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| </pre><pre class="rust"><code><span class="doccomment">//! A stably addressed token buffer supporting efficient traversal based on a</span> |
| <span class="doccomment">//! cheaply copyable cursor.</span> |
| <span class="doccomment">//!</span> |
| <span class="doccomment">//! *This module is available only if Syn is built with the `"parsing"` feature.*</span> |
| |
| <span class="comment">// This module is heavily commented as it contains most of the unsafe code in</span> |
| <span class="comment">// Syn, and caution should be used when editing it. The public-facing interface</span> |
| <span class="comment">// is 100% safe but the implementation is fragile internally.</span> |
| |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>( |
| <span class="ident">not</span>(<span class="ident">all</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"wasm32"</span>, <span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"unknown"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"wasi"</span>))), |
| <span class="ident">feature</span> <span class="op">=</span> <span class="string">"proc-macro"</span> |
| ))]</span> |
| <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::proc_macro</span> <span class="kw">as</span> <span class="ident">pm</span>; |
| <span class="kw">use</span> <span class="ident"><span class="kw">crate</span>::Lifetime</span>; |
| <span class="kw">use</span> <span class="ident">proc_macro2</span>::{<span class="ident">Delimiter</span>, <span class="ident">Group</span>, <span class="ident">Ident</span>, <span class="ident">Literal</span>, <span class="ident">Punct</span>, <span class="ident">Spacing</span>, <span class="ident">Span</span>, <span class="ident">TokenStream</span>, <span class="ident">TokenTree</span>}; |
| <span class="kw">use</span> <span class="ident">std::marker::PhantomData</span>; |
| <span class="kw">use</span> <span class="ident">std::ptr</span>; |
| <span class="kw">use</span> <span class="ident">std::slice</span>; |
| |
| <span class="doccomment">/// Internal type which is used instead of `TokenTree` to represent a token tree</span> |
| <span class="doccomment">/// within a `TokenBuffer`.</span> |
| <span class="kw">enum</span> <span class="ident">Entry</span> { |
| <span class="comment">// Mimicking types from proc-macro.</span> |
| <span class="ident">Group</span>(<span class="ident">Group</span>, <span class="ident">TokenBuffer</span>), |
| <span class="ident">Ident</span>(<span class="ident">Ident</span>), |
| <span class="ident">Punct</span>(<span class="ident">Punct</span>), |
| <span class="ident">Literal</span>(<span class="ident">Literal</span>), |
| <span class="comment">// End entries contain a raw pointer to the entry from the containing</span> |
| <span class="comment">// token tree, or null if this is the outermost level.</span> |
| <span class="ident">End</span>(<span class="kw-2">*const</span> <span class="ident">Entry</span>), |
| } |
| |
| <span class="doccomment">/// A buffer that can be efficiently traversed multiple times, unlike</span> |
| <span class="doccomment">/// `TokenStream` which requires a deep copy in order to traverse more than</span> |
| <span class="doccomment">/// once.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// *This type is available only if Syn is built with the `"parsing"` feature.*</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">TokenBuffer</span> { |
| <span class="comment">// NOTE: Do not implement clone on this - there are raw pointers inside</span> |
| <span class="comment">// these entries which will be messed up. Moving the `TokenBuffer` itself is</span> |
| <span class="comment">// safe as the data pointed to won't be moved.</span> |
| <span class="ident">ptr</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>, |
| <span class="ident">len</span>: <span class="ident">usize</span>, |
| } |
| |
| <span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">TokenBuffer</span> { |
| <span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) { |
| <span class="kw">unsafe</span> { |
| <span class="kw">let</span> <span class="ident">slice</span> <span class="op">=</span> <span class="ident">slice::from_raw_parts_mut</span>(<span class="self">self</span>.<span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*mut</span> <span class="ident">Entry</span>, <span class="self">self</span>.<span class="ident">len</span>); |
| <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">Box::from_raw</span>(<span class="ident">slice</span>); |
| } |
| } |
| } |
| |
| <span class="kw">impl</span> <span class="ident">TokenBuffer</span> { |
| <span class="comment">// NOTE: Do not mutate the Vec returned from this function once it returns;</span> |
| <span class="comment">// the address of its backing memory must remain stable.</span> |
| <span class="kw">fn</span> <span class="ident">inner_new</span>(<span class="ident">stream</span>: <span class="ident">TokenStream</span>, <span class="ident">up</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>) -> <span class="ident">TokenBuffer</span> { |
