chore: import upstream snapshot with attribution

server/expression/is_not_null.go

@@ -0,0 +1,95 @@
+// 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 expression
+
+import (
+	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/expression"
+
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// IsNotNull is an implementation of sql.Expression for the IS NOT NULL operator
+// and includes Postgres-specific logic for handling records and composites.
+type IsNotNull struct {
+	expression.UnaryExpressionStub
+}
+
+var _ sql.Expression = (*IsNotNull)(nil)
+var _ sql.CollationCoercible = (*IsNotNull)(nil)
+var _ sql.IsNotNullExpression = (*IsNotNull)(nil)
+
+// NewIsNotNull creates a new IsNotNull expression.
+func NewIsNotNull(child sql.Expression) *IsNotNull {
+	return &IsNotNull{expression.UnaryExpressionStub{Child: child}}
+}
+
+// IsNotNullExpression implements the sql.IsNotNullExpression interface. This function exists primarily
+// to ensure the IsNotNullExpression interface has a unique signature.
+func (e *IsNotNull) IsNotNullExpression() bool {
+	return true
+}
+
+// Type implements the Expression interface.
+func (e *IsNotNull) Type(ctx *sql.Context) sql.Type {
+	return pgtypes.Bool
+}
+
+// CollationCoercibility implements the interface sql.CollationCoercible.
+func (*IsNotNull) CollationCoercibility(ctx *sql.Context) (collation sql.CollationID, coercibility byte) {
+	return sql.Collation_binary, 5
+}
+
+// IsNullable implements the Expression interface.
+func (e *IsNotNull) IsNullable(ctx *sql.Context) bool {
+	return false
+}
+
+// Eval implements the Expression interface.
+func (e *IsNotNull) Eval(ctx *sql.Context, row sql.Row) (interface{}, error) {
+	v, err := e.Child.Eval(ctx, row)
+	if err != nil {
+		return nil, err
+	}
+
+	// Slices of typed values (e.g. Record and Composite types in Postgres) evaluate
+	// true for IS NOT NULL only if ALL of their entries are not NULL.
+	if tupleValue, ok := v.([]pgtypes.RecordValue); ok {
+		for _, typedValue := range tupleValue {
+			if typedValue.Value == nil {
+				return false, nil
+			}
+		}
+		return true, nil
+	}
+
+	return v != nil, nil
+}
+
+func (e *IsNotNull) String() string {
+	return e.Child.String() + " IS NOT NULL"
+}
+
+func (e *IsNotNull) DebugString(ctx *sql.Context) string {
+	return sql.DebugString(ctx, e.Child) + " IS NOT NULL"
+}
+
+// WithChildren implements the Expression interface.
+func (e *IsNotNull) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
+	if len(children) != 1 {
+		return nil, sql.ErrInvalidChildrenNumber.New(e, len(children), 1)
+	}
+	return NewIsNotNull(children[0]), nil
+}