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
main()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 }
95