wehub-resource-sync
84 lines
3.0 KiB
Go
84 lines
3.0 KiB
Go
// Copyright 2023 Dolthub, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package ast
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import (
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"github.com/cockroachdb/errors"
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"github.com/dolthub/go-mysql-server/sql/expression"
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vitess "github.com/dolthub/vitess/go/vt/sqlparser"
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"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
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pgexprs "github.com/dolthub/doltgresql/server/expression"
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)
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// nodeOrderBy handles *tree.OrderBy nodes.
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func nodeOrderBy(ctx *Context, node tree.OrderBy) (vitess.OrderBy, error) {
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if len(node) == 0 {
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return nil, nil
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}
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orderBys := make([]*vitess.Order, len(node))
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for i := range node {
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if node[i].OrderType != tree.OrderByColumn {
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return nil, errors.Errorf("ORDER BY type is not yet supported")
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}
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var direction string
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switch node[i].Direction {
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case tree.DefaultDirection:
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direction = vitess.AscScr
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case tree.Ascending:
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direction = vitess.AscScr
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case tree.Descending:
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direction = vitess.DescScr
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default:
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return nil, errors.Errorf("unknown ORDER BY sorting direction")
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}
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switch node[i].NullsOrder {
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case tree.DefaultNullsOrder:
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//TODO: the default NULL order is reversed compared to MySQL, so the default is technically always wrong.
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// To prevent choking on every ORDER BY, we allow this to proceed (even with incorrect results) for now.
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// If the NULL order is explicitly declared, then we want to error rather than return incorrect results.
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case tree.NullsFirst:
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if direction != vitess.AscScr {
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return nil, errors.Errorf("this NULL ordering is not yet supported for this ORDER BY direction")
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}
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case tree.NullsLast:
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if direction != vitess.DescScr {
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return nil, errors.Errorf("this NULL ordering is not yet supported for this ORDER BY direction")
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}
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default:
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return nil, errors.Errorf("unknown NULL ordering in ORDER BY")
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}
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expr, err := nodeExpr(ctx, node[i].Expr)
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if err != nil {
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return nil, err
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}
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// GMS order by is hardcoded to expect vitess.SQLVal for expressions such as `ORDER BY 1`.
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// In addition, there is the requirement that columns in the order by also need to be referenced somewhere in
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// the query, which is not a requirement for Postgres. Whenever we add that functionality, we also need to
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// remove the dependency on vitess.SQLVal. For now, we'll just convert our literals to a vitess.SQLVal.
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if injectedExpr, ok := expr.(vitess.InjectedExpr); ok {
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if literal, ok := injectedExpr.Expression.(*expression.Literal); ok {
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expr = pgexprs.ToVitessLiteral(literal)
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}
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}
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orderBys[i] = &vitess.Order{
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Expr: expr,
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Direction: direction,
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}
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}
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return orderBys, nil
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}
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