GH-43455: [Go] Add Opaque canonical extension type

go/arrow/extensions/doc.go

@@ -0,0 +1,20 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Package extensions provides implementations of Arrow canonical extension
+// types as defined in the Arrow specification.
+// https://arrow.apache.org/docs/format/CanonicalExtensions.html
+package extensions

go/arrow/extensions/opaque.go

@@ -0,0 +1,106 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package extensions
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"unsafe"
+
+	"github.com/apache/arrow/go/v18/arrow"
+	"github.com/apache/arrow/go/v18/arrow/array"
+)
+
+// OpaqueType is a placeholder for a type from an external (usually
+// non-Arrow) system that could not be interpreted.
+type OpaqueType struct {
+	arrow.ExtensionBase `json:"-"`
+
+	TypeName   string `json:"type_name"`
+	VendorName string `json:"vendor_name"`
+}
+
+// NewOpaqueType creates a new OpaqueType with the provided storage type, type name, and vendor name.
+func NewOpaqueType(storageType arrow.DataType, name, vendorName string) *OpaqueType {
+	return &OpaqueType{ExtensionBase: arrow.ExtensionBase{Storage: storageType},
+		TypeName: name, VendorName: vendorName}
+}
+
+func (*OpaqueType) ArrayType() reflect.Type {
+	return reflect.TypeOf(OpaqueArray{})
+}
+
+func (*OpaqueType) ExtensionName() string {
+	return "arrow.opaque"
+}
+
+func (o *OpaqueType) String() string {
+	return fmt.Sprintf("extension<%s[storage_type=%s, type_name=%s, vendor_name=%s]>",
+		o.ExtensionName(), o.Storage, o.TypeName, o.VendorName)
+}
+
+func (o *OpaqueType) Serialize() string {
+	data, _ := json.Marshal(o)
+	return string(data)
+}
+
+func (*OpaqueType) Deserialize(storageType arrow.DataType, data string) (arrow.ExtensionType, error) {
+	var out OpaqueType
+	err := json.Unmarshal(unsafe.Slice(unsafe.StringData(data), len(data)), &out)
+	if err != nil {
+		return nil, err
+	}
+
+	switch {
+	case out.TypeName == "":
+		return nil, fmt.Errorf("%w: serialized JSON data for OpaqueType missing type_name",
+			arrow.ErrInvalid)
+	case out.VendorName == "":
+		return nil, fmt.Errorf("%w: serialized JSON data for OpaqueType missing vendor_name",
+			arrow.ErrInvalid)
+	}
+
+	out.ExtensionBase = arrow.ExtensionBase{Storage: storageType}
+	return &out, nil
+}
+
+func (o *OpaqueType) ExtensionEquals(other arrow.ExtensionType) bool {
+	if o.ExtensionName() != other.ExtensionName() {
+		return false
+	}
+
+	rhs, ok := other.(*OpaqueType)
+	if !ok {
+		return false
+	}
+
+	return arrow.TypeEqual(o.Storage, rhs.Storage) &&
+		o.TypeName == rhs.TypeName &&
+		o.VendorName == rhs.VendorName
+}
+
+// OpaqueArray is a placeholder for data from an external (usually
+// non-Arrow) system that could not be interpreted.
+type OpaqueArray struct {
+	array.ExtensionArrayBase
+}
+
+var (
+	_ arrow.ExtensionType  = (*OpaqueType)(nil)
+	_ array.ExtensionArray = (*OpaqueArray)(nil)
+)

