Adds serializer format specific field names

Allows different field names to be used for different external formats.

Field names are specified using the `rename` field attribute, e.g:

    #[serde(rename(xml= "a4", json="a5"))]

Reverts #62

Addresses #61

serde_macros/src/de.rs

@@ -1,3 +1,5 @@
+use std::collections::HashSet;
+
 use syntax::ast::{
     Ident,
     MetaItem,
@@ -353,7 +355,8 @@ fn deserialize_item_enum(
         cx,
         builder,
         enum_def.variants.iter()
-            .map(|variant| builder.expr().str(variant.node.name))
+            .map(|variant|
+                 field::FieldLit::Global(builder.expr().str(variant.node.name)))
             .collect()
     );
 
@@ -531,7 +534,7 @@ fn deserialize_struct_variant(
 fn deserialize_field_visitor(
     cx: &ExtCtxt,
     builder: &aster::AstBuilder,
-    field_exprs: Vec<P<ast::Expr>>,
+    field_exprs: Vec<field::FieldLit>,
 ) -> Vec<P<ast::Item>> {
     // Create the field names for the fields.
     let field_idents: Vec<ast::Ident> = (0 .. field_exprs.len())
@@ -548,14 +551,80 @@ fn deserialize_field_visitor(
         )
         .build();
 
+
+    let fmts = field_exprs.iter()
+        .fold(HashSet::new(), |mut set, field_expr|
+              match field_expr {
+                  &field::FieldLit::Format{ref formats, default: _} => {
+                      for (fmt, _) in formats.iter() {
+                          set.insert(fmt.clone());
+                      };
+                      set
+                  },
+                  _ => set
+            });
+
     // Match arms to extract a field from a string
-    let field_arms: Vec<_> = field_idents.iter()
+    let default_field_arms: Vec<_> = field_idents.iter()
-        .zip(field_exprs.into_iter())
+        .zip(field_exprs.iter())
         .map(|(field_ident, field_expr)| {
-            quote_arm!(cx, $field_expr => { Ok(__Field::$field_ident) })
+            match field_expr {
+                &field::FieldLit::Global(ref expr) =>
+                    quote_arm!(cx, $expr => { Ok(__Field::$field_ident) }),
+                &field::FieldLit::Format{formats: _, ref default} =>
+                    quote_arm!(cx, $default => { Ok(__Field::$field_ident)})
+            }
         })
         .collect();
 
+    let body = if fmts.is_empty() {
+        quote_expr!(cx,
+                    match value {
+                        $default_field_arms,
+                        _ => Err(::serde::de::Error::unknown_field_error(value)),
+                    })
+    } else {
+        let field_arms : Vec<_> = fmts.iter()
+            .map(|fmt| {
+                field_idents.iter()
+                    .zip(field_exprs.iter())
+                    .map(|(field_ident, field_expr)| {
+                        match field_expr {
+                            &field::FieldLit::Global(ref expr) =>
+                                quote_arm!(cx,
+                                           $expr => { Ok(__Field::$field_ident) }),
+                            &field::FieldLit::Format{ref formats, ref default} => {
+                            let expr = formats.get(fmt).unwrap_or(default);
+                                quote_arm!(cx,
+                                           $expr => { Ok(__Field::$field_ident) })}}
+                    })
+                    .collect::<Vec<_>>()
+            })
+            .collect();
+
+        let fmt_matches : Vec<_> = fmts.iter()
+            .zip(field_arms.iter())
+            .map(|(ref fmt, ref arms)| {
+                quote_arm!(cx, $fmt => {
+                    match value {
+                        $arms,
+                        _ => {
+                            Err(::serde::de::Error::unknown_field_error(value))
+                        }
+                    }})
+            })
+            .collect();
+
+        quote_expr!(cx,
+                    match D::fmt() {
+                        $fmt_matches,
+                        _ => match value {
+                            $default_field_arms,
+                            _ => Err(::serde::de::Error::unknown_field_error(value)),
+                        }
+                    })
+    };
+
     vec![
         field_enum,
 
@@ -565,22 +634,26 @@ fn deserialize_field_visitor(
                 fn deserialize<D>(deserializer: &mut D) -> ::std::result::Result<__Field, D::Error>
                     where D: ::serde::de::Deserializer,
                 {
-                    struct __FieldVisitor;
+                    use std::marker::PhantomData;
 
