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|
use proc_macro::{TokenStream, TokenTree};
use proc_macro2::TokenStream as TS2;
use quote::quote;
pub(crate) fn flag(input: TokenStream) -> TokenStream {
let tokens: Vec<TokenTree> = input.into_iter().collect();
let args = split_at_commas(&tokens);
if args.is_empty() {
return quote! { compile_error!("flag! flaguires at least one argument") }.into();
}
let first = &args[0];
let rest = &args[1..];
// Validate: at most one char literal
let char_count = rest.iter().filter(|a| is_char_literal(a)).count();
if char_count > 1 {
return quote! { compile_error!("flag! only supports at most one short name") }.into();
}
// Extract short char and string aliases
let short_char: Option<char> = rest
.iter()
.find(|a| is_char_literal(a))
.and_then(|a| extract_char(a));
let aliases: Vec<String> = rest
.iter()
.filter(|a| is_string_literal(a))
.filter_map(|a| extract_string(a))
.collect();
// Parse first argument
// flag![name: Type] → name, with explicit type
// flag![Type] → positional type, no name
let colon_pos = first
.iter()
.position(|t| matches!(t, TokenTree::Punct(p) if p.as_char() == ':'));
let has_named_colon = colon_pos.is_some_and(|pos| pos > 0 && !is_double_colon(first, pos));
let first_slice = first.as_slice();
let (name, ty, is_named) = if has_named_colon {
let pos = colon_pos.unwrap();
// `name : Type`
(
Some(&first_slice[..pos]),
Some(&first_slice[pos + 1..]),
true,
)
} else {
// No `name:` prefix → the entire first argument is the type
(None, Some(first_slice), false)
};
// Build full names
let full_names: Vec<String> = match name {
Some(n) => {
let mut v = vec![join_idents(n)];
v.extend(aliases);
v
}
None => aliases,
};
let path: TS2 = {
let ty_ts: TS2 = ty
.map(|t| {
let ts: TokenStream = t.iter().cloned().collect();
TS2::from(ts)
})
.unwrap_or(TS2::new());
#[cfg(feature = "mingling_support")]
let import = quote! { ::mingling::picker::PickerFlag };
#[cfg(not(feature = "mingling_support"))]
let import = quote! { ::mingling_picker::PickerFlag };
if ty.is_some() {
quote! { #import::<#ty_ts> }
} else {
quote! { #import::<_> }
}
};
// full: &["name", "alias", ...] or &[]
let full_value: TS2 = if !full_names.is_empty() {
let strs: Vec<proc_macro2::Literal> = full_names
.iter()
.map(|s| proc_macro2::Literal::string(s))
.collect();
quote! { &[#(#strs),*] }
} else {
quote! { &[] }
};
// short: Some('c') or None
let short_value: TS2 = match short_char {
Some(c) => {
let lit = proc_macro2::Literal::character(c);
quote! { ::std::option::Option::Some(#lit) }
}
None => quote! { ::std::option::Option::None },
};
let positional_value: bool = !is_named;
let result = quote! {
#path {
full: #full_value,
short: #short_value,
positional: #positional_value,
internal_type: ::std::marker::PhantomData,
}
};
result.into()
}
fn split_at_commas(tokens: &[TokenTree]) -> Vec<Vec<TokenTree>> {
let mut result = vec![Vec::new()];
let mut depth = 0u32;
for t in tokens {
match t {
TokenTree::Group(_g) => {
depth += 1;
result.last_mut().unwrap().push(t.clone());
depth -= 1;
}
TokenTree::Punct(p) if p.as_char() == ',' && depth == 0 => {
result.push(Vec::new());
}
_ => result.last_mut().unwrap().push(t.clone()),
}
}
result
}
fn is_double_colon(tokens: &[TokenTree], pos: usize) -> bool {
pos > 0 && matches!(&tokens[pos - 1], TokenTree::Punct(p) if p.as_char() == ':')
}
fn is_char_literal(tokens: &[TokenTree]) -> bool {
tokens.len() == 1
&& matches!(&tokens[0], TokenTree::Literal(l) if {
let s = l.to_string();
s.starts_with('\'') && s.len() >= 3
})
}
fn is_string_literal(tokens: &[TokenTree]) -> bool {
tokens.len() == 1
&& matches!(&tokens[0], TokenTree::Literal(l) if {
l.to_string().starts_with('"')
})
}
fn extract_char(tokens: &[TokenTree]) -> Option<char> {
match &tokens[0] {
TokenTree::Literal(l) => {
let s = l.to_string();
let cs: Vec<char> = s.chars().collect();
if cs.len() >= 3 && cs[0] == '\'' && cs[cs.len() - 1] == '\'' {
let inner: String = cs[1..cs.len() - 1].iter().collect();
match inner.as_str() {
"n" => Some('\n'),
"t" => Some('\t'),
"r" => Some('\r'),
"0" => Some('\0'),
"\\\\" => Some('\\'),
"\\'" => Some('\''),
_ => inner.chars().next(),
}
} else {
None
}
}
_ => None,
}
}
fn extract_string(tokens: &[TokenTree]) -> Option<String> {
match &tokens[0] {
TokenTree::Literal(l) => {
let s = l.to_string();
let cs: Vec<char> = s.chars().collect();
if cs.len() >= 2 && cs[0] == '"' && cs[cs.len() - 1] == '"' {
Some(cs[1..cs.len() - 1].iter().collect())
} else {
None
}
}
_ => None,
}
}
fn join_idents(tokens: &[TokenTree]) -> String {
tokens
.iter()
.map(|t| match t {
TokenTree::Ident(id) => id.to_string(),
_ => String::new(),
})
.collect()
}
|
