chore: import upstream snapshot with attribution

server/functions/char_length.go

@@ -0,0 +1,48 @@
+// Copyright 2024 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 (
+	"github.com/dolthub/go-mysql-server/sql"
+
+	"github.com/dolthub/doltgresql/server/functions/framework"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// initCharLength registers the functions to the catalog.
+func initCharLength() {
+	framework.RegisterFunction(char_length_text)
+	// Register alias
+	character_length_text := char_length_text
+	character_length_text.Name = "character_length"
+	framework.RegisterFunction(character_length_text)
+}
+
+// char_length_text represents the PostgreSQL function of the same name, taking the same parameters.
+var char_length_text = framework.Function1{
+	Name:       "char_length",
+	Return:     pgtypes.Int32,
+	Parameters: [1]*pgtypes.DoltgresType{pgtypes.Text},
+	Strict:     true,
+	Callable: func(ctx *sql.Context, _ [2]*pgtypes.DoltgresType, val1 any) (any, error) {
+		// We can't use Wrapper.MaxByteLength to avoid unwrapping because that gives byte length, not char length.
+		valString, _, err := sql.Unwrap[string](ctx, val1)
+		if err != nil {
+			return nil, err
+		}
+
+		return int32(len([]rune(valString))), nil
+	},
+}