| <span class="comment">// Build up the entries list, recording the locations of any Groups</span> |
| <span class="comment">// in the list to be processed later.</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">entries</span> <span class="op">=</span> <span class="ident">Vec::new</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">groups</span> <span class="op">=</span> <span class="ident">Vec::new</span>(); |
| <span class="kw">for</span> <span class="ident">tt</span> <span class="kw">in</span> <span class="ident">stream</span> { |
| <span class="kw">match</span> <span class="ident">tt</span> { |
| <span class="ident">TokenTree::Ident</span>(<span class="ident">sym</span>) => { |
| <span class="ident">entries</span>.<span class="ident">push</span>(<span class="ident">Entry::Ident</span>(<span class="ident">sym</span>)); |
| } |
| <span class="ident">TokenTree::Punct</span>(<span class="ident">op</span>) => { |
| <span class="ident">entries</span>.<span class="ident">push</span>(<span class="ident">Entry::Punct</span>(<span class="ident">op</span>)); |
| } |
| <span class="ident">TokenTree::Literal</span>(<span class="ident">l</span>) => { |
| <span class="ident">entries</span>.<span class="ident">push</span>(<span class="ident">Entry::Literal</span>(<span class="ident">l</span>)); |
| } |
| <span class="ident">TokenTree::Group</span>(<span class="ident">g</span>) => { |
| <span class="comment">// Record the index of the interesting entry, and store an</span> |
| <span class="comment">// `End(null)` there temporarily.</span> |
| <span class="ident">groups</span>.<span class="ident">push</span>((<span class="ident">entries</span>.<span class="ident">len</span>(), <span class="ident">g</span>)); |
| <span class="ident">entries</span>.<span class="ident">push</span>(<span class="ident">Entry::End</span>(<span class="ident">ptr::null</span>())); |
| } |
| } |
| } |
| <span class="comment">// Add an `End` entry to the end with a reference to the enclosing token</span> |
| <span class="comment">// stream which was passed in.</span> |
| <span class="ident">entries</span>.<span class="ident">push</span>(<span class="ident">Entry::End</span>(<span class="ident">up</span>)); |
| |
| <span class="comment">// NOTE: This is done to ensure that we don't accidentally modify the</span> |
| <span class="comment">// length of the backing buffer. The backing buffer must remain at a</span> |
| <span class="comment">// constant address after this point, as we are going to store a raw</span> |
| <span class="comment">// pointer into it.</span> |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">entries</span> <span class="op">=</span> <span class="ident">entries</span>.<span class="ident">into_boxed_slice</span>(); |
| <span class="kw">for</span> (<span class="ident">idx</span>, <span class="ident">group</span>) <span class="kw">in</span> <span class="ident">groups</span> { |
| <span class="comment">// We know that this index refers to one of the temporary</span> |
| <span class="comment">// `End(null)` entries, and we know that the last entry is</span> |
| <span class="comment">// `End(up)`, so the next index is also valid.</span> |
| <span class="kw">let</span> <span class="ident">group_up</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">entries</span>.<span class="ident">as_ptr</span>().<span class="ident">add</span>(<span class="ident">idx</span> <span class="op">+</span> <span class="number">1</span>) }; |
| |
| <span class="comment">// The end entry stored at the end of this Entry::Group should</span> |
| <span class="comment">// point to the Entry which follows the Group in the list.</span> |
| <span class="kw">let</span> <span class="ident">inner</span> <span class="op">=</span> <span class="ident"><span class="self">Self</span>::inner_new</span>(<span class="ident">group</span>.<span class="ident">stream</span>(), <span class="ident">group_up</span>); |
| <span class="ident">entries</span>[<span class="ident">idx</span>] <span class="op">=</span> <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="ident">inner</span>); |
| } |
| |
| <span class="kw">let</span> <span class="ident">len</span> <span class="op">=</span> <span class="ident">entries</span>.<span class="ident">len</span>(); |
| <span class="kw">let</span> <span class="ident">ptr</span> <span class="op">=</span> <span class="ident">Box::into_raw</span>(<span class="ident">entries</span>); |
| <span class="ident">TokenBuffer</span> { |
| <span class="ident">ptr</span>: <span class="ident">ptr</span> <span class="kw">as</span> <span class="kw-2">*const</span> <span class="ident">Entry</span>, |
| <span class="ident">len</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Creates a `TokenBuffer` containing all the tokens from the input</span> |
| <span class="doccomment">/// `proc_macro::TokenStream`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// *This method is available only if Syn is built with both the `"parsing"` and</span> |
| <span class="doccomment">/// `"proc-macro"` features.*</span> |
| <span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">all</span>( |
