in midst of refactor

orchid-base/src/virt_fs/decl.rs

@@ -0,0 +1,73 @@
+use std::rc::Rc;
+use std::sync::Arc;
+
+use super::common::CodeNotFound;
+use super::{FSResult, Loaded, VirtFS};
+use crate::intern::Token;
+use crate::proj_error::ErrorSansOrigin;
+use crate::name::PathSlice;
+use crate::tree::{ModEntry, ModMember};
+use crate::combine::Combine;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub struct ConflictingTrees;
+
+impl Combine for Rc<dyn VirtFS> {
+  type Error = ConflictingTrees;
+  fn combine(self, _: Self) -> Result<Self, Self::Error> { Err(ConflictingTrees) }
+}
+
+impl Combine for Arc<dyn VirtFS> {
+  type Error = ConflictingTrees;
+  fn combine(self, _: Self) -> Result<Self, Self::Error> { Err(ConflictingTrees) }
+}
+
+impl<'a> Combine for &'a dyn VirtFS {
+  type Error = ConflictingTrees;
+  fn combine(self, _: Self) -> Result<Self, Self::Error> { Err(ConflictingTrees) }
+}
+
+/// A declarative in-memory tree with [VirtFS] objects for leaves. Paths are
+/// followed to a leaf and the leftover handled by it.
+pub type DeclTree = ModEntry<Rc<dyn VirtFS>, (), ()>;
+
+impl VirtFS for DeclTree {
+  fn get(&self, path: &[Token<String>], full_path: &PathSlice) -> FSResult {
+    match &self.member {
+      ModMember::Item(it) => it.get(path, full_path),
+      ModMember::Sub(module) => match path.split_first() {
+        None => Ok(Loaded::collection(module.keys(|_| true))),
+        Some((head, tail)) => (module.entries.get(head))
+          .ok_or_else(|| CodeNotFound::new(full_path.to_vpath()).pack())
+          .and_then(|ent| ent.get(tail, full_path)),
+      },
+    }
+  }
+
+  fn display(&self, path: &[Token<String>]) -> Option<String> {
+    let (head, tail) = path.split_first()?;
+    match &self.member {
+      ModMember::Item(it) => it.display(path),
+      ModMember::Sub(module) => module.entries.get(head)?.display(tail),
+    }
+  }
+}
+
+impl VirtFS for String {
+  fn display(&self, _: &[Token<String>]) -> Option<String> { None }
+  fn get(&self, path: &[Token<String>], full_path: &PathSlice) -> FSResult {
+    (path.is_empty().then(|| Loaded::Code(Arc::new(self.as_str().to_string()))))
+      .ok_or_else(|| CodeNotFound::new(full_path.to_vpath()).pack())
+  }
+}
+
+impl<'a> VirtFS for &'a str {
+  fn display(&self, _: &[Token<String>]) -> Option<String> { None }
+  fn get(&self, path: &[Token<String>], full_path: &PathSlice) -> FSResult {
+    (path.is_empty().then(|| Loaded::Code(Arc::new(self.to_string()))))
+      .ok_or_else(|| CodeNotFound::new(full_path.to_vpath()).pack())
+  }
+}
+
+/// Insert a file by cleartext contents in the [DeclTree].
+pub fn decl_file(s: &str) -> DeclTree { DeclTree::leaf(Rc::new(s.to_string())) }