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Implement very basic template parser

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This commit is contained in:
Dirkjan Ochtman 2016-12-24 08:28:56 +01:00
parent df8b05d0a4
commit b83ad3582f
2 changed files with 47 additions and 9 deletions
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54
askama_codegen/src/lib.rs
View File

@ -7,10 +7,12 @@ extern crate proc_macro;
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 {
@ -51,6 +53,28 @@ fn get_template_source(tpl_file: &str) -> String {
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();
@ -65,14 +89,28 @@ pub fn derive_template(input: TokenStream) -> TokenStream {
let path = get_path_from_attrs(&ast.attrs);
let src = get_template_source(&path);
let (impl_generics, ty_generics, where_clause) = ast.generics.split_for_impl();
let expanded = quote! {
impl #impl_generics askama::Template for #name #ty_generics #where_clause {
fn render(&self) -> String {
#src.into()
}
}
let root = match parse_template(src.as_bytes()) {
IResult::Done(_, res) => res,
_ => panic!("problems parsing template source"),
};
expanded.parse().unwrap()
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()
}

2
askama_test/tests/simple.rs
View File

@ -15,5 +15,5 @@ struct TestTemplate {
#[test]
fn it_works() {
let s = TestTemplate { var: "foo".to_string() }.render();
assert_eq!(s, "hello world, foo");
assert_eq!(s, "hello world, foo\n");
}