| <span class="ident">not</span>(<span class="ident">all</span>(<span class="ident">target_arch</span> <span class="op">=</span> <span class="string">"wasm32"</span>, <span class="ident">any</span>(<span class="ident">target_os</span> <span class="op">=</span> <span class="string">"unknown"</span>, <span class="ident">target_os</span> <span class="op">=</span> <span class="string">"wasi"</span>))), |
| <span class="ident">feature</span> <span class="op">=</span> <span class="string">"proc-macro"</span> |
| ))]</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">stream</span>: <span class="ident">pm::TokenStream</span>) -> <span class="self">Self</span> { |
| <span class="ident"><span class="self">Self</span>::new2</span>(<span class="ident">stream</span>.<span class="ident">into</span>()) |
| } |
| |
| <span class="doccomment">/// Creates a `TokenBuffer` containing all the tokens from the input</span> |
| <span class="doccomment">/// `proc_macro2::TokenStream`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new2</span>(<span class="ident">stream</span>: <span class="ident">TokenStream</span>) -> <span class="self">Self</span> { |
| <span class="ident"><span class="self">Self</span>::inner_new</span>(<span class="ident">stream</span>, <span class="ident">ptr::null</span>()) |
| } |
| |
| <span class="doccomment">/// Creates a cursor referencing the first token in the buffer and able to</span> |
| <span class="doccomment">/// traverse until the end of the buffer.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">begin</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="ident">Cursor</span> { |
| <span class="kw">unsafe</span> { <span class="ident">Cursor::create</span>(<span class="self">self</span>.<span class="ident">ptr</span>, <span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">add</span>(<span class="self">self</span>.<span class="ident">len</span> <span class="op">-</span> <span class="number">1</span>)) } |
| } |
| } |
| |
| <span class="doccomment">/// A cheaply copyable cursor into a `TokenBuffer`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This cursor holds a shared reference into the immutable data which is used</span> |
| <span class="doccomment">/// internally to represent a `TokenStream`, and can be efficiently manipulated</span> |
| <span class="doccomment">/// and copied around.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// An empty `Cursor` can be created directly, or one may create a `TokenBuffer`</span> |
| <span class="doccomment">/// object and get a cursor to its first token with `begin()`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Two cursors are equal if they have the same location in the same input</span> |
| <span class="doccomment">/// stream, and have the same scope.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// *This type is available only if Syn is built with the `"parsing"` feature.*</span> |
| <span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> { |
| <span class="comment">// The current entry which the `Cursor` is pointing at.</span> |
| <span class="ident">ptr</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>, |
| <span class="comment">// This is the only `Entry::End(..)` object which this cursor is allowed to</span> |
| <span class="comment">// point at. All other `End` objects are skipped over in `Cursor::create`.</span> |
| <span class="ident">scope</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>, |
| <span class="comment">// Cursor is covariant in 'a. This field ensures that our pointers are still</span> |
| <span class="comment">// valid.</span> |
| <span class="ident">marker</span>: <span class="ident">PhantomData</span><span class="op"><</span><span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Entry</span><span class="op">></span>, |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> { |
| <span class="doccomment">/// Creates a cursor referencing a static empty TokenStream.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">empty</span>() -> <span class="self">Self</span> { |
| <span class="comment">// It's safe in this situation for us to put an `Entry` object in global</span> |
| <span class="comment">// storage, despite it not actually being safe to send across threads</span> |
| <span class="comment">// (`Ident` is a reference into a thread-local table). This is because</span> |
| <span class="comment">// this entry never includes a `Ident` object.</span> |
| <span class="comment">//</span> |
| <span class="comment">// This wrapper struct allows us to break the rules and put a `Sync`</span> |
| <span class="comment">// object in global storage.</span> |
| <span class="kw">struct</span> <span class="ident">UnsafeSyncEntry</span>(<span class="ident">Entry</span>); |
| <span class="kw">unsafe</span> <span class="kw">impl</span> <span class="ident">Sync</span> <span class="kw">for</span> <span class="ident">UnsafeSyncEntry</span> {} |
| <span class="kw">static</span> <span class="ident">EMPTY_ENTRY</span>: <span class="ident">UnsafeSyncEntry</span> <span class="op">=</span> <span class="ident">UnsafeSyncEntry</span>(<span class="ident">Entry::End</span>(<span class="number">0</span> <span class="kw">as</span> <span class="kw-2">*const</span> <span class="ident">Entry</span>)); |
