split pre-method into parsePreMethod

src/ast.zig

@@ -22,11 +22,18 @@ pub const ParamDecl = struct {
     typ: Token,
 };
 
+pub const MethodData = struct {
+    variable: Token,
+    typ: Token,
+    mutable: bool,
+};
+
 pub const FnDecl = struct {
     func_name: Token,
     params: ParamList,
     return_type: Token,
     body: StmtList,
+    method: ?*MethodData,
 };
 
 pub const SingleConst = struct {

src/parser.zig

@@ -139,6 +139,7 @@ pub const Parser = struct {
         params: ast.ParamList,
         return_type: Token,
         block: ast.StmtList,
+        method: ?*ast.MethodData,
     ) !*ast.Node {
         var node = try self.allocator.create(Node);
         node.* = Node{
@@ -147,6 +148,7 @@ pub const Parser = struct {
                 .params = params,
                 .return_type = return_type,
                 .body = block,
+                .method = method,
             },
         };
         return node;
@@ -389,22 +391,12 @@ pub const Parser = struct {
         var param_list = ast.ParamList.init(self.allocator);
         errdefer param_list.deinit();
 
+        var method: ?*ast.MethodData = null;
+
         _ = try self.consumeSingle(.Fn);
 
         if (self.check(.LeftParen)) {
-            _ = try self.consumeSingle(.LeftParen);
-
-            var mutable_ref: bool = false;
-            const method_var = try self.consumeSingle(.Identifier);
-
-            if (self.check(.Mut)) {
-                _ = try self.consumeSingle(.Mut);
-                mutable_ref = true;
-            }
-
-            const method_typ = try self.consumeSingle(.Identifier);
-
-            _ = try self.consumeSingle(.RightParen);
+            method = try self.parsePreMethod();
         }
 
         const name = try self.consumeSingle(.Identifier);
@@ -435,7 +427,35 @@ pub const Parser = struct {
         }
 
         var block_node = try self.parseBlock();
-        return try self.mkFnDecl(name, param_list, return_type, block_node.Block);
+        return try self.mkFnDecl(name, param_list, return_type, block_node.Block, method);
+    }
+
+    /// parse the (v [mut] T) part of the method (defined here
+    /// as a premethod)
+    fn parsePreMethod(self: *@This()) !?*ast.MethodData {
+        _ = try self.consumeSingle(.LeftParen);
+
+        var mutable_ref: bool = false;
+        const variable = try self.consumeSingle(.Identifier);
+
+        if (self.check(.Mut)) {
+            _ = try self.consumeSingle(.Mut);
+            mutable_ref = true;
+        }
+
+        const typ = try self.consumeSingle(.Identifier);
+
+        _ = try self.consumeSingle(.RightParen);
+
+        // create method data and assign the values we got into it
+        var method = try self.allocator.create(ast.MethodData);
+        method.* = ast.MethodData{
+            .variable = variable,
+            .typ = typ,
+            .mutable = mutable_ref,
+        };
+
+        return method;
     }
 
     fn parseConstDecl(self: *@This()) !*Node {