fix: (close #98) correctly parse negative number in queries

driver/driver_test.go

@@ -1244,6 +1244,8 @@ func TestFloat(t *testing.T) {
 		`INSERT INTO user (name, surname, age) VALUES (Homer, Simpson, 40);`,
 		`INSERT INTO user (name, surname, age) VALUES (Marge, Simpson, 40);`,
 		`INSERT INTO user (name, surname, age) VALUES (Bruce, Wayne, 3333);`,
+		`INSERT INTO user (name, surname, age) VALUES (Bruce, Future, -3333);`,
+		`INSERT INTO user (name, surname, age) VALUES (Bruce, Demo, -1.0);`,
 	}
 
 	db, err := sql.Open("ramsql", "TestFloat")
@@ -1295,6 +1297,14 @@ func TestFloat(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Cannot run UPDATE query with AND: %s\n", err)
 	}
+
+	db.QueryRow(`SELECT age FROM user WHERE surname = 'Demo'`).Scan(&age)
+	if err != nil {
+		t.Fatalf("Cannot load negative age: %s", err)
+	}
+	if age != -1.0 {
+		t.Fatalf("Expected age to be -1.0, got %f", age)
+	}
 }
 
 func TestDrop(t *testing.T) {

engine/parser/lexer.go

@@ -367,7 +367,7 @@ func (l *lexer) MatchStringToken() bool {
 func (l *lexer) MatchFloatToken() bool {
 
 	i := l.pos
-	for i < l.instructionLen && (unicode.IsDigit(rune(l.instruction[i]))) {
+	for i < l.instructionLen && (unicode.IsDigit(rune(l.instruction[i])) || l.instruction[i] == '-') {
 		i++
 	}
 	if i == l.pos || i >= l.instructionLen {