Module match_arg 

match.arg-style string conversion for enums.

Provides the MatchArg trait for converting Rust enums to/from R character strings with partial matching, like R’s match.arg(). Use #[derive(MatchArg)] on C-style enums to auto-generate the implementation. match.arg-style enum conversion for R string arguments.

This module provides the MatchArg trait for converting between Rust fieldless enums and R character strings with match.arg semantics (exact match or unique partial matching).

Usage

use miniextendr_api::MatchArg;

#[derive(Copy, Clone, MatchArg)]
#[match_arg(rename_all = "snake_case")]
enum Mode {
    Fast,
    Safe,
    Debug,
}

#[miniextendr]
fn run(#[miniextendr(match_arg)] mode: Mode) -> String {
    format!("{mode:?}")
}

The generated R wrapper uses base::match.arg() for validation before the main .Call(), giving users familiar R error messages and partial matching.

Enums

MatchArgError

Error type for MatchArg conversion failures.

Traits

MatchArg

Trait for enum types that support match.arg-style string conversion.

Functions

choices_sexp

Build an R character vector (STRSXP) from the choices of a MatchArg type.

escape_r_string

Escape a Rust &str for embedding inside an R double-quoted string literal.

factor_elt_to_choice 🔒

Extract a single choice from a factor SEXP (INTSXP with levels attribute).

match_arg_from_sexp

Extract a single string from an R SEXP and match it against a MatchArg type.

match_arg_vec_from_sexp

Extract multiple strings from an R SEXP (STRSXP) and match each against the choices of a MatchArg type.

match_arg_vec_into_sexp

Convert a Vec<T: MatchArg> to an R character vector (STRSXP).

match_choice 🔒

Match a string against the choices of a MatchArg type (exact or partial).

sexp_err_to_match_arg_err 🔒

Map a SexpError from a string TryFromSexp conversion into a MatchArgError.