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|
use super::parser::Parser;
use {SyntaxKind};
use tree::EOF;
use syntax_kinds::*;
// Items //
pub(crate) fn file(p: &mut Parser) {
node(p, FILE, |p| {
p.optional(SHEBANG);
inner_attributes(p);
many(p, |p| {
skip_to_first(
p, item_first, item,
"expected item",
)
});
})
}
fn item_first(p: &Parser) -> bool {
match p.current() {
STRUCT_KW | FN_KW => true,
_ => false,
}
}
fn item(p: &mut Parser) {
outer_attributes(p);
visibility(p);
node_if(p, STRUCT_KW, STRUCT_ITEM, struct_item)
|| node_if(p, FN_KW, FN_ITEM, fn_item);
}
fn struct_item(p: &mut Parser) {
p.expect(IDENT)
&& p.curly_block(|p| comma_list(p, EOF, struct_field));
}
fn struct_field(p: &mut Parser) -> bool {
node_if(p, IDENT, STRUCT_FIELD, |p| {
p.expect(COLON) && p.expect(IDENT);
})
}
fn fn_item(p: &mut Parser) {
p.expect(IDENT) && p.expect(L_PAREN) && p.expect(R_PAREN)
&& p.curly_block(|p| ());
}
// Paths, types, attributes, and stuff //
fn inner_attributes(p: &mut Parser) {
many(p, |p| attribute(p, true))
}
fn attribute(p: &mut Parser, inner: bool) -> bool {
let attr_start = inner && p.lookahead(&[POUND, EXCL, L_BRACK])
|| !inner && p.lookahead(&[POUND, L_BRACK]);
if !attr_start {
return false;
}
node(p, ATTR, |p| {
p.bump_n(if inner { 3 } else { 2 });
meta_item(p) && p.expect(R_BRACK);
});
true
}
fn meta_item(p: &mut Parser) -> bool {
node_if(p, IDENT, META_ITEM, |p| {
if p.eat(EQ) {
if !literal(p) {
p.error()
.message("expected literal")
.emit();
}
} else if p.eat(L_PAREN) {
comma_list(p, R_PAREN, meta_item_inner);
p.expect(R_PAREN);
}
})
}
fn meta_item_inner(p: &mut Parser) -> bool {
meta_item(p) || literal(p)
}
fn literal(p: &mut Parser) -> bool {
p.eat(INT_NUMBER) || p.eat(FLOAT_NUMBER)
}
fn outer_attributes(_: &mut Parser) {
}
fn visibility(_: &mut Parser) {
}
// Expressions //
// Error recovery and high-order utils //
fn node_if<F: FnOnce(&mut Parser)>(
p: &mut Parser,
first: SyntaxKind,
node_kind: SyntaxKind,
rest: F
) -> bool {
p.current() == first && { node(p, node_kind, |p| { p.bump(); rest(p); }); true }
}
fn node<F: FnOnce(&mut Parser)>(p: &mut Parser, node_kind: SyntaxKind, rest: F) {
p.start(node_kind);
rest(p);
p.finish();
}
fn many<F: Fn(&mut Parser) -> bool>(p: &mut Parser, f: F) {
while f(p) { }
}
fn comma_list<F: Fn(&mut Parser) -> bool>(p: &mut Parser, end: SyntaxKind, f: F) {
many(p, |p| {
if !f(p) || p.current() == end {
false
} else {
p.expect(COMMA);
true
}
})
}
fn skip_to_first<C, F>(p: &mut Parser, cond: C, f: F, message: &str) -> bool
where
C: Fn(&Parser) -> bool,
F: FnOnce(&mut Parser),
{
let mut skipped = false;
loop {
if cond(p) {
if skipped {
p.finish();
}
f(p);
return true;
}
if p.current() == EOF {
if skipped {
p.finish();
}
return false;
}
if !skipped {
p.start(ERROR);
p.error()
.message(message)
.emit();
}
p.bump();
skipped = true;
}
}
impl<'p> Parser<'p> {
pub(crate) fn expect(&mut self, kind: SyntaxKind) -> bool {
if self.current() == kind {
self.bump();
true
} else {
self.error()
.message(format!("expected {:?}", kind))
.emit();
false
}
}
fn optional(&mut self, kind: SyntaxKind) {
if self.current() == kind {
self.bump();
}
}
fn bump_n(&mut self, n: u8) {
for _ in 0..n {
self.bump();
}
}
fn eat(&mut self, kind: SyntaxKind) -> bool {
self.current() == kind && { self.bump(); true }
}
}
|