-                    impl ::serde::de::Visitor for __FieldVisitor {
+                    struct __FieldVisitor<D> {
+                        phantom: PhantomData<D>
+                    }
+
+                    impl<D> ::serde::de::Visitor for __FieldVisitor<D>
+                        where D: ::serde::de::Deserializer
+                    {
                         type Value = __Field;
 
                         fn visit_str<E>(&mut self, value: &str) -> ::std::result::Result<__Field, E>
                             where E: ::serde::de::Error,
                         {
-                            match value {
+                            $body
-                                $field_arms
-                                _ => Err(::serde::de::Error::unknown_field_error(value)),
-                            }
                         }
                     }
 
-                    deserializer.visit(__FieldVisitor)
+                    deserializer.visit(
+                        __FieldVisitor::<D>{ phantom: PhantomData })
                 }
             }
         ).unwrap(),
@@ -596,7 +669,7 @@ fn deserialize_struct_visitor(
     let field_visitor = deserialize_field_visitor(
         cx,
         builder,
-        field::struct_field_strs(cx, builder, struct_def, field::Direction::Deserialize),
+        field::struct_field_strs(cx, builder, struct_def),
     );
 
     let visit_map_expr = deserialize_map(
@@ -639,11 +712,16 @@ fn deserialize_map(
     let extract_values: Vec<P<ast::Stmt>> = field_names.iter()
         .zip(struct_def.fields.iter())
         .map(|(field_name, field)| {
-            let rename = field::field_rename(field, &field::Direction::Deserialize);
+            let rename = field::field_rename(builder, field);
             let name_str = match (rename, field.node.kind) {
-                (Some(rename), _) => builder.expr().build_lit(P(rename.clone())),
+                (field::Rename::Global(rename), _)
-                (None, ast::NamedField(name, _)) => builder.expr().str(name),
+                    => builder.expr().build_lit(P(rename.clone())),
-                (None, ast::UnnamedField(_)) => panic!("struct contains unnamed fields"),
+                (field::Rename::None, ast::NamedField(name, _))
+                    => builder.expr().str(name),
+                (field::Rename::None, ast::UnnamedField(_))
+                    => panic!("struct contains unnamed fields"),
+                (field::Rename::Format(renames), _)
+                    => builder.expr().str("fixme"),
             };
 
             let missing_expr = if field::default_value(field) {

serde_macros/src/field.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 use syntax::ast;
 use syntax::attr;
 use syntax::ext::base::ExtCtxt;
@@ -5,19 +7,17 @@ use syntax::ptr::P;
 
 use aster;
 
-pub enum Direction {
+pub enum Rename<'a> {
-    Serialize,
+    None,
-    Deserialize,
+    Global(&'a ast::Lit),
+    // Format(HashMap<InternedString, &'a ast::Lit>)
+    Format(HashMap<P<ast::Expr>, &'a ast::Lit>)
 }
 
 pub fn field_rename<'a>(
+    builder: &aster::AstBuilder,
     field: &'a ast::StructField,
-    direction: &Direction,
+) -> Rename<'a> {
-) -> Option<&'a ast::Lit> {
-    let dir_attr = match *direction {
-        Direction::Serialize => "rename_serialize",
-        Direction::Deserialize => "rename_deserialize",
-    };
     field.node.attrs.iter()
         .find(|sa| {
             if let ast::MetaList(ref n, _) = sa.node.value.node {
@@ -30,34 +30,89 @@ pub fn field_rename<'a>(
             if let ast::MetaList(_, ref vals) = sa.node.value.node {
                 attr::mark_used(&sa);
                 vals.iter().fold(None, |v, mi| {
-                    if let ast::MetaNameValue(ref n, ref lit) = mi.node {
+                    match mi.node {
-                        if n == &"rename" || n == &dir_attr {
+                        ast::MetaNameValue(ref n, ref lit) => {
-                            Some(lit)
+                            if n == &"rename" {
+                                Some(Rename::Global(lit))
                             } else {
                                 v
                             }
+                        },
+                        ast::MetaList(ref n, ref items) => {
+                            if n == &"rename" {
+                                let mut m = HashMap::new();
+                                m.extend(
+                                    items.iter()
+                                        .filter_map(
+                                            |item|
+                                            match item.node {
+                                                ast::MetaNameValue(ref n, ref lit) =>
+                                                    Some((// (n.to_owned(), lit)
+                                                        builder.expr().str(n),
+                                                        lit
+                                                        )),
+                                                _ => None
+                                            }));
+                                Some(Rename::Format(m))
                             } else {
                                 v
                             }
+                        },
+                        _ => {v}
+                    }
                 })
             } else {
                 None
             }
         })
+        .unwrap_or(Rename::None)
+}
+
+pub enum FieldLit {
+    Global(P<ast::Expr>),
+    Format{
+        formats: HashMap<P<ast::Expr>, P<ast::Expr>>,
+        default: P<ast::Expr>,
+    }
 }
 
