2019-05-21 23:30:36 -05:00
|
|
|
use crate::{TokenTree, Subtree, Leaf};
|
|
|
|
|
|
|
|
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
|
|
|
|
struct EntryId(usize);
|
|
|
|
|
|
|
|
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
|
|
|
|
struct EntryPtr(EntryId, usize);
|
|
|
|
|
|
|
|
/// Internal type which is used instead of `TokenTree` to represent a token tree
|
|
|
|
/// within a `TokenBuffer`.
|
|
|
|
#[derive(Debug)]
|
|
|
|
enum Entry {
|
|
|
|
// Mimicking types from proc-macro.
|
|
|
|
Subtree(Subtree, EntryId),
|
|
|
|
Leaf(Leaf),
|
|
|
|
// End entries contain a pointer to the entry from the containing
|
|
|
|
// token tree, or None if this is the outermost level.
|
|
|
|
End(Option<EntryPtr>),
|
|
|
|
}
|
|
|
|
|
|
|
|
/// A token tree buffer
|
|
|
|
/// The safe version of `syn` [`TokenBuffer`](https://github.com/dtolnay/syn/blob/6533607f91686545cb034d2838beea338d9d0742/src/buffer.rs#L41)
|
|
|
|
#[derive(Debug)]
|
|
|
|
pub struct TokenBuffer {
|
|
|
|
buffers: Vec<Box<[Entry]>>,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl TokenBuffer {
|
|
|
|
pub fn new(tokens: &[TokenTree]) -> TokenBuffer {
|
|
|
|
let mut buffers = vec![];
|
|
|
|
|
2019-05-23 08:05:22 -05:00
|
|
|
let idx = TokenBuffer::new_inner(tokens, &mut buffers, None);
|
2019-05-21 23:30:36 -05:00
|
|
|
assert_eq!(idx, 0);
|
|
|
|
|
|
|
|
TokenBuffer { buffers }
|
|
|
|
}
|
|
|
|
|
|
|
|
fn new_inner(
|
2019-05-23 08:05:22 -05:00
|
|
|
tokens: &[TokenTree],
|
2019-05-21 23:30:36 -05:00
|
|
|
buffers: &mut Vec<Box<[Entry]>>,
|
|
|
|
next: Option<EntryPtr>,
|
|
|
|
) -> usize {
|
|
|
|
let mut entries = vec![];
|
|
|
|
let mut children = vec![];
|
|
|
|
|
2019-05-23 08:05:22 -05:00
|
|
|
for (idx, tt) in tokens.iter().cloned().enumerate() {
|
2019-05-21 23:30:36 -05:00
|
|
|
match tt {
|
|
|
|
TokenTree::Leaf(leaf) => {
|
|
|
|
entries.push(Entry::Leaf(leaf));
|
|
|
|
}
|
|
|
|
TokenTree::Subtree(subtree) => {
|
|
|
|
entries.push(Entry::End(None));
|
|
|
|
children.push((idx, subtree));
|
|
|
|
}
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
entries.push(Entry::End(next));
|
|
|
|
let res = buffers.len();
|
|
|
|
buffers.push(entries.into_boxed_slice());
|
|
|
|
|
|
|
|
for (child_idx, subtree) in children {
|
|
|
|
let idx = TokenBuffer::new_inner(
|
2019-05-23 08:05:22 -05:00
|
|
|
&subtree.token_trees,
|
2019-05-21 23:30:36 -05:00
|
|
|
buffers,
|
|
|
|
Some(EntryPtr(EntryId(res), child_idx + 1)),
|
|
|
|
);
|
|
|
|
buffers[res].as_mut()[child_idx] = Entry::Subtree(subtree, EntryId(idx));
|
|
|
|
}
|
|
|
|
|
|
|
|
res
|
|
|
|
}
|
|
|
|
|
|
|
|
/// 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 {
|
|
|
|
Cursor::create(self, EntryPtr(EntryId(0), 0))
|
|
|
|
}
|
|
|
|
|
|
|
|
fn entry(&self, ptr: &EntryPtr) -> Option<&Entry> {
|
|
|
|
let id = ptr.0;
|
|
|
|
self.buffers[id.0].get(ptr.1)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// A safe version of `Cursor` from `syn` crate https://github.com/dtolnay/syn/blob/6533607f91686545cb034d2838beea338d9d0742/src/buffer.rs#L125
|
|
|
|
