parser: fix statement parsing

internal/sql/parser/parser.go

@@ -80,28 +80,37 @@ func (p *Parser) ParseQuery() (query.Query, error) {
 
 // ParseQuery parses a Genji SQL string and returns a Query.
 func (p *Parser) Parse(fn func(statement.Statement) error) error {
-	semi := true
-
 	for {
-		if tok, pos, lit := p.ScanIgnoreWhitespace(); tok == scanner.EOF {
+		err := p.skipMany(scanner.SEMICOLON)
+		if err != nil {
+			return err
+		}
+
+		end, err := p.parseOptional(scanner.EOF)
+		if err != nil {
+			return err
+		}
+		if end {
 			return nil
-		} else if tok == scanner.SEMICOLON {
+		}
-			semi = true
+
-		} else {
+		s, err := p.ParseStatement()
-			if !semi {
+		if err != nil {
-				return newParseError(scanner.Tokstr(tok, lit), []string{";"}, pos)
+			return err
-			}
+		}
-			p.Unscan()
+
-			s, err := p.ParseStatement()
+		tok, pos, lit := p.ScanIgnoreWhitespace()
-			if err != nil {
+		switch tok {
-				return err
+		case scanner.EOF:
-			}
+			return fn(s)
+		case scanner.SEMICOLON:
 			err = fn(s)
 			if err != nil {
 				return err
 			}
-
+		default:
-			semi = false
+			p.Unscan()
+			return newParseError(scanner.Tokstr(tok, lit), []string{";"}, pos)
 		}
 	}
 }
@@ -142,6 +151,16 @@ func (p *Parser) ParseStatement() (statement.Statement, error) {
 	}, pos)
 }
 
+func (p *Parser) skipMany(tok scanner.Token) error {
+	for {
+		t, _, _ := p.ScanIgnoreWhitespace()
+		if t != tok {
+			p.Unscan()
+			return nil
+		}
+	}
+}
+
 // parseCondition parses the "WHERE" clause of the query, if it exists.
 func (p *Parser) parseCondition() (expr.Expr, error) {
 	// Check if the WHERE token exists.

internal/sql/parser/select.go

@@ -27,13 +27,13 @@ func (p *Parser) parseSelectStatement() (*statement.SelectStmt, error) {
 	// Parse limit: "LIMIT expr"
 	stmt.LimitExpr, err = p.parseLimit()
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "failed to parse LIMIT clause")
 	}
 
 	// Parse offset: "OFFSET expr"
 	stmt.OffsetExpr, err = p.parseOffset()
 	if err != nil {
-		return nil, err
+		return nil, errors.Wrap(err, "failed to parse OFFSET clause")
 	}
 
 	return stmt, nil