ezno_ast_generator/
generator.rs

1use proc_macro::{token_stream, Delimiter, Spacing, TokenStream, TokenTree};
2use proc_macro2::Span;
3use quote::{format_ident, quote};
4
5/// Used for generating ezno_parser::ASTNodes using proc macros
6///
7/// Turns token stream into string.
8/// - Finds expressions and registers marker locations
9/// - Parses structure from string and turns it into Rust tokens
10#[proc_macro]
11pub fn expr(item: TokenStream) -> TokenStream {
12	token_stream_to_ast_node::<ezno_parser::Expression>(item)
13}
14
15#[proc_macro]
16pub fn stmt(item: TokenStream) -> TokenStream {
17	token_stream_to_ast_node::<ezno_parser::StatementOrDeclaration>(item)
18}
19
20fn token_stream_to_ast_node<T: ezno_parser::ASTNode + self_rust_tokenize::SelfRustTokenize>(
21	item: TokenStream,
22) -> TokenStream {
23	let mut string_to_parse = String::new();
24	let mut marker_items = Vec::new();
25	parse_token_stream(item.into_iter(), &mut string_to_parse, &mut marker_items);
26
27	// TODO can you get new lines in macro?
28	let line_starts = ezno_parser::source_map::LineStarts::new("");
29	let options = ezno_parser::ParseOptions { interpolation_points: true, ..Default::default() };
30	let parse_result =
31		ezno_parser::lex_and_parse_script::<T>(line_starts, options, &string_to_parse, None);
32
33	let node = match parse_result {
34		Ok((node, _state)) => node,
35		Err(err) => {
36			let reason = err.reason;
37			return quote!(compile_error!(#reason)).into();
38		}
39	};
40
41	let node_as_tokens = self_rust_tokenize::SelfRustTokenize::to_tokens(&node);
42
43	let interpolation_tokens = marker_items.iter().enumerate().map(|(idx, name)| {
44		let ident = format_ident!("_marker_{idx}");
45		let expr_ident = proc_macro2::Ident::new(name, Span::call_site());
46		quote!(let #ident = #expr_ident)
47	});
48
49	let tokens = quote! {
50		{
51			use ezno_parser::ast::*;
52			use ezno_parser::{generator_helpers::IntoAST, source_map};
53
54			#(#interpolation_tokens;)*
55			const CURRENT_SOURCE_ID: source_map::SourceId = source_map::Nullable::NULL;
56			#node_as_tokens
57		}
58	};
59
60	// eprintln!("output: {tokens}");
61
62	tokens.into()
63}
64
65fn parse_token_stream(
66	mut token_iter: token_stream::IntoIter,
67	string: &mut String,
68	marker_items: &mut Vec<String>,
69) {
70	let mut last_was_ident = false;
71	while let Some(token_tree) = token_iter.next() {
72		let current_is_ident = matches!(token_tree, TokenTree::Ident(_));
73
74		match token_tree {
75			TokenTree::Group(group) => {
76				let delimiter = group.delimiter();
77				let (start, end) = match delimiter {
78					Delimiter::Parenthesis => ("(", ")"),
79					Delimiter::Brace => ("{", "}"),
80					Delimiter::Bracket => ("[", "]"),
81					Delimiter::None => ("", ""),
82				};
83				string.push_str(start);
84				parse_token_stream(group.stream().into_iter(), string, marker_items);
85				string.push_str(end);
86			}
87			TokenTree::Ident(ident) => {
88				if last_was_ident {
89					string.push(' ');
90				}
91				string.push_str(ident.to_string().as_str());
92			}
93			TokenTree::Punct(punctuation) => {
94				let chr = punctuation.as_char();
95				if chr == '#' {
96					if let Some(TokenTree::Ident(ident)) = token_iter.next() {
97						let expr_name = ident.to_string();
98						marker_items.push(expr_name);
99					} else {
100						panic!("Expected ident")
101					}
102					// spaces break up the node
103					string.push(' ');
104					string.push_str(ezno_parser::marker::MARKER);
105					string.push(' ');
106				} else {
107					let spacing = matches!(punctuation.spacing(), Spacing::Alone)
108						&& !matches!(chr, '<' | '>' | '/');
109					if spacing && !string.ends_with("</") {
110						string.push(' ');
111					}
112					string.push(chr);
113					if spacing {
114						string.push(' ');
115					}
116				}
117			}
118			TokenTree::Literal(literal) => {
119				string.push_str(literal.to_string().as_str());
120			}
121		}
122
123		last_was_ident = current_is_ident;
124	}
125}
ezno_ast_generator/generator.rs

ezno_ast_generator/
generator.rs
