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// SPDX-License-Identifier: GPL-2.0
use proc_macro::{token_stream, Group, Punct, Spacing, TokenStream, TokenTree};
pub(crate) fn try_ident(it: &mut token_stream::IntoIter) -> Option<String> {
if let Some(TokenTree::Ident(ident)) = it.next() {
Some(ident.to_string())
} else {
None
}
}
pub(crate) fn try_literal(it: &mut token_stream::IntoIter) -> Option<String> {
if let Some(TokenTree::Literal(literal)) = it.next() {
Some(literal.to_string())
} else {
None
}
}
pub(crate) fn try_string(it: &mut token_stream::IntoIter) -> Option<String> {
try_literal(it).and_then(|string| {
if string.starts_with('\"') && string.ends_with('\"') {
let content = &string[1..string.len() - 1];
if content.contains('\\') {
panic!("Escape sequences in string literals not yet handled");
}
Some(content.to_string())
} else if string.starts_with("r\"") {
panic!("Raw string literals are not yet handled");
} else {
None
}
})
}
pub(crate) fn expect_ident(it: &mut token_stream::IntoIter) -> String {
try_ident(it).expect("Expected Ident")
}
pub(crate) fn expect_punct(it: &mut token_stream::IntoIter) -> char {
if let TokenTree::Punct(punct) = it.next().expect("Reached end of token stream for Punct") {
punct.as_char()
} else {
panic!("Expected Punct");
}
}
pub(crate) fn expect_string(it: &mut token_stream::IntoIter) -> String {
try_string(it).expect("Expected string")
}
pub(crate) fn expect_string_ascii(it: &mut token_stream::IntoIter) -> String {
let string = try_string(it).expect("Expected string");
assert!(string.is_ascii(), "Expected ASCII string");
string
}
pub(crate) fn expect_group(it: &mut token_stream::IntoIter) -> Group {
if let TokenTree::Group(group) = it.next().expect("Reached end of token stream for Group") {
group
} else {
panic!("Expected Group");
}
}
pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
if it.next().is_some() {
panic!("Expected end");
}
}
pub(crate) struct Generics {
pub(crate) impl_generics: Vec<TokenTree>,
pub(crate) ty_generics: Vec<TokenTree>,
}
/// Parses the given `TokenStream` into `Generics` and the rest.
///
/// The generics are not present in the rest, but a where clause might remain.
pub(crate) fn parse_generics(input: TokenStream) -> (Generics, Vec<TokenTree>) {
// `impl_generics`, the declared generics with their bounds.
let mut impl_generics = vec![];
// Only the names of the generics, without any bounds.
let mut ty_generics = vec![];
// Tokens not related to the generics e.g. the `where` token and definition.
let mut rest = vec![];
// The current level of `<`.
let mut nesting = 0;
let mut toks = input.into_iter();
// If we are at the beginning of a generic parameter.
let mut at_start = true;
for tt in &mut toks {
match tt.clone() {
TokenTree::Punct(p) if p.as_char() == '<' => {
if nesting >= 1 {
// This is inside of the generics and part of some bound.
impl_generics.push(tt);
}
nesting += 1;
}
TokenTree::Punct(p) if p.as_char() == '>' => {
// This is a parsing error, so we just end it here.
if nesting == 0 {
break;
} else {
nesting -= 1;
if nesting >= 1 {
// We are still inside of the generics and part of some bound.
impl_generics.push(tt);
}
if nesting == 0 {
break;
}
}
}
tt => {
if nesting == 1 {
// Here depending on the token, it might be a generic variable name.
match &tt {
// Ignore const.
TokenTree::Ident(i) if i.to_string() == "const" => {}
TokenTree::Ident(_) if at_start => {
ty_generics.push(tt.clone());
// We also already push the `,` token, this makes it easier to append
// generics.
ty_generics.push(TokenTree::Punct(Punct::new(',', Spacing::Alone)));
at_start = false;
}
TokenTree::Punct(p) if p.as_char() == ',' => at_start = true,
// Lifetimes begin with `'`.
TokenTree::Punct(p) if p.as_char() == '\'' && at_start => {
ty_generics.push(tt.clone());
}
_ => {}
}
}
if nesting >= 1 {
impl_generics.push(tt);
} else if nesting == 0 {
// If we haven't entered the generics yet, we still want to keep these tokens.
rest.push(tt);
}
}
}
}
rest.extend(toks);
(
Generics {
impl_generics,
ty_generics,
},
rest,
)
}
|
