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.

Attribute Macros

replicate

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

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.