#[derive(Copy, Clone, Debug)]
|
|
|
|
pub struct Cursor<'a> {
|
|
|
|
buffer: &'a TokenBuffer,
|
|
|
|
ptr: EntryPtr,
|
|
|
|
}
|
|
|
|
|
|
|
|
impl<'a> PartialEq for Cursor<'a> {
|
|
|
|
fn eq(&self, other: &Cursor) -> bool {
|
|
|
|
self.ptr == other.ptr && std::ptr::eq(self.buffer, other.buffer)
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
impl<'a> Eq for Cursor<'a> {}
|
|
|
|
|
|
|
|
impl<'a> Cursor<'a> {
|
|
|
|
/// Check whether it is eof
|
|
|
|
pub fn eof(self) -> bool {
|
|
|
|
match self.buffer.entry(&self.ptr) {
|
|
|
|
None | Some(Entry::End(None)) => true,
|
|
|
|
_ => false,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// If the cursor is pointing at the end of a subtree, returns
|
|
|
|
/// the parent subtree
|
|
|
|
pub fn end(self) -> Option<(&'a Subtree)> {
|
|
|
|
match self.entry() {
|
|
|
|
Some(Entry::End(Some(ptr))) => {
|
|
|
|
let idx = ptr.1;
|
|
|
|
if let Some(Entry::Subtree(subtree, _)) =
|
|
|
|
self.buffer.entry(&EntryPtr(ptr.0, idx - 1))
|
|
|
|
{
|
|
|
|
return Some(subtree);
|
|
|
|
}
|
|
|
|
|
|
|
|
None
|
|
|
|
}
|
|
|
|
_ => None,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn entry(self) -> Option<(&'a Entry)> {
|
|
|
|
self.buffer.entry(&self.ptr)
|
|
|
|
}
|
|
|
|
|
|
|
|
/// If the cursor is pointing at a `Subtree`, returns
|
|
|
|
/// a cursor into that subtree
|
|
|
|
pub fn subtree(self) -> Option<Cursor<'a>> {
|
|
|
|
match self.entry() {
|
|
|
|
Some(Entry::Subtree(_, entry_id)) => {
|
|
|
|
Some(Cursor::create(self.buffer, EntryPtr(*entry_id, 0)))
|
|
|
|
}
|
|
|
|
_ => None,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// If the cursor is pointing at a `TokenTree`, returns it
|
|
|
|
pub fn token_tree(self) -> Option<(TokenTree)> {
|
|
|
|
match self.entry() {
|
|
|
|
Some(Entry::Leaf(leaf)) => Some(leaf.clone().into()),
|
|
|
|
Some(Entry::Subtree(subtree, _)) => Some(subtree.clone().into()),
|
|
|
|
Some(Entry::End(_)) => None,
|
|
|
|
None => None,
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
fn create(buffer: &'a TokenBuffer, ptr: EntryPtr) -> Cursor<'a> {
|
|
|
|
Cursor { buffer, ptr }
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Bump the cursor
|
|
|
|
pub fn bump(self) -> Cursor<'a> {
|
|
|
|
if let Some(Entry::End(exit)) = self.buffer.entry(&self.ptr) {
|
|
|
|
if let Some(exit) = exit {
|
|
|
|
Cursor::create(self.buffer, *exit)
|
|
|
|
} else {
|
|
|
|
self
|
|
|
|
}
|
|
|
|
} else {
|
|
|
|
Cursor::create(self.buffer, EntryPtr(self.ptr.0, self.ptr.1 + 1))
|
|
|
|
}
|
|
|
|
}
|
2019-05-27 10:33:23 -05:00
|
|
|
|
|
|
|
/// Bump the cursor, if it is a subtree, returns
|
|
|
|
/// a cursor into that subtree
|
|
|
|
pub fn bump_subtree(self) -> Cursor<'a> {
|
|
|
|
match self.entry() {
|
|
|
|
Some(Entry::Subtree(_, _)) => self.subtree().unwrap(),
|
|
|
|
_ => self.bump(),
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Check whether it is a top level
|
|
|
|
pub fn is_root(&self) -> bool {
|
|
|
|
let entry_id = self.ptr.0;
|
|
|
|
return entry_id.0 == 0;
|
|
|
|
}
|
2019-05-21 23:30:36 -05:00
|
|
|
}
|