From 4357840e95f3646494ddeea4aae12425dfab2db8 Mon Sep 17 00:00:00 2001
From: Ryan Leckey <ryan@launchbadge.com>
Date: Thu, 1 Jun 2017 22:06:50 -0700
Subject: Handle Option<T> in deserializer

---
 lib/src/config.rs | 21 +++++++++------------
 lib/src/de.rs     | 28 ++++++++++++++++++++++------
 2 files changed, 31 insertions(+), 18 deletions(-)

diff --git a/lib/src/config.rs b/lib/src/config.rs
index 0767f87..93d7fc0 100644
--- a/lib/src/config.rs
+++ b/lib/src/config.rs
@@ -43,7 +43,8 @@ pub struct Config {
 impl Config {
     /// Merge in a configuration property source.
     pub fn merge<T>(&mut self, source: T) -> Result<()>
-        where T: 'static, T: Source + Send + Sync
+        where T: 'static,
+              T: Source + Send + Sync
     {
         match self.kind {
             ConfigKind::Mutable { ref mut sources, .. } => {
@@ -65,14 +66,12 @@ impl Config {
     /// operation (`set`, `merge`, `set_default`, etc.).
     pub fn refresh(&mut self) -> Result<()> {
         self.cache = match self.kind {
-            ConfigKind::Mutable { ref overrides, ref sources, ref defaults } => {
-                let mut cache = Value::new(None, HashMap::<String, Value>::new());
-
-                // HACK!
-                cache = sources[0].collect()?;
-
-                cache
-            }
+            // TODO: We need to actually merge in all the stuff
+            ConfigKind::Mutable {
+                ref overrides,
+                ref sources,
+                ref defaults,
+            } => sources[0].collect()?,
 
             ConfigKind::Frozen => {
                 return Err(ConfigError::Frozen);
@@ -95,9 +94,7 @@ impl Config {
                 T::deserialize(value)
             }
 
-            None => {
-                Err(ConfigError::NotFound(key.into()))
-            }
+            None => Err(ConfigError::NotFound(key.into())),
         }
     }
 }
diff --git a/lib/src/de.rs b/lib/src/de.rs
index 369d6de..89a3bcf 100644
--- a/lib/src/de.rs
+++ b/lib/src/de.rs
@@ -11,7 +11,7 @@ impl de::Deserializer for Value {
 
     #[inline]
     fn deserialize<V>(self, visitor: V) -> Result<V::Value>
-        where V: de::Visitor,
+        where V: de::Visitor
     {
         // Deserialize based on the underlying type
         match self.kind {
@@ -21,14 +21,27 @@ impl de::Deserializer for Value {
             ValueKind::String(s) => visitor.visit_string(s),
             ValueKind::Array(values) => unimplemented!(),
             ValueKind::Table(map) => visitor.visit_map(MapVisitor::new(map)),
-            _ => { unimplemented!(); }
+            _ => {
+                unimplemented!();
+            }
+        }
+    }
+
+    #[inline]
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
+        where V: de::Visitor
+    {
+        // Match an explicit nil as None and everything else as Some
+        match self.kind {
+            ValueKind::Nil => visitor.visit_none(),
+            _ => visitor.visit_some(self),
         }
     }
 
     forward_to_deserialize! {
         bool u8 u16 u32 u64 i8 i16 i32 i64 f32 f64 char str string seq
         seq_fixed_size bytes byte_buf map struct unit enum newtype_struct
-        struct_field ignored_any unit_struct tuple_struct tuple option
+        struct_field ignored_any unit_struct tuple_struct tuple
     }
 }
 
@@ -62,7 +75,10 @@ struct MapVisitor {
 
 impl MapVisitor {
     fn new(mut table: HashMap<String, Value>) -> Self {
-        MapVisitor { elements: table.drain().collect(), index: 0 }
+        MapVisitor {
+            elements: table.drain().collect(),
+            index: 0,
+        }
     }
 }
 
@@ -70,7 +86,7 @@ impl de::MapVisitor for MapVisitor {
     type Error = ConfigError;
 
     fn visit_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
-        where K: de::DeserializeSeed,
+        where K: de::DeserializeSeed
     {
         if self.index >= self.elements.len() {
             return Ok(None);
@@ -84,7 +100,7 @@ impl de::MapVisitor for MapVisitor {
     }
 
     fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
-        where V: de::DeserializeSeed,
+        where V: de::DeserializeSeed
     {
         de::DeserializeSeed::deserialize(seed, self.elements.remove(0).1)
     }
-- 
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