Add switch case statement

ast.cpp

@@ -26,6 +26,8 @@ enum Ast_Kind: U32{
   AST_LENGTH_OF,
   AST_ALIGN_OF,
 
+  AST_SWITCH,
+  AST_SWITCH_CASE,
   AST_VAR_UNPACK,
   AST_BREAK,
   AST_COMPOUND,
@@ -174,6 +176,18 @@ struct Ast_Array: Ast_Expr{
   Ast_Expr *expr;
 };
 
+struct Ast_Switch_Case: Ast{
+  Array<Ast_Expr *> labels;
+  Ast_Scope *scope;
+  B32 fallthrough;
+};
+
+struct Ast_Switch: Ast{
+  Ast_Expr *value;
+  Array<Ast_Switch_Case *> cases;
+  Ast_Scope *default_scope;
+};
+
 /*
 How does current declaration order resolver works:
 * First we put all the global declarations into the global scope (when parsing) all unresolved
@@ -251,6 +265,18 @@ struct Ast_Decl: Ast{
   result->pos     = ipos;                                              \
   result->di      = ++pctx->unique_ids
 
+#define MAKE_AST(T,kind,pos,flags) (T *)ast_new(sizeof(T), kind, pos, flags)
+function Ast *
+ast_new(SizeU size, Ast_Kind kind, Token *pos, Ast_Flag flags = 0){
+  Ast *result = (Ast *)exp_alloc(pctx->perm, size, AF_ZeroMemory);
+  result->flags   = flags;
+  result->kind    = kind;
+  result->parent_scope = pctx->currently_parsed_scope;
+  result->pos     = pos;
+  result->di      = ++pctx->unique_ids;
+  return result;
+}
+
 function Ast_Atom *
 ast_str(Token *pos, Intern_String string){
   AST_NEW(Atom, VALUE, pos, AST_EXPR | AST_ATOM);