matcher proc macro

A proc macro to generate an SExpr pattern matcher - for everything(-lang) and macro-lang Provides two macros: match_syntax and match_syntax_as, which are pretty much the same, except the type the match_syntax generates is basically opaque.

Will only work in everything(-lang) or macro-lang as it relies on some data structures and functions that they both share, at a later point I might split out those data structures into another crate, in which case this would usuable without those crates.

pattern syntax

sexpr => <symbol>
        | <symbol>":id"
        | "id"
        | "("<sexpr>+ "." <sexpr>")"
        | "("<sexpr>*")"
        | <sexpr> "..."
        | <sexpr> "..+"
symbol => ([a-zA-Z]|_)([a-zA-Z0-9]|_)*

macro syntax

• match_syntax!(sexpr)
• match_syntax_as(StructName as sexpr)

Example: let matcher = match_syntax((foo bar));.

Running a matcher

The result of match_syntax or match_syntax_as is the matches method of opaque struct or a the creation of a new struct with a matches method on it (in the case of match_syntax_as).

In the case of match_syntax: do match_syntax(sexpr)(sexpr_to_run_matcher_on). In the case of match_syntax_as: use the matches method on the newline generated struct like StructName::matches(sexpr_to_run_matcher_on).

Note: sexpr_to_run_matcher_on has different syntax then sexpr. See note at the beggining.

Example: let results = matcher(sexpr!((a (b c))))?, sexpr! is a macro from everything(-lang) or macro-lang.

Using the results

Assuming you ran the matcher and unrwapped the result, you just do access the field like you declared in the original sexpr.

Example: results.foo.

Note: if you used an :id postfix for your symbol pattern then to access from the struct it will be <symbol>_id.