使用Boost Spirit X3编写解析器是如何安全的？

Question

我考虑从永远开始写作本质上是我的第一个解析器（=自Uni的编译器类以来，我已经忘记了）。

因为我使用C ++，所以我想使用Boost Spirit。然后我注意到了＃34;常规＆＃34; 2.5.2并且有一些名为Spirit X3的代码的神奇子集。

我＆＃39;还注意到Boost Spirit X3已于2年前宣布/讨论/预先发布，但Boost Spirit的正式版本为2.5.2。最后，我读到了：

Where is boost-spirit 3? Is it abandoned?

所以我＆＃34;知道＆＃34;它不是一个废弃的项目 - 但不是一个非常积极维护的项目。怎么＆＃34;安全＆＃34;是不是我用Spirit X3编写了一个解析器？它可能会失败/被丢弃/被抛弃，还是肯定会成为Boost Spirit释放的主线？

Answer 1

It's already released, so there's little chance of it just vanishing.

I liberally use X3 even in production code: After all, we do have tests for a reason.

That said, I know a number of hairy issues surround the linking of rules spread across separate translation units¹.

Here's a list of things that make me consider not using X3 in the following cases:

• where Qi's attribute transformation logic is more enticing (makes for more readable rules). See e.g.
• Phoenix integration is desired Boost Spirit X3 cannot compile repeat directive with variable factor
• Sharing rules across TUs is desired

Slightly less pressing differences are when:

• locals are involved ("X3 becomes a real tedium, (if not completely unbearable) with stateful rules (by which I mean rules with "locals")"). A lot of it can be solved using with<>: Boost Spirit X3 cannot compile repeat directive with variable factor but I'm not convinced it's re-entrant
• lazy rule invocation is required²
• Lexer is desired (i.e. I wouldn't port a Qi/Lex grammar to X3, except by rewrite)

Note however, there are definite areas where X3 shines:

• compilation time
• ease of generating dynamic rules/custom directives (see boost::spirit::x3 attribute compatibility rules, intuition or code? or Recursive x3 parser with results passing around)
• ease of creating custom parsers (e.g. Spirit-Qi: How can I write a nonterminal parser?)

---

¹ see the mailing list, and e.g. x3 linker error with separate TU and linking errors while separate parser using boost spirit x3

² In fact, it might be "easy" to create one by creating a custom parser, building on with<> and any_parser<>