Add FOR JSON clause parsing support

Add JsonForClause and JsonForClauseOption AST types to handle
FOR JSON AUTO, PATH, ROOT('name'), INCLUDE_NULL_VALUES, and
WITHOUT_ARRAY_WRAPPER options in SELECT statements.

Author: claude

ast/for_clause.go

@@ -41,3 +41,19 @@ type XmlForClauseOption struct {
 }
 
 func (*XmlForClauseOption) node() {}
+
+// JsonForClause represents a FOR JSON clause with its options.
+type JsonForClause struct {
+	Options []*JsonForClauseOption `json:"Options,omitempty"`
+}
+
+func (*JsonForClause) node()      {}
+func (*JsonForClause) forClause() {}
+
+// JsonForClauseOption represents an option in a FOR JSON clause.
+type JsonForClauseOption struct {
+	OptionKind string         `json:"OptionKind,omitempty"`
+	Value      *StringLiteral `json:"Value,omitempty"`
+}
+
+func (*JsonForClauseOption) node() {}

parser/marshal.go

@@ -1300,6 +1300,16 @@ func forClauseToJSON(fc ast.ForClause) jsonNode {
 			node["Options"] = opts
 		}
 		return node
+	case *ast.JsonForClause:
+		node := jsonNode{"$type": "JsonForClause"}
+		if len(f.Options) > 0 {
+			opts := make([]jsonNode, len(f.Options))
+			for i, opt := range f.Options {
+				opts[i] = jsonForClauseOptionToJSON(opt)
+			}
+			node["Options"] = opts
+		}
+		return node
 	default:
 		return jsonNode{"$type": "UnknownForClause"}
 	}
@@ -1316,6 +1326,17 @@ func xmlForClauseOptionToJSON(opt *ast.XmlForClauseOption) jsonNode {
 	return node
 }
 
+func jsonForClauseOptionToJSON(opt *ast.JsonForClauseOption) jsonNode {
+	node := jsonNode{"$type": "JsonForClauseOption"}
+	if opt.OptionKind != "" {
+		node["OptionKind"] = opt.OptionKind
+	}
+	if opt.Value != nil {
+		node["Value"] = stringLiteralToJSON(opt.Value)
+	}
+	return node
+}
+
 func topRowFilterToJSON(t *ast.TopRowFilter) jsonNode {
 	node := jsonNode{
 		"$type": "TopRowFilter",

parser/parse_select.go

@@ -3495,6 +3495,10 @@ func (p *Parser) parseForClause() (ast.ForClause, error) {
 		p.nextToken() // consume XML
 		return p.parseXmlForClause()
 
+	case "JSON":
+		p.nextToken() // consume JSON
+		return p.parseJsonForClause()
+
 	default:
 		return nil, fmt.Errorf("unexpected token after FOR: %s", p.curTok.Literal)
 	}
@@ -3613,3 +3617,60 @@ func (p *Parser) parseXmlForClauseOption() (*ast.XmlForClauseOption, error) {
 
 	return option, nil
 }
+
+// parseJsonForClause parses FOR JSON options.
+func (p *Parser) parseJsonForClause() (*ast.JsonForClause, error) {
+	clause := &ast.JsonForClause{}
+
+	// Parse JSON options separated by commas
+	for {
+		option, err := p.parseJsonForClauseOption()
+		if err != nil {
+			return nil, err
+		}
+		clause.Options = append(clause.Options, option)
+
+		if p.curTok.Type != TokenComma {
+			break
+		}
+		p.nextToken() // consume comma
+	}
+
+	return clause, nil
+}
+
+// parseJsonForClauseOption parses a single JSON FOR clause option.
+func (p *Parser) parseJsonForClauseOption() (*ast.JsonForClauseOption, error) {
+	option := &ast.JsonForClauseOption{}
+
+	keyword := strings.ToUpper(p.curTok.Literal)
+	p.nextToken() // consume the option keyword
+
+	switch keyword {
+	case "AUTO":
+		option.OptionKind = "Auto"
+	case "PATH":
+		option.OptionKind = "Path"
+	case "ROOT":
+		option.OptionKind = "Root"
+		// Check for optional root name: ROOT('name')
+		if p.curTok.Type == TokenLParen {
+			p.nextToken() // consume (
+			if p.curTok.Type == TokenString {
+				option.Value = p.parseStringLiteralValue()
+				p.nextToken() // consume string
+			}
+			if p.curTok.Type == TokenRParen {
+				p.nextToken() // consume )
+			}
+		}
+	case "INCLUDE_NULL_VALUES":
+		option.OptionKind = "IncludeNullValues"
+	case "WITHOUT_ARRAY_WRAPPER":
+		option.OptionKind = "WithoutArrayWrapper"
+	default:
+		option.OptionKind = keyword
+	}
+
+	return option, nil
+}

parser/testdata/Baselines130_JsonForClauseTests130/metadata.json

@@ -1 +1 @@
-{"todo": true}
+{}

parser/testdata/JsonForClauseTests130/metadata.json

@@ -1 +1 @@
-{"todo": true}
+{}