Merge pull request #61 from oli-obk/serde

Serde

2 files changed, 159 insertions, 34 deletions

diff --git a/src/decoder/mod.rs b/src/decoder/mod.rs
index a3cc29a..62de223 100644
--- a/src/decoder/mod.rs
+++ b/src/decoder/mod.rs
@@ -35,6 +35,8 @@ pub enum DecodeErrorKind {
     ApplicationError(String),
     /// A field was expected, but none was found.
     ExpectedField(/* type */ Option<&'static str>),
+    /// A field was found, but it was not an expected one.
+    UnknownField,
     /// A field was found, but it had the wrong type.
     ExpectedType(/* expected */ &'static str, /* found */ &'static str),
     /// The nth map key was expected, but none was found.
@@ -149,6 +151,7 @@ impl fmt::Display for DecodeError {
                     None => write!(f, "expected a value"),
                 }
             }
+            UnknownField => write!(f, "unknown field"),
             ExpectedType(expected, found) => {
                 fn humanize(s: &str) -> String {
                     if s == "section" {
@@ -194,6 +197,7 @@ impl error::Error for DecodeError {
         match self.kind {
             ApplicationError(ref s) => &**s,
             ExpectedField(..) => "expected a field",
+            UnknownField => "found an unknown field",
             ExpectedType(..) => "expected a type",
             ExpectedMapKey(..) => "expected a map key",
             ExpectedMapElement(..) => "expected a map element",
diff --git a/src/decoder/serde.rs b/src/decoder/serde.rs
index 6f60892..048fede 100644
--- a/src/decoder/serde.rs
+++ b/src/decoder/serde.rs
@@ -1,10 +1,9 @@
 use serde::de;
 use Value;
 use super::{Decoder, DecodeError, DecodeErrorKind};
+use std::collections::BTreeMap;
 
-struct DecodeValue(Value);
-struct MapVisitor<I>(I, Option<Value>);
-struct SubDecoder(Decoder);
+struct MapVisitor<'a, I>(I, Option<Value>, &'a mut Option<Value>, Option<String>);
 
 fn se2toml(err: de::value::Error, ty: &'static str) -> DecodeError {
     match err {
@@ -15,7 +14,13 @@ fn se2toml(err: de::value::Error, ty: &'static str) -> DecodeError {
                 field: Some(s.to_string()),
                 kind: DecodeErrorKind::ExpectedField(Some(ty)),
             }
-        }
+        },
+        de::value::Error::UnknownFieldError(s) => {
+            DecodeError {
+                field: Some(s.to_string()),
+                kind: DecodeErrorKind::UnknownField,
+            }
+        },
     }
 }
 
@@ -43,13 +48,11 @@ impl de::Deserializer for Decoder {
             }
             Some(Value::Array(a)) => {
                 let len = a.len();
-                let iter = a.into_iter().map(DecodeValue);
-                let e = visitor.visit_seq(de::value::SeqDeserializer::new(iter,
-                                                                          len));
-                e.map_err(|e| se2toml(e, "array"))
+                let iter = a.into_iter();
+                visitor.visit_seq(SeqDeserializer::new(iter, len, &mut self.toml))
             }
             Some(Value::Table(t)) => {
-                visitor.visit_map(MapVisitor(t.into_iter(), None))
+                visitor.visit_map(MapVisitor(t.into_iter(), None, &mut self.toml, None))
             }
             None => Err(de::Error::end_of_stream_error()),
         }
@@ -78,6 +81,81 @@ impl de::Deserializer for Decoder {
     }
 }
 
+struct SeqDeserializer<'a, I> {
+    iter: I,
+    len: usize,
+    toml: &'a mut Option<Value>,
+}
+
+impl<'a, I> SeqDeserializer<'a, I>
+    where I: Iterator<Item=Value>,
+{
+    pub fn new(iter: I, len: usize, toml: &'a mut Option<Value>) -> Self {
+        SeqDeserializer {
+            iter: iter,
+            len: len,
+            toml: toml,
+        }
+    }
+    fn remember(&mut self, v: Value) {
+        *self.toml = self.toml.take().or(Some(Value::Array(Vec::new())));
+        // remember unknown field
+        match self.toml.as_mut().unwrap() {
+            &mut Value::Array(ref mut a) => {
+                a.push(v);
+            },
+            _ => unreachable!(),
+        }
+    }
+}
+
+impl<'a, I> de::Deserializer for SeqDeserializer<'a, I>
+    where I: Iterator<Item=Value>,
+{
+    type Error = DecodeError;
+
+    fn visit<V>(&mut self, mut visitor: V) -> Result<V::Value, DecodeError>
+        where V: de::Visitor,
+    {
+        visitor.visit_seq(self)
+    }
+}
+
+impl<'a, I> de::SeqVisitor for SeqDeserializer<'a, I>
+    where I: Iterator<Item=Value>
+{
+    type Error = DecodeError;
+
+    fn visit<V>(&mut self) -> Result<Option<V>, DecodeError>
+        where V: de::Deserialize
+    {
+        match self.iter.next() {
+            Some(value) => {
+                self.len -= 1;
+                let mut de = Decoder::new(value);
+                let v = try!(de::Deserialize::deserialize(&mut de));
+                if let Some(t) = de.toml {
+                    self.remember(t);
+                }
+                Ok(Some(v))
+            }
+            None => Ok(None),
+        }
+    }
+
+    fn end(&mut self) -> Result<(), DecodeError> {
+        if self.len == 0 {
+            Ok(())
+        } else {
+            Err(de::Error::end_of_stream_error())
+        }
+    }
+
+    fn size_hint(&self) -> (usize, Option<usize>) {
+        (self.len, Some(self.len))
+    }
+}
+
 impl de::Error for DecodeError {
     fn syntax_error() -> DecodeError {
         DecodeError { field: None, kind: DecodeErrorKind::SyntaxError }
@@ -91,33 +169,28 @@ impl de::Error for DecodeError {
             kind: DecodeErrorKind::ExpectedField(None),
         }
     }
-}
-
-impl de::Deserializer for SubDecoder {
-    type Error = de::value::Error;
-
-    fn visit<V>(&mut self, visitor: V) -> Result<V::Value, de::value::Error>
-        where V: de::Visitor
-    {
-        self.0.visit(visitor).map_err(|e| {
-            match e.kind {
-                DecodeErrorKind::SyntaxError => de::value::Error::SyntaxError,
-                DecodeErrorKind::EndOfStream => de::value::Error::EndOfStreamError,
-                _ => de::value::Error::SyntaxError,
-            }
-        })
+    fn unknown_field_error(name: &str) -> DecodeError {
+        DecodeError {
+            field: Some(name.to_string()),
+            kind: DecodeErrorKind::UnknownField,
+        }
     }
 }
 
