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#![feature(proc_macro, proc_macro_lib)]
#[macro_use]
extern crate nom;
extern crate proc_macro;
#[macro_use]
extern crate quote;
extern crate syn;
use nom::IResult;
use proc_macro::TokenStream;
use std::fs::File;
use std::io::Read;
use std::path::{Path, PathBuf};
use std::str;
fn get_path_from_attrs(attrs: &Vec<syn::Attribute>) -> String {
for attr in attrs {
if attr.name() == "template" {
match attr.value {
syn::MetaItem::List(_, ref inner) => {
match inner[0] {
syn::NestedMetaItem::MetaItem(ref item) => {
match item {
&syn::MetaItem::NameValue(ref key, ref val) => {
assert_eq!(key.as_ref(), "path");
match val {
&syn::Lit::Str(ref s, _) => { return s.clone(); },
_ => panic!("template path must be a string"),
}
},
_ => panic!("template annotation must contain key/value pair"),
}
},
_ => panic!("template annotation must contain item"),
}
},
_ => panic!("template annotation must be of List type"),
}
}
}
panic!("template annotation not found");
}
fn get_template_source(tpl_file: &str) -> String {
let root = ::std::env::var("CARGO_MANIFEST_DIR").unwrap();
let mut path = PathBuf::from(root);
path.push("templates");
path.push(Path::new(tpl_file));
let mut f = File::open(path).unwrap();
let mut s = String::new();
f.read_to_string(&mut s).unwrap();
s
}
fn take_content(i: &[u8]) -> IResult<&[u8], &[u8]> {
if i.len() < 1 || i[0] == b'{' {
return IResult::Error(error_position!(nom::ErrorKind::TakeUntil, i));
}
for (j, c) in i.iter().enumerate() {
if *c == b'{' {
if i.len() < j + 2 {
return IResult::Done(&i[..0], &i[..]);
} else if i[j + 1] == '{' as u8 {
return IResult::Done(&i[j..], &i[..j]);
} else if i[j + 1] == '%' as u8 {
return IResult::Done(&i[j..], &i[..j]);
}
}
}
IResult::Done(&i[..0], &i[..])
}
named!(var_expr, delimited!(tag!("{{"), take_until!("}}"), tag!("}}")));
named!(parse_template< Vec<&[u8]> >, many1!(alt!(take_content | var_expr)));
#[proc_macro_derive(Template, attributes(template))]
pub fn derive_template(input: TokenStream) -> TokenStream {
let source = input.to_string();
let ast = syn::parse_macro_input(&source).unwrap();
let _ctx = match ast.body {
syn::Body::Struct(ref data) => data,
_ => panic!("#[derive(Template)] can only be used with structs"),
};
let name = &ast.ident;
let path = get_path_from_attrs(&ast.attrs);
let src = get_template_source(&path);
let root = match parse_template(src.as_bytes()) {
IResult::Done(_, res) => res,
_ => panic!("problems parsing template source"),
};
let mut code = String::new();
code.push_str("impl askama::Template for ");
code.push_str(name.as_ref());
code.push_str(" {\n");
code.push_str(" fn render(&self) -> String {\n");
code.push_str(" let mut buf = String::new();\n");
code.push_str(" buf.push_str(\"");
code.push_str(str::from_utf8(root[0]).unwrap());
code.push_str("\");\n");
code.push_str(" buf.push_str(&self.");
code.push_str(str::from_utf8(root[1]).unwrap());
code.push_str(");\n");
code.push_str(" buf.push_str(\"");
code.push_str(str::from_utf8(root[2]).unwrap());
code.push_str("\");\n");
code.push_str(" buf");
code.push_str(" }\n");
code.push_str("}\n\n");
code.parse().unwrap()
}
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