From 2a41b2cd94582f7ab395a6e92d01f579bb2fc1a5 Mon Sep 17 00:00:00 2001
From: Pavan Kumar Sunkara <pavan.sss1991@gmail.com>
Date: Wed, 6 Mar 2024 21:09:30 +0000
Subject: [PATCH] Improve readability of the parser code
---
crates/parser/src/grammar.rs | 4 +-
crates/parser/src/grammar/expressions.rs | 14 +++----
crates/parser/src/grammar/expressions/atom.rs | 5 +--
crates/parser/src/grammar/generic_params.rs | 2 +-
crates/parser/src/grammar/items.rs | 40 +++++++------------
crates/parser/src/grammar/items/traits.rs | 6 +--
crates/parser/src/grammar/params.rs | 7 +---
crates/parser/src/grammar/patterns.rs | 8 +---
crates/parser/src/grammar/types.rs | 6 +--
crates/parser/src/parser.rs | 9 ++---
10 files changed, 38 insertions(+), 63 deletions(-)
diff --git a/crates/parser/src/grammar.rs b/crates/parser/src/grammar.rs
index 34715628f18..de8c3a2e08c 100644
--- a/crates/parser/src/grammar.rs
+++ b/crates/parser/src/grammar.rs
@@ -416,14 +416,12 @@ fn delimited(
if !parser(p) {
break;
}
- if !p.at(delim) {
+ if !p.eat(delim) {
if p.at_ts(first_set) {
p.error(format!("expected {:?}", delim));
} else {
break;
}
- } else {
- p.bump(delim);
}
}
p.expect(ket);
diff --git a/crates/parser/src/grammar/expressions.rs b/crates/parser/src/grammar/expressions.rs
index 6b660180f82..861fcedda2a 100644
--- a/crates/parser/src/grammar/expressions.rs
+++ b/crates/parser/src/grammar/expressions.rs
@@ -211,9 +211,8 @@ fn current_op(p: &Parser<'_>) -> (u8, SyntaxKind, Associativity) {
T![>] if p.at(T![>>]) => (9, T![>>], Left),
T![>] if p.at(T![>=]) => (5, T![>=], Left),
T![>] => (5, T![>], Left),
- T![=] if p.at(T![=>]) => NOT_AN_OP,
T![=] if p.at(T![==]) => (5, T![==], Left),
- T![=] => (1, T![=], Right),
+ T![=] if !p.at(T![=>]) => (1, T![=], Right),
T![<] if p.at(T![<=]) => (5, T![<=], Left),
T![<] if p.at(T![<<=]) => (1, T![<<=], Right),
T![<] if p.at(T![<<]) => (9, T![<<], Left),
@@ -247,7 +246,7 @@ fn current_op(p: &Parser<'_>) -> (u8, SyntaxKind, Associativity) {
fn expr_bp(
p: &mut Parser<'_>,
m: Option<Marker>,
- mut r: Restrictions,
+ r: Restrictions,
bp: u8,
) -> Option<(CompletedMarker, BlockLike)> {
let m = m.unwrap_or_else(|| {
@@ -295,10 +294,6 @@ fn expr_bp(
let m = lhs.precede(p);
p.bump(op);
- // test binop_resets_statementness
- // fn f() { v = {1}&2; }
- r = Restrictions { prefer_stmt: false, ..r };
-
if is_range {
// test postfix_range
// fn foo() {
@@ -319,6 +314,9 @@ fn expr_bp(
Associativity::Left => op_bp + 1,
Associativity::Right => op_bp,
};
+
+ // test binop_resets_statementness
+ // fn f() { v = {1}&2; }
expr_bp(p, None, Restrictions { prefer_stmt: false, ..r }, op_bp);
lhs = m.complete(p, if is_range { RANGE_EXPR } else { BIN_EXPR });
}
@@ -345,7 +343,7 @@ fn lhs(p: &mut Parser<'_>, r: Restrictions) -> Option<(CompletedMarker, BlockLik
T![&] => {
m = p.start();
p.bump(T![&]);
- if p.at_contextual_kw(T![raw]) && (p.nth_at(1, T![mut]) || p.nth_at(1, T![const])) {
+ if p.at_contextual_kw(T![raw]) && [T![mut], T![const]].contains(&p.nth(1)) {
p.bump_remap(T![raw]);
p.bump_any();
} else {