 pub fn struct_field_strs(
     cx: &ExtCtxt,
     builder: &aster::AstBuilder,
     struct_def: &ast::StructDef,
-    direction: Direction,
+) -> Vec<FieldLit> {
-) -> Vec<P<ast::Expr>> {
     struct_def.fields.iter()
         .map(|field| {
-            match field_rename(field, &direction) {
+            match field_rename(builder, field) {
-                Some(rename) => builder.expr().build_lit(P(rename.clone())),
+                Rename::Global(rename) =>
-                None => {
+                    FieldLit::Global(
-                    match field.node.kind {
+                        builder.expr().build_lit(P(rename.clone()))),
+                Rename::Format(renames) => {
+                    let mut res = HashMap::new();
+                    res.extend(
+                        renames.into_iter()
+                            .map(|(k,v)|
+                                 (k, builder.expr().build_lit(P(v.clone())))));
+                    FieldLit::Format{
+                        formats: res,
+                        default: default_field(cx, builder, field.node.kind),
+                    }
+                },
+                Rename::None => {
+                    FieldLit::Global(
+                        default_field(cx, builder, field.node.kind))
+                }
+            }
+        })
+        .collect()
+}
+
+fn default_field(
+    cx: &ExtCtxt,
+    builder: &aster::AstBuilder,
+    kind: ast::StructFieldKind,
+) -> P<ast::Expr> {
+    match kind {
         ast::NamedField(name, _) => {
             builder.expr().str(name)
         }
@@ -66,10 +121,7 @@ pub fn struct_field_strs(
         }
     }
 }
-            }
+
-        })
-        .collect()
-}
 
 pub fn default_value(field: &ast::StructField) -> bool {
     field.node.attrs.iter()

serde_macros/src/ser.rs

@@ -13,7 +13,7 @@ use syntax::ptr::P;
 
 use aster;
 
-use field::{Direction, struct_field_strs};
+use field::{FieldLit, struct_field_strs};
 
 pub fn expand_derive_serialize(
     cx: &mut ExtCtxt,
@@ -517,12 +517,29 @@ fn serialize_struct_visitor<I>(
 {
     let len = struct_def.fields.len();
 
-    let key_exprs = struct_field_strs(cx, builder, struct_def, Direction::Serialize);
+    let key_exprs = struct_field_strs(cx, builder, struct_def);
 
-    let arms: Vec<ast::Arm> = key_exprs.iter()
+    let arms: Vec<ast::Arm> = key_exprs.into_iter()
         .zip(value_exprs)
         .enumerate()
-        .map(|(i, (key_expr, value_expr))| {
+        .map(|(i, (field, value_expr))| {
+            let key_expr = match field {
+                FieldLit::Global(x) => x,
+                FieldLit::Format{formats, default} => {
+                    let arms = formats.iter()
+                        .map(|(fmt, lit)| {
+                            quote_arm!(cx, $fmt => { $lit })
+                        })
+                        .collect::<Vec<_>>();
+                    quote_expr!(cx,
+                        {
+                            match S::fmt() {
+                                $arms,
+                                _ => $default
+                            }
+                        })
+                },
+            };
             quote_arm!(cx,
                 $i => {
                     self.state += 1;

src/de/mod.rs

@@ -113,6 +113,10 @@ pub trait Deserializer {
     {
         self.visit(visitor)
     }
+
+    fn fmt() -> &'static str {
+        ""
+    }
 }
 
