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Avoid repeated get_span in quote_spanned #329

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Avoid repeated get_span in quote_spanned #329

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87 changes: 51 additions & 36 deletions src/lib.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -639,44 +639,59 @@ __quote_spanned![
__quote_spanned![
#[macro_export]
macro_rules! quote_spanned {
($span:expr=>) => {{
let _: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::__private::TokenStream::new()
}};

// Special case rule for a single tt, for performance.
($span:expr=> $tt:tt) => {{
let mut _s = $crate::__private::TokenStream::new();
let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::quote_token_spanned!{$tt _s _span}
_s
}};

// Special case rules for two tts, for performance.
($span:expr=> # $var:ident) => {{
let mut _s = $crate::__private::TokenStream::new();
let _: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::ToTokens::to_tokens(&$var, &mut _s);
_s
}};
($span:expr=> $tt1:tt $tt2:tt) => {{
let mut _s = $crate::__private::TokenStream::new();
($span:expr=>$($tt:tt)*) => {{
let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::quote_token_spanned!{$tt1 _s _span}
$crate::quote_token_spanned!{$tt2 _s _span}
_s
}};

// Rule for any other number of tokens.
($span:expr=> $($tt:tt)*) => {{
let mut _s = $crate::__private::TokenStream::new();
let _span: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::quote_each_token_spanned!{_s _span $($tt)*}
_s
$crate::quote_spanned_with_expanded_span!{_span => $($tt)*}
}};
}
];

// We want to ensure that `get_span` only gets called for the actual user invocation and not
// for recursive calls from groups, which will call this inner macro instead.
#[macro_export]
#[doc(hidden)]
macro_rules! quote_spanned_with_expanded_span {
($span:ident=>) => {
$crate::__private::TokenStream::new()
};

// Special case rule for a single tt, for performance.
($span:ident=> $tt:tt) => {
let mut _s = $crate::__private::TokenStream::new();
$crate::quote_token_spanned!{$tt _s $span}
_s
};

// Special case rules for two tts, for performance.
($span:ident=> # $var:ident) => {
let mut _s = $crate::__private::TokenStream::new();
let _: $crate::__private::Span = $crate::__private::get_span($span).__into_span();
$crate::ToTokens::to_tokens(&$var, &mut _s);
_s
};
($span:ident=> $tt1:tt $tt2:tt) => {
let mut _s = $crate::__private::TokenStream::new();
$crate::quote_token_spanned!{$tt1 _s $span}
$crate::quote_token_spanned!{$tt2 _s $span}
_s
};

// Rule for any other number of tokens.
($span:ident=> $($tt:tt)*) => {
let mut _s = $crate::__private::TokenStream::new();
$crate::quote_each_token_spanned!{_s $span $($tt)*}
_s
};
}

#[macro_export]
#[doc(hidden)]
macro_rules! quote_spanned_with_expanded_span_as_expr {
($($tt:tt)*) => {{
$crate::quote_spanned_with_expanded_span!{$($tt)*}
}};
}

// Extract the names of all #metavariables and pass them to the $call macro.
//
// in: pounded_var_names!(then!(...) a #b c #( #d )* #e)
Expand Down Expand Up @@ -1261,7 +1276,7 @@ macro_rules! quote_token_spanned {
&mut $tokens,
$span,
$crate::__private::Delimiter::Parenthesis,
$crate::quote_spanned!($span=> $($inner)*),
$crate::quote_spanned_with_expanded_span_as_expr!($span=> $($inner)*),
);
};

Expand All @@ -1270,7 +1285,7 @@ macro_rules! quote_token_spanned {
&mut $tokens,
$span,
$crate::__private::Delimiter::Bracket,
$crate::quote_spanned!($span=> $($inner)*),
$crate::quote_spanned_with_expanded_span_as_expr!($span=> $($inner)*),
);
};

Expand All @@ -1279,7 +1294,7 @@ macro_rules! quote_token_spanned {
&mut $tokens,
$span,
$crate::__private::Delimiter::Brace,
$crate::quote_spanned!($span=> $($inner)*),
$crate::quote_spanned_with_expanded_span_as_expr!($span=> $($inner)*),
);
};

Expand Down