refactor(clickhouse): use AST-based parameter detection instead of regex

Replace regex-based parameter detection with AST walking using the doubleclick parser. This avoids issues with parameters in comments being incorrectly detected. For INSERT VALUES clauses (which doubleclick doesn't fully parse), extract the VALUES content and parse it as a SELECT to properly detect parameters through AST walking. 🤖 Generated with [Claude Code](https://claude.ai/code) Co-Authored-By: Claude <noreply@anthropic.com>
sqlc-dev · kyleconroy · Dec 24, 2025 · Dec 24, 2025 · Dec 24, 2025 · Dec 24, 2025
commit c96d9fe715a6423571e1126787395b2812a77135
diff --git a/internal/engine/clickhouse/analyzer/analyze.go b/internal/engine/clickhouse/analyzer/analyze.go
@@ -9,6 +9,8 @@ import (
 	"sync"
 
 	_ "github.com/ClickHouse/clickhouse-go/v2" // ClickHouse driver
+	dcast "github.com/sqlc-dev/doubleclick/ast"
+	"github.com/sqlc-dev/doubleclick/parser"
 
 	core "github.com/sqlc-dev/sqlc/internal/analysis"
 	"github.com/sqlc-dev/sqlc/internal/config"
@@ -331,25 +333,40 @@ type paramInfo struct {
 	Type string
 }
 
-// detectParameters finds parameters in a ClickHouse query.
+// detectParameters finds parameters in a ClickHouse query using the doubleclick parser.
 // ClickHouse supports {name:Type} and ? style parameters.
 func detectParameters(query string) []paramInfo {
 	var params []paramInfo
 
-	// Find all {name:Type} style parameters using regex
-	// This is more reliable than AST walking as it works for all statement types
-	matches := namedParamRegex.FindAllStringSubmatch(query, -1)
-	for _, match := range matches {
-		if len(match) >= 3 {
-			name := match[1]
-			dataType := normalizeType(match[2])
-			params = append(params, paramInfo{
-				Name: name,
-				Type: dataType,
+	ctx := context.Background()
+
+	// First, try to parse and walk the query AST for named parameters
+	stmts, err := parser.Parse(ctx, strings.NewReader(query))
+	if err == nil {
+		for _, stmt := range stmts {
+			walkStatement(stmt, func(expr dcast.Expression) {
+				if param, ok := expr.(*dcast.Parameter); ok {
+					if param.Name != "" {
+						dataType := "any"
+						if param.Type != nil {
+							dataType = normalizeType(param.Type.Name)
+						}
+						params = append(params, paramInfo{
+							Name: param.Name,
+							Type: dataType,
+						})
+					}
+				}
 			})
 		}
 	}
 
+	// If no named parameters found from AST, try to extract VALUES clause for INSERT statements
+	// The doubleclick parser doesn't fully parse VALUES, so we parse it as a SELECT
+	if len(params) == 0 {
+		params = extractValuesParameters(ctx, query)
+	}
+
 	// Count ? placeholders and add them after any named parameters
 	count := strings.Count(query, "?")
 	for i := 0; i < count; i++ {
@@ -362,6 +379,174 @@ func detectParameters(query string) []paramInfo {
 	return params
 }
 