| |
| <span class="ident">Cursor</span> { |
| <span class="ident">ptr</span>: <span class="kw-2">&</span><span class="ident">EMPTY_ENTRY</span>.<span class="number">0</span>, |
| <span class="ident">scope</span>: <span class="kw-2">&</span><span class="ident">EMPTY_ENTRY</span>.<span class="number">0</span>, |
| <span class="ident">marker</span>: <span class="ident">PhantomData</span>, |
| } |
| } |
| |
| <span class="doccomment">/// This create method intelligently exits non-explicitly-entered</span> |
| <span class="doccomment">/// `None`-delimited scopes when the cursor reaches the end of them,</span> |
| <span class="doccomment">/// allowing for them to be treated transparently.</span> |
| <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">create</span>(<span class="kw-2">mut</span> <span class="ident">ptr</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>, <span class="ident">scope</span>: <span class="kw-2">*const</span> <span class="ident">Entry</span>) -> <span class="self">Self</span> { |
| <span class="comment">// NOTE: If we're looking at a `End(..)`, we want to advance the cursor</span> |
| <span class="comment">// past it, unless `ptr == scope`, which means that we're at the edge of</span> |
| <span class="comment">// our cursor's scope. We should only have `ptr != scope` at the exit</span> |
| <span class="comment">// from None-delimited groups entered with `ignore_none`.</span> |
| <span class="kw">while</span> <span class="kw">let</span> <span class="ident">Entry::End</span>(<span class="ident">exit</span>) <span class="op">=</span> <span class="kw-2">*</span><span class="ident">ptr</span> { |
| <span class="kw">if</span> <span class="ident">ptr</span> <span class="op">==</span> <span class="ident">scope</span> { |
| <span class="kw">break</span>; |
| } |
| <span class="ident">ptr</span> <span class="op">=</span> <span class="ident">exit</span>; |
| } |
| |
| <span class="ident">Cursor</span> { |
| <span class="ident">ptr</span>, |
| <span class="ident">scope</span>, |
| <span class="ident">marker</span>: <span class="ident">PhantomData</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Get the current entry.</span> |
| <span class="kw">fn</span> <span class="ident">entry</span>(<span class="self">self</span>) -> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Entry</span> { |
| <span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">*</span><span class="self">self</span>.<span class="ident">ptr</span> } |
| } |
| |
| <span class="doccomment">/// Bump the cursor to point at the next token after the current one. This</span> |
| <span class="doccomment">/// is undefined behavior if the cursor is currently looking at an</span> |
| <span class="doccomment">/// `Entry::End`.</span> |
| <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">bump</span>(<span class="self">self</span>) -> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> { |
| <span class="ident">Cursor::create</span>(<span class="self">self</span>.<span class="ident">ptr</span>.<span class="ident">offset</span>(<span class="number">1</span>), <span class="self">self</span>.<span class="ident">scope</span>) |
| } |
| |
| <span class="doccomment">/// While the cursor is looking at a `None`-delimited group, move it to look</span> |
| <span class="doccomment">/// at the first token inside instead. If the group is empty, this will move</span> |
| <span class="doccomment">/// the cursor past the `None`-delimited group.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// WARNING: This mutates its argument.</span> |
| <span class="kw">fn</span> <span class="ident">ignore_none</span>(<span class="kw-2">&mut</span> <span class="self">self</span>) { |
| <span class="kw">while</span> <span class="kw">let</span> <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="ident">buf</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="kw">if</span> <span class="ident">group</span>.<span class="ident">delimiter</span>() <span class="op">==</span> <span class="ident">Delimiter::None</span> { |
| <span class="comment">// NOTE: We call `Cursor::create` here to make sure that</span> |
| <span class="comment">// situations where we should immediately exit the span after</span> |
| <span class="comment">// entering it are handled correctly.</span> |
| <span class="kw">unsafe</span> { |
| <span class="kw-2">*</span><span class="self">self</span> <span class="op">=</span> <span class="ident">Cursor::create</span>(<span class="ident">buf</span>.<span class="ident">ptr</span>, <span class="self">self</span>.<span class="ident">scope</span>); |
| } |
| } <span class="kw">else</span> { |
| <span class="kw">break</span>; |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Checks whether the cursor is currently pointing at the end of its valid</span> |
| <span class="doccomment">/// scope.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">eof</span>(<span class="self">self</span>) -> <span class="ident">bool</span> { |
