1 files changed, 135 insertions, 0 deletions
diff --git a/src/repo/profile/make_defaults/mod.rs b/src/repo/profile/make_defaults/mod.rs
new file mode 100644
index 0000000..334f165
--- /dev/null
+++ b/src/repo/profile/make_defaults/mod.rs
@@ -0,0 +1,135 @@
+use std::{
+    collections::{HashMap, HashSet},
+    fs, io,
+    path::{Path, PathBuf},
+};
+
+use mon::{Parser, ParserIter, ascii_whitespace1, input::InputIter};
+
+use crate::{
+    Parseable,
+    repo::profile::{LineBasedFileExpr, Profile},
+};
+
+mod parsers;
+
+#[derive(Debug, thiserror::Error)]
+pub enum Error {
+    #[error("{0}: io error: {1}")]
+    Io(PathBuf, io::Error),
+    #[error("parser error: {0}")]
+    Parser(String),
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+struct Key(String);
+
+#[derive(Debug, Clone)]
+struct Literal(String);
+
+#[derive(Debug, Clone)]
+struct Interpolation(String);
+
+#[derive(Debug, Clone)]
+enum Segment {
+    Literal(Literal),
+    Interpolation(Interpolation),
+}
+
+#[derive(Debug, Clone)]
+struct Assignment(Key, Vec<Segment>);
+
+pub(super) fn evaluate<P: AsRef<Path>>(
+    parents: &[Profile],
+    path: P,
+) -> Result<HashMap<String, String>, Error> {
+    let parsed = match fs::read_to_string(path.as_ref().join("make.defaults")) {
+        Ok(contents) => parse(&contents)?,
+        Err(e) if matches!(e.kind(), io::ErrorKind::NotFound) => HashMap::new(),
+        Err(e) => return Err(Error::Io(path.as_ref().to_path_buf(), e)),
+    };
+
+    let mut vars = interpolate(parents, parsed);
+
+    incremental(parents, &mut vars);
+
+    Ok(vars)
+}
+
+fn incremental(parents: &[Profile], vars: &mut HashMap<String, String>) {
+    for key in [
+        "USE",
+        "USE_EXPAND",
+        "USE_EXPAND_HIDDEN",
+        "CONFIG_PROTECT",
+        "CONFIG_PROTECT_MASK",
+    ] {
+        let mut accumulated = Vec::new();
+
+        for parent in parents {
+            if let Some(values) = parent.make_defaults().get(key) {
+                accumulated.extend(values.split_ascii_whitespace());
+            }
+        }
+
+        if let Some(values) = vars.get(key) {
+            accumulated.extend(values.split_ascii_whitespace());
+        }
+
+        let mut final_values = Vec::new();
+
+        for var in accumulated {
+            if var == "-*" {
+                final_values.clear();
+            } else if let Some(stripped) = var.strip_prefix("-") {
+                final_values.retain(|v| *v != stripped);
+            } else {
+                final_values.push(var);
+            }
+        }
+
+        let mut seen = HashSet::new();
+        final_values.retain(|v| seen.insert(*v));
+
+        if !final_values.is_empty() {
+            vars.insert(key.to_string(), final_values.join(" "));
+        }
+    }
+}
+
+fn interpolate(parents: &[Profile], vars: HashMap<Key, Vec<Segment>>) -> HashMap<String, String> {
+    let parent_vars = parents
+        .iter()
+        .flat_map(|parent| parent.make_defaults().clone().into_iter())
+        .collect::<HashMap<_, _>>();
+
+    vars.into_iter()
+        .map(|(key, segments)| {
+            let interpolated = segments
+                .into_iter()
+                .map(|segment| match segment {
+                    Segment::Interpolation(i) => parent_vars.get(&i.0).cloned().unwrap_or_default(),
+                    Segment::Literal(literal) => literal.0.trim().to_string(),
+                })
+                .collect::<Vec<_>>();
+
+            let joined = interpolated.join("");
+
+            (key.0, joined)
+        })
+        .collect::<HashMap<String, String>>()
+}
+
+fn parse(contents: &str) -> Result<HashMap<Key, Vec<Segment>>, Error> {
+    Ok(LineBasedFileExpr::<Assignment>::parser()
+        .separated_by_with_opt_trailing(ascii_whitespace1())
+        .many()
+        .parse_finished(InputIter::new(contents))
+        .map_err(|e| Error::Parser(dbg!(e).rest().to_string()))?
+        .into_iter()
+        .filter_map(|expr| match expr {
+            LineBasedFileExpr::Comment => None,
+            LineBasedFileExpr::Expr(Assignment(key, value)) => Some((key, value)),
+        })
+        .collect())
+}