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use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, quote};
use yarte_hir::{Struct, HIR};
use crate::CodeGen;
pub struct FmtCodeGen<'a, T: CodeGen> {
codegen: T,
s: &'a Struct<'a>,
parent: Ident,
}
impl<'a, T: CodeGen> FmtCodeGen<'a, T> {
pub fn new<'n>(codegen: T, s: &'n Struct, parent: &'static str) -> FmtCodeGen<'n, T> {
FmtCodeGen {
codegen,
s,
parent: format_ident!("{}", parent),
}
}
#[inline]
fn template(&self, size_hint: usize, tokens: &mut TokenStream) {
tokens.extend(self.s.implement_head(
quote!(yarte::TemplateTrait),
"e!(
fn size_hint() -> usize {
#size_hint
}),
));
}
fn display(&mut self, nodes: Vec<HIR>, tokens: &mut TokenStream) -> usize {
let nodes = self.codegen.gen(nodes);
let size_hint = nodes.to_string().len();
let parent = &self.parent;
let func = quote!(
fn fmt(&self, _fmt: &mut std::fmt::Formatter) -> std::fmt::Result {
#[allow(unused_imports)]
use std::fmt::Display;
#[allow(unused_imports)]
use #parent::*;
#nodes
Ok(())
}
);
tokens.extend(self.s.implement_head(quote!(std::fmt::Display), &func));
size_hint
}
}
impl<'a, T: CodeGen> CodeGen for FmtCodeGen<'a, T> {
fn gen(&mut self, v: Vec<HIR>) -> TokenStream {
let mut tokens = TokenStream::new();
let size_hint = self.display(v, &mut tokens);
self.template(size_hint, &mut tokens);
tokens
}
}