chore: import upstream snapshot with attribution

server/ast/func_expr.go

@@ -0,0 +1,142 @@
+// Copyright 2023 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 ast
+
+import (
+	"strings"
+
+	"github.com/cockroachdb/errors"
+	vitess "github.com/dolthub/vitess/go/vt/sqlparser"
+
+	"github.com/dolthub/doltgresql/postgres/parser/sem/tree"
+	"github.com/dolthub/doltgresql/server/auth"
+	pgexprs "github.com/dolthub/doltgresql/server/expression"
+)
+
+// nodeFuncExpr handles *tree.FuncExpr nodes.
+func nodeFuncExpr(ctx *Context, node *tree.FuncExpr) (vitess.Expr, error) {
+	if node == nil {
+		return nil, nil
+	}
+	if node.Filter != nil {
+		return nil, errors.Errorf("function filters are not yet supported")
+	}
+	if node.AggType == tree.OrderedSetAgg {
+		return nil, errors.Errorf("WITHIN GROUP is not yet supported")
+	}
+
+	var qualifier vitess.TableIdent
+	var name vitess.ColIdent
+	switch funcRef := node.Func.FunctionReference.(type) {
+	case *tree.FunctionDefinition:
+		name = vitess.NewColIdent(funcRef.Name)
+	case *tree.UnresolvedName:
+		colName, err := unresolvedNameToColName(funcRef)
+		if err != nil {
+			return nil, err
+		}
+		qualifier = colName.Qualifier.Name
+		name = colName.Name
+	default:
+		return nil, errors.Errorf("unknown function reference")
+	}
+	var distinct bool
+	switch node.Type {
+	case 0, tree.AllFuncType:
+		distinct = false
+	case tree.DistinctFuncType:
+		distinct = true
+	default:
+		return nil, errors.Errorf("unknown function spec type %d", node.Type)
+	}
+	windowDef, err := nodeWindowDef(ctx, node.WindowDef)
+	if err != nil {
+		return nil, err
+	}
+	exprs, err := nodeExprsToSelectExprs(ctx, node.Exprs)
+	if err != nil {
+		return nil, err
+	}
+
+	switch strings.ToLower(name.String()) {
+	// special case for string_agg, which maps to the mysql aggregate function group_concat
+	case "string_agg":
+		if len(node.Exprs) != 2 {
+			return nil, errors.Errorf("string_agg requires two arguments")
+		}
+
+		sepString := ""
+		if sep, ok := node.Exprs[1].(*tree.StrVal); ok {
+			sepString = strings.Trim(sep.String(), "'")
+		} else {
+			// TODO: need to support this function in doltgres
+			c, is := node.Exprs[1].(*tree.CastExpr)
+			if !is && c.Type.SQLString() != "TEXT" {
+				return nil, errors.Errorf("string_agg requires a string separator")
+			}
+			sepString = strings.Trim(c.Expr.String(), "'")
+		}
+
+		var orderBy vitess.OrderBy
+		if len(node.OrderBy) > 0 {
+			orderBy, err = nodeOrderBy(ctx, node.OrderBy)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		return &vitess.GroupConcatExpr{
+			Exprs: exprs[:1],
+			Separator: vitess.Separator{
+				SeparatorString: sepString,
+			},
+			OrderBy: orderBy,
+		}, nil
+	case "array_agg":
+		var orderBy vitess.OrderBy
+		if len(node.OrderBy) > 0 {
+			orderBy, err = nodeOrderBy(ctx, node.OrderBy)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		return &vitess.OrderedInjectedExpr{
+			InjectedExpr: vitess.InjectedExpr{
+				Expression:         &pgexprs.ArrayAgg{Distinct: distinct},
+				SelectExprChildren: exprs,
+				Auth:               vitess.AuthInformation{},
+			},
+			OrderBy: orderBy,
+		}, nil
+	}
+
+	if len(node.OrderBy) > 0 {
+		return nil, errors.Errorf("function ORDER BY is not yet supported")
+	}
+
+	return &vitess.FuncExpr{
+		Qualifier: qualifier,
+		Name:      name,
+		Distinct:  distinct,
+		Exprs:     exprs,
+		Over:      (*vitess.Over)(windowDef),
+		Auth: vitess.AuthInformation{
+			AuthType:    auth.AuthType_EXECUTE,
+			TargetType:  auth.AuthTargetType_FunctionIdentifiers,
+			TargetNames: []string{qualifier.String(), name.String()},
+		},
+	}, nil
+}