chore: import upstream snapshot with attribution

server/analyzer/split.go

@@ -0,0 +1,65 @@
+// 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 analyzer
+
+import (
+	"github.com/dolthub/go-mysql-server/sql"
+	"github.com/dolthub/go-mysql-server/sql/expression"
+
+	pgexprs "github.com/dolthub/doltgresql/server/expression"
+	pgtypes "github.com/dolthub/doltgresql/server/types"
+)
+
+// splitConjunction breaks AND expressions into their left and right parts, recursively.
+func splitConjunction(ctx *sql.Context, expr sql.Expression) []sql.Expression {
+	if expr == nil {
+		return nil
+	}
+	switch expr := expr.(type) {
+	case *expression.And:
+		return append(
+			splitConjunction(ctx, expr.LeftChild),
+			splitConjunction(ctx, expr.RightChild)...,
+		)
+	case *pgexprs.GMSCast:
+		// We should check to see if we need to preserve the cast on each child individually
+		split := splitConjunction(ctx, expr.Child())
+		for i := range split {
+			if _, ok := split[i].Type(ctx).(*pgtypes.DoltgresType); !ok {
+				split[i] = pgexprs.NewGMSCast(split[i])
+			}
+		}
+		return split
+	default:
+		return []sql.Expression{expr}
+	}
+}
+
+// LogicTreeWalker is a walker that removes GMSCast and other Doltgres specific expression nodes from
+// logic expression trees. This allows the analyzer logic to correctly reason about expressions in filters
+// to apply indexes.
+type LogicTreeWalker struct{}
+
+var _ sql.ExpressionTreeFilter = &LogicTreeWalker{}
+
+// Next implements the sql.ExpressionTreeFilter interface.
+func (l *LogicTreeWalker) Next(e sql.Expression) sql.Expression {
+	switch expr := e.(type) {
+	case *pgexprs.GMSCast:
+		return l.Next(expr.Child())
+	default:
+		return e
+	}
+}