Address listed flaws in implementation

code/compiler/02/ast.hpp

@@ -24,6 +24,16 @@ struct branch {
 
 using branch_ptr = std::unique_ptr<branch>;
 
+struct constructor {
+    std::string name;
+    std::vector<std::string> types;
+
+    constructor(std::string n, std::vector<std::string> ts)
+        : name(std::move(n)), types(std::move(ts)) {}
+};
+
+using constructor_ptr = std::unique_ptr<constructor>;
+
 struct definition {
     virtual ~definition() = default;
 };
@@ -108,3 +118,11 @@ struct definition_defn : public definition {
 
     }
 };
+
+struct definition_data : public definition {
+    std::string name;
+    std::vector<constructor_ptr> constructors;
+
+    definition_data(std::string n, std::vector<constructor_ptr> cs)
+        : name(std::move(n)), constructors(std::move(cs)) {}
+};

code/compiler/02/main.cpp

@@ -2,7 +2,7 @@
 #include "parser.hpp"
 
 void yy::parser::error(const std::string& msg) {
-    std::cout << "An error occured: " << std::endl;
+    std::cout << "An error occured: " << msg << std::endl;
 }
 
 extern std::vector<definition_ptr> program;

code/compiler/02/parser.y

@@ -35,10 +35,12 @@ extern yy::parser::symbol_type yylex();
 %type <std::vector<std::string>> lowercaseParams
 %type <std::vector<definition_ptr>> program definitions
 %type <std::vector<branch_ptr>> branches
+%type <std::vector<constructor_ptr>> constructors
 %type <ast_ptr> aAdd aMul case app appBase
-%type <definition_ptr> definition
+%type <definition_ptr> definition defn data 
 %type <branch_ptr> branch
 %type <pattern_ptr> pattern
+%type <constructor_ptr> constructor
 
 %start program
 
@@ -54,6 +56,11 @@ definitions
     ;
 
 definition
+    : defn { $$ = std::move($1); }
+    | data { $$ = std::move($1); }
+    ;
+
+defn
     : DEFN LID lowercaseParams EQUAL OCURLY aAdd CCURLY
         { $$ = definition_ptr(
             new definition_defn(std::move($2), std::move($3), std::move($6))); }
@@ -109,3 +116,20 @@ pattern
     | UID lowercaseParams
         { $$ = pattern_ptr(new pattern_constr(std::move($1), std::move($2))); }
     ;
+
+data
+    : DATA UID EQUAL OCURLY constructors CCURLY
+        { $$ = definition_ptr(new definition_data(std::move($2), std::move($5))); }
+    ;
+
+constructors
+    : constructors COMMA constructor { $$ = std::move($1); $$.push_back(std::move($3)); }
+    | constructor
+        { $$ = std::vector<constructor_ptr>(); $$.push_back(std::move($1)); }
+    ;
+
+constructor
+    : UID lowercaseParams
+        { $$ = constructor_ptr(new constructor(std::move($1), std::move($2))); }
+    ;
+

content/blog/02_compiler_parsing.md

@@ -288,12 +288,6 @@ wrong:
 ./a.out
 }{
 ```
-We are told an error occured. Excellent!
-
-There's still a number of flaws with our parser:
-
-2. We don't print errors properly.
-3. We also have no way of verifying our tree was built correctly.
-1. We're missing the data declaration, from both our C++ source and from the Bison grammars. 
-
-This post is getting a little long, so we will revisit the parser in the next one. See you then!
+We are told an error occured. Excellent! We're not really sure what our tree looks like, though.
+We just know there's __stuff__ in the list of definitions. We will revisit our trees
+in the next post, adding code to print them and to verify that our programs make some sense.