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Formal arg with ellipsis #7

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Formal arg with ellipsis #7

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29 changes: 21 additions & 8 deletions nix-parser/src/parser/expr/func.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,7 +5,7 @@ use nom::combinator::{map, opt};
use nom::multi::many0;
use nom::sequence::{delimited, pair, preceded, terminated};

use super::{expr, util};
use super::{expr, util::error_expr_if};
use crate::ast::tokens::Ident;
use crate::ast::{ExprFnDecl, FnDeclFormals, FnDeclSimple, Formal};
use crate::error::{Errors, ExpectedFoundError};
Expand All @@ -23,30 +23,43 @@ pub fn fn_decl(input: Tokens) -> IResult<Partial<ExprFnDecl>> {
}

fn simple(input: Tokens) -> IResult<Partial<FnDeclSimple>> {
let expr = alt((expr, util::error_expr_if(tokens::eof, "<eof>")));
let expr = alt((expr, error_expr_if(tokens::eof, "<eof>")));
map_partial(pair_partial(identifier_arg, expr), |(ident, body)| {
let span = Span::merge(ident.span(), body.span());
FnDeclSimple::new(ident, body, span)
})(input)
}

fn formals(input: Tokens) -> IResult<Partial<FnDeclFormals>> {
let value = alt((expr, util::error_expr_if(tokens::comma, "comma")));
let value = alt((expr, error_expr_if(tokens::comma, "comma")));
let default = opt(preceded(tokens::op_question, verify_full(value)));
let formal = map(pair(tokens::identifier, default), |(name, def)| {
let name_span = name.span();
let default_span = def.as_ref().map(|d| d.span()).unwrap_or(name_span);
Partial::from(Formal::new(name, def, Span::merge(name_span, default_span)))
});

let args = separated_list_partial(tokens::comma, tokens::brace_right, formal);
// overloading trailing comma
let ellipsis = alt((
map(tokens::comma, |_| None),
map(preceded(tokens::comma, tokens::ellipsis), |ellipsis| {
Some(ellipsis)
}),
Comment on lines +45 to +47
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I think the closure could just as easily be replaced with:

map(preceded(tokens::comma, tokens::ellipsis), Some),

));
let args = pair_partial(
separated_list_partial(tokens::comma, tokens::brace_right, formal),
map(opt(ellipsis), |e: Option<_>| {
Partial::from(e.and_then(std::convert::identity))
}),
);
let term = pair(tokens::brace_right, tokens::colon);
let formals = delimited(tokens::brace_left, args, term);

let expr = alt((expr, util::error_expr_if(tokens::eof, "<eof>")));
map_partial_spanned(pair_partial(formals, expr), |span, (formals, expr)| {
FnDeclFormals::new(formals, None, None, expr, span)
})(input)
let expr = alt((expr, error_expr_if(tokens::eof, "<eof>")));
map_partial_spanned(
pair_partial(formals, expr),
|span, ((formals, ellipsis), expr)| FnDeclFormals::new(formals, ellipsis, None, expr, span),
)(input)
}

fn identifier_arg(input: Tokens) -> IResult<Partial<Ident>> {
Expand Down
3 changes: 3 additions & 0 deletions nix-parser/src/parser/expr/util.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,9 @@ use crate::parser::partial::Partial;
use crate::parser::IResult;
use crate::ToSpan;

/// parser transformer that peeks for a reasonable termination token and
/// provides designated grammatical hint `found` and hint for expected
/// "expression" grammatical tokens
pub fn error_expr_if<'a, O, F>(
parser: F,
found: &'a str,
Expand Down