-impl de::value::ValueDeserializer for DecodeValue {
-    type Deserializer = SubDecoder;
-
-    fn into_deserializer(self) -> SubDecoder {
-        SubDecoder(Decoder::new(self.0))
+impl<'a, I> MapVisitor<'a, I> {
+    fn remember(&mut self, v: Value) {
+        *self.2 = self.2.take().or(Some(Value::Table(BTreeMap::new())));
+        // remember unknown field
+        match self.2.as_mut().unwrap() {
+            &mut Value::Table(ref mut t) => {
+                t.insert(self.3.take().unwrap(), v);
+            },
+            _ => unreachable!(),
+        }
     }
 }
 
-impl<I> de::MapVisitor for MapVisitor<I>
+impl<'a, I> de::MapVisitor for MapVisitor<'a, I>
     where I: Iterator<Item=(String, Value)>
 {
     type Error = DecodeError;
@@ -127,9 +200,19 @@ impl<I> de::MapVisitor for MapVisitor<I>
     {
         match self.0.next() {
             Some((k, v)) => {
-                self.1 = Some(v);
-                de::Deserialize::deserialize(&mut Decoder::new(Value::String(k)))
-                   .map(|v| Some(v))
+                self.3 = Some(k.clone());
+                let dec = &mut Decoder::new(Value::String(k));
+                match de::Deserialize::deserialize(dec) {
+                    Err(DecodeError {kind: DecodeErrorKind::UnknownField, ..}) => {
+                        self.remember(v);
+                        self.visit_key()
+                    }
+                    Ok(val) => {
+                        self.1 = Some(v);
+                        Ok(Some(val))
+                    },
+                    Err(e) => Err(e),
+                }
             }
             None => Ok(None),
         }
@@ -140,7 +223,14 @@ impl<I> de::MapVisitor for MapVisitor<I>
         where V: de::Deserialize
     {
         match self.1.take() {
-            Some(t) => de::Deserialize::deserialize(&mut Decoder::new(t)),
+            Some(t) => {
+                let mut dec = Decoder::new(t);
+                let v = try!(de::Deserialize::deserialize(&mut dec));
+                if let Some(t) = dec.toml {
+                    self.remember(t);
+                }
+                Ok(v)
+            },
             None => Err(de::Error::end_of_stream_error())
         }
     }
@@ -149,4 +239,35 @@ impl<I> de::MapVisitor for MapVisitor<I>
         Ok(())
     }
 
+    fn missing_field<V>(&mut self, field_name: &'static str) -> Result<V, DecodeError>
+        where V: de::Deserialize,
+    {
+        println!("missing field: {}", field_name);
+        // See if the type can deserialize from a unit.
+        match de::Deserialize::deserialize(&mut UnitDeserializer) {
+            Err(DecodeError {kind: DecodeErrorKind::SyntaxError, field}) => Err(DecodeError {
+                field: field.or(Some(field_name.to_string())),
+                kind: DecodeErrorKind::ExpectedField(None),
+            }),
+            v => v,
+        }
+    }
+}
+
+struct UnitDeserializer;
+
+impl de::Deserializer for UnitDeserializer {
+    type Error = DecodeError;
+
+    fn visit<V>(&mut self, mut visitor: V) -> Result<V::Value, DecodeError>
+        where V: de::Visitor,
+    {
+        visitor.visit_unit()
+    }
+
+    fn visit_option<V>(&mut self, mut visitor: V) -> Result<V::Value, DecodeError>
+        where V: de::Visitor,
+    {
+        visitor.visit_none()
+    }
 }