[parser] parser: SetText for trace statement and set default format to json (#46)

parser/parser.y

@@ -2375,8 +2375,19 @@ TraceStmt:
 	{
 		$$ = &ast.TraceStmt{
 			Stmt:	$2,
-			Format: "row",
+			Format: "json",
 		}
+		startOffset := parser.startOffset(&yyS[yypt])
+		$2.SetText(string(parser.src[startOffset:]))
+	}
+|	"TRACE" "FORMAT" "=" stringLit TraceableStmt
+	{
+		$$ = &ast.TraceStmt{
+			Stmt: $5,
+			Format: $4,
+		}
+		startOffset := parser.startOffset(&yyS[yypt])
+		$5.SetText(string(parser.src[startOffset:]))
 	}
 
 ExplainSym:

parser/parser_test.go

@@ -2206,6 +2206,8 @@ func (s *testParserSuite) TestTrace(c *C) {
 		{"trace replace into foo values (1 || 2)", true},
 		{"trace update t set id = id + 1 order by id desc;", true},
 		{"trace select c1 from t1 union (select c2 from t2) limit 1, 1", true},
+		{"trace format = 'row' select c1 from t1 union (select c2 from t2) limit 1, 1", true},
+		{"trace format = 'json' update t set id = id + 1 order by id desc;", true},
 	}
 	s.RunTest(c, table)
 }
@@ -2568,4 +2570,17 @@ func (s *testParserSuite) TestFieldText(c *C) {
 	c.Assert(err, IsNil)
 	tmp := stmts[0].(*ast.SelectStmt)
 	c.Assert(tmp.Fields.Fields[0].Text(), Equals, "a")
+
+	sqls := []string{
+		"trace select a from t",
+		"trace format = 'row' select a from t",
+		"trace format = 'json' select a from t",
+	}
+	for _, sql := range sqls {
+		stmts, err = parser.Parse(sql, "", "")
+		c.Assert(err, IsNil)
+		traceStmt := stmts[0].(*ast.TraceStmt)
+		c.Assert(traceStmt.Text(), Equals, sql)
+		c.Assert(traceStmt.Stmt.Text(), Equals, "select a from t")
+	}
 }