| <span class="comment">// We're at eof if we're at the end of our scope.</span> |
| <span class="self">self</span>.<span class="ident">ptr</span> <span class="op">==</span> <span class="self">self</span>.<span class="ident">scope</span> |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `Group` with the given delimiter, returns</span> |
| <span class="doccomment">/// a cursor into that group and one pointing to the next `TokenTree`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">group</span>(<span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">delim</span>: <span class="ident">Delimiter</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>, <span class="ident">Span</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="comment">// If we're not trying to enter a none-delimited group, we want to</span> |
| <span class="comment">// ignore them. We have to make sure to _not_ ignore them when we want</span> |
| <span class="comment">// to enter them, of course. For obvious reasons.</span> |
| <span class="kw">if</span> <span class="ident">delim</span> <span class="op">!</span><span class="op">=</span> <span class="ident">Delimiter::None</span> { |
| <span class="self">self</span>.<span class="ident">ignore_none</span>(); |
| } |
| |
| <span class="kw">if</span> <span class="kw">let</span> <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="ident">buf</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="kw">if</span> <span class="ident">group</span>.<span class="ident">delimiter</span>() <span class="op">==</span> <span class="ident">delim</span> { |
| <span class="kw">return</span> <span class="prelude-val">Some</span>((<span class="ident">buf</span>.<span class="ident">begin</span>(), <span class="ident">group</span>.<span class="ident">span</span>(), <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() })); |
| } |
| } |
| |
| <span class="prelude-val">None</span> |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `Ident`, returns it along with a cursor</span> |
| <span class="doccomment">/// pointing at the next `TokenTree`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">ident</span>(<span class="kw-2">mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">Ident</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="self">self</span>.<span class="ident">ignore_none</span>(); |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Ident</span>(<span class="ident">ident</span>) => <span class="prelude-val">Some</span>((<span class="ident">ident</span>.<span class="ident">clone</span>(), <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() })), |
| <span class="kw">_</span> => <span class="prelude-val">None</span>, |
| } |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `Punct`, returns it along with a cursor</span> |
| <span class="doccomment">/// pointing at the next `TokenTree`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">punct</span>(<span class="kw-2">mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">Punct</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="self">self</span>.<span class="ident">ignore_none</span>(); |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Punct</span>(<span class="ident">op</span>) <span class="kw">if</span> <span class="ident">op</span>.<span class="ident">as_char</span>() <span class="op">!</span><span class="op">=</span> <span class="string">'\''</span> => <span class="prelude-val">Some</span>((<span class="ident">op</span>.<span class="ident">clone</span>(), <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() })), |
| <span class="kw">_</span> => <span class="prelude-val">None</span>, |
| } |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `Literal`, return it along with a cursor</span> |
| <span class="doccomment">/// pointing at the next `TokenTree`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">literal</span>(<span class="kw-2">mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">Literal</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="self">self</span>.<span class="ident">ignore_none</span>(); |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Literal</span>(<span class="ident">lit</span>) => <span class="prelude-val">Some</span>((<span class="ident">lit</span>.<span class="ident">clone</span>(), <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() })), |
| <span class="kw">_</span> => <span class="prelude-val">None</span>, |
| } |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `Lifetime`, returns it along with a</span> |
| <span class="doccomment">/// cursor pointing at the next `TokenTree`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">lifetime</span>(<span class="kw-2">mut</span> <span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">Lifetime</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="self">self</span>.<span class="ident">ignore_none</span>(); |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Punct</span>(<span class="ident">op</span>) <span class="kw">if</span> <span class="ident">op</span>.<span class="ident">as_char</span>() <span class="op">==</span> <span class="string">'\''</span> <span class="op">&&</span> <span class="ident">op</span>.<span class="ident">spacing</span>() <span class="op">==</span> <span class="ident">Spacing::Joint</span> => { |
