src/test/run-pass/html-literals.rs

   1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 // A test of the macro system. Can we do HTML literals?
  12
  13 /*
  14
  15 This is an HTML parser written as a macro. It's all CPS, and we have
  16 to carry around a bunch of state. The arguments to macros all look like this:
  17
  18 { tag_stack* # expr* # tokens }
  19
  20 The stack keeps track of where we are in the tree. The expr is a list
  21 of children of the current node. The tokens are everything that's
  22 left.
  23
  24 */
  25 use HTMLFragment::{tag, text};
  26
  27 macro_rules! html {
  28     ( $($body:tt)* ) => (
  29         parse_node!( []; []; $($body)* )
  30     )
  31 }
  32
  33 macro_rules! parse_node {
  34     (
  35         [:$head:ident ($(:$head_nodes:expr),*)
  36          $(:$tags:ident ($(:$tag_nodes:expr),*))*];
  37         [$(:$nodes:expr),*];
  38         </$tag:ident> $($rest:tt)*
  39     ) => (
  40         parse_node!(
  41             [$(: $tags ($(:$tag_nodes),*))*];
  42             [$(:$head_nodes,)* :tag(stringify!($head).to_string(),
  43                                     vec![$($nodes),*])];
  44             $($rest)*
  45         )
  46     );
  47
  48     (
  49         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  50         [$(:$nodes:expr),*];
  51         <$tag:ident> $($rest:tt)*
  52     ) => (
  53         parse_node!(
  54             [:$tag ($(:$nodes)*) $(: $tags ($(:$tag_nodes),*) )*];
  55             [];
  56             $($rest)*
  57         )
  58     );
  59
  60     (
  61         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  62         [$(:$nodes:expr),*];
  63         . $($rest:tt)*
  64     ) => (
  65         parse_node!(
  66             [$(: $tags ($(:$tag_nodes),*))*];
  67             [$(:$nodes,)* :text(".".to_string())];
  68             $($rest)*
  69         )
  70     );
  71
  72     (
  73         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  74         [$(:$nodes:expr),*];
  75         $word:ident $($rest:tt)*
  76     ) => (
  77         parse_node!(
  78             [$(: $tags ($(:$tag_nodes),*))*];
  79             [$(:$nodes,)* :text(stringify!($word).to_string())];
  80             $($rest)*
  81         )
  82     );
  83
  84     ( []; [:$e:expr]; ) => ( $e );
  85 }
  86
  87 pub fn main() {
  88     let _page = html! (
  89         <html>
  90             <head><title>This is the title.</title></head>
  91             <body>
  92             <p>This is some text</p>
  93             </body>
  94         </html>
  95     );
  96 }
  97
  98 enum HTMLFragment {
  99     tag(String, Vec<HTMLFragment> ),
 100     text(String),
 101 }