libsyntax: abstract most of the deriving boilerplate into a simpler(r) interface.

Pulls out many of the common patterns from the Eq and Clone deriving code (and
invents a few of its own), so that deriving instances are very easy to write
for a certain class of traits. (Basically, those which don't have parameters
and where all methods only take arguments of type `&Self` and return either
`Self` or types with no parameters.)

Author: huonw

src/libsyntax/ext/deriving/clone.rs

@@ -55,7 +55,8 @@ fn create_derived_clone_impl(cx: @ext_ctxt,
         cx.ident_of(~"Clone"),
     ];
     let trait_path = build::mk_raw_path_global(span, trait_path);
-    create_derived_impl(cx, span, type_ident, generics, methods, trait_path, opt_vec::Empty)
+    create_derived_impl(cx, span, type_ident, generics, methods, trait_path,
+                        opt_vec::Empty, opt_vec::Empty)
 }
 // Creates a method from the given expression conforming to the signature of
 // the `clone` method.
@@ -219,7 +220,7 @@ fn expand_deriving_clone_tuple_struct_method(cx: @ext_ctxt,
     let mut subcalls = ~[];
     for uint::range(0, struct_def.fields.len()) |i| {
         // Create the expression for this field.
-        let field_ident = cx.ident_of(~"__self" + i.to_str());
+        let field_ident = cx.ident_of(~"__self_" + i.to_str());
         let field = build::mk_path(cx, span, ~[ field_ident ]);
 
         // Call the substructure method.
@@ -262,7 +263,7 @@ fn expand_deriving_clone_enum_method(cx: @ext_ctxt,
         let mut subcalls = ~[];
         for uint::range(0, variant_arg_count(cx, span, variant)) |j| {
             // Create the expression for this field.
-            let field_ident = cx.ident_of(~"__self" + j.to_str());
+            let field_ident = cx.ident_of(~"__self_" + j.to_str());
             let field = build::mk_path(cx, span, ~[ field_ident ]);
 
             // Call the substructure method.

src/libsyntax/ext/deriving/decodable.rs

@@ -81,7 +81,8 @@ fn create_derived_decodable_impl(
         generics,
         methods,
         trait_path,
-        generic_ty_params
+        generic_ty_params,
+        opt_vec::Empty
     )
 }
 

src/libsyntax/ext/deriving/encodable.rs

@@ -81,7 +81,8 @@ fn create_derived_encodable_impl(
         generics,
         methods,
         trait_path,
-        generic_ty_params
+        generic_ty_params,
+        opt_vec::Empty
     )
 }
 
@@ -306,7 +307,7 @@ fn expand_deriving_encodable_enum_method(
         let variant_arg_len = variant_arg_count(cx, span, variant);
         for uint::range(0, variant_arg_len) |j| {
             // Create the expression for this field.
-            let field_ident = cx.ident_of(~"__self" + j.to_str());
+            let field_ident = cx.ident_of(~"__self_" + j.to_str());
             let field = build::mk_path(cx, span, ~[ field_ident ]);
 
             // Call the substructure method.

src/libsyntax/ext/deriving/eq.rs

@@ -131,7 +131,7 @@ fn create_derived_eq_impl(cx: @ext_ctxt,
         cx.ident_of(~"Eq")
     ];
     let trait_path = build::mk_raw_path_global(span, trait_path);
-    create_derived_impl(cx, span, type_ident, generics, methods, trait_path, opt_vec::Empty)
+    create_derived_impl(cx, span, type_ident, generics, methods, trait_path, opt_vec::Empty, [])
 }
 
 fn call_substructure_eq_method(cx: @ext_ctxt,
@@ -338,13 +338,13 @@ fn expand_deriving_eq_enum_method(cx: @ext_ctxt,
         let mut matching_body_expr = None;
         for uint::range(0, variant_arg_count(cx, span, self_variant)) |i| {
             // Create the expression for the other field.
-            let other_field_ident = cx.ident_of(~"__other" + i.to_str());
+            let other_field_ident = cx.ident_of(~"__other_" + i.to_str());
             let other_field = build::mk_path(cx,
                                              span,
                                              ~[ other_field_ident ]);
 
             // Create the expression for this field.
-            let self_field_ident = cx.ident_of(~"__self" + i.to_str());
+            let self_field_ident = cx.ident_of(~"__self_" + i.to_str());
             let self_field = build::mk_path(cx, span, ~[ self_field_ident ]);
 
             // Call the substructure method.
@@ -456,10 +456,10 @@ fn expand_deriving_eq_struct_tuple_method(cx: @ext_ctxt,
     // Create comparison expression, comparing each of the fields
     let mut match_body = None;
     for fields.eachi |i, _| {
-        let other_field_ident = cx.ident_of(other_str + i.to_str());
+        let other_field_ident = cx.ident_of(fmt!("%s_%u", other_str, i));
         let other_field = build::mk_path(cx, span, ~[ other_field_ident ]);
 
-        let self_field_ident = cx.ident_of(self_str + i.to_str());
+        let self_field_ident = cx.ident_of(fmt!("%s_%u", self_str, i));
         let self_field = build::mk_path(cx, span, ~[ self_field_ident ]);
 
         call_substructure_eq_method(cx, span, self_field, other_field,