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|
//! TokenStream implementation used by sysroot ABI
use crate::tt::{self, TokenTree};
#[derive(Debug, Default, Clone)]
pub struct TokenStream {
pub token_trees: Vec<TokenTree>,
}
impl TokenStream {
pub fn new() -> Self {
TokenStream::default()
}
pub fn with_subtree(subtree: tt::Subtree) -> Self {
if subtree.delimiter.kind != tt::DelimiterKind::Invisible {
TokenStream { token_trees: vec![TokenTree::Subtree(subtree)] }
} else {
TokenStream { token_trees: subtree.token_trees }
}
}
pub fn into_subtree(self) -> tt::Subtree {
tt::Subtree { delimiter: tt::Delimiter::UNSPECIFIED, token_trees: self.token_trees }
}
pub fn is_empty(&self) -> bool {
self.token_trees.is_empty()
}
}
/// Creates a token stream containing a single token tree.
impl From<TokenTree> for TokenStream {
fn from(tree: TokenTree) -> TokenStream {
TokenStream { token_trees: vec![tree] }
}
}
/// Collects a number of token trees into a single stream.
impl FromIterator<TokenTree> for TokenStream {
fn from_iter<I: IntoIterator<Item = TokenTree>>(trees: I) -> Self {
trees.into_iter().map(TokenStream::from).collect()
}
}
/// A "flattening" operation on token streams, collects token trees
/// from multiple token streams into a single stream.
impl FromIterator<TokenStream> for TokenStream {
fn from_iter<I: IntoIterator<Item = TokenStream>>(streams: I) -> Self {
let mut builder = TokenStreamBuilder::new();
streams.into_iter().for_each(|stream| builder.push(stream));
builder.build()
}
}
impl Extend<TokenTree> for TokenStream {
fn extend<I: IntoIterator<Item = TokenTree>>(&mut self, trees: I) {
self.extend(trees.into_iter().map(TokenStream::from));
}
}
impl Extend<TokenStream> for TokenStream {
fn extend<I: IntoIterator<Item = TokenStream>>(&mut self, streams: I) {
for item in streams {
for tkn in item {
match tkn {
tt::TokenTree::Subtree(subtree)
if subtree.delimiter.kind == tt::DelimiterKind::Invisible =>
{
self.token_trees.extend(subtree.token_trees);
}
_ => {
self.token_trees.push(tkn);
}
}
}
}
}
}
pub struct TokenStreamBuilder {
acc: TokenStream,
}
/// Public implementation details for the `TokenStream` type, such as iterators.
pub mod token_stream {
use std::str::FromStr;
use super::{tt, TokenStream, TokenTree};
/// An iterator over `TokenStream`'s `TokenTree`s.
/// The iteration is "shallow", e.g., the iterator doesn't recurse into delimited groups,
/// and returns whole groups as token trees.
impl IntoIterator for TokenStream {
type Item = TokenTree;
type IntoIter = std::vec::IntoIter<TokenTree>;
fn into_iter(self) -> Self::IntoIter {
self.token_trees.into_iter()
}
}
type LexError = String;
/// Attempts to break the string into tokens and parse those tokens into a token stream.
/// May fail for a number of reasons, for example, if the string contains unbalanced delimiters
/// or characters not existing in the language.
/// All tokens in the parsed stream get `Span::call_site()` spans.
///
/// NOTE: some errors may cause panics instead of returning `LexError`. We reserve the right to
/// change these errors into `LexError`s later.
impl FromStr for TokenStream {
type Err = LexError;
fn from_str(src: &str) -> Result<TokenStream, LexError> {
let (subtree, _token_map) =
mbe::parse_to_token_tree(src).ok_or("Failed to parse from mbe")?;
let subtree = subtree_replace_token_ids_with_unspecified(subtree);
Ok(TokenStream::with_subtree(subtree))
}
}
impl ToString for TokenStream {
fn to_string(&self) -> String {
::tt::pretty(&self.token_trees)
}
}
fn subtree_replace_token_ids_with_unspecified(subtree: tt::Subtree) -> tt::Subtree {
tt::Subtree {
delimiter: tt::Delimiter {
open: tt::TokenId::UNSPECIFIED,
close: tt::TokenId::UNSPECIFIED,
..subtree.delimiter
},
token_trees: subtree
.token_trees
.into_iter()
.map(token_tree_replace_token_ids_with_unspecified)
.collect(),
}
}
fn token_tree_replace_token_ids_with_unspecified(tt: tt::TokenTree) -> tt::TokenTree {
match tt {
tt::TokenTree::Leaf(leaf) => {
tt::TokenTree::Leaf(leaf_replace_token_ids_with_unspecified(leaf))
}
tt::TokenTree::Subtree(subtree) => {
tt::TokenTree::Subtree(subtree_replace_token_ids_with_unspecified(subtree))
}
}
}
fn leaf_replace_token_ids_with_unspecified(leaf: tt::Leaf) -> tt::Leaf {
match leaf {
tt::Leaf::Literal(lit) => {
tt::Leaf::Literal(tt::Literal { span: tt::TokenId::unspecified(), ..lit })
}
tt::Leaf::Punct(punct) => {
tt::Leaf::Punct(tt::Punct { span: tt::TokenId::unspecified(), ..punct })
}
tt::Leaf::Ident(ident) => {
tt::Leaf::Ident(tt::Ident { span: tt::TokenId::unspecified(), ..ident })
}
}
}
}
impl TokenStreamBuilder {
pub(super) fn new() -> TokenStreamBuilder {
TokenStreamBuilder { acc: TokenStream::new() }
}
pub(super) fn push(&mut self, stream: TokenStream) {
self.acc.extend(stream.into_iter())
}
pub(super) fn build(self) -> TokenStream {
self.acc
}
}
|
