ReadOnly{meta: m}
+}
+
+// Clone makes a deep copy.
+func (m *Meta) Clone() *Meta {
+	res := &Meta{
+		Keys:   make([]string, len(m.Keys)),
+		Values: make(map[string]ipld.Node, len(m.Values)),
+	}
+	copy(res.Keys, m.Keys)
+	for k, v := range m.Values {
+		res.Values[k] = v
+	}
+	return res
 }

pkg/meta/meta_test.go

@@ -2,8 +2,11 @@ package meta_test
 
 import (
 	"crypto/rand"
+	"maps"
 	"testing"
 
+	"github.com/ipld/go-ipld-prime"
+	"github.com/ipld/go-ipld-prime/node/basicnode"
 	"github.com/stretchr/testify/require"
 
 	"github.com/ucan-wg/go-ucan/pkg/meta"
@@ -75,3 +78,53 @@ func TestMeta_Add(t *testing.T) {
 		})
 	})
 }
+
+func TestIterCloneEquals(t *testing.T) {
+	m := meta.NewMeta()
+
+	require.NoError(t, m.Add("foo", "bar"))
+	require.NoError(t, m.Add("baz", 1234))
+
+	expected := map[string]ipld.Node{
+		"foo": basicnode.NewString("bar"),
+		"baz": basicnode.NewInt(1234),
+	}
+
+	// meta -> iter
+	require.Equal(t, expected, maps.Collect(m.Iter()))
+
+	// readonly -> iter
+	ro := m.ReadOnly()
+	require.Equal(t, expected, maps.Collect(ro.Iter()))
+
+	// meta -> clone -> iter
+	clone := m.Clone()
+	require.Equal(t, expected, maps.Collect(clone.Iter()))
+
+	// readonly -> WriteableClone -> iter
+	wclone := ro.WriteableClone()
+	require.Equal(t, expected, maps.Collect(wclone.Iter()))
+
+	require.True(t, m.Equals(wclone))
+	require.True(t, ro.Equals(wclone.ReadOnly()))
+}
+
+func TestInclude(t *testing.T) {
+	m1 := meta.NewMeta()
+
+	require.NoError(t, m1.Add("samekey", "bar"))
+	require.NoError(t, m1.Add("baz", 1234))
+
+	m2 := meta.NewMeta()
+
+	require.NoError(t, m2.Add("samekey", "othervalue")) // check no overwrite
+	require.NoError(t, m2.Add("otherkey", 1234))
+
+	m1.Include(m2)
+
+	require.Equal(t, map[string]ipld.Node{
+		"samekey":  basicnode.NewString("bar"),
+		"baz":      basicnode.NewInt(1234),
+		"otherkey": basicnode.NewInt(1234),
+	}, maps.Collect(m1.Iter()))
+}

pkg/meta/readonly.go

@@ -1,50 +1,60 @@
 package meta
 
 import (
+	"iter"
+
 	"github.com/ipld/go-ipld-prime"
 )
 
 // ReadOnly wraps a Meta into a read-only facade.
 type ReadOnly struct {
-	m *Meta
+	meta *Meta
 }
 
 func (r ReadOnly) GetBool(key string) (bool, error) {
-	return r.m.GetBool(key)
+	return r.meta.GetBool(key)
 }
 
 func (r ReadOnly) GetString(key string) (string, error) {
-	return r.m.GetString(key)
+	return r.meta.GetString(key)
 }
 
 func (r ReadOnly) GetEncryptedString(key string, encryptionKey []byte) (string, error) {
-	return r.m.GetEncryptedString(key, encryptionKey)
+	return r.meta.GetEncryptedString(key, encryptionKey)
 }
 
 func (r ReadOnly) GetInt64(key string) (int64, error) {
-	return r.m.GetInt64(key)
+	return r.meta.GetInt64(key)
 }
 
 func (r ReadOnly) GetFloat64(key string) (float64, error) {
-	return r.m.GetFloat64(key)
+	return r.meta.GetFloat64(key)
 }
 
 func (r ReadOnly) GetBytes(key string) ([]byte, error) {
-	return r.m.GetBytes(key)
+	return r.meta.GetBytes(key)
 }
 
 func (r ReadOnly) GetEncryptedBytes(key string, encryptionKey []byte) ([]byte, error) {
-	return r.m.GetEncryptedBytes(key, encryptionKey)
+	return r.meta.GetEncryptedBytes(key, encryptionKey)
 }
 
 func (r ReadOnly) GetNode(key string) (ipld.Node, error) {
-	return r.m.GetNode(key)
+	return r.meta.GetNode(key)
+}
+
+func (r ReadOnly) Iter() iter.Seq2[string, ipld.Node] {
+	return r.meta.Iter()
 }
 
 func (r ReadOnly) Equals(other ReadOnly) bool {
-	return r.m.Equals(other.m)
+	return r.meta.Equals(other.meta)
 }
 
 func (r ReadOnly) String() string {
-	return r.m.String()
+	return r.meta.String()
+}
+
+func (r ReadOnly) WriteableClone() *Meta {
+	return r.meta.Clone()
 }