More context for errors (value key if possible)

2 files changed, 209 insertions, 45 deletions

diff --git a/src/de.rs b/src/de.rs
index 9a9ef58..6487f8b 100644
--- a/src/de.rs
+++ b/src/de.rs
@@ -1,107 +1,216 @@
 use serde::de;
-use value::{Value, ValueKind};
+use value::{Value, ValueWithKey, ValueKind};
 use error::*;
 use std::borrow::Cow;
 use std::iter::Peekable;
 use std::collections::HashMap;
 use std::collections::hash_map::Drain;
 
-impl de::Deserializer for Value {
+// TODO: Use a macro or some other magic to reduce the code duplication here
+
+impl<'de> de::Deserializer<'de> for ValueWithKey<'de> {
     type Error = ConfigError;
 
     #[inline]
-    fn deserialize<V>(self, visitor: V) -> Result<V::Value>
-        where V: de::Visitor
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
+        where V: de::Visitor<'de>
+    {
+        // Deserialize based on the underlying type
+        match self.0.kind {
+            ValueKind::Nil => visitor.visit_unit(),
+            ValueKind::Integer(i) => visitor.visit_i64(i),
+            ValueKind::Boolean(b) => visitor.visit_bool(b),
+            ValueKind::Float(f) => visitor.visit_f64(f),
+            ValueKind::String(s) => visitor.visit_string(s),
+            ValueKind::Array(values) => visitor.visit_seq(SeqAccess::new(values)),
+            ValueKind::Table(map) => visitor.visit_map(MapAccess::new(map)),
+        }
+    }
+
+    #[inline]
+    fn deserialize_bool<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_bool(self.into_bool()?)
+    }
+
+    #[inline]
+    fn deserialize_i8<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_i8(self.into_int()? as i8)
+    }
+
+    #[inline]
+    fn deserialize_i16<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_i16(self.into_int()? as i16)
+    }
+
+    #[inline]
+    fn deserialize_i32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_i32(self.into_int()? as i32)
+    }
+
+    #[inline]
+    fn deserialize_i64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_i64(self.into_int()?)
+    }
+
+    #[inline]
+    fn deserialize_u8<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_u8(self.into_int()? as u8)
+    }
+
+    #[inline]
+    fn deserialize_u16<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_u16(self.into_int()? as u16)
+    }
+
+    #[inline]
+    fn deserialize_u32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_u32(self.into_int()? as u32)
+    }
+
+    #[inline]
+    fn deserialize_u64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        // FIXME: This should *fail* if the value does not fit in the requets integer type
+        visitor.visit_u64(self.into_int()? as u64)
+    }
+
+    #[inline]
+    fn deserialize_f32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_f32(self.into_float()? as f32)
+    }
+
+    #[inline]
+    fn deserialize_f64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_f64(self.into_float()?)
+    }
+
+    #[inline]
+    fn deserialize_str<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_string(self.into_str()?)
+    }
+
+    #[inline]
+    fn deserialize_string<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
+        visitor.visit_string(self.into_str()?)
+    }
+
+    #[inline]
+    fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
+        where V: de::Visitor<'de>
+    {
+        // Match an explicit nil as None and everything else as Some
+        match self.0.kind {
+            ValueKind::Nil => visitor.visit_none(),
+            _ => visitor.visit_some(self),
+        }
+    }
+
+    forward_to_deserialize_any! {
+        char seq
+        bytes byte_buf map struct unit enum newtype_struct
+        identifier ignored_any unit_struct tuple_struct tuple
+    }
+}
+
+impl<'de> de::Deserializer<'de> for Value {
+    type Error = ConfigError;
+
+    #[inline]
+    fn deserialize_any<V>(self, visitor: V) -> Result<V::Value>
+        where V: de::Visitor<'de>
     {
         // Deserialize based on the underlying type
         match self.kind {
+            ValueKind::Nil => visitor.visit_unit(),
             ValueKind::Integer(i) => visitor.visit_i64(i),
             ValueKind::Boolean(b) => visitor.visit_bool(b),
             ValueKind::Float(f) => visitor.visit_f64(f),
             ValueKind::String(s) => visitor.visit_string(s),
-            ValueKind::Array(values) => unimplemented!(),
-            ValueKind::Table(map) => visitor.visit_map(MapVisitor::new(map)),
-            _ => {
-                unimplemented!();
-            }
+            ValueKind::Array(values) => visitor.visit_seq(SeqAccess::new(values)),
+            ValueKind::Table(map) => visitor.visit_map(MapAccess::new(map)),
         }
     }
 
