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</pre><pre class="rust"><code><span class="kw">use </span><span class="kw">crate</span>::error::Result;
<span class="kw">use </span><span class="kw">crate</span>::segment::{<span class="self">self</span>, Segment};
<span class="kw">use </span>proc_macro::{Delimiter, Group, Spacing, Span, TokenStream, TokenTree};
<span class="kw">use </span>std::iter;
<span class="kw">use </span>std::mem;
<span class="kw">use </span>std::str::FromStr;
<span class="kw">pub fn </span>expand_attr(
attr: TokenStream,
span: Span,
contains_paste: <span class="kw-2">&mut </span>bool,
) -> <span class="prelude-ty">Result</span><TokenStream> {
<span class="kw">let </span><span class="kw-2">mut </span>tokens = attr.clone().into_iter();
<span class="kw">let </span><span class="kw-2">mut </span>leading_colons = <span class="number">0</span>; <span class="comment">// $(::)?
</span><span class="kw">let </span><span class="kw-2">mut </span>leading_path = <span class="number">0</span>; <span class="comment">// $($ident)::+
</span><span class="kw">let </span><span class="kw-2">mut </span>token;
<span class="kw">let </span>group = <span class="kw">loop </span>{
token = tokens.next();
<span class="kw">match </span>token {
<span class="comment">// colon after `$(:)?`
</span><span class="prelude-val">Some</span>(TokenTree::Punct(<span class="kw-2">ref </span>punct))
<span class="kw">if </span>punct.as_char() == <span class="string">':' </span>&& leading_colons < <span class="number">2 </span>&& leading_path == <span class="number">0 </span>=>
{
leading_colons += <span class="number">1</span>;
}
<span class="comment">// ident after `$(::)? $($ident ::)*`
</span><span class="prelude-val">Some</span>(TokenTree::Ident(<span class="kw">_</span>)) <span class="kw">if </span>leading_colons != <span class="number">1 </span>&& leading_path % <span class="number">3 </span>== <span class="number">0 </span>=> {
leading_path += <span class="number">1</span>;
}
<span class="comment">// colon after `$(::)? $($ident ::)* $ident $(:)?`
</span><span class="prelude-val">Some</span>(TokenTree::Punct(<span class="kw-2">ref </span>punct)) <span class="kw">if </span>punct.as_char() == <span class="string">':' </span>&& leading_path % <span class="number">3 </span>> <span class="number">0 </span>=> {
leading_path += <span class="number">1</span>;
}
<span class="comment">// eq+value after `$(::)? $($ident)::+`
</span><span class="prelude-val">Some</span>(TokenTree::Punct(<span class="kw-2">ref </span>punct))
<span class="kw">if </span>punct.as_char() == <span class="string">'=' </span>&& leading_path % <span class="number">3 </span>== <span class="number">1 </span>=>
{
<span class="kw">let </span><span class="kw-2">mut </span>count = <span class="number">0</span>;
<span class="kw">if </span>tokens.inspect(|<span class="kw">_</span>| count += <span class="number">1</span>).all(|tt| is_stringlike(<span class="kw-2">&</span>tt)) && count > <span class="number">1 </span>{
<span class="kw-2">*</span>contains_paste = <span class="bool-val">true</span>;
<span class="kw">let </span>leading = leading_colons + leading_path;
<span class="kw">return </span>do_paste_name_value_attr(attr, span, leading);
}
<span class="kw">return </span><span class="prelude-val">Ok</span>(attr);
}
<span class="comment">// parens after `$(::)? $($ident)::+`
</span><span class="prelude-val">Some</span>(TokenTree::Group(<span class="kw-2">ref </span>group))
<span class="kw">if </span>group.delimiter() == Delimiter::Parenthesis && leading_path % <span class="number">3 </span>== <span class="number">1 </span>=>
{
<span class="kw">break </span>group;
}
<span class="comment">// bail out
</span><span class="kw">_ </span>=> <span class="kw">return </span><span class="prelude-val">Ok</span>(attr),
}
};
<span class="comment">// There can't be anything else after the first group in a valid attribute.
