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Folkert 2021-02-20 13:47:01 +01:00
parent e007430584
commit f6fac092a4
4 changed files with 290 additions and 317 deletions
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307
compiler/parse/src/expr.rs
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@ -13,7 +13,7 @@ use crate::parser::{
fail, map, newline_char, not, not_followed_by, optional, sep_by1, then, unexpected,
unexpected_eof, Either, ParseResult, Parser, State, SyntaxError,
};
use crate::pattern::underscore_pattern;
use crate::pattern::{loc_closure_param, loc_pattern};
use crate::type_annotation;
use bumpalo::collections::string::String;
use bumpalo::collections::Vec;
@ -244,7 +244,10 @@ fn parse_expr<'a>(
/// If the given Expr would parse the same way as a valid Pattern, convert it.
/// Example: (foo) could be either an Expr::Var("foo") or Pattern::Identifier("foo")
fn expr_to_pattern<'a>(arena: &'a Bump, expr: &Expr<'a>) -> Result<Pattern<'a>, SyntaxError<'a>> {
pub fn expr_to_pattern<'a>(
arena: &'a Bump,
expr: &Expr<'a>,
) -> Result<Pattern<'a>, SyntaxError<'a>> {
match expr {
Expr::Var { module_name, ident } => {
if module_name.is_empty() {
@ -1009,306 +1012,6 @@ fn closure<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, SyntaxError<'a>> {
)
}
fn loc_closure_param<'a>(
min_indent: u16,
) -> impl Parser<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
move |arena, state| parse_closure_param(arena, state, min_indent)
}
fn parse_closure_param<'a>(
arena: &'a Bump,
state: State<'a>,
min_indent: u16,
) -> ParseResult<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
one_of!(
// An ident is the most common param, e.g. \foo -> ...
loc_ident_pattern(min_indent, true),
// Underscore is also common, e.g. \_ -> ...
loc!(underscore_pattern()),
// You can destructure records in params, e.g. \{ x, y } -> ...
// loc!(record_destructure(min_indent)),
loc!(crate::pattern::record_pattern(min_indent)),
// If you wrap it in parens, you can match any arbitrary pattern at all.
// e.g. \User.UserId userId -> ...
between!(
ascii_char(b'('),
space0_around(loc_pattern(min_indent), min_indent),
ascii_char(b')')
)
)
.parse(arena, state)
}
pub fn loc_pattern<'a>(min_indent: u16) -> impl Parser<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
skip_first!(
// If this is a reserved keyword ("if", "then", "case, "when"), then
// it is not a pattern!
not(reserved_keyword()),
one_of!(
loc_parenthetical_pattern(min_indent),
loc!(underscore_pattern()),
loc_ident_pattern(min_indent, true),
// loc!(record_destructure(min_indent)),
loc!(crate::pattern::record_pattern(min_indent)),
loc!(string_pattern()),
loc!(number_pattern())
)
)
}
fn loc_tag_pattern_args<'a>(
min_indent: u16,
) -> impl Parser<'a, Vec<'a, Located<Pattern<'a>>>, SyntaxError<'a>> {
zero_or_more!(space1_before(loc_tag_pattern_arg(min_indent), min_indent))
}
fn loc_tag_pattern_arg<'a>(
min_indent: u16,
) -> impl Parser<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
skip_first!(
// If this is a reserved keyword ("if", "then", "case, "when"), then
// it is not a function argument!
not(reserved_keyword()),
// Don't parse operators, because they have a higher precedence than function application.
// If we encounter one, we're done parsing function args!
move |arena, state| loc_parse_tag_pattern_arg(min_indent, arena, state)
)
}
fn loc_parse_tag_pattern_arg<'a>(
min_indent: u16,
arena: &'a Bump,
state: State<'a>,
) -> ParseResult<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
one_of!(
loc_parenthetical_pattern(min_indent),
loc!(underscore_pattern()),
// Make sure `Foo Bar 1` is parsed as `Foo (Bar) 1`, and not `Foo (Bar 1)`
loc_ident_pattern(min_indent, false),
// loc!(record_destructure(min_indent)),
loc!(crate::pattern::record_pattern(min_indent)),
loc!(string_pattern()),
loc!(number_pattern())
)
.parse(arena, state)
}
fn loc_parenthetical_pattern<'a>(
min_indent: u16,
) -> impl Parser<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
between!(
ascii_char(b'('),
space0_around(
move |arena, state| loc_pattern(min_indent).parse(arena, state),
min_indent,
),
ascii_char(b')')
)
}
fn number_pattern<'a>() -> impl Parser<'a, Pattern<'a>, SyntaxError<'a>> {
map_with_arena!(number_literal(), |arena, expr| {
expr_to_pattern(arena, &expr).unwrap()
})
}
fn string_pattern<'a>() -> impl Parser<'a, Pattern<'a>, SyntaxError<'a>> {
map!(crate::string_literal::parse(), Pattern::StrLiteral)
}
fn record_destructure<'a>(min_indent: u16) -> impl Parser<'a, Pattern<'a>, SyntaxError<'a>> {
then(
collection!(
ascii_char(b'{'),
move |arena: &'a bumpalo::Bump,
state: crate::parser::State<'a>|
-> crate::parser::ParseResult<
'a,
Located<crate::ast::Pattern<'a>>,
SyntaxError,
> {
use crate::blankspace::{space0, space0_before};
use crate::ident::lowercase_ident;
use crate::parser::Either::*;
use roc_region::all::Region;
// You must have a field name, e.g. "email"
let (p1, loc_label, state) = loc!(lowercase_ident()).parse(arena, state)?;
let (p2, spaces, state) = space0(min_indent).parse(arena, state)?;
// Having a value is optional; both `{ email }` and `{ email: blah }` work.