go/arrow/extensions/opaque_test.go

@@ -0,0 +1,200 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package extensions_test
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/apache/arrow/go/v18/arrow"
+	"github.com/apache/arrow/go/v18/arrow/array"
+	"github.com/apache/arrow/go/v18/arrow/extensions"
+	"github.com/apache/arrow/go/v18/arrow/ipc"
+	"github.com/apache/arrow/go/v18/arrow/memory"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestOpaqueTypeBasics(t *testing.T) {
+	typ := extensions.NewOpaqueType(arrow.Null, "type", "vendor")
+	typ2 := extensions.NewOpaqueType(arrow.Null, "type2", "vendor")
+
+	assert.Equal(t, "arrow.opaque", typ.ExtensionName())
+	assert.True(t, typ.ExtensionEquals(typ))
+	assert.False(t, arrow.TypeEqual(arrow.Null, typ))
+	assert.False(t, arrow.TypeEqual(typ, typ2))
+	assert.True(t, arrow.TypeEqual(arrow.Null, typ.StorageType()))
+	assert.JSONEq(t, `{"type_name": "type", "vendor_name": "vendor"}`, typ.Serialize())
+	assert.Equal(t, "type", typ.TypeName)
+	assert.Equal(t, "vendor", typ.VendorName)
+	assert.Equal(t, "extension<arrow.opaque[storage_type=null, type_name=type, vendor_name=vendor]>",
+		typ.String())
+}
+
+func TestOpaqueTypeEquals(t *testing.T) {
+	typ := extensions.NewOpaqueType(arrow.Null, "type", "vendor")
+	typ2 := extensions.NewOpaqueType(arrow.Null, "type2", "vendor")
+	typ3 := extensions.NewOpaqueType(arrow.Null, "type", "vendor2")
+	typ4 := extensions.NewOpaqueType(arrow.PrimitiveTypes.Int64, "type", "vendor")
+	typ5 := extensions.NewOpaqueType(arrow.Null, "type", "vendor")
+
+	tests := []struct {
+		lhs, rhs arrow.ExtensionType
+		expected bool
+	}{
+		{typ, typ, true},
+		{typ2, typ2, true},
+		{typ3, typ3, true},
+		{typ4, typ4, true},
+		{typ5, typ5, true},
+		{typ, typ5, true},
+		{typ, typ2, false},
+		{typ, typ3, false},
+		{typ, typ4, false},
+		{typ2, typ, false},
+		{typ2, typ3, false},
+		{typ2, typ4, false},
+		{typ3, typ, false},
+		{typ3, typ2, false},
+		{typ3, typ4, false},
+		{typ4, typ, false},
+		{typ4, typ2, false},
+		{typ4, typ3, false},
+	}
+
+	for _, tt := range tests {
+		assert.Equalf(t, tt.expected, arrow.TypeEqual(tt.lhs, tt.rhs),
+			"%s == %s", tt.lhs, tt.rhs)
+	}
+}
+
+func TestOpaqueTypeCreateFromArray(t *testing.T) {
+	typ := extensions.NewOpaqueType(arrow.BinaryTypes.String, "geometry", "adbc.postgresql")
+	storage, _, err := array.FromJSON(memory.DefaultAllocator, arrow.BinaryTypes.String,
+		strings.NewReader(`["foobar", null]`))
+	require.NoError(t, err)
+	defer storage.Release()
+
+	arr := array.NewExtensionArrayWithStorage(typ, storage)
+	defer arr.Release()
+
+	assert.Equal(t, 2, arr.Len())
+	assert.Equal(t, 1, arr.NullN())
+}
+
+func TestOpaqueTypeDeserialize(t *testing.T) {
+	tests := []struct {
+		serialized string
+		expected   *extensions.OpaqueType
+	}{
+		{`{"type_name": "type", "vendor_name": "vendor"}`,
+			extensions.NewOpaqueType(arrow.Null, "type", "vendor")},
+		{`{"type_name": "long name", "vendor_name": "long name"}`,
+			extensions.NewOpaqueType(arrow.Null, "long name", "long name")},
+		{`{"type_name": "名前", "vendor_name": "名字"}`,
+			extensions.NewOpaqueType(arrow.Null, "名前", "名字")},
+		{`{"type_name": "type", "vendor_name": "vendor", "extra_field": 2}`,
+			extensions.NewOpaqueType(arrow.Null, "type", "vendor")},
