add oct.go impl

Author: elianddb

sql/expression/function/oct.go

@@ -0,0 +1,80 @@
+// 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 function
+
+import (
+	"fmt"
+	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/expression"
+	"github.com/dolthub/go-mysql-server/sql/types"
+)
+
+// Oct function provides a string representation for the octal value of N, where N is a decimal number.
+type Oct struct {
+	n sql.Expression
+}
+
+var _ sql.FunctionExpression = (*Oct)(nil)
+var _ sql.CollationCoercible = (*Oct)(nil)
+
+func NewOct(n sql.Expression) sql.Expression { return &Oct{n} }
+
+func (o *Oct) FunctionName() string {
+	return "oct"
+}
+
+func (o *Oct) Description() string {
+	return "returns a string representation for octal value of N, where N is a decimal number."
+}
+
+func (o *Oct) Type() sql.Type {
+	return types.LongText
+}
+
+func (o *Oct) IsNullable() bool {
+	return o.n.IsNullable()
+}
+
+func (o *Oct) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+	// Convert a decimal (base 10) number to octal (base 8)
+	return NewConv(
+		o.n,
+		expression.NewLiteral(10, types.Int64),
+		expression.NewLiteral(8, types.Int64),
+	).Eval(ctx, row)
+}
+
+func (o *Oct) Resolved() bool {
+	return o.n.Resolved()
+}
+
+func (o *Oct) Children() []sql.Expression {
+	return []sql.Expression{o.n}
+}
+
+func (o *Oct) WithChildren(children ...sql.Expression) (sql.Expression, error) {
+	if len(children) != 1 {
+		return nil, sql.ErrInvalidChildrenNumber.New(o, len(children), 1)
+	}
+	return NewOct(children[0]), nil
+}
+
+func (o *Oct) String() string {
+	return fmt.Sprintf("%s(%s)", o.FunctionName(), o.n)
+}
+
+func (*Oct) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
+	return ctx.GetCollation(), 4 // strings with collations
+}