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refactor in-parens parsing
This commit is contained in:
Folkert
parent
a1d72fd74d
commit
abd56c16b9
2 changed files with 190 additions and 88 deletions
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@ -32,7 +32,18 @@ pub fn expr<'a>(min_indent: u16) -> impl Parser<'a, Expr<'a>, SyntaxError<'a>> {
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fn loc_expr_in_parens<'a>(min_indent: u16) -> impl Parser<'a, Located<Expr<'a>>, SyntaxError<'a>> {
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specialize(
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|e, r, c| SyntaxError::Expr(EExpr::InParens(e, r, c)),
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loc_expr_in_parens_help(min_indent),
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move |arena, state| {
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let (_, loc_expr, state) = loc_expr_in_parens_help(min_indent).parse(arena, state)?;
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Ok((
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MadeProgress,
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Located {
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region: loc_expr.region,
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value: Expr::ParensAround(arena.alloc(loc_expr.value)),
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},
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state,
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))
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},
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)
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}
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@ -55,19 +66,53 @@ fn loc_expr_in_parens_help<'a>(
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)
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}
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fn loc_expr_in_parens_etc<'a, P>(
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min_indent: u16,
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args_parser: P,
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) -> impl Parser<'a, Located<Expr<'a>>, SyntaxError<'a>>
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where
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P: Parser<'a, Vec<'a, Located<Expr<'a>>>, SyntaxError<'a>> + Copy,
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{
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then(
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loc!(and!(
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loc_expr_in_parens(min_indent),
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optional(either!(
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// There may optionally be function args after the ')'
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// e.g. ((foo bar) baz)
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args_parser,
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// If there aren't any args, there may be a '=' or ':' after it.
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//
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// (It's a syntax error to write e.g. `foo bar =` - so if there
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// were any args, there is definitely no need to parse '=' or ':'!)
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//
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// Also, there may be a '.' for field access (e.g. `(foo).bar`),
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// but we only want to look for that if there weren't any args,
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// as if there were any args they'd have consumed it anyway
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// e.g. in `((foo bar) baz.blah)` the `.blah` will be consumed by the `baz` parser
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either!(
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one_or_more!(skip_first!(ascii_char(b'.'), lowercase_ident())),
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and!(space0(min_indent), equals_with_indent())
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)
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))
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)),
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move |arena, state, _progress, parsed| helper(arena, state, parsed, min_indent),
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)
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}
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type Extras<'a> = Located<(
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Located<Expr<'a>>,
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Option<
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Either<
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Vec<'a, Located<Expr<'a>>>,
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Either<Vec<'a, &'a str>, (&'a [CommentOrNewline<'a>], u16)>,
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>,
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>,
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)>;
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macro_rules! loc_parenthetical_expr {
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($min_indent:expr, $args_parser:expr) => {
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then(
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loc!(and!(
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map_with_arena!(
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loc_expr_in_parens($min_indent),
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|arena: &'a Bump, loc_expr: Located<Expr<'a>>| {
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Located {
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region: loc_expr.region,
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value: Expr::ParensAround(arena.alloc(loc_expr.value)),
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}
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}
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),
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loc!(and!( loc_expr_in_parens($min_indent),
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optional(either!(
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// There may optionally be function args after the ')'
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@ -88,87 +133,141 @@ macro_rules! loc_parenthetical_expr {
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)
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))
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)),
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move |arena, state, progress, loc_expr_with_extras: Located<(Located<Expr<'a>>, Option<Either<Vec<'a, Located<Expr<'a>>>, Either<Vec<'a, &'a str>, (&'a [CommentOrNewline<'a>], u16)>>>)> | {
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// We parse the parenthetical expression *and* the arguments after it
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// in one region, so that (for example) the region for Apply includes its args.
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let (loc_expr, opt_extras) = loc_expr_with_extras.value;
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match opt_extras {
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Some(Either::First(loc_args)) => {
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let mut allocated_args = Vec::with_capacity_in(loc_args.len(), arena);
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for loc_arg in loc_args {
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allocated_args.push(&*arena.alloc(loc_arg));
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}
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Ok((
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progress,
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Located {
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region: loc_expr_with_extras.region,
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value: Expr::Apply(
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arena.alloc(loc_expr),
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allocated_args.into_bump_slice(),
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CalledVia::Space,
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),
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},
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state,
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))
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}
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// '=' after optional spaces
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Some(Either::Second(Either::Second((spaces_before_equals, equals_indent)))) => {
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let region = loc_expr.region;
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// Re-parse the Expr as a Pattern.
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let pattern = match expr_to_pattern(arena, &loc_expr.value) {
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Ok(valid) => valid,
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Err(fail) => return Err((progress, fail, state)),
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};
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// Make sure we don't discard the spaces - might be comments in there!
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let value = if spaces_before_equals.is_empty() {
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pattern
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} else {
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Pattern::SpaceAfter(arena.alloc(pattern), spaces_before_equals)
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};
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let loc_first_pattern = Located { region, value };
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// Continue parsing the expression as a Def.
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let (p1, spaces_after_equals, state) = space0($min_indent).parse(arena, state)?;
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// Use loc_expr_with_extras because we want to include the opening '(' char.
