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|
use crate::ast::Field;
use crate::attr::Display;
use proc_macro2::TokenTree;
use quote::{format_ident, quote_spanned};
use std::collections::HashSet as Set;
use syn::ext::IdentExt;
use syn::parse::{ParseStream, Parser};
use syn::{Ident, Index, LitStr, Member, Result, Token};
impl Display<'_> {
// Transform `"error {var}"` to `"error {}", var`.
pub fn expand_shorthand(&mut self, fields: &[Field]) {
let raw_args = self.args.clone();
let mut named_args = explicit_named_args.parse2(raw_args).unwrap();
let fields: Set<Member> = fields.iter().map(|f| f.member.clone()).collect();
let span = self.fmt.span();
let fmt = self.fmt.value();
let mut read = fmt.as_str();
let mut out = String::new();
let mut args = self.args.clone();
let mut has_bonus_display = false;
let mut has_trailing_comma = false;
if let Some(TokenTree::Punct(punct)) = args.clone().into_iter().last() {
if punct.as_char() == ',' {
has_trailing_comma = true;
}
}
while let Some(brace) = read.find('{') {
out += &read[..brace + 1];
read = &read[brace + 1..];
if read.starts_with('{') {
out.push('{');
read = &read[1..];
continue;
}
let next = match read.chars().next() {
Some(next) => next,
None => return,
};
let member = match next {
'0'..='9' => {
let int = take_int(&mut read);
let member = match int.parse::<u32>() {
Ok(index) => Member::Unnamed(Index { index, span }),
Err(_) => return,
};
if !fields.contains(&member) {
out += ∫
continue;
}
member
}
'a'..='z' | 'A'..='Z' | '_' => {
let ident = take_ident(&mut read);
Member::Named(Ident::new(&ident, span))
}
_ => continue,
};
let local = match &member {
Member::Unnamed(index) => format_ident!("_{}", index),
Member::Named(ident) => ident.clone(),
};
let mut formatvar = local.clone();
if formatvar.to_string().starts_with('_') {
// Work around leading underscore being rejected by 1.40 and
// older compilers. https://github.com/rust-lang/rust/pull/66847
formatvar = format_ident!("field_{}", formatvar);
}
out += &formatvar.to_string();
if !named_args.insert(formatvar.clone()) {
// Already specified in the format argument list.
continue;
}
if !has_trailing_comma {
args.extend(quote_spanned!(span=> ,));
}
args.extend(quote_spanned!(span=> #formatvar = #local));
if read.starts_with('}') && fields.contains(&member) {
has_bonus_display = true;
args.extend(quote_spanned!(span=> .as_display()));
}
has_trailing_comma = false;
}
out += read;
self.fmt = LitStr::new(&out, self.fmt.span());
self.args = args;
self.has_bonus_display = has_bonus_display;
}
}
fn explicit_named_args(input: ParseStream) -> Result<Set<Ident>> {
let mut named_args = Set::new();
while !input.is_empty() {
if input.peek(Token![,]) && input.peek2(Ident::peek_any) && input.peek3(Token![=]) {
input.parse::<Token![,]>()?;
let ident: Ident = input.parse()?;
input.parse::<Token![=]>()?;
named_args.insert(ident);
} else {
input.parse::<TokenTree>()?;
}
}
Ok(named_args)
}
fn take_int(read: &mut &str) -> String {
let mut int = String::new();
for (i, ch) in read.char_indices() {
match ch {
'0'..='9' => int.push(ch),
_ => {
*read = &read[i..];
break;
}
}
}
int
}
fn take_ident(read: &mut &str) -> String {
let mut ident = String::new();
for (i, ch) in read.char_indices() {
match ch {
'a'..='z' | 'A'..='Z' | '0'..='9' | '_' => ident.push(ch),
_ => {
*read = &read[i..];
break;
}
}
}
ident
}
|
