chore: import upstream snapshot with attribution

core/functions/collection_funcs.go

@@ -0,0 +1,126 @@
+// Copyright 2025 Dolthub, Inc.
+//
+// Licensed 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 functions
+
+import (
+	"context"
+
+	"github.com/cockroachdb/errors"
+	"github.com/dolthub/dolt/go/libraries/doltcore/doltdb"
+	"github.com/dolthub/dolt/go/libraries/doltcore/merge"
+	"github.com/dolthub/dolt/go/store/hash"
+	"github.com/dolthub/dolt/go/store/prolly"
+
+	"github.com/dolthub/doltgresql/core/id"
+	pgmerge "github.com/dolthub/doltgresql/core/merge"
+	"github.com/dolthub/doltgresql/core/rootobject/objinterface"
+	"github.com/dolthub/doltgresql/flatbuffers/gen/serial"
+)
+
+// storage is used to read from and write to the root.
+var storage = objinterface.RootObjectSerializer{
+	Bytes:        (*serial.RootValue).FunctionsBytes,
+	RootValueAdd: serial.RootValueAddFunctions,
+}
+
+// HandleMerge implements the interface objinterface.Collection.
+func (*Collection) HandleMerge(ctx context.Context, mro merge.MergeRootObject) (doltdb.RootObject, *merge.MergeStats, error) {
+	ourFunc := mro.OurRootObj.(Function)
+	theirFunc := mro.TheirRootObj.(Function)
+	// Ensure that they have the same identifier
+	if ourFunc.ID != theirFunc.ID {
+		return nil, nil, errors.Newf("attempted to merge different functions: `%s` and `%s`",
+			ourFunc.Name().String(), theirFunc.Name().String())
+	}
+	ourHash, err := ourFunc.HashOf(ctx)
+	if err != nil {
+		return nil, nil, err
+	}
+	theirHash, err := theirFunc.HashOf(ctx)
+	if err != nil {
+		return nil, nil, err
+	}
+	if ourHash.Equal(theirHash) {
+		return mro.OurRootObj, &merge.MergeStats{
+			Operation:            merge.TableUnmodified,
+			Adds:                 0,
+			Deletes:              0,
+			Modifications:        0,
+			DataConflicts:        0,
+			SchemaConflicts:      0,
+			RootObjectConflicts:  0,
+			ConstraintViolations: 0,
+		}, nil
+	}
+	return pgmerge.CreateConflict(ctx, mro.RightSrc, ourFunc, theirFunc, mro.AncestorRootObj)
+}
+
+// LoadCollection implements the interface objinterface.Collection.
+func (*Collection) LoadCollection(ctx context.Context, root objinterface.RootValue) (objinterface.Collection, error) {
+	return LoadFunctions(ctx, root)
+}
+
+// LoadCollectionHash implements the interface objinterface.Collection.
+func (*Collection) LoadCollectionHash(ctx context.Context, root objinterface.RootValue) (hash.Hash, error) {
+	m, ok, err := storage.GetProllyMap(ctx, root)
+	if err != nil || !ok {
+		return hash.Hash{}, err
+	}
+	return m.HashOf(), nil
+}
+
+// LoadFunctions loads the functions collection from the given root.
+func LoadFunctions(ctx context.Context, root objinterface.RootValue) (*Collection, error) {
+	m, ok, err := storage.GetProllyMap(ctx, root)
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		m, err = prolly.NewEmptyAddressMap(root.NodeStore())
+		if err != nil {
+			return nil, err
+		}
+	}
+	return NewCollection(ctx, m, root.NodeStore())
+}
+
+// ResolveNameFromObjects implements the interface objinterface.Collection.
+func (*Collection) ResolveNameFromObjects(ctx context.Context, name doltdb.TableName, rootObjects []objinterface.RootObject) (doltdb.TableName, id.Id, error) {
+	tempCollection := Collection{
+		accessCache: make(map[id.Function]Function),
+		idCache:     make([]id.Function, 0, len(rootObjects)),
+	}
+	for _, rootObject := range rootObjects {
+		if obj, ok := rootObject.(Function); ok {
+			tempCollection.accessCache[obj.ID] = obj
+			tempCollection.idCache = append(tempCollection.idCache, obj.ID)
+		}
+	}
+	return tempCollection.ResolveName(ctx, name)
+}
+
+// Serializer implements the interface objinterface.Collection.
+func (*Collection) Serializer() objinterface.RootObjectSerializer {
+	return storage
+}
+
+// UpdateRoot implements the interface objinterface.Collection.
+func (pgf *Collection) UpdateRoot(ctx context.Context, root objinterface.RootValue) (objinterface.RootValue, error) {
+	m, err := pgf.Map(ctx)
+	if err != nil {
+		return nil, err
+	}
+	return storage.WriteProllyMap(ctx, root, m)
+}