chore: import upstream snapshot with attribution

server/expression/assignment_cast.go

@@ -0,0 +1,106 @@
+// 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 expression
+
+import (
+	"github.com/cockroachdb/errors"
+	"github.com/dolthub/go-mysql-server/sql"
+
+	"github.com/dolthub/doltgresql/core"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// AssignmentCast handles assignment casts.
+type AssignmentCast struct {
+	expr       sql.Expression
+	sourceType *pgtypes.DoltgresType
+	targetType *pgtypes.DoltgresType
+}
+
+var _ sql.Expression = (*AssignmentCast)(nil)
+
+// NewAssignmentCast returns a new *AssignmentCast expression.
+func NewAssignmentCast(expr sql.Expression, sourceType *pgtypes.DoltgresType, targetType *pgtypes.DoltgresType) *AssignmentCast {
+	targetType = checkForDomainType(targetType)
+	sourceType = checkForDomainType(sourceType)
+	return &AssignmentCast{
+		expr:       expr,
+		sourceType: sourceType,
+		targetType: targetType,
+	}
+}
+
+// Children implements the sql.Expression interface.
+func (ac *AssignmentCast) Children() []sql.Expression {
+	return []sql.Expression{ac.expr}
+}
+
+// Eval implements the sql.Expression interface.
+func (ac *AssignmentCast) Eval(ctx *sql.Context, row sql.Row) (any, error) {
+	val, err := ac.expr.Eval(ctx, row)
+	if err != nil || val == nil {
+		return val, err
+	}
+	castsColl, err := core.GetCastsCollectionFromContext(ctx, "")
+	if err != nil {
+		return nil, err
+	}
+	cast, err := castsColl.GetAssignmentCast(ctx, ac.sourceType, ac.targetType)
+	if err != nil {
+		return nil, err
+	}
+	if !cast.ID.IsValid() {
+		return nil, errors.Errorf("ASSIGNMENT_CAST: target is of type %s but expression is of type %s: %s",
+			ac.targetType.String(), ac.sourceType.String(), ac.expr.String())
+	}
+	return cast.Eval(ctx, val, ac.sourceType, ac.targetType)
+}
+
+// IsNullable implements the sql.Expression interface.
+func (ac *AssignmentCast) IsNullable(ctx *sql.Context) bool {
+	return true
+}
+
+// Resolved implements the sql.Expression interface.
+func (ac *AssignmentCast) Resolved() bool {
+	return ac.expr.Resolved()
+}
+
+// String implements the sql.Expression interface.
+func (ac *AssignmentCast) String() string {
+	return ac.expr.String()
+}
+
+// Type implements the sql.Expression interface.
+func (ac *AssignmentCast) Type(ctx *sql.Context) sql.Type {
+	return ac.targetType
+}
+
+// WithChildren implements the sql.Expression interface.
+func (ac *AssignmentCast) WithChildren(ctx *sql.Context, children ...sql.Expression) (sql.Expression, error) {
+	if len(children) != 1 {
+		return nil, sql.ErrInvalidChildrenNumber.New(ac, len(children), 1)
+	}
+	return NewAssignmentCast(children[0], ac.sourceType, ac.targetType), nil
+}
+
+// checkForDomainType returns the underlying type if the given type is a domain type. Casting always applies to the base
+// type.
+func checkForDomainType(t *pgtypes.DoltgresType) *pgtypes.DoltgresType {
+	if t.TypType == pgtypes.TypeType_Domain {
+		t = t.DomainUnderlyingBaseType()
+	}
+	return t
+}