| <span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() }; |
| <span class="kw">match</span> <span class="ident">next</span>.<span class="ident">ident</span>() { |
| <span class="prelude-val">Some</span>((<span class="ident">ident</span>, <span class="ident">rest</span>)) => { |
| <span class="kw">let</span> <span class="ident">lifetime</span> <span class="op">=</span> <span class="ident">Lifetime</span> { |
| <span class="ident">apostrophe</span>: <span class="ident">op</span>.<span class="ident">span</span>(), |
| <span class="ident">ident</span>, |
| }; |
| <span class="prelude-val">Some</span>((<span class="ident">lifetime</span>, <span class="ident">rest</span>)) |
| } |
| <span class="prelude-val">None</span> => <span class="prelude-val">None</span>, |
| } |
| } |
| <span class="kw">_</span> => <span class="prelude-val">None</span>, |
| } |
| } |
| |
| <span class="doccomment">/// Copies all remaining tokens visible from this cursor into a</span> |
| <span class="doccomment">/// `TokenStream`.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">token_stream</span>(<span class="self">self</span>) -> <span class="ident">TokenStream</span> { |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">tts</span> <span class="op">=</span> <span class="ident">Vec::new</span>(); |
| <span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">cursor</span> <span class="op">=</span> <span class="self">self</span>; |
| <span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>((<span class="ident">tt</span>, <span class="ident">rest</span>)) <span class="op">=</span> <span class="ident">cursor</span>.<span class="ident">token_tree</span>() { |
| <span class="ident">tts</span>.<span class="ident">push</span>(<span class="ident">tt</span>); |
| <span class="ident">cursor</span> <span class="op">=</span> <span class="ident">rest</span>; |
| } |
| <span class="ident">tts</span>.<span class="ident">into_iter</span>().<span class="ident">collect</span>() |
| } |
| |
| <span class="doccomment">/// If the cursor is pointing at a `TokenTree`, returns it along with a</span> |
| <span class="doccomment">/// cursor pointing at the next `TokenTree`.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// Returns `None` if the cursor has reached the end of its stream.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This method does not treat `None`-delimited groups as transparent, and</span> |
| <span class="doccomment">/// will return a `Group(None, ..)` if the cursor is looking at one.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">token_tree</span>(<span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span>(<span class="ident">TokenTree</span>, <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span>)<span class="op">></span> { |
| <span class="kw">let</span> <span class="ident">tree</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="kw">_</span>) => <span class="ident">group</span>.<span class="ident">clone</span>().<span class="ident">into</span>(), |
| <span class="ident">Entry::Literal</span>(<span class="ident">lit</span>) => <span class="ident">lit</span>.<span class="ident">clone</span>().<span class="ident">into</span>(), |
| <span class="ident">Entry::Ident</span>(<span class="ident">ident</span>) => <span class="ident">ident</span>.<span class="ident">clone</span>().<span class="ident">into</span>(), |
| <span class="ident">Entry::Punct</span>(<span class="ident">op</span>) => <span class="ident">op</span>.<span class="ident">clone</span>().<span class="ident">into</span>(), |
| <span class="ident">Entry::End</span>(..) => <span class="kw">return</span> <span class="prelude-val">None</span>, |
| }; |
| |
| <span class="prelude-val">Some</span>((<span class="ident">tree</span>, <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() })) |
| } |
| |
| <span class="doccomment">/// Returns the `Span` of the current token, or `Span::call_site()` if this</span> |
| <span class="doccomment">/// cursor points to eof.</span> |
| <span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">span</span>(<span class="self">self</span>) -> <span class="ident">Span</span> { |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="kw">_</span>) => <span class="ident">group</span>.<span class="ident">span</span>(), |
| <span class="ident">Entry::Literal</span>(<span class="ident">l</span>) => <span class="ident">l</span>.<span class="ident">span</span>(), |
| <span class="ident">Entry::Ident</span>(<span class="ident">t</span>) => <span class="ident">t</span>.<span class="ident">span</span>(), |
| <span class="ident">Entry::Punct</span>(<span class="ident">o</span>) => <span class="ident">o</span>.<span class="ident">span</span>(), |
| <span class="ident">Entry::End</span>(..) => <span class="ident">Span::call_site</span>(), |
| } |
| } |
| |
| <span class="doccomment">/// Skip over the next token without cloning it. Returns `None` if this</span> |
