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