From 405bc3d80c0e169ea74dd12422b9504b7383dab3 Mon Sep 17 00:00:00 2001
From: FintanH
Date: Mon, 12 Aug 2019 22:22:24 +0100
Subject: Refactor of File to be the combination of Directory and the file
 name, where Directory is the Vector of component paths.

The refactor meant changing some sections of the code where we were
parsing and manipulating Files/Directories.

This also includes a new trait Canonicalization which is needed for
import logic.
---
 dhall_syntax/src/core/import.rs | 122 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 120 insertions(+), 2 deletions(-)

(limited to 'dhall_syntax/src/core/import.rs')

diff --git a/dhall_syntax/src/core/import.rs b/dhall_syntax/src/core/import.rs
index c328e34..ea42dbc 100644
--- a/dhall_syntax/src/core/import.rs
+++ b/dhall_syntax/src/core/import.rs
@@ -11,10 +11,41 @@ pub enum FilePrefix {
     Home,
 }
 
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Directory {
+    pub components: Vec<String>,
+}
+
+impl IntoIterator for Directory {
+    type Item = String;
+    type IntoIter = ::std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.components.into_iter()
+    }
+}
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct File {
+    pub directory: Directory,
+    pub file: String,
+}
+
+impl IntoIterator for File {
+    type Item = String;
+    type IntoIter = ::std::vec::IntoIter<Self::Item>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        let mut paths = self.directory.components;
+        paths.push(self.file);
+        paths.into_iter()
+    }
+}
+
 /// The location of import (i.e. local vs. remote vs. environment)
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum ImportLocation {
-    Local(FilePrefix, Vec<String>),
+    Local(FilePrefix, File),
     Remote(URL),
     Env(String),
     Missing,
@@ -24,7 +55,7 @@ pub enum ImportLocation {
 pub struct URL {
     pub scheme: Scheme,
     pub authority: String,
-    pub path: Vec<String>,
+    pub path: File,
     pub query: Option<String>,
     pub headers: Option<Box<ImportHashed>>,
 }
@@ -59,3 +90,90 @@ pub struct Import {
     pub mode: ImportMode,
     pub location_hashed: ImportHashed,
 }
+
+pub trait Canonicalize {
+    fn canonicalize(&self) -> Self;
+}
+
+impl Canonicalize for Directory {
+    fn canonicalize(&self) -> Directory {
+        let mut components = Vec::new();
+        let mut dir_components = self.clone().into_iter();
+
+        loop {
+           let component = dir_components.next();
+           match component.as_ref() {
+               // ───────────────────
+               // canonicalize(ε) = ε
+               None => break,
+
+               // canonicalize(directory₀) = directory₁
+               // ───────────────────────────────────────
+               // canonicalize(directory₀/.) = directory₁
+               Some(c) if c == "." => continue,
+
+               Some(c) if c == ".." => match dir_components.next() {
+                   // canonicalize(directory₀) = ε
+                   // ────────────────────────────
+                   // canonicalize(directory₀/..) = /..
+                   None => components.push("..".to_string()),
+
+                   // canonicalize(directory₀) = directory₁/..
+                   // ──────────────────────────────────────────────
+                   // canonicalize(directory₀/..) = directory₁/../..
+                   Some(ref c) if c == ".." => {
+                       components.push("..".to_string());
+                       components.push("..".to_string());
+                   },
+
+                   // canonicalize(directory₀) = directory₁/component
+                   // ───────────────────────────────────────────────  ; If "component" is not
+                   // canonicalize(directory₀/..) = directory₁         ; ".."
+                   Some(_) => continue,
+               },
+
+               // canonicalize(directory₀) = directory₁
+               // ─────────────────────────────────────────────────────────  ; If no other
+               // canonicalize(directory₀/component) = directory₁/component  ; rule matches
+               Some(c) => components.push(c.clone()),
+           }
+        }
+
+        Directory { components: components }
+    }
+}
+
+impl Canonicalize for File {
+    fn canonicalize(&self) -> File {
+        File { directory: self.directory.canonicalize(), file: self.file.clone() }
+    }
+}
+
+impl Canonicalize for ImportLocation {
+    fn canonicalize(&self) -> ImportLocation {
+        match self {
+            ImportLocation::Local(prefix, file) => ImportLocation::Local(*prefix, file.canonicalize()),
+            ImportLocation::Remote(url) => ImportLocation::Remote(URL {
+                    scheme: url.scheme,
+                    authority: url.authority.clone(),
+                    path: url.path.canonicalize(),
+                    query: url.query.clone(),
+                    headers: url.headers.clone().map(|boxed_hash| Box::new(boxed_hash.canonicalize())),
+            }),
+            ImportLocation::Env(name) => ImportLocation::Env(name.to_string()),
+            ImportLocation::Missing => ImportLocation::Missing,
+        }
+    }
+}
+
+impl Canonicalize for ImportHashed {
+    fn canonicalize(&self) -> ImportHashed {
+        ImportHashed { hash: self.hash.clone(), location: self.location.canonicalize() }
+    }
+}
+
+impl Canonicalize for Import {
+    fn canonicalize(&self) -> Import {
+        Import { mode: self.mode, location_hashed: self.location_hashed.canonicalize() }
+    }
+}
-- 
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