     #[inline]
-    fn deserialize_bool<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_bool<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_bool(self.into_bool()?)
     }
 
     #[inline]
-    fn deserialize_i8<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_i8<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_i8(self.into_int()? as i8)
     }
 
     #[inline]
-    fn deserialize_i16<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_i16<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_i16(self.into_int()? as i16)
     }
 
     #[inline]
-    fn deserialize_i32<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_i32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_i32(self.into_int()? as i32)
     }
 
     #[inline]
-    fn deserialize_i64<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_i64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_i64(self.into_int()?)
     }
 
     #[inline]
-    fn deserialize_u8<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_u8<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_u8(self.into_int()? as u8)
     }
 
     #[inline]
-    fn deserialize_u16<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_u16<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_u16(self.into_int()? as u16)
     }
 
     #[inline]
-    fn deserialize_u32<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_u32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_u32(self.into_int()? as u32)
     }
 
     #[inline]
-    fn deserialize_u64<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_u64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         // FIXME: This should *fail* if the value does not fit in the requets integer type
         visitor.visit_u64(self.into_int()? as u64)
     }
 
     #[inline]
-    fn deserialize_f32<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_f32<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_f32(self.into_float()? as f32)
     }
 
     #[inline]
-    fn deserialize_f64<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_f64<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_f64(self.into_float()?)
     }
 
     #[inline]
-    fn deserialize_str<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_str<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_string(self.into_str()?)
     }
 
     #[inline]
-    fn deserialize_string<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_string<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_string(self.into_str()?)
     }
 
     #[inline]
     fn deserialize_option<V>(self, visitor: V) -> Result<V::Value>
-        where V: de::Visitor
+        where V: de::Visitor<'de>
     {
         // Match an explicit nil as None and everything else as Some
         match self.kind {
@@ -110,10 +219,10 @@ impl de::Deserializer for Value {
         }
     }
 
-    forward_to_deserialize! {
+    forward_to_deserialize_any! {
         char seq
-        seq_fixed_size bytes byte_buf map struct unit enum newtype_struct
-        struct_field ignored_any unit_struct tuple_struct tuple
+        bytes byte_buf map struct unit enum newtype_struct
+        identifier ignored_any unit_struct tuple_struct tuple
     }
 }
 
@@ -125,54 +234,86 @@ impl<'a> StrDeserializer<'a> {
     }
 }
 
-impl<'a> de::Deserializer for StrDeserializer<'a> {
+impl<'de, 'a> de::Deserializer<'de> for StrDeserializer<'a> {
     type Error = ConfigError;
 
     #[inline]
-    fn deserialize<V: de::Visitor>(self, visitor: V) -> Result<V::Value> {
+    fn deserialize_any<V: de::Visitor<'de>>(self, visitor: V) -> Result<V::Value> {
         visitor.visit_str(self.0)
     }
 
-    forward_to_deserialize! {
+    forward_to_deserialize_any! {
         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
+        bytes byte_buf map struct unit enum newtype_struct
+        identifier ignored_any unit_struct tuple_struct tuple option
+    }
+}
+
+struct SeqAccess {
+    elements: ::std::vec::IntoIter<Value>,
+}
+
+impl SeqAccess {
+    fn new(elements: Vec<Value>) -> Self {
+        SeqAccess {
+            elements: elements.into_iter(),
+        }
+    }
+}
+
+impl<'de> de::SeqAccess<'de> for SeqAccess {
+    type Error = ConfigError;
+
+    fn next_element_seed<T>(&mut self, seed: T) -> Result<Option<T::Value>>
+        where T: de::DeserializeSeed<'de>
+    {
+        match self.elements.next() {
+            Some(value) => seed.deserialize(value).map(Some),
+            None => Ok(None),
+        }
+    }
+
+    fn size_hint(&self) -> Option<usize> {
+        match self.elements.size_hint() {
+            (lower, Some(upper)) if lower == upper => Some(upper),
+            _ => None,
+        }
     }
 }
 
