From 437a776d78bda8ab9143ff3785af178c07820f72 Mon Sep 17 00:00:00 2001
From: Krzosa Karol <krzosa.karol@gmail.com>
Date: Tue, 31 May 2022 13:10:56 +0200
Subject: [PATCH] Folding constant enum access into constant int value

---
 ccodegen.cpp     | 16 ++++++++++++----
 enums.kl         | 12 +++++++++++-
 new_ast.cpp      | 10 ++++++++++
 new_type.cpp     |  7 ++++++-
 typechecking.cpp | 43 ++++++++++++++++++++++++++++++++-----------
 5 files changed, 71 insertions(+), 17 deletions(-)

diff --git a/ccodegen.cpp b/ccodegen.cpp
index e3f1ad8..f1caa9f 100644
--- a/ccodegen.cpp
+++ b/ccodegen.cpp
@@ -103,10 +103,15 @@ gen_expr(Ast_Expr *ast){
     CASE(BINARY, Binary){
       if(node->op == TK_Dot){
         Sym *sym = resolved_get(node->left);
-        gen_expr(node->left);
-        if(sym->type->kind == TYPE_POINTER) gen("->");
-        else gen(".");
-        gen_expr(node->right);
+        if(sym->kind == SYM_CONST){
+          gen("%lld", sym->int_val);
+        }
+        else{
+          gen_expr(node->left);
+          if(sym->type->kind == TYPE_POINTER) gen("->");
+          else gen(".");
+          gen_expr(node->right);
+        }
       }
       else{
         gen("(");
@@ -305,6 +310,9 @@ gen_ast(Ast *ast){
       else if(sym->type == type_string){
         gen("String %s = LIT(\"%s\");", node->name.str, sym->intern_val.str);
       }
+      else if(sym->type->kind == TYPE_ENUM){
+        gen("enum { %s = %lld };", node->name.str, sym->int_val);
+      }
       else if(sym->type == type_type){
         if(sym->type_val->kind == TYPE_STRUCT){
           Ast_Struct *agg = (Ast_Struct *)sym->type_val->ast;
diff --git a/enums.kl b/enums.kl
index 8678ad0..79cf7c5 100644
--- a/enums.kl
+++ b/enums.kl
@@ -1,5 +1,15 @@
 
+Thing :: struct
+  len: int
+
+thing: Thing
+access := thing.len
+
+
 Allocator_Kind :: enum
   Null
   Arena
-  Heap = Arena
+  Heap
+
+
+kind := Allocator_Kind.Heap
\ No newline at end of file
diff --git a/new_ast.cpp b/new_ast.cpp
index 6b08660..88b0fb9 100644
--- a/new_ast.cpp
+++ b/new_ast.cpp
@@ -593,4 +593,14 @@ query_struct(Ast_Struct *agg, Intern_String string){
     }
   }
   return 0;
+}
+
+function Ast_Enum_Member *
+query_enum(Ast_Enum *enu, Intern_String string){
+  For(enu->members){
+    if(it->name == string){
+      return it;
+    }
+  }
+  return 0;
 }
\ No newline at end of file
diff --git a/new_type.cpp b/new_type.cpp
index 3cf1404..542593f 100644
--- a/new_type.cpp
+++ b/new_type.cpp
@@ -89,6 +89,12 @@ is_struct(Ast_Resolved_Type *type){
   return result;
 }
 
+function B32
+is_enum(Ast_Resolved_Type *type){
+  B32 result = type->kind == TYPE_ENUM;
+  return result;
+}
+
 function B32
 is_pointer(Ast_Resolved_Type *type){
   B32 result = type->kind == TYPE_POINTER;
@@ -183,7 +189,6 @@ type_incomplete(Ast *ast){
   return result;
 }
 
-//Array<Ast_Resolved_Member> members
 function void
 type_complete(Ast_Resolved_Type *type){
   if(type->kind == TYPE_COMPLETING){
diff --git a/typechecking.cpp b/typechecking.cpp
index c0b678a..905b6f7 100644
--- a/typechecking.cpp
+++ b/typechecking.cpp
@@ -607,21 +607,24 @@ resolve_expr(Ast_Expr *ast, Ast_Resolved_Type *expected_type, Sym *const_sym){
         //        second part requires searching through a struct
         // resolve.x.y
         Operand resolved_ident = resolve_expr(node->left);
-        // @copy_paste
         Ast_Resolved_Type *type = resolved_ident.type;
+        if(type == type_type){
+          type = resolved_ident.type_val;
+        }
+        // @copy_paste
         if(is_pointer(type)){
           type = type->base;
         }
         type_complete(type);
-        if(!is_struct(type)){
-          parsing_error(node->pos, "Trying to access inside a value that is not a struct");
+        if(!(is_struct(type) || is_enum(type))){
+          parsing_error(node->pos, "Trying to access inside a value that is not a struct or enum");
         }
         sym_new_resolved(SYM_VAR, {}, resolved_ident.type, {}, node->left);
 
         // This happens only on binary nodes which further chain with dots and require lookups
         // x.resolve.y
         Ast_Binary *binary = (Ast_Binary *)node->right;
-        for(; !is_ident(binary); binary=(Ast_Binary *)binary->right){
+        for(;!is_ident(binary); binary=(Ast_Binary *)binary->right){
           assert(is_ident(binary->left));
           Ast_Atom *ident = (Ast_Atom *)binary->left;
           assert(is_binary(binary));
@@ -648,13 +651,31 @@ resolve_expr(Ast_Expr *ast, Ast_Resolved_Type *expected_type, Sym *const_sym){
         // x.y.resolve
         // @copy_paste
         Ast_Atom *ident = (Ast_Atom *)binary;
-        Ast_Struct *agg = (Ast_Struct *)type->ast;
-        Ast *query = query_struct(agg, ident->intern_val);
-        if(query){
-          Sym *sym = resolved_get(query);
-          result = operand(sym);
-          sym_new_resolved(SYM_VAR, {}, sym->type, {}, ident);
-        } else parsing_error(ident->pos, "No such member in struct");
+        if(is_enum(type)){
+          Ast_Enum *enu = (Ast_Enum *)type->ast;
+          Ast_Enum_Member *query = query_enum(enu, ident->intern_val);
+          if(query){
+            Sym *resolved = resolved_get(query);
+            assert(resolved);
+            // @warning: rewrite into a constant
+            {
+              sym_new_resolved(SYM_CONST, {}, resolved->type, resolved->value, node->left);
+              node->right = 0;
+            }
+            result = operand(resolved);
+          }
+        }
+        else if(is_struct(type)){
+          Ast_Struct *agg = (Ast_Struct *)type->ast;
+          Ast *query = query_struct(agg, ident->intern_val);
+          if(query){
+            Sym *sym = resolved_get(query);
+            assert(sym);
+            result = operand(sym);
+            sym_new_resolved(SYM_VAR, {}, sym->type, {}, ident);
+          } else parsing_error(ident->pos, "No such member in struct");
+        }
+        else parsing_error(ident->pos, "Trying to [.] access a value that is not [Enum] or [Struct]");
 
       }
       else{