4. Cheatsheet 备忘单

https://lalrpop.github.io/lalrpop/cheatsheet.html

Users of Lalrpop have compiled the following cheatsheet table as a quick way to look up useful Lalrpop-isms. If you are looking for a specific piece of functionality, use this table to jump to the right section.

gpt --- Lalrpop 的用户编制了以下这张备忘单，作为快速查找常用 Lalrpop 语法的工具。如果你正在寻找某个特定功能，可以通过这张表快速跳转到相应的部分。

ms --- Lalrpop 的用户编译了以下 cheatsheet 表，作为查找有用的 Lalrpop-isms 的快速方法。如果要查找特定功能，请使用此表跳转到右侧部分。

name	snippet	description	tutorial
position	<left: @L> T <right: @R>	captures the offset of the first byte and the offset of the last byte plus one (as left and right respectively)	Location tracking
error_recovery	! =>	recovers from parser errors	Error recovery
grammar_parameter	grammar(scale: isize);	input parameters usable in the generated parser	Passing state parameter
custom_error	"e" =>? Err(ParseError::User { error: "an error" })	makes an action fallible	Fallible actions
custom_macros	Comma =	makes a non-terminal generic in other non-terminals	Macros
quantifier_macros	<Num?> <Num*> <Num+>	a non-terminal which can appear 0..1, 0+, 1+ times	Macros
tuple_macro	<a:( ",")*>	applies a quantifier to a group of matches	Macros
extern	extern	allows to override some parts of the generated parser	Writing a custom lexer
extern_error	type Error = MyError;	sets the error to use in the ParseError::User variant	Writing a custom lexer
extern_location	type Location = MyLoc;	sets the type to for locations instead of usize	Writing a custom lexer
extern_tok	enum MyToken	declares the type of lexer tokens to be consumed by the generated parser	Using tokens with references
auto_parameters	<>	refers to all the parameters of the non-terminal as a tuple	Type inference
conditional actions	Expr = { ... , if I == "a" => (), ...}	Conditional definition of a macro's alternative	index pointer
precedence	#[precedence(level="0")]	creates a hierarchy to parser actions for which ones should be applied first	Handling full expressions