+// extractValuesParameters extracts parameters from INSERT VALUES clause by parsing it as a SELECT.
+// This works around the limitation that doubleclick doesn't parse VALUES clause expressions.
+func extractValuesParameters(ctx context.Context, query string) []paramInfo {
+	var params []paramInfo
+
+	// Find VALUES clause (case insensitive)
+	upperQuery := strings.ToUpper(query)
+	valuesIdx := strings.Index(upperQuery, "VALUES")
+	if valuesIdx == -1 {
+		return params
+	}
+
+	// Extract everything after VALUES
+	valuesClause := query[valuesIdx+6:]
+
+	// Find the parentheses containing the values
+	start := strings.Index(valuesClause, "(")
+	if start == -1 {
+		return params
+	}
+
+	// Find matching closing parenthesis
+	depth := 0
+	end := -1
+	for i := start; i < len(valuesClause); i++ {
+		switch valuesClause[i] {
+		case '(':
+			depth++
+		case ')':
+			depth--
+			if depth == 0 {
+				end = i
+				break
+			}
+		}
+		if end != -1 {
+			break
+		}
+	}
+
+	if end == -1 {
+		return params
+	}
+
+	// Extract the values list and convert to SELECT query
+	valuesList := valuesClause[start+1 : end]
+	selectQuery := "SELECT " + valuesList
+
+	// Parse the synthetic SELECT query
+	stmts, err := parser.Parse(ctx, strings.NewReader(selectQuery))
+	if err != nil {
+		return params
+	}
+
+	// Walk the AST to find Parameter nodes
+	for _, stmt := range stmts {
+		walkStatement(stmt, func(expr dcast.Expression) {
+			if param, ok := expr.(*dcast.Parameter); ok {
+				if param.Name != "" {
+					dataType := "any"
+					if param.Type != nil {
+						dataType = normalizeType(param.Type.Name)
+					}
+					params = append(params, paramInfo{
+						Name: param.Name,
+						Type: dataType,
+					})
+				}
+			}
+		})
+	}
+
+	return params
+}
+
+// walkStatement walks a statement and calls fn for each expression.
+func walkStatement(stmt dcast.Statement, fn func(dcast.Expression)) {
+	switch s := stmt.(type) {
+	case *dcast.SelectQuery:
+		walkSelectQuery(s, fn)
+	case *dcast.SelectWithUnionQuery:
+		for _, sel := range s.Selects {
+			walkStatement(sel, fn)
+		}
+	case *dcast.InsertQuery:
+		if s.Select != nil {
+			walkStatement(s.Select, fn)
+		}
+	}
+}
+
+// walkSelectQuery walks a SELECT query and calls fn for each expression.
+func walkSelectQuery(s *dcast.SelectQuery, fn func(dcast.Expression)) {
+	// Walk columns
+	for _, col := range s.Columns {
+		walkExpression(col, fn)
+	}
+	// Walk WHERE clause
+	if s.Where != nil {
+		walkExpression(s.Where, fn)
+	}
+	// Walk GROUP BY
+	for _, g := range s.GroupBy {
+		walkExpression(g, fn)
+	}
+	// Walk HAVING
+	if s.Having != nil {
+		walkExpression(s.Having, fn)
+	}
+	// Walk ORDER BY
+	for _, o := range s.OrderBy {
+		walkExpression(o.Expression, fn)
+	}
+	// Walk LIMIT
+	if s.Limit != nil {
+		walkExpression(s.Limit, fn)
+	}
+	// Walk OFFSET
+	if s.Offset != nil {
+		walkExpression(s.Offset, fn)
+	}
+}
+
+// walkExpression walks an expression and calls fn for each sub-expression.
+func walkExpression(expr dcast.Expression, fn func(dcast.Expression)) {
+	if expr == nil {
+		return
+	}
+	fn(expr)
+
+	switch e := expr.(type) {
+	case *dcast.BinaryExpr:
+		walkExpression(e.Left, fn)
+		walkExpression(e.Right, fn)
+	case *dcast.UnaryExpr:
+		walkExpression(e.Operand, fn)
+	case *dcast.FunctionCall:
+		for _, arg := range e.Arguments {
+			walkExpression(arg, fn)
+		}
+	case *dcast.Subquery:
+		walkStatement(e.Query, fn)
+	case *dcast.CaseExpr:
+		if e.Operand != nil {
+			walkExpression(e.Operand, fn)
+		}
+		for _, when := range e.Whens {
+			walkExpression(when.Condition, fn)
+			walkExpression(when.Result, fn)
+		}
+		if e.Else != nil {
+			walkExpression(e.Else, fn)
+		}
+	case *dcast.InExpr:
+		walkExpression(e.Expr, fn)
+		for _, v := range e.List {
+			walkExpression(v, fn)
+		}
+		if e.Query != nil {
+			walkStatement(e.Query, fn)
+		}
+	case *dcast.BetweenExpr:
+		walkExpression(e.Expr, fn)
+		walkExpression(e.Low, fn)
+		walkExpression(e.High, fn)
+	}
+}
+
 // namedParamRegex matches ClickHouse named parameters like {name:Type}
 var namedParamRegex = regexp.MustCompile(`\{(\w+):(\w+)\}`)