1 | #pragma once |
---|---|
2 | |
3 | #include <Parsers/IParser.h> |
4 | |
5 | |
6 | namespace DB |
7 | { |
8 | |
9 | /** Base class for most parsers |
10 | */ |
11 | class IParserBase : public IParser |
12 | { |
13 | public: |
14 | template <typename F> |
15 | static bool wrapParseImpl(Pos & pos, const F & func) |
16 | { |
17 | Pos begin = pos; |
18 | bool res = func(); |
19 | if (!res) |
20 | pos = begin; |
21 | return res; |
22 | } |
23 | |
24 | struct IncreaseDepthTag {}; |
25 | |
26 | template <typename F> |
27 | static bool wrapParseImpl(Pos & pos, IncreaseDepthTag, const F & func) |
28 | { |
29 | Pos begin = pos; |
30 | pos.increaseDepth(); |
31 | bool res = func(); |
32 | pos.decreaseDepth(); |
33 | if (!res) |
34 | pos = begin; |
35 | return res; |
36 | } |
37 | |
38 | bool parse(Pos & pos, ASTPtr & node, Expected & expected); |
39 | |
40 | protected: |
41 | virtual bool parseImpl(Pos & pos, ASTPtr & node, Expected & expected) = 0; |
42 | }; |
43 | |
44 | } |
45 |