1 files changed, 103 insertions, 0 deletions
diff --git a/audio/src/parse/macros.rs b/audio/src/parse/macros.rs
new file mode 100644
index 0000000..1dc33eb
--- /dev/null
+++ b/audio/src/parse/macros.rs
@@ -0,0 +1,103 @@
+use std::{borrow::Cow, collections::HashMap, str::Lines};
+
+struct PreProcessor<'s> {
+	src: &'s str,
+	pos: usize,
+	lines: Lines<'s>,
+	macros: HashMap<&'s str, &'s str>,
+}
+impl<'s> PreProcessor<'s> {
+	fn new(src: &'s str) -> Self {
+		let lines = src.lines();
+		let macros = HashMap::new();
+		Self {
+			src,
+			pos: 0,
+			lines,
+			macros,
+		}
+	}
+
+	fn next(&mut self) -> Option<&'s str> {
+		self.lines.next().map(|line| {
+			self.pos += line.len() + 1;
+			line.trim()
+		})
+	}
+
+	fn read_macro(&mut self, full_name: &'s str) {
+		let name = &full_name[8..];
+		let start = self.pos;
+		let mut end = start;
+		while let Some(line) = self.next()
+			&& !matches!(line, "%end")
+		{
+			end = self.pos;
+		}
+		let str = &self.src[start..end];
+		self.macros.insert(name, str);
+	}
+
+	fn read_macros(&mut self) -> String {
+		let mut buf = String::new();
+		while let Some(line) = self.next() {
+			if line.starts_with("%define ") {
+				self.read_macro(line);
+			} else {
+				buf.push_str(line);
+				buf.push('\n');
+			}
+		}
+		buf
+	}
+
+	fn process(&mut self) -> String {
+		let rest = self.read_macros();
+		let mut lines = rest.lines().map(Cow::Borrowed).collect::<Vec<_>>();
+		loop {
+			let mut count = 0;
+			for (name, body) in &self.macros {
+				count += fill_macro(&mut lines, name, body);
+			}
+			if count == 0 {
+				break;
+			}
+		}
+		lines.join("\n")
+	}
+}
+
+fn fill_macro(contents: &mut Vec<Cow<'_, str>>, name: &str, body: &str) -> usize {
+	let mut count = 0;
+	let mut idx = 0;
+	loop {
+		if idx >= contents.len() {
+			break;
+		}
+		let line = &contents[idx];
+		if line.starts_with(name) {
+			fill_macro_once(contents, idx, body);
+			count += 1;
+		}
+		idx += 1;
+	}
+	count
+}
+
+fn fill_macro_once(contents: &mut Vec<Cow<'_, str>>, idx: usize, body: &str) {
+	let invoke_line = contents.remove(idx);
+	let args = invoke_line.split_whitespace().skip(1).collect::<Vec<_>>();
+
+	for line in body.lines().rev() {
+		let mut buf = String::from(line);
+		for (idx, arg) in args.iter().enumerate() {
+			let key = format!("${}", idx + 1);
+			buf = buf.replace(&key, arg);
+		}
+		contents.insert(idx, Cow::Owned(buf));
+	}
+}
+
+pub fn process(src: &str) -> String {
+	PreProcessor::new(src).process()
+}