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Use Pat::Rest to represent dots in PatSlice or PatTuple
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@dtolnay
dtolnay committed Jul 29, 2019
1 parent dab8097 commit a73e111
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Showing 2 changed files with 25 additions and 116 deletions.
139 changes: 24 additions & 115 deletions src/expr.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -854,11 +854,7 @@ ast_enum_of_structs! {
pub Slice(PatSlice {
pub attrs: Vec<Attribute>,
pub bracket_token: token::Bracket,
pub front: Punctuated<Pat, Token![,]>,
pub middle: Option<Box<Pat>>,
pub dot2_token: Option<Token![..]>,
pub comma_token: Option<Token![,]>,
pub back: Punctuated<Pat, Token![,]>,
pub elems: Punctuated<Pat, Token![,]>,
}),

/// A struct or struct variant pattern: `Variant { x, y, .. }`.
Expand All @@ -878,10 +874,7 @@ ast_enum_of_structs! {
pub Tuple(PatTuple {
pub attrs: Vec<Attribute>,
pub paren_token: token::Paren,
pub front: Punctuated<Pat, Token![,]>,
pub dot2_token: Option<Token![..]>,
pub comma_token: Option<Token![,]>,
pub back: Punctuated<Pat, Token![,]>,
pub elems: Punctuated<Pat, Token![,]>,
}),

/// A tuple struct or tuple variant pattern: `Variant(x, y, .., z)`.
Expand Down Expand Up @@ -2686,6 +2679,8 @@ pub mod parsing {
input.call(pat_reference).map(Pat::Reference)
} else if lookahead.peek(token::Bracket) {
input.call(pat_slice).map(Pat::Slice)
} else if lookahead.peek(Token![..]) {
input.call(pat_rest).map(Pat::Rest)
} else {
Err(lookahead.error())
}
Expand Down Expand Up @@ -2965,45 +2960,21 @@ pub mod parsing {
let content;
let paren_token = parenthesized!(content in input);

let mut front = Punctuated::new();
let mut dot2_token = None::<Token![..]>;
let mut comma_token = None::<Token![,]>;
loop {
if content.is_empty() {
break;
}
if content.peek(Token![..]) {
dot2_token = Some(content.parse()?);
comma_token = content.parse()?;
break;
}
let value: Pat = content.parse()?;
front.push_value(value);
if content.is_empty() {
break;
}
let punct = content.parse()?;
front.push_punct(punct);
}

let mut back = Punctuated::new();
let mut elems = Punctuated::new();
while !content.is_empty() {
let value: Pat = content.parse()?;
back.push_value(value);
elems.push_value(value);
if content.is_empty() {
break;
}
let punct = content.parse()?;
back.push_punct(punct);
elems.push_punct(punct);
}

Ok(PatTuple {
attrs: Vec::new(),
paren_token: paren_token,
front: front,
dot2_token: dot2_token,
comma_token: comma_token,
back: back,
elems: elems,
})
}

Expand Down Expand Up @@ -3072,54 +3043,29 @@ pub mod parsing {
let content;
let bracket_token = bracketed!(content in input);

let mut front = Punctuated::new();
let mut middle = None;
loop {
if content.is_empty() || content.peek(Token![..]) {
break;
}
let mut elems = Punctuated::new();
while !content.is_empty() {
let value: Pat = content.parse()?;
if content.peek(Token![..]) {
middle = Some(Box::new(value));
break;
}
front.push_value(value);
elems.push_value(value);
if content.is_empty() {
break;
}
let punct = content.parse()?;
front.push_punct(punct);
}

let dot2_token: Option<Token![..]> = content.parse()?;
let mut comma_token = None::<Token![,]>;
let mut back = Punctuated::new();
if dot2_token.is_some() {
comma_token = content.parse()?;
if comma_token.is_some() {
loop {
if content.is_empty() {
break;
}
let value: Pat = content.parse()?;
back.push_value(value);
if content.is_empty() {
break;
}
let punct = content.parse()?;
back.push_punct(punct);
}
}
elems.push_punct(punct);
}

Ok(PatSlice {
attrs: Vec::new(),
bracket_token: bracket_token,
front: front,
middle: middle,
dot2_token: dot2_token,
comma_token: comma_token,
back: back,
elems: elems,
})
}

#[cfg(feature = "full")]
fn pat_rest(input: ParseStream) -> Result<PatRest> {
Ok(PatRest {
attrs: Vec::new(),
dot2_token: input.parse()?,
})
}

Expand Down Expand Up @@ -3786,20 +3732,7 @@ mod printing {
impl ToTokens for PatTuple {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.paren_token.surround(tokens, |tokens| {
self.front.to_tokens(tokens);
if let Some(ref dot2_token) = self.dot2_token {
if !self.front.empty_or_trailing() {
// Ensure there is a comma before the .. token.
<Token![,]>::default().to_tokens(tokens);
}
dot2_token.to_tokens(tokens);
self.comma_token.to_tokens(tokens);
if self.comma_token.is_none() && !self.back.is_empty() {
// Ensure there is a comma after the .. token.
<Token![,]>::default().to_tokens(tokens);
}
}
self.back.to_tokens(tokens);
self.elems.to_tokens(tokens);
});
}
}
Expand Down Expand Up @@ -3851,32 +3784,8 @@ mod printing {
impl ToTokens for PatSlice {
fn to_tokens(&self, tokens: &mut TokenStream) {
self.bracket_token.surround(tokens, |tokens| {
self.front.to_tokens(tokens);

// If we need a comma before the middle or standalone .. token,
// then make sure it's present.
if !self.front.empty_or_trailing()
&& (self.middle.is_some() || self.dot2_token.is_some())
{
<Token![,]>::default().to_tokens(tokens);
}

// If we have an identifier, we always need a .. token.
if self.middle.is_some() {
self.middle.to_tokens(tokens);
TokensOrDefault(&self.dot2_token).to_tokens(tokens);
} else if self.dot2_token.is_some() {
self.dot2_token.to_tokens(tokens);
}

// Make sure we have a comma before the back half.
if !self.back.is_empty() {
TokensOrDefault(&self.comma_token).to_tokens(tokens);
self.back.to_tokens(tokens);
} else {
self.comma_token.to_tokens(tokens);
}
})
self.elems.to_tokens(tokens);
});
}
}

Expand Down
2 changes: 1 addition & 1 deletion tests/test_size.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -22,5 +22,5 @@ fn test_type_size() {

#[test]
fn test_pat_size() {
assert_eq!(mem::size_of::<Pat>(), 192);
assert_eq!(mem::size_of::<Pat>(), 144);
}

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