| <span class="doccomment">/// cursor points to eof.</span> |
| <span class="doccomment">///</span> |
| <span class="doccomment">/// This method treats `'lifetimes` as a single token.</span> |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">skip</span>(<span class="self">self</span>) -> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span><span class="op">></span> { |
| <span class="kw">match</span> <span class="self">self</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::End</span>(..) => <span class="prelude-val">None</span>, |
| |
| <span class="comment">// Treat lifetimes as a single tt for the purposes of 'skip'.</span> |
| <span class="ident">Entry::Punct</span>(<span class="ident">op</span>) <span class="kw">if</span> <span class="ident">op</span>.<span class="ident">as_char</span>() <span class="op">==</span> <span class="string">'\''</span> <span class="op">&&</span> <span class="ident">op</span>.<span class="ident">spacing</span>() <span class="op">==</span> <span class="ident">Spacing::Joint</span> => { |
| <span class="kw">let</span> <span class="ident">next</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() }; |
| <span class="kw">match</span> <span class="ident">next</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Ident</span>(<span class="kw">_</span>) => <span class="prelude-val">Some</span>(<span class="kw">unsafe</span> { <span class="ident">next</span>.<span class="ident">bump</span>() }), |
| <span class="kw">_</span> => <span class="prelude-val">Some</span>(<span class="ident">next</span>), |
| } |
| } |
| <span class="kw">_</span> => <span class="prelude-val">Some</span>(<span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">bump</span>() }), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Copy</span> <span class="kw">for</span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> {} |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> { |
| <span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="self">Self</span> { |
| <span class="kw-2">*</span><span class="self">self</span> |
| } |
| } |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">Eq</span> <span class="kw">for</span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> {} |
| |
| <span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> <span class="ident">PartialEq</span> <span class="kw">for</span> <span class="ident">Cursor</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> { |
| <span class="kw">fn</span> <span class="ident">eq</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">other</span>: <span class="kw-2">&</span><span class="self">Self</span>) -> <span class="ident">bool</span> { |
| <span class="kw">let</span> <span class="ident">Cursor</span> { <span class="ident">ptr</span>, <span class="ident">scope</span>, <span class="ident">marker</span> } <span class="op">=</span> <span class="self">self</span>; |
| <span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">marker</span>; |
| <span class="kw-2">*</span><span class="ident">ptr</span> <span class="op">==</span> <span class="ident">other</span>.<span class="ident">ptr</span> <span class="op">&&</span> <span class="kw-2">*</span><span class="ident">scope</span> <span class="op">==</span> <span class="ident">other</span>.<span class="ident">scope</span> |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">same_scope</span>(<span class="ident">a</span>: <span class="ident">Cursor</span>, <span class="ident">b</span>: <span class="ident">Cursor</span>) -> <span class="ident">bool</span> { |
| <span class="ident">a</span>.<span class="ident">scope</span> <span class="op">==</span> <span class="ident">b</span>.<span class="ident">scope</span> |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">open_span_of_group</span>(<span class="ident">cursor</span>: <span class="ident">Cursor</span>) -> <span class="ident">Span</span> { |
| <span class="kw">match</span> <span class="ident">cursor</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="kw">_</span>) => <span class="ident">group</span>.<span class="ident">span_open</span>(), |
| <span class="kw">_</span> => <span class="ident">cursor</span>.<span class="ident">span</span>(), |
| } |
| } |
| |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">close_span_of_group</span>(<span class="ident">cursor</span>: <span class="ident">Cursor</span>) -> <span class="ident">Span</span> { |
| <span class="kw">match</span> <span class="ident">cursor</span>.<span class="ident">entry</span>() { |
| <span class="ident">Entry::Group</span>(<span class="ident">group</span>, <span class="kw">_</span>) => <span class="ident">group</span>.<span class="ident">span_close</span>(), |
| <span class="kw">_</span> => <span class="ident">cursor</span>.<span class="ident">span</span>(), |
| } |
| } |
| </code></pre></div> |
| </section><section id="search" class="content hidden"></section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="syn" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.60.0-nightly (1bd4fdc94 2022-01-12)" ></div> |
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