// (This is true in both literals and types.)
let (p3, opt_loc_val, state) = crate::parser::optional(either!(
skip_first!(
ascii_char(b':'),
space0_before(loc_pattern(min_indent), min_indent)
),
skip_first!(
ascii_char(b'?'),
space0_before(loc!(expr(min_indent)), min_indent)
)
))
.parse(arena, state)?;
let answer = match opt_loc_val {
Some(either) => match either {
First(loc_val) => Located {
region: Region::span_across(&loc_label.region, &loc_val.region),
value: Pattern::RequiredField(loc_label.value, arena.alloc(loc_val)),
},
Second(loc_val) => Located {
region: Region::span_across(&loc_label.region, &loc_val.region),
value: Pattern::OptionalField(loc_label.value, arena.alloc(loc_val)),
},
},
// If no value was provided, record it as a Var.
// Canonicalize will know what to do with a Var later.
None => {
if !spaces.is_empty() {
Located {
region: loc_label.region,
value: Pattern::SpaceAfter(
arena.alloc(Pattern::Identifier(loc_label.value)),
spaces,
),
}
} else {
Located {
region: loc_label.region,
value: Pattern::Identifier(loc_label.value),
}
}
}
};
let progress = p1.or(p2).or(p3);
debug_assert_eq!(progress, MadeProgress);
Ok((MadeProgress, answer, state))
},
ascii_char(b','),
ascii_char(b'}'),
min_indent
),
move |_arena, state, progress, loc_patterns| {
Ok((
progress,
Pattern::RecordDestructure(loc_patterns.into_bump_slice()),
state,
))
},
)
}
fn loc_ident_pattern<'a>(
min_indent: u16,
can_have_arguments: bool,
) -> impl Parser<'a, Located<Pattern<'a>>, SyntaxError<'a>> {
move |arena: &'a Bump, state: State<'a>| {
let (_, loc_ident, state) = loc!(ident()).parse(arena, state)?;
match loc_ident.value {
Ident::GlobalTag(tag) => {
let loc_tag = Located {
region: loc_ident.region,
value: Pattern::GlobalTag(tag),
};
// Make sure `Foo Bar 1` is parsed as `Foo (Bar) 1`, and not `Foo (Bar 1)`
if can_have_arguments {
let (_, loc_args, state) =
loc_tag_pattern_args(min_indent).parse(arena, state)?;
if loc_args.is_empty() {
Ok((MadeProgress, loc_tag, state))
} else {
let region = Region::across_all(
std::iter::once(&loc_ident.region)
.chain(loc_args.iter().map(|loc_arg| &loc_arg.region)),
);
let value =
Pattern::Apply(&*arena.alloc(loc_tag), loc_args.into_bump_slice());
Ok((MadeProgress, Located { region, value }, state))
}
} else {
Ok((MadeProgress, loc_tag, state))
}
}
Ident::PrivateTag(tag) => {
let loc_tag = Located {
region: loc_ident.region,
value: Pattern::PrivateTag(tag),
};
// Make sure `Foo Bar 1` is parsed as `Foo (Bar) 1`, and not `Foo (Bar 1)`
if can_have_arguments {
let (_, loc_args, state) =
loc_tag_pattern_args(min_indent).parse(arena, state)?;
if loc_args.is_empty() {
Ok((MadeProgress, loc_tag, state))
} else {
let region = Region::across_all(
std::iter::once(&loc_ident.region)
.chain(loc_args.iter().map(|loc_arg| &loc_arg.region)),
);
let value =
Pattern::Apply(&*arena.alloc(loc_tag), loc_args.into_bump_slice());
Ok((MadeProgress, Located { region, value }, state))
}
} else {
Ok((MadeProgress, loc_tag, state))
}
}
Ident::Access { module_name, parts } => {
// Plain identifiers (e.g. `foo`) are allowed in patterns, but
// more complex ones (e.g. `Foo.bar` or `foo.bar.baz`) are not.
if module_name.is_empty() && parts.len() == 1 {
Ok((
MadeProgress,
Located {
region: loc_ident.region,
value: Pattern::Identifier(parts[0]),
},
state,
))
} else {
let malformed_str = if module_name.is_empty() {
parts.join(".")
} else {
format!("{}.{}", module_name, parts.join("."))
};
Ok((
MadeProgress,
Located {
region: loc_ident.region,
value: Pattern::Malformed(
String::from_str_in(&malformed_str, &arena).into_bump_str(),
),
},
state,
))
}
}
Ident::AccessorFunction(string) => Ok((
MadeProgress,
Located {
region: loc_ident.region,
value: Pattern::Malformed(string),
},
state,
)),
Ident::Malformed(malformed) => {
debug_assert!(!malformed.is_empty());
Err((MadeProgress, SyntaxError::InvalidPattern, state))
}
}
}
}
mod when {
use super::*;
use crate::ast::WhenBranch;