| //@ run-pass |
| |
| #![allow(non_camel_case_types)] |
| // A test of the macro system. Can we do HTML literals? |
| |
| /* |
| |
| This is an HTML parser written as a macro. It's all CPS, and we have |
| to carry around a bunch of state. The arguments to macros all look like this: |
| |
| { tag_stack* # expr* # tokens } |
| |
| The stack keeps track of where we are in the tree. The expr is a list |
| of children of the current node. The tokens are everything that's |
| left. |
| |
| */ |
| use HTMLFragment::{tag, text}; |
| |
| macro_rules! html { |
| ( $($body:tt)* ) => ( |
| parse_node!( []; []; $($body)* ) |
| ) |
| } |
| |
| macro_rules! parse_node { |
| ( |
| [:$head:ident ($(:$head_nodes:expr),*) |
| $(:$tags:ident ($(:$tag_nodes:expr),*))*]; |
| [$(:$nodes:expr),*]; |
| </$tag:ident> $($rest:tt)* |
| ) => ( |
| parse_node!( |
| [$(: $tags ($(:$tag_nodes),*))*]; |
| [$(:$head_nodes,)* :tag(stringify!($head).to_string(), |
| vec![$($nodes),*])]; |
| $($rest)* |
| ) |
| ); |
| |
| ( |
| [$(:$tags:ident ($(:$tag_nodes:expr),*) )*]; |
| [$(:$nodes:expr),*]; |
| <$tag:ident> $($rest:tt)* |
| ) => ( |
| parse_node!( |
| [:$tag ($(:$nodes)*) $(: $tags ($(:$tag_nodes),*) )*]; |
| []; |
| $($rest)* |
| ) |
| ); |
| |
| ( |
| [$(:$tags:ident ($(:$tag_nodes:expr),*) )*]; |
| [$(:$nodes:expr),*]; |
| . $($rest:tt)* |
| ) => ( |
| parse_node!( |
| [$(: $tags ($(:$tag_nodes),*))*]; |
| [$(:$nodes,)* :text(".".to_string())]; |
| $($rest)* |
| ) |
| ); |
| |
| ( |
| [$(:$tags:ident ($(:$tag_nodes:expr),*) )*]; |
| [$(:$nodes:expr),*]; |
| $word:ident $($rest:tt)* |
| ) => ( |
| parse_node!( |
| [$(: $tags ($(:$tag_nodes),*))*]; |
| [$(:$nodes,)* :text(stringify!($word).to_string())]; |
| $($rest)* |
| ) |
| ); |
| |
| ( []; [:$e:expr]; ) => ( $e ); |
| } |
| |
| pub fn main() { |
| let _page = html! ( |
| <html> |
| <head><title>This is the title.</title></head> |
| <body> |
| <p>This is some text</p> |
| </body> |
| </html> |
| ); |
| } |
| |
| #[allow(dead_code)] |
| enum HTMLFragment { |
| tag(String, Vec<HTMLFragment> ), |
| text(String), |
| } |