diff --git a/crates/parser/src/grammar/expressions/atom.rs b/crates/parser/src/grammar/expressions/atom.rs
index 48600641ad0..72848a1f2b7 100644
--- a/crates/parser/src/grammar/expressions/atom.rs
+++ b/crates/parser/src/grammar/expressions/atom.rs
@@ -147,7 +147,7 @@ pub(super) fn atom_expr(
T![async] if la == T![move] && p.nth(2) == T!['{'] => {
let m = p.start();
p.bump(T![async]);
- p.eat(T![move]);
+ p.bump(T![move]);
stmt_list(p);
m.complete(p, BLOCK_EXPR)
}
@@ -390,8 +390,7 @@ fn if_expr(p: &mut Parser<'_>) -> CompletedMarker {
p.bump(T![if]);
expr_no_struct(p);
block_expr(p);
- if p.at(T![else]) {
- p.bump(T![else]);
+ if p.eat(T![else]) {
if p.at(T![if]) {
if_expr(p);
} else {
diff --git a/crates/parser/src/grammar/generic_params.rs b/crates/parser/src/grammar/generic_params.rs
index 4498daf21a3..6c05abc0238 100644
--- a/crates/parser/src/grammar/generic_params.rs
+++ b/crates/parser/src/grammar/generic_params.rs
@@ -170,7 +170,7 @@ fn type_bound(p: &mut Parser<'_>) -> bool {
_ => (),
}
if paths::is_use_path_start(p) {
- types::path_type_(p, false);
+ types::path_type_bounds(p, false);
} else {
m.abandon(p);
return false;
diff --git a/crates/parser/src/grammar/items.rs b/crates/parser/src/grammar/items.rs
index 243a219525a..ee11571307c 100644
--- a/crates/parser/src/grammar/items.rs
+++ b/crates/parser/src/grammar/items.rs
@@ -156,27 +156,19 @@ pub(super) fn opt_item(p: &mut Parser<'_>, m: Marker) -> Result<(), Marker> {
// impl T for Foo {
// default async fn foo() {}
// }
- T![async] => {
- let mut maybe_fn = p.nth(2);
- let is_unsafe = if matches!(maybe_fn, T![unsafe]) {
- // test default_async_unsafe_fn
- // impl T for Foo {
- // default async unsafe fn foo() {}
- // }
- maybe_fn = p.nth(3);
- true
- } else {
- false
- };
+ T![async]
+ if p.nth_at(2, T![fn]) || (p.nth_at(2, T![unsafe]) && p.nth_at(3, T![fn])) =>
+ {
+ p.bump_remap(T![default]);
+ p.bump(T![async]);
- if matches!(maybe_fn, T![fn]) {
- p.bump_remap(T![default]);
- p.bump(T![async]);
- if is_unsafe {
- p.bump(T![unsafe]);
- }
- has_mods = true;
- }
+ // test default_async_unsafe_fn
+ // impl T for Foo {
+ // default async unsafe fn foo() {}
+ // }
+ p.eat(T![unsafe]);
+
+ has_mods = true;
}
_ => (),
}
@@ -419,11 +411,9 @@ fn fn_(p: &mut Parser<'_>, m: Marker) {
// fn foo<T>() where T: Copy {}
generic_params::opt_where_clause(p);
- if p.at(T![;]) {
- // test fn_decl
- // trait T { fn foo(); }
- p.bump(T![;]);
- } else {
+ // test fn_decl
+ // trait T { fn foo(); }
+ if !p.eat(T![;]) {
expressions::block_expr(p);
}
m.complete(p, FN);
diff --git a/crates/parser/src/grammar/items/traits.rs b/crates/parser/src/grammar/items/traits.rs
index a8a1ccb15e6..c215185d632 100644
--- a/crates/parser/src/grammar/items/traits.rs
+++ b/crates/parser/src/grammar/items/traits.rs
@@ -119,11 +119,11 @@ fn not_a_qualified_path(p: &Parser<'_>) -> bool {
// we disambiguate it in favor of generics (`impl<T> ::absolute::Path<T> { ... }`)
// because this is what almost always expected in practice, qualified paths in impls
// (`impl <Type>::AssocTy { ... }`) aren't even allowed by type checker at the moment.
- if p.nth(1) == T![#] || p.nth(1) == T![>] || p.nth(1) == T![const] {
+ if [T![#], T![>], T![const]].contains(&p.nth(1)) {
return true;
}
- (p.nth(1) == LIFETIME_IDENT || p.nth(1) == IDENT)
- && (p.nth(2) == T![>] || p.nth(2) == T![,] || p.nth(2) == T![:] || p.nth(2) == T![=])
+ ([LIFETIME_IDENT, IDENT].contains(&p.nth(1)))
+ && ([T![>], T![,], T![:], T![=]].contains(&p.nth(2)))
}
// test_err impl_type
diff --git a/crates/parser/src/grammar/params.rs b/crates/parser/src/grammar/params.rs
index 846da28cb01..c535267c165 100644
--- a/crates/parser/src/grammar/params.rs
+++ b/crates/parser/src/grammar/params.rs
@@ -76,19 +76,16 @@ fn list_(p: &mut Parser<'_>, flavor: Flavor) {
m.abandon(p);
if p.eat(T![,]) {
continue;
- } else {
- break;
}
+ break;
}
param(p, m, flavor);
- if !p.at(T![,]) {
+ if !p.eat(T![,]) {
if p.at_ts(PARAM_FIRST.union(ATTRIBUTE_FIRST)) {
p.error("expected `,`");
} else {
break;
}
- } else {
- p.bump(T![,]);
}
}
diff --git a/crates/parser/src/grammar/patterns.rs b/crates/parser/src/grammar/patterns.rs
index 50367423379..eff6b664049 100644
--- a/crates/parser/src/grammar/patterns.rs
+++ b/crates/parser/src/grammar/patterns.rs
@@ -255,9 +255,7 @@ fn is_literal_pat_start(p: &Parser<'_>) -> bool {
fn literal_pat(p: &mut Parser<'_>) -> CompletedMarker {
assert!(is_literal_pat_start(p));
let m = p.start();
- if p.at(T![-]) {
- p.bump(T![-]);
- }
+ p.eat(T![-]);
expressions::literal(p);
m.complete(p, LITERAL_PAT)
}
@@ -468,14 +466,12 @@ fn slice_pat(p: &mut Parser<'_>) -> CompletedMarker {
fn pat_list(p: &mut Parser<'_>, ket: SyntaxKind) {
while !p.at(EOF) && !p.at(ket) {
pattern_top(p);
- if !p.at(T![,]) {
+ if !p.eat(T![,]) {
if p.at_ts(PAT_TOP_FIRST) {
p.error(format!("expected {:?}, got {:?}", T![,], p.current()));
} else {
break;
}
- } else {
- p.bump(T![,]);
}
}
}
diff --git a/crates/parser/src/grammar/types.rs b/crates/parser/src/grammar/types.rs
index 96a6cdeaaff..18ec570cd56 100644
--- a/crates/parser/src/grammar/types.rs
+++ b/crates/parser/src/grammar/types.rs
@@ -48,7 +48,7 @@ fn type_with_bounds_cond(p: &mut Parser<'_>, allow_bounds: bool) {
T![impl] => impl_trait_type(p),
T![dyn] => dyn_trait_type(p),
// Some path types are not allowed to have bounds (no plus)
- T![<] => path_type_(p, allow_bounds),
+ T![<] => path_type_bounds(p, allow_bounds),
_ if paths::is_path_start(p) => path_or_macro_type_(p, allow_bounds),
LIFETIME_IDENT if p.nth_at(1, T![+]) => bare_dyn_trait_type(p),
_ => {
@@ -294,7 +294,7 @@ fn bare_dyn_trait_type(p: &mut Parser<'_>) {
// type C = self::Foo;
// type D = super::Foo;
pub(super) fn path_type(p: &mut Parser<'_>) {
- path_type_(p, true);
+ path_type_bounds(p, true);
}
// test macro_call_type
@@ -323,7 +323,7 @@ fn path_or_macro_type_(p: &mut Parser<'_>, allow_bounds: bool) {
}
}
-pub(super) fn path_type_(p: &mut Parser<'_>, allow_bounds: bool) {
+pub(super) fn path_type_bounds(p: &mut Parser<'_>, allow_bounds: bool) {
assert!(paths::is_path_start(p));
let m = p.start();
paths::type_path(p);
diff --git a/crates/parser/src/parser.rs b/crates/parser/src/parser.rs
index ef413c63754..051461243af 100644
--- a/crates/parser/src/parser.rs
+++ b/crates/parser/src/parser.rs
@@ -250,12 +250,9 @@ impl<'t> Parser<'t> {
/// Create an error node and consume the next token.
pub(crate) fn err_recover(&mut self, message: &str, recovery: TokenSet) {
- match self.current() {
- T!['{'] | T!['}'] => {
- self.error(message);
- return;
- }
- _ => (),
+ if matches!(self.current(), T!['{'] | T!['}']) {
+ self.error(message);
+ return;
}
if self.at_ts(recovery) {