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use crate::error::{Error, Result};
use crate::iter::Iter;
use proc_macro::{Delimiter, Group, Ident, Literal, Span, TokenTree};
pub fn parse_punct(iter: Iter, ch: char) -> Result<()> {
match iter.next() {
Some(TokenTree::Punct(ref punct)) if punct.as_char() == ch => Ok(()),
unexpected => {
let span = unexpected
.as_ref()
.map_or_else(Span::call_site, TokenTree::span);
Err(Error::new(span, format!("expected `{}`", ch)))
}
}
}
pub fn parse_optional_punct(iter: Iter, ch: char) -> Option<()> {
match iter.peek() {
Some(TokenTree::Punct(punct)) if punct.as_char() == ch => iter.next().map(drop),
_ => None,
}
}
pub fn parse_optional_keyword(iter: Iter, keyword: &str) -> Option<Span> {
match iter.peek() {
Some(TokenTree::Ident(ident)) if ident.to_string() == keyword => {
Some(iter.next().unwrap().span())
}
_ => None,
}
}
pub fn parse_literal(iter: Iter) -> Result<Literal> {
match iter.next() {
Some(TokenTree::Literal(literal)) => Ok(literal),
unexpected => {
let span = unexpected
.as_ref()
.map_or_else(Span::call_site, TokenTree::span);
Err(Error::new(span, "expected literal"))
}
}
}
pub fn parse_paren(introducer: &Ident, iter: Iter) -> Result<Group> {
match iter.peek() {
Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Parenthesis => {
match iter.next() {
Some(TokenTree::Group(group)) => Ok(group),
_ => unreachable!(),
}
}
Some(unexpected) => Err(Error::new(unexpected.span(), "expected `(`")),
None => Err(Error::new(
introducer.span(),
format!("expected `(` after `{}`", introducer),
)),
}
}
pub fn parse_optional_paren(iter: Iter) -> Option<Group> {
match iter.peek() {
Some(TokenTree::Group(group)) if group.delimiter() == Delimiter::Parenthesis => {
match iter.next() {
Some(TokenTree::Group(group)) => Some(group),
_ => unreachable!(),
}
}
_ => None,
}
}
pub fn parse_end(iter: Iter) -> Result<()> {
match iter.next() {
None => Ok(()),
Some(unexpected) => Err(Error::new(unexpected.span(), "unexpected token")),
}
}
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