-struct MapVisitor {
+struct MapAccess {
     elements: Vec<(String, Value)>,
     index: usize,
 }
 
-impl MapVisitor {
+impl MapAccess {
     fn new(mut table: HashMap<String, Value>) -> Self {
-        MapVisitor {
+        MapAccess {
             elements: table.drain().collect(),
             index: 0,
         }
     }
 }
 
-impl de::MapVisitor for MapVisitor {
+impl<'de> de::MapAccess<'de> for MapAccess {
     type Error = ConfigError;
 
-    fn visit_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
-        where K: de::DeserializeSeed
+    fn next_key_seed<K>(&mut self, seed: K) -> Result<Option<K::Value>>
+        where K: de::DeserializeSeed<'de>
     {
         if self.index >= self.elements.len() {
             return Ok(None);
         }
 
-        let key_s = &self.elements[0].0;
+        let key_s = &(self.elements[0].0);
         let key_de = StrDeserializer(key_s);
         let key = de::DeserializeSeed::deserialize(seed, key_de)?;
 
         Ok(Some(key))
     }
 
-    fn visit_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
-        where V: de::DeserializeSeed
+    fn next_value_seed<V>(&mut self, seed: V) -> Result<V::Value>
+        where V: de::DeserializeSeed<'de>
     {
         de::DeserializeSeed::deserialize(seed, self.elements.remove(0).1)
     }
diff --git a/src/error.rs b/src/error.rs
index 8af5cee..92709c2 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -50,12 +50,13 @@ pub enum ConfigError {
         origin: Option<String>,
         unexpected: Unexpected,
         expected: &'static str,
+        key: Option<String>,
     },
 
     /// Custom message
     Message(String),
 
-    /// Unadorned error from a foreign source.
+    /// Unadorned error from a foreign origin.
     Foreign(Box<Error>),
 }
 
@@ -66,9 +67,27 @@ impl ConfigError {
         ConfigError::Type {
             origin: origin,
             unexpected: unexpected,
-            expected: expected
+            expected: expected,
+            key: None,
          }
     }
+
+    // FIXME: pub(crate)
+    #[doc(hidden)]
+    pub fn extend_with_key(self, key: &str) -> Self {
+        match self {
+            ConfigError::Type { origin, unexpected, expected, .. } => {
+                ConfigError::Type {
+                    origin: origin,
+                    unexpected: unexpected,
+                    expected: expected,
+                    key: Some(key.into()),
+                }
+            }
+
+            _ => self,
+        }
+    }
 }
 
 /// Alias for a `Result` with the error type set to `ConfigError`.
@@ -100,12 +119,16 @@ impl fmt::Display for ConfigError {
                 write!(f, "configuration property {:?} not found", key)
             }
 
-            ConfigError::Type { ref origin, ref unexpected, expected } => {
+            ConfigError::Type { ref origin, ref unexpected, expected, ref key } => {
                 write!(f, "invalid type: {}, expected {}",
                     unexpected, expected)?;
 
+                if let Some(ref key) = *key {
+                    write!(f, " for key `{}`", key)?;
+                }
+
                 if let Some(ref origin) = *origin {
-                    write!(f, " from {}", origin)?;
+                    write!(f, " in {}", origin)?;
                 }
 
                 Ok(())
@@ -115,7 +138,7 @@ impl fmt::Display for ConfigError {
                 write!(f, "{}", cause)?;
 
                 if let Some(ref uri) = *uri {
-                    write!(f, " from {}", uri)?;
+                    write!(f, " in {}", uri)?;
                 }
 
                 Ok(())