Move route from context to VM

1 files changed, 25 insertions, 3 deletions

diff --git a/src/eval/machine.rs b/src/eval/machine.rs
index 168cedcb..14633978 100644
--- a/src/eval/machine.rs
+++ b/src/eval/machine.rs
@@ -1,12 +1,18 @@
+use std::path::PathBuf;
+
 use super::{Scopes, Value};
-use crate::diag::TypError;
+use crate::diag::{StrResult, TypError};
+use crate::source::SourceId;
 use crate::syntax::Span;
+use crate::util::PathExt;
 use crate::Context;
 
 /// A virtual machine.
 pub struct Machine<'a> {
     /// The core context.
     pub ctx: &'a mut Context,
+    /// The route of source ids at which the machine is located.
+    pub route: Vec<SourceId>,
     /// The stack of scopes.
     pub scopes: Scopes<'a>,
     /// A control flow event that is currently happening.
@@ -15,8 +21,24 @@ pub struct Machine<'a> {
 
 impl<'a> Machine<'a> {
     /// Create a new virtual machine.
-    pub fn new(ctx: &'a mut Context, scopes: Scopes<'a>) -> Self {
-        Self { ctx, scopes, flow: None }
+    pub fn new(ctx: &'a mut Context, route: Vec<SourceId>, scopes: Scopes<'a>) -> Self {
+        Self { ctx, route, scopes, flow: None }
+    }
+
+    /// Resolve a user-entered path to be relative to the compilation
+    /// environment's root.
+    pub fn locate(&self, path: &str) -> StrResult<PathBuf> {
+        if let Some(&id) = self.route.last() {
+            if let Some(path) = path.strip_prefix('/') {
+                return Ok(self.ctx.config.root.join(path).normalize());
+            }
+
+            if let Some(dir) = self.ctx.sources.get(id).path().parent() {
+                return Ok(dir.join(path).normalize());
+            }
+        }
+
+        return Err("cannot access file system from here".into());
     }
 }