use std::collections::HashSet as Set;
use std::iter::FromIterator;
use proc_macro2::{Delimiter, Group, TokenStream, TokenTree};
use quote::{format_ident, quote, quote_spanned, ToTokens};
use syn::ext::IdentExt;
use syn::parse::{ParseStream, Parser};
use syn::{braced, bracketed, parenthesized, Ident, Index, LitStr, Member, Result, Token};
#[derive(Clone)]
pub struct Display {
pub fmt: LitStr,
pub args: TokenStream,
pub has_bonus_display: bool,
}
impl ToTokens for Display {
fn to_tokens(&self, tokens: &mut TokenStream) {
let fmt = &self.fmt;
let args = &self.args;
tokens.extend(quote! {
write!(__formatter, #fmt #args)
});
}
}
impl Display {
pub fn expand_shorthand(&mut self, members: &Set<Member>) {
let raw_args = self.args.clone();
let mut named_args = explicit_named_args.parse2(raw_args).unwrap();
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 !members.contains(&member) {
out += ∫
continue;
}
member
}
'a'..='z' | 'A'..='Z' | '_' => {
let mut ident = take_ident(&mut read);
ident.set_span(span);
Member::Named(ident)
}
_ => 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("r#") {
formatvar = format_ident!("r_{}", formatvar);
}
if formatvar.to_string().starts_with('_') {
formatvar = format_ident!("field_{}", formatvar);
}
out += &formatvar.to_string();
if !named_args.insert(formatvar.clone()) {
continue;
}
if !has_trailing_comma {
args.extend(quote_spanned!(span=> ,));
}
args.extend(quote_spanned!(span=> #formatvar = #local));
if read.starts_with('}') && members.contains(&member) {
has_bonus_display = true;
}
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 = input.call(Ident::parse_any)?;
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) -> Ident {
let mut ident = String::new();
let raw = read.starts_with("r#");
if raw {
ident.push_str("r#");
*read = &read[2..];
}
for (i, ch) in read.char_indices() {
match ch {
'a'..='z' | 'A'..='Z' | '0'..='9' | '_' => ident.push(ch),
_ => {
*read = &read[i..];
break;
}
}
}
Ident::parse_any.parse_str(&ident).unwrap()
}
pub fn parse_token_expr(input: ParseStream, mut begin_expr: bool) -> Result<TokenStream> {
let mut tokens = Vec::new();
while !input.is_empty() {
if begin_expr && input.peek(Token![.]) {
if input.peek2(Ident) {
input.parse::<Token![.]>()?;
begin_expr = false;
continue;
}
if input.peek2(syn::LitInt) {
input.parse::<Token![.]>()?;
let int: Index = input.parse()?;
let ident = format_ident!("_{}", int.index, span = int.span);
tokens.push(TokenTree::Ident(ident));
begin_expr = false;
continue;
}
}
begin_expr = input.peek(Token![break])
|| input.peek(Token![continue])
|| input.peek(Token![if])
|| input.peek(Token![in])
|| input.peek(Token![match])
|| input.peek(Token![mut])
|| input.peek(Token![return])
|| input.peek(Token![while])
|| input.peek(Token![+])
|| input.peek(Token![&])
|| input.peek(Token![!])
|| input.peek(Token![^])
|| input.peek(Token![,])
|| input.peek(Token![/])
|| input.peek(Token![=])
|| input.peek(Token![>])
|| input.peek(Token![<])
|| input.peek(Token![|])
|| input.peek(Token![%])
|| input.peek(Token![;])
|| input.peek(Token![*])
|| input.peek(Token![-]);
let token: TokenTree = if input.peek(syn::token::Paren) {
let content;
let delimiter = parenthesized!(content in input);
let nested = parse_token_expr(&content, true)?;
let mut group = Group::new(Delimiter::Parenthesis, nested);
group.set_span(delimiter.span.join());
TokenTree::Group(group)
} else if input.peek(syn::token::Brace) {
let content;
let delimiter = braced!(content in input);
let nested = parse_token_expr(&content, true)?;
let mut group = Group::new(Delimiter::Brace, nested);
group.set_span(delimiter.span.join());
TokenTree::Group(group)
} else if input.peek(syn::token::Bracket) {
let content;
let delimiter = bracketed!(content in input);
let nested = parse_token_expr(&content, true)?;
let mut group = Group::new(Delimiter::Bracket, nested);
group.set_span(delimiter.span.join());
TokenTree::Group(group)
} else {
input.parse()?
};
tokens.push(token);
}
Ok(TokenStream::from_iter(tokens))
}