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don't use a tuple to ensure non-emptiness

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Stoeffel 2020-01-08 11:05:53 +01:00
parent 64a562ebc6
commit a98113c88d
6 changed files with 46 additions and 67 deletions
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45
src/parse/mod.rs
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@ -863,46 +863,29 @@ pub fn when_expr<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>> {
pub fn case_branches<'a>(
min_indent: u16,
) -> impl Parser<
'a,
Vec<
'a,
&'a (
(Located<Pattern<'a>>, Vec<'a, Located<Pattern<'a>>>),
Located<Expr<'a>>,
),
>,
> {
) -> impl Parser<'a, Vec<'a, &'a (Vec<'a, Located<Pattern<'a>>>, Located<Expr<'a>>)>> {
move |arena, state| {
let mut branches: Vec<
'a,
&'a (
(Located<Pattern<'a>>, Vec<'a, Located<Pattern<'a>>>),
Located<Expr<'a>>,
),
> = Vec::with_capacity_in(2, arena);
let mut branches: Vec<'a, &'a (Vec<'a, Located<Pattern<'a>>>, Located<Expr<'a>>)> =
Vec::with_capacity_in(2, arena);
// 1. Parse the first branch and get its indentation level. (It must be >= min_indent.)
// 2. Parse the other branches. Their indentation levels must be == the first branch's.
let (mut loc_first_pattern, state) =
space1_before(loc!(pattern(min_indent)), min_indent).parse(arena, state)?;
let (mut loc_first_pattern, state) = sep_by1(
map!(and!(space1(min_indent), char('|')), |_| ()),
space1_before(loc!(pattern(min_indent)), min_indent),
)
.parse(arena, state)?;
let original_indent = state.indent_col;
let indented_more = original_indent + 1;
let (loc_first_pattern_alt, state) = zero_or_more!(skip_first!(
and!(space0(min_indent), char('|')),
space0_before(loc!(pattern(min_indent)), min_indent)
))
.parse(arena, state)?;
let (spaces_before_arrow, state) = space0(min_indent).parse(arena, state)?;
// Record the spaces before the first "->", if any.
if !spaces_before_arrow.is_empty() {
let region = loc_first_pattern.region;
let value =
Pattern::SpaceAfter(arena.alloc(loc_first_pattern.value), spaces_before_arrow);
loc_first_pattern = Located { region, value };
let last = loc_first_pattern.pop().unwrap();
let region = last.region;
let value = Pattern::SpaceAfter(arena.alloc(last.value), spaces_before_arrow);
loc_first_pattern.push(Located { region, value });
};
// Parse the first "->" and the expression after it.
@ -917,14 +900,14 @@ pub fn case_branches<'a>(
.parse(arena, state)?;
// Record this as the first branch, then optionally parse additional branches.
branches.push(arena.alloc(((loc_first_pattern, loc_first_pattern_alt), loc_first_expr)));
branches.push(arena.alloc((loc_first_pattern, loc_first_expr)));
let branch_parser = and!(
then(
space1_around(loc!(pattern(min_indent)), min_indent),
move |_arena, state, loc_pattern| {
if state.indent_col == original_indent {
Ok(((loc_pattern, Vec::with_capacity_in(0, arena)), state))
Ok((bumpalo::vec![in arena; loc_pattern ], state))
} else {
panic!(
"TODO additional branch didn't have same indentation as first branch"