From 97eba132276c0fb391f38b4ab997c719ffdc3f31 Mon Sep 17 00:00:00 2001
From: Lukas Krickl <lukas@krickl.dev>
Date: Sat, 18 Nov 2023 14:37:17 +0100
Subject: [PATCH] WIP: Expression parsing

---
 doc/ulas.man   | 16 ++++++++++++++++
 include/ulas.h | 11 ++++++++++-
 2 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/doc/ulas.man b/doc/ulas.man
index 9efe742..83a566b 100644
--- a/doc/ulas.man
+++ b/doc/ulas.man
@@ -51,6 +51,22 @@ name ; will be replaced with 'value'
 .SH ASSEMBLY SYNTAX
 
 
+
+.SH EXPRESSION SYNTAX
+
+Expressions are written in Reverse Polish Notation style and evaluated based on their expected data type.
+For example when an expression expects an int type the expression will assume all values that are pushed to it 
+are integers.
+
+.SH ASSEMBLY DIRECTIVES 
+
+During assembly sometimