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Remove useless allocations in macro_rules follow logic. #61646

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Jun 9, 2019
Merged

Remove useless allocations in macro_rules follow logic. #61646

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30 changes: 15 additions & 15 deletions src/libsyntax/ext/tt/macro_rules.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -909,7 +909,7 @@ fn check_matcher_core(sess: &ParseSess,
continue 'each_last;
}
IsInFollow::Yes => {}
IsInFollow::No(ref possible) => {
IsInFollow::No(possible) => {
let may_be = if last.tokens.len() == 1 &&
suffix_first.tokens.len() == 1
{
Expand All @@ -933,7 +933,7 @@ fn check_matcher_core(sess: &ParseSess,
format!("not allowed after `{}` fragments", frag_spec),
);
let msg = "allowed there are: ";
match &possible[..] {
match possible {
&[] => {}
&[t] => {
err.note(&format!(
Expand Down Expand Up @@ -997,7 +997,7 @@ fn frag_can_be_followed_by_any(frag: &str) -> bool {

enum IsInFollow {
Yes,
No(Vec<&'static str>),
No(&'static [&'static str]),
Invalid(String, &'static str),
}

Expand Down Expand Up @@ -1029,28 +1029,28 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> IsInFollow {
IsInFollow::Yes
},
"stmt" | "expr" => {
let tokens = vec!["`=>`", "`,`", "`;`"];
const TOKENS: &[&str] = &["`=>`", "`,`", "`;`"];
match tok {
TokenTree::Token(token) => match token.kind {
FatArrow | Comma | Semi => IsInFollow::Yes,
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
},
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
}
},
"pat" => {
let tokens = vec!["`=>`", "`,`", "`=`", "`|`", "`if`", "`in`"];
const TOKENS: &[&str] = &["`=>`", "`,`", "`=`", "`|`", "`if`", "`in`"];
match tok {
TokenTree::Token(token) => match token.kind {
FatArrow | Comma | Eq | BinOp(token::Or) => IsInFollow::Yes,
Ident(name, false) if name == kw::If || name == kw::In => IsInFollow::Yes,
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
},
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
}
},
"path" | "ty" => {
let tokens = vec![
const TOKENS: &[&str] = &[
"`{`", "`[`", "`=>`", "`,`", "`>`","`=`", "`:`", "`;`", "`|`", "`as`",
"`where`",
];
Expand All @@ -1062,11 +1062,11 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> IsInFollow {
BinOp(token::Or) => IsInFollow::Yes,
Ident(name, false) if name == kw::As ||
name == kw::Where => IsInFollow::Yes,
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
},
TokenTree::MetaVarDecl(_, _, frag) if frag.name == sym::block =>
IsInFollow::Yes,
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
}
},
"ident" | "lifetime" => {
Expand All @@ -1084,22 +1084,22 @@ fn is_in_follow(tok: &quoted::TokenTree, frag: &str) -> IsInFollow {
},
"vis" => {
// Explicitly disallow `priv`, on the off chance it comes back.
let tokens = vec!["`,`", "an ident", "a type"];
const TOKENS: &[&str] = &["`,`", "an ident", "a type"];
match tok {
TokenTree::Token(token) => match token.kind {
Comma => IsInFollow::Yes,
Ident(name, is_raw) if is_raw || name != kw::Priv => IsInFollow::Yes,
_ => if token.can_begin_type() {
IsInFollow::Yes
} else {
IsInFollow::No(tokens)
IsInFollow::No(TOKENS)
}
},
TokenTree::MetaVarDecl(_, _, frag) if frag.name == sym::ident
|| frag.name == sym::ty
|| frag.name == sym::path =>
IsInFollow::Yes,
_ => IsInFollow::No(tokens),
_ => IsInFollow::No(TOKENS),
}
},
"" => IsInFollow::Yes, // kw::Invalid
Expand Down