From 79595b1ae1a12fa2414d4b6c3c4bb2f7a0a9c094 Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Tue, 3 Sep 2019 16:24:07 +0200
Subject: Resolve imports by mutating Expr instead of cloning it

---
 dhall_syntax/src/core/import.rs | 34 +++++++++++++++++++++++++++++-----
 1 file changed, 29 insertions(+), 5 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 d1f3fca..43597df 100644
--- a/dhall_syntax/src/core/import.rs
+++ b/dhall_syntax/src/core/import.rs
@@ -57,7 +57,7 @@ pub struct Import<SubExpr> {
 }
 
 impl<SE> URL<SE> {
-    pub fn visit_subexpr<'a, Err, SE2>(
+    pub fn traverse_ref<'a, Err, SE2>(
         &'a self,
         f: impl FnOnce(&'a SE) -> Result<SE2, Err>,
     ) -> Result<URL<SE2>, Err> {
@@ -70,32 +70,56 @@ impl<SE> URL<SE> {
             headers,
         })
     }
+    pub fn traverse_mut<'a, Err>(
+        &'a mut self,
+        f: impl FnOnce(&'a mut SE) -> Result<(), Err>,
+    ) -> Result<(), Err> {
+        if let Some(header) = &mut self.headers {
+            f(header)?;
+        }
+        Ok(())
+    }
 }
 
 impl<SE> ImportLocation<SE> {
-    pub fn visit_subexpr<'a, Err, SE2>(
+    pub fn traverse_ref<'a, Err, SE2>(
         &'a self,
         f: impl FnOnce(&'a SE) -> Result<SE2, Err>,
     ) -> Result<ImportLocation<SE2>, Err> {
         use ImportLocation::*;
         Ok(match self {
             Local(prefix, path) => Local(*prefix, path.clone()),
-            Remote(url) => Remote(url.visit_subexpr(f)?),
+            Remote(url) => Remote(url.traverse_ref(f)?),
             Env(env) => Env(env.clone()),
             Missing => Missing,
         })
     }
+    pub fn traverse_mut<'a, Err>(
+        &'a mut self,
+        f: impl FnOnce(&'a mut SE) -> Result<(), Err>,
+    ) -> Result<(), Err> {
+        if let ImportLocation::Remote(url) = self {
+            url.traverse_mut(f)?;
+        }
+        Ok(())
+    }
 }
 
 impl<SE> Import<SE> {
-    pub fn visit_subexpr<'a, Err, SE2>(
+    pub fn traverse_ref<'a, Err, SE2>(
         &'a self,
         f: impl FnOnce(&'a SE) -> Result<SE2, Err>,
     ) -> Result<Import<SE2>, Err> {
         Ok(Import {
             mode: self.mode,
-            location: self.location.visit_subexpr(f)?,
+            location: self.location.traverse_ref(f)?,
             hash: self.hash.clone(),
         })
     }
+    pub fn traverse_mut<'a, Err>(
+        &'a mut self,
+        f: impl FnOnce(&'a mut SE) -> Result<(), Err>,
+    ) -> Result<(), Err> {
+        self.location.traverse_mut(f)
+    }
 }
-- 
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