Crate metamatch 

metamatch!

A zero dependency proc-macro for practical metaprogramming.

Macro expressions using familiar Rust syntax, evaluated by a tiny interpreter.

Supported Rust Syntax:

• let statements and pattern matching.
• loop, while, while let, and for loops, including continue and break
• if and else blocks
• Functions (fn) and lambdas (|..|)
• Arrays ([1,2,3])
• Ranges (0..=10)
• All expression operators like + or <<.

Not supported:

• struct, enum, type, trait, generics, …

Builtin functions:

• lowercase(str) -> str
• uppercase(str) -> str
• capitalize(str) -> str
• enumerate([T]) -> [(int, T)]
• zip([A], [B], ..) -> [(A, B, ..)]
• map([T], Fn(T) -> U) -> [U]
• chars(str) -> [char]
• bytes(str) -> [int]
• ident(str) -> token
• str(any) -> str
• len([T]) -> int

String functions also work on tokens.

All functions support UFCS, so [1,2,3].len() == len([1,2,3])

Special Purpose Macros:

• quote! {..} -> [token]: nested version of quote!.
• raw! {..} -> [token]: raw Rust, no template tags or expanded meta variables

Just like Rust macros, you can use any of {}, [], and () interchangably for the macro invocations.

Macros

metamatch

Generate repetitive match arms for differently typed variants.

unquote

Evaluates arbitrary expressions.

quote

Like unquote!, but starts out in quoted mode, meaning that tokens will be pasted verbatim.

Attribute Macros

replicate

Generate repetitive syntax like trait impls without giving up on rustfmt or rust-analyzer.