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let def_start_col = loc_expr_with_extras.region.start_col;
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let (p2, parsed_expr, state) =
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parse_def_expr($min_indent, def_start_col, equals_indent, arena, state, loc_first_pattern, spaces_after_equals)?;
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Ok((progress.or(p1).or(p2), Located { value: parsed_expr, region }, state))
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}
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// '.' and a record field immediately after ')', no optional spaces
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Some(Either::Second(Either::First(fields))) => {
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let mut value = loc_expr.value;
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for field in fields {
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// Wrap the previous answer in the new one, so we end up
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// with a nested Expr. That way, `foo.bar.baz` gets represented
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// in the AST as if it had been written (foo.bar).baz all along.
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value = Expr::Access(arena.alloc(value), field);
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}
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Ok((
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progress,
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Located {
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region: loc_expr.region,
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value,
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},
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state,
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))
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}
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None => Ok((progress, loc_expr, state)),
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}
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},
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move |arena, state, _progress, parsed| helper(arena, state, parsed, $min_indent)
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)
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}
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}
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fn helper<'a>(
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arena: &'a Bump,
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state: State<'a>,
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loc_expr_with_extras: Extras<'a>,
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min_indent: u16,
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) -> ParseResult<'a, Located<Expr<'a>>, SyntaxError<'a>> {
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// We parse the parenthetical expression *and* the arguments after it
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// in one region, so that (for example) the region for Apply includes its args.
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let (loc_expr, opt_extras) = loc_expr_with_extras.value;
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match opt_extras {
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Some(Either::First(loc_args)) => Ok((
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MadeProgress,
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expr_in_parens_then_arguments(arena, loc_expr, loc_args, loc_expr_with_extras.region),
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state,
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)),
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Some(Either::Second(Either::Second((spaces_before_equals, equals_indent)))) => {
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// '=' after optional spaces
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expr_in_parens_then_equals(
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min_indent,
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loc_expr,
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spaces_before_equals,
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equals_indent,
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loc_expr_with_extras.region.start_col,
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)
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.parse(arena, state)
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}
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Some(Either::Second(Either::First(fields))) => {
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// '.' and a record field immediately after ')', no optional spaces
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Ok((
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MadeProgress,
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expr_in_parens_then_access(arena, loc_expr, fields),
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state,
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))
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}
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None => Ok((MadeProgress, loc_expr, state)),
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}
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}
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fn expr_in_parens_then_equals<'a>(
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min_indent: u16,
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loc_expr: Located<Expr<'a>>,
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spaces_before_equals: &'a [CommentOrNewline],
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equals_indent: u16,
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def_start_col: u16,
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) -> impl Parser<'a, Located<Expr<'a>>, SyntaxError<'a>> {
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move |arena, state| {
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let region = loc_expr.region;
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// Re-parse the Expr as a Pattern.
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let pattern = match expr_to_pattern(arena, &loc_expr.value) {
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Ok(valid) => valid,
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Err(fail) => return Err((MadeProgress, fail, state)),
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};
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// Make sure we don't discard the spaces - might be comments in there!
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let value = if spaces_before_equals.is_empty() {
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pattern
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} else {
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Pattern::SpaceAfter(arena.alloc(pattern), spaces_before_equals)
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};
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let loc_first_pattern = Located { region, value };
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// Continue parsing the expression as a Def.
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let (_, spaces_after_equals, state) = space0(min_indent).parse(arena, state)?;
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// Use loc_expr_with_extras because we want to include the opening '(' char.
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let (_, parsed_expr, state) = parse_def_expr(
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min_indent,
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def_start_col,
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equals_indent,
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arena,
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state,
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loc_first_pattern,
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spaces_after_equals,
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)?;
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Ok((
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MadeProgress,
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Located {
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value: parsed_expr,
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region,
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},
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state,
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))
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}
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}
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fn expr_in_parens_then_arguments<'a>(
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arena: &'a Bump,
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loc_expr: Located<Expr<'a>>,
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loc_args: Vec<'a, Located<Expr<'a>>>,
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region: Region,
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) -> Located<Expr<'a>> {
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let mut allocated_args = Vec::with_capacity_in(loc_args.len(), arena);
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for loc_arg in loc_args {
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allocated_args.push(&*arena.alloc(loc_arg));
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}
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Located {
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region,
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value: Expr::Apply(
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arena.alloc(loc_expr),
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allocated_args.into_bump_slice(),
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CalledVia::Space,
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),
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}
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}
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fn expr_in_parens_then_access<'a>(
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arena: &'a Bump,
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loc_expr: Located<Expr<'a>>,
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fields: Vec<'a, &'a str>,
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) -> Located<Expr<'a>> {
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let mut value = loc_expr.value;
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for field in fields {
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// Wrap the previous answer in the new one, so we end up
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// with a nested Expr. That way, `foo.bar.baz` gets represented
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// in the AST as if it had been written (foo.bar).baz all along.
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value = Expr::Access(arena.alloc(value), field);
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}
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Located {
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region: loc_expr.region,
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value,
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}
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}
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fn loc_parse_expr_body_without_operators<'a>(
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min_indent: u16,
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arena: &'a Bump,
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@ -376,6 +376,9 @@ pub enum EExpr<'a> {
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End(Row, Col),
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Space(BadInputError, Row, Col),
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Dot(Row, Col),
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Access(Row, Col),
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When(When<'a>, Row, Col),
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If(If<'a>, Row, Col),
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