pagetop/helpers/pagetop-macros/src/maud.rs

60 lines
2 KiB
Rust

// #![doc(html_root_url = "https://docs.rs/maud_macros/0.27.0")]
// TokenStream values are reference counted, and the mental overhead of tracking
// lifetimes outweighs the marginal gains from explicit borrowing
// #![allow(clippy::needless_pass_by_value)]
mod ast;
mod escape;
mod generate;
use ast::DiagnosticParse;
use proc_macro2::{Ident, Span, TokenStream};
use proc_macro2_diagnostics::Diagnostic;
use proc_macro_crate::{crate_name, FoundCrate};
use quote::quote;
use syn::parse::{ParseStream, Parser};
pub fn expand(input: TokenStream) -> TokenStream {
// Heuristic: the size of the resulting markup tends to correlate with the
// code size of the template itself
let size_hint = input.to_string().len();
let mut diagnostics = Vec::new();
let markups = match Parser::parse2(
|input: ParseStream| ast::Markups::diagnostic_parse(input, &mut diagnostics),
input,
) {
Ok(data) => data,
Err(err) => {
let err = err.to_compile_error();
let diag_tokens = diagnostics.into_iter().map(Diagnostic::emit_as_expr_tokens);
return quote! {{
#err
#(#diag_tokens)*
}};
}
};
let diag_tokens = diagnostics.into_iter().map(Diagnostic::emit_as_expr_tokens);
let output_ident = Ident::new("__maud_output", Span::mixed_site());
let stmts = generate::generate(markups, output_ident.clone());
let found_crate = crate_name("pagetop").expect("pagetop must be in Cargo.toml");
let crate_ident = match found_crate {
FoundCrate::Itself => Ident::new("pagetop", Span::call_site()),
FoundCrate::Name(ref name) => Ident::new(name, Span::call_site()),
};
let pre_escaped = quote! {
#crate_ident::html::PreEscaped(#output_ident)
};
quote! {{
extern crate alloc;
let mut #output_ident = alloc::string::String::with_capacity(#size_hint);
#stmts
#(#diag_tokens)*
#pre_escaped
}}
}