+	}
+
+	for _, tt := range tests {
+		deserialized, err := tt.expected.Deserialize(tt.expected.Storage, tt.serialized)
+		require.NoError(t, err)
+		assert.Truef(t, arrow.TypeEqual(tt.expected, deserialized), "%s != %s",
+			tt.expected, deserialized)
+	}
+
+	typ := extensions.NewOpaqueType(arrow.Null, "type", "vendor")
+	_, err := typ.Deserialize(arrow.Null, "")
+	assert.ErrorContains(t, err, "unexpected end of JSON input")
+
+	_, err = typ.Deserialize(arrow.Null, "[]")
+	assert.ErrorContains(t, err, "cannot unmarshal array")
+
+	_, err = typ.Deserialize(arrow.Null, "{}")
+	assert.ErrorIs(t, err, arrow.ErrInvalid)
+	assert.ErrorContains(t, err, "serialized JSON data for OpaqueType missing type_name")
+
+	_, err = typ.Deserialize(arrow.Null, `{"type_name": ""}`)
+	assert.ErrorIs(t, err, arrow.ErrInvalid)
+	assert.ErrorContains(t, err, "serialized JSON data for OpaqueType missing type_name")
+
+	_, err = typ.Deserialize(arrow.Null, `{"type_name": "type"}`)
+	assert.ErrorIs(t, err, arrow.ErrInvalid)
+	assert.ErrorContains(t, err, "serialized JSON data for OpaqueType missing vendor_name")
+
+	_, err = typ.Deserialize(arrow.Null, `{"type_name": "type", "vendor_name": ""}`)
+	assert.ErrorIs(t, err, arrow.ErrInvalid)
+	assert.ErrorContains(t, err, "serialized JSON data for OpaqueType missing vendor_name")
+}
+
+func TestOpaqueTypeMetadataRoundTrip(t *testing.T) {
+	tests := []*extensions.OpaqueType{
+		extensions.NewOpaqueType(arrow.Null, "foo", "bar"),
+		extensions.NewOpaqueType(arrow.BinaryTypes.Binary, "geometry", "postgis"),
+		extensions.NewOpaqueType(arrow.FixedSizeListOf(4, arrow.PrimitiveTypes.Int64), "foo", "bar"),
+		extensions.NewOpaqueType(arrow.BinaryTypes.String, "foo", "bar"),
+	}
+
+	for _, tt := range tests {
+		serialized := tt.Serialize()
+		deserialized, err := tt.Deserialize(tt.Storage, serialized)
+		require.NoError(t, err)
+		assert.Truef(t, arrow.TypeEqual(tt, deserialized), "%s != %s", tt, deserialized)
+	}
+}
+
+func TestOpaqueTypeBatchRoundTrip(t *testing.T) {
+	typ := extensions.NewOpaqueType(arrow.BinaryTypes.String, "geometry", "adbc.postgresql")
+	arrow.RegisterExtensionType(typ)
+	defer arrow.UnregisterExtensionType(typ.ExtensionName())
+
+	storage, _, err := array.FromJSON(memory.DefaultAllocator, arrow.BinaryTypes.String,
+		strings.NewReader(`["foobar", null]`))
+	require.NoError(t, err)
+	defer storage.Release()
+
+	arr := array.NewExtensionArrayWithStorage(typ, storage)
+	defer arr.Release()
+
+	batch := array.NewRecord(arrow.NewSchema([]arrow.Field{{Name: "field", Type: typ, Nullable: true}}, nil),
+		[]arrow.Array{arr}, -1)
+	defer batch.Release()
+
+	var written arrow.Record
+	{
+		var buf bytes.Buffer
+		wr := ipc.NewWriter(&buf, ipc.WithSchema(batch.Schema()))
+		require.NoError(t, wr.Write(batch))
+		require.NoError(t, wr.Close())
+
+		rdr, err := ipc.NewReader(&buf)
+		require.NoError(t, err)
+		written, err = rdr.Read()
+		require.NoError(t, err)
+		written.Retain()
+		defer written.Release()
+		rdr.Release()
+	}
+
+	assert.Truef(t, batch.Schema().Equal(written.Schema()), "expected: %s, got: %s",
+		batch.Schema(), written.Schema())
+
+	assert.Truef(t, array.RecordEqual(batch, written), "expected: %s, got: %s",
+		batch, written)
+}