rust/syn/buffer.rs

Source file repositories/reference/linux-study-clean/rust/syn/buffer.rs

File Facts

System
Linux kernel
Corpus path
rust/syn/buffer.rs
Extension
.rs
Size
16165 bytes
Lines
437
Domain
Rust Kernel Layer
Bucket
Rust API Membrane
Inferred role
Rust Kernel Layer: implementation source
Status
source implementation candidate

Why This File Exists

Rust-side wrappers and abstractions around kernel C APIs, ownership contracts, allocation, synchronization, and module integration.

Dependency Surface

Detected Declarations

Annotated Snippet

fn recursive_new(entries: &mut Vec<Entry>, stream: TokenStream) {
        for tt in stream {
            match tt {
                TokenTree::Ident(ident) => entries.push(Entry::Ident(ident)),
                TokenTree::Punct(punct) => entries.push(Entry::Punct(punct)),
                TokenTree::Literal(literal) => entries.push(Entry::Literal(literal)),
                TokenTree::Group(group) => {
                    let group_start_index = entries.len();
                    entries.push(Entry::End(0, 0)); // we replace this below
                    Self::recursive_new(entries, group.stream());
                    let group_end_index = entries.len();
                    let group_offset = group_end_index - group_start_index;
                    entries.push(Entry::End(
                        -(group_end_index as isize),
                        -(group_offset as isize),
                    ));
                    entries[group_start_index] = Entry::Group(group, group_offset);
                }
            }
        }
    }

    /// Creates a `TokenBuffer` containing all the tokens from the input
    /// `proc_macro::TokenStream`.
    #[cfg(feature = "proc-macro")]
    #[cfg_attr(docsrs, doc(cfg(feature = "proc-macro")))]
    pub fn new(stream: proc_macro::TokenStream) -> Self {
        Self::new2(stream.into())
    }

    /// Creates a `TokenBuffer` containing all the tokens from the input
    /// `proc_macro2::TokenStream`.
    pub fn new2(stream: TokenStream) -> Self {
        let mut entries = Vec::new();
        Self::recursive_new(&mut entries, stream);
        entries.push(Entry::End(-(entries.len() as isize), 0));
        Self {
            entries: entries.into_boxed_slice(),
        }
    }

    /// Creates a cursor referencing the first token in the buffer and able to
    /// traverse until the end of the buffer.
    pub fn begin(&self) -> Cursor {
        let ptr = self.entries.as_ptr();
        unsafe { Cursor::create(ptr, ptr.add(self.entries.len() - 1)) }
    }
}

/// A cheaply copyable cursor into a `TokenBuffer`.
///
/// This cursor holds a shared reference into the immutable data which is used
/// internally to represent a `TokenStream`, and can be efficiently manipulated
/// and copied around.
///
/// An empty `Cursor` can be created directly, or one may create a `TokenBuffer`
/// object and get a cursor to its first token with `begin()`.
pub struct Cursor<'a> {
    // The current entry which the `Cursor` is pointing at.
    ptr: *const Entry,
    // This is the only `Entry::End` object which this cursor is allowed to
    // point at. All other `End` objects are skipped over in `Cursor::create`.
    scope: *const Entry,
    // Cursor is covariant in 'a. This field ensures that our pointers are still
    // valid.
    marker: PhantomData<&'a Entry>,
}

impl<'a> Cursor<'a> {
    /// Creates a cursor referencing a static empty TokenStream.
    pub fn empty() -> Self {
        // It's safe in this situation for us to put an `Entry` object in global
        // storage, despite it not actually being safe to send across threads
        // (`Ident` is a reference into a thread-local table). This is because
        // this entry never includes a `Ident` object.
        //
        // This wrapper struct allows us to break the rules and put a `Sync`
        // object in global storage.
        struct UnsafeSyncEntry(Entry);
        unsafe impl Sync for UnsafeSyncEntry {}
        static EMPTY_ENTRY: UnsafeSyncEntry = UnsafeSyncEntry(Entry::End(0, 0));

        Cursor {
            ptr: &EMPTY_ENTRY.0,
            scope: &EMPTY_ENTRY.0,
            marker: PhantomData,
        }
    }

    /// This create method intelligently exits non-explicitly-entered

Annotation

Implementation Notes