 ///////////////////////////////////////////////////////////////////////////////

src/json/de.rs

@@ -463,6 +463,11 @@ impl<Iter> de::Deserializer for Deserializer<Iter>
             Err(self.error(ErrorCode::ExpectedSomeValue))
         }
     }
+
+    #[inline]
+    fn fmt() -> &'static str {
+        "json"
+    }
 }
 
 struct SeqVisitor<'a, Iter: 'a + Iterator<Item=io::Result<u8>>> {

src/json/ser.rs

@@ -256,6 +256,11 @@ impl<W, F> ser::Serializer for Serializer<W, F>
         try!(self.formatter.colon(&mut self.writer));
         value.serialize(self)
     }
+
+    #[inline]
+    fn fmt() -> &'static str {
+        "json"
+    }
 }
 
 pub trait Formatter {

src/json/value.rs

@@ -571,6 +571,11 @@ impl ser::Serializer for Serializer {
 
         Ok(())
     }
+
+    #[inline]
+    fn fmt() -> &'static str {
+        "value"
+    }
 }
 
 pub struct Deserializer {
@@ -677,6 +682,11 @@ impl de::Deserializer for Deserializer {
             None => Ok(value)
         }
     }
+
+    #[inline]
+    fn fmt() -> &'static str {
+        "value"
+    }
 }
 
 struct SeqDeserializer<'a> {

src/ser/mod.rs

@@ -179,6 +179,10 @@ pub trait Serializer {
     fn visit_map_elt<K, V>(&mut self, key: K, value: V) -> Result<(), Self::Error>
         where K: Serialize,
               V: Serialize;
+
+    fn fmt() -> &'static str {
+        ""
+    }
 }
 
 pub trait SeqVisitor {

tests/test_annotations.rs

@@ -21,9 +21,9 @@ struct Rename {
 }
 
 #[derive(Debug, PartialEq, Serialize, Deserialize)]
-struct DirectionRename {
+struct FormatRename {
     a1: i32,
-    #[serde(rename_serialize="a3", rename_deserialize="a4")]
+    #[serde(rename(xml= "a4", json="a5"))]
     a2: i32,
 }
 
@@ -47,11 +47,11 @@ fn test_rename() {
 }
 
 #[test]
-fn test_direction_rename() {
+fn test_format_rename() {
-    let value = DirectionRename { a1: 1, a2: 2 };
+    let value = FormatRename { a1: 1, a2: 2 };
     let serialized_value = json::to_string(&value).unwrap();
-    assert_eq!(serialized_value, "{\"a1\":1,\"a3\":2}");
+    assert_eq!(serialized_value, "{\"a1\":1,\"a5\":2}");
 
-    let deserialized_value = json::from_str("{\"a1\":1,\"a4\":2}").unwrap();
+    let deserialized_value = json::from_str("{\"a1\":1,\"a5\":2}").unwrap();
     assert_eq!(value, deserialized_value);
 }

tests/test_json.rs

@@ -1024,7 +1024,7 @@ fn test_missing_field() {
 fn test_missing_renamed_field() {
     #[derive(Debug, PartialEq, Deserialize)]
     struct Foo {
-        #[serde(rename_deserialize="y")]
+        #[serde(rename="y")]
         x: Option<u32>,
     }
 
@@ -1042,3 +1042,26 @@ fn test_missing_renamed_field() {
     ))).unwrap();
     assert_eq!(value, Foo { x: Some(5) });
 }
+
+#[test]
+fn test_missing_fmt_renamed_field() {
+    #[derive(Debug, PartialEq, Deserialize)]
+    struct Foo {
+        #[serde(rename(json="y", value="z"))]
+        x: Option<u32>,
+    }
+
+    let value: Foo = from_str("{}").unwrap();
+    assert_eq!(value, Foo { x: None });
+
+    let value: Foo = from_str("{\"y\": 5}").unwrap();
+    assert_eq!(value, Foo { x: Some(5) });
+
+    let value: Foo = from_value(Value::Object(treemap!())).unwrap();
+    assert_eq!(value, Foo { x: None });
+
+    let value : Foo = from_value(Value::Object(treemap!(
+        "z".to_string() => Value::I64(5)
+            ))).unwrap();
+    assert_eq!(value, Foo { x: Some(5) });
+}