snapshot of https://github.com/sqlc-dev/sqlc.git (main, 2026-09-16; blobs > 131072B omitted)

internal/engine/dolphin/fingerprint.go

@@ -0,0 +1,55 @@
+package dolphin
+
+import (
+	"fmt"
+	"strings"
+
+	pcast "github.com/sqlc-dev/marino/ast"
+	"github.com/sqlc-dev/marino/format"
+	"github.com/sqlc-dev/marino/parser"
+)
+
+// deparen unwraps parenthesized expressions so a redundant pair of
+// parentheses added or dropped by formatting does not change the
+// fingerprint. Everything else about the tree survives untouched.
+type deparen struct{}
+
+func (v deparen) Enter(n pcast.Node) (pcast.Node, bool) { return n, false }
+func (v deparen) Leave(n pcast.Node) (pcast.Node, bool) {
+	if p, ok := n.(*pcast.ParenthesesExpr); ok {
+		return p.Expr, true
+	}
+	return n, true
+}
+
+// Fingerprint reduces a statement to a canonical form that survives changes
+// in whitespace, keyword case, quoting style and redundant parentheses —
+// and nothing else. Identifier case is preserved: MySQL table names are
+// case-sensitive on most servers, so a formatting pass that changes one is
+// a semantic change and must not fingerprint equal. fmt uses this as its
+// proof that a formatted statement still means what the author wrote; a
+// statement whose fingerprint it cannot match is left exactly as written.
+func (p *Parser) Fingerprint(sql string) (string, error) {
+	// A fresh parser: p.pingcap carries per-parse comment state that
+	// ParseFile is still using.
+	stmts, _, err := parser.New().Parse(sql, "", "")
+	if err != nil {
+		return "", normalizeErr(err)
+	}
+	flags := format.RestoreStringSingleQuotes |
+		format.RestoreKeyWordUppercase |
+		format.RestoreNameBackQuotes
+	parts := make([]string, 0, len(stmts))
+	for _, s := range stmts {
+		n, ok := s.Accept(deparen{})
+		if !ok {
+			return "", fmt.Errorf("fingerprint: rewrite failed")
+		}
+		var sb strings.Builder
+		if err := n.Restore(format.NewRestoreCtx(flags, &sb)); err != nil {
+			return "", fmt.Errorf("fingerprint: %w", err)
+		}
+		parts = append(parts, sb.String())
+	}
+	return strings.Join(parts, "; "), nil
+}