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use proc_macro::{token_stream, Group, 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_byte_string(it: &mut token_stream::IntoIter) -> Option<String> {
try_literal(it).and_then(|byte_string| {
if byte_string.starts_with("b\"") && byte_string.ends_with('\"') {
Some(byte_string[2..byte_string.len() - 1].to_string())
} 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_literal(it: &mut token_stream::IntoIter) -> String {
try_literal(it).expect("Expected Literal")
}
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_byte_string(it: &mut token_stream::IntoIter) -> String {
try_byte_string(it).expect("Expected byte string")
}
pub(crate) fn expect_end(it: &mut token_stream::IntoIter) {
if it.next().is_some() {
panic!("Expected end");
}
}
pub(crate) fn get_literal(it: &mut token_stream::IntoIter, expected_name: &str) -> String {
assert_eq!(expect_ident(it), expected_name);
assert_eq!(expect_punct(it), ':');
let literal = expect_literal(it);
assert_eq!(expect_punct(it), ',');
literal
}
pub(crate) fn get_byte_string(it: &mut token_stream::IntoIter, expected_name: &str) -> String {
assert_eq!(expect_ident(it), expected_name);
assert_eq!(expect_punct(it), ':');
let byte_string = expect_byte_string(it);
assert_eq!(expect_punct(it), ',');
byte_string
}
