src/test/ui/html-literals.rs

   1 // run-pass
   2
   3 #![allow(non_camel_case_types)]
   4 // A test of the macro system. Can we do HTML literals?
   5
   6 /*
   7
   8 This is an HTML parser written as a macro. It's all CPS, and we have
   9 to carry around a bunch of state. The arguments to macros all look like this:
  10
  11 { tag_stack* # expr* # tokens }
  12
  13 The stack keeps track of where we are in the tree. The expr is a list
  14 of children of the current node. The tokens are everything that's
  15 left.
  16
  17 */
  18 use HTMLFragment::{tag, text};
  19
  20 macro_rules! html {
  21     ( $($body:tt)* ) => (
  22         parse_node!( []; []; $($body)* )
  23     )
  24 }
  25
  26 macro_rules! parse_node {
  27     (
  28         [:$head:ident ($(:$head_nodes:expr),*)
  29          $(:$tags:ident ($(:$tag_nodes:expr),*))*];
  30         [$(:$nodes:expr),*];
  31         </$tag:ident> $($rest:tt)*
  32     ) => (
  33         parse_node!(
  34             [$(: $tags ($(:$tag_nodes),*))*];
  35             [$(:$head_nodes,)* :tag(stringify!($head).to_string(),
  36                                     vec![$($nodes),*])];
  37             $($rest)*
  38         )
  39     );
  40
  41     (
  42         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  43         [$(:$nodes:expr),*];
  44         <$tag:ident> $($rest:tt)*
  45     ) => (
  46         parse_node!(
  47             [:$tag ($(:$nodes)*) $(: $tags ($(:$tag_nodes),*) )*];
  48             [];
  49             $($rest)*
  50         )
  51     );
  52
  53     (
  54         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  55         [$(:$nodes:expr),*];
  56         . $($rest:tt)*
  57     ) => (
  58         parse_node!(
  59             [$(: $tags ($(:$tag_nodes),*))*];
  60             [$(:$nodes,)* :text(".".to_string())];
  61             $($rest)*
  62         )
  63     );
  64
  65     (
  66         [$(:$tags:ident ($(:$tag_nodes:expr),*) )*];
  67         [$(:$nodes:expr),*];
  68         $word:ident $($rest:tt)*
  69     ) => (
  70         parse_node!(
  71             [$(: $tags ($(:$tag_nodes),*))*];
  72             [$(:$nodes,)* :text(stringify!($word).to_string())];
  73             $($rest)*
  74         )
  75     );
  76
  77     ( []; [:$e:expr]; ) => ( $e );
  78 }
  79
  80 pub fn main() {
  81     let _page = html! (
  82         <html>
  83             <head><title>This is the title.</title></head>
  84             <body>
  85             <p>This is some text</p>
  86             </body>
  87         </html>
  88     );
  89 }
  90
  91 enum HTMLFragment {
  92     tag(String, Vec<HTMLFragment> ),
  93     text(String),
  94 }