</span><span class="kw">if </span>tokens.next().is_some() {
<span class="kw">return </span><span class="prelude-val">Ok</span>(attr);
}
<span class="kw">let </span><span class="kw-2">mut </span>group_contains_paste = <span class="bool-val">false</span>;
<span class="kw">let </span><span class="kw-2">mut </span>expanded = TokenStream::new();
<span class="kw">let </span><span class="kw-2">mut </span>nested_attr = TokenStream::new();
<span class="kw">for </span>tt <span class="kw">in </span>group.stream() {
<span class="kw">match </span><span class="kw-2">&</span>tt {
TokenTree::Punct(punct) <span class="kw">if </span>punct.as_char() == <span class="string">',' </span>=> {
expanded.extend(expand_attr(
nested_attr,
group.span(),
<span class="kw-2">&mut </span>group_contains_paste,
)<span class="question-mark">?</span>);
expanded.extend(iter::once(tt));
nested_attr = TokenStream::new();
}
<span class="kw">_ </span>=> nested_attr.extend(iter::once(tt)),
}
}
<span class="kw">if </span>!nested_attr.is_empty() {
expanded.extend(expand_attr(
nested_attr,
group.span(),
<span class="kw-2">&mut </span>group_contains_paste,
)<span class="question-mark">?</span>);
}
<span class="kw">if </span>group_contains_paste {
<span class="kw-2">*</span>contains_paste = <span class="bool-val">true</span>;
<span class="kw">let </span><span class="kw-2">mut </span>group = Group::new(Delimiter::Parenthesis, expanded);
group.set_span(span);
<span class="prelude-val">Ok</span>(attr
.into_iter()
<span class="comment">// Just keep the initial ident in `#[ident(...)]`.
</span>.take(leading_colons + leading_path)
.chain(iter::once(TokenTree::Group(group)))
.collect())
} <span class="kw">else </span>{
<span class="prelude-val">Ok</span>(attr)
}
}
<span class="kw">fn </span>do_paste_name_value_attr(attr: TokenStream, span: Span, leading: usize) -> <span class="prelude-ty">Result</span><TokenStream> {
<span class="kw">let </span><span class="kw-2">mut </span>expanded = TokenStream::new();
<span class="kw">let </span><span class="kw-2">mut </span>tokens = attr.into_iter().peekable();
expanded.extend(tokens.by_ref().take(leading + <span class="number">1</span>)); <span class="comment">// `doc =`
</span><span class="kw">let </span><span class="kw-2">mut </span>segments = segment::parse(<span class="kw-2">&mut </span>tokens)<span class="question-mark">?</span>;
<span class="kw">for </span>segment <span class="kw">in </span><span class="kw-2">&mut </span>segments {
<span class="kw">if let </span>Segment::String(string) = segment {
<span class="kw">if let </span><span class="prelude-val">Some</span>(open_quote) = string.value.find(<span class="string">'"'</span>) {
<span class="kw">if </span>open_quote == <span class="number">0 </span>{
string.value.truncate(string.value.len() - <span class="number">1</span>);
string.value.remove(<span class="number">0</span>);
} <span class="kw">else </span>{
<span class="kw">let </span>begin = open_quote + <span class="number">1</span>;
<span class="kw">let </span>end = string.value.rfind(<span class="string">'"'</span>).unwrap();
<span class="kw">let </span>raw_string = mem::replace(<span class="kw-2">&mut </span>string.value, String::new());
<span class="kw">for </span>ch <span class="kw">in </span>raw_string[begin..end].chars() {
string.value.extend(ch.escape_default());
}
}
}
}
}
<span class="kw">let </span><span class="kw-2">mut </span>lit = segment::paste(<span class="kw-2">&</span>segments)<span class="question-mark">?</span>;
lit.insert(<span class="number">0</span>, <span class="string">'"'</span>);
lit.push(<span class="string">'"'</span>);
<span class="kw">let </span><span class="kw-2">mut </span>lit = TokenStream::from_str(<span class="kw-2">&</span>lit)
.unwrap()
.into_iter()
.next()
.unwrap();
lit.set_span(span);
expanded.extend(iter::once(lit));
<span class="prelude-val">Ok</span>(expanded)
}
<span class="kw">fn </span>is_stringlike(token: <span class="kw-2">&</span>TokenTree) -> bool {
<span class="kw">match </span>token {
TokenTree::Ident(<span class="kw">_</span>) => <span class="bool-val">true</span>,
TokenTree::Literal(literal) => {
<span class="kw">let </span>repr = literal.to_string();
!repr.starts_with(<span class="string">'b'</span>) && !repr.starts_with(<span class="string">'\''</span>)
}
TokenTree::Group(group) => {
<span class="kw">if </span>group.delimiter() != Delimiter::None {
<span class="kw">return </span><span class="bool-val">false</span>;
}
<span class="kw">let </span><span class="kw-2">mut </span>inner = group.stream().into_iter();
<span class="kw">match </span>inner.next() {
<span class="prelude-val">Some</span>(first) => inner.next().is_none() && is_stringlike(<span class="kw-2">&</span>first),
<span class="prelude-val">None </span>=> <span class="bool-val">false</span>,
}
}
TokenTree::Punct(punct) => {
punct.as_char() == <span class="string">'\'' </span>|| punct.as_char() == <span class="string">':' </span>&& punct.spacing() == Spacing::Alone
}
}
}
</code></pre></div>
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