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unary operations

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This commit is contained in:
Folkert 2021-02-27 22:17:07 +01:00
parent 492ae4c943
commit 95acd939c8
2 changed files with 61 additions and 5 deletions
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64
compiler/parse/src/expr.rs
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@ -356,16 +356,68 @@ where
}
}
fn unary_not<'a>() -> impl Parser<'a, (), EExpr<'a>> {
move |_arena: &'a Bump, state: State<'a>| {
if state.bytes.starts_with(b"!") && state.bytes.get(1) != Some(&b'=') {
// don't parse the `!` if it's followed by a `=`
Ok((
MadeProgress,
(),
State {
bytes: &state.bytes[1..],
column: state.column + 1,
..state
},
))
} else {
// this is not a negated expression
Err((NoProgress, EExpr::UnaryNot(state.line, state.column), state))
}
}
}
fn unary_negate<'a>() -> impl Parser<'a, (), EExpr<'a>> {
move |_arena: &'a Bump, state: State<'a>| {
let followed_by_whitespace = state
.bytes
.get(1)
.map(|c| c.is_ascii_whitespace())
.unwrap_or(false);
if state.bytes.starts_with(b"!") && !followed_by_whitespace {
// don't parse the `!` if it's followed by a `!=`
Ok((
MadeProgress,
(),
State {
bytes: &state.bytes[1..],
column: state.column + 1,
..state
},
))
} else {
// this is not a negated expression
Err((NoProgress, EExpr::UnaryNot(state.line, state.column), state))
}
}
}
/// Unary (!) or (-)
///
/// e.g. `!x` or `-x`
pub fn unary_op<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, SyntaxError<'a>> {
fn unary_op<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, SyntaxError<'a>> {
specialize(|e, _, _| SyntaxError::Expr(e), unary_op_help(min_indent))
}
fn unary_op_help<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, EExpr<'a>> {
one_of!(
map_with_arena!(
// must backtrack to distinguish `!x` from `!= y`
and!(
loc!(backtrackable(ascii_char(b'!'))),
loc!(move |arena, state| parse_expr(min_indent, arena, state))
loc!(unary_not()),
loc!(specialize_ref(EExpr::Syntax, move |arena, state| {
parse_expr(min_indent, arena, state)
}))
),
|arena: &'a Bump, (loc_op, loc_expr): (Located<()>, Located<Expr<'a>>)| {
Expr::UnaryOp(arena.alloc(loc_expr), loc_op.map(|_| UnaryOp::Not))
@ -374,8 +426,10 @@ pub fn unary_op<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, SyntaxError<'a
map_with_arena!(
and!(
// must backtrack to distinguish `x - 1` from `-1`
loc!(backtrackable(ascii_char(b'-'))),
loc!(move |arena, state| parse_expr(min_indent, arena, state))
loc!(unary_negate()),
loc!(specialize_ref(EExpr::Syntax, move |arena, state| {
parse_expr(min_indent, arena, state)
}))
),
|arena: &'a Bump, (loc_op, loc_expr): (Located<()>, Located<Expr<'a>>)| {
Expr::UnaryOp(arena.alloc(loc_expr), loc_op.map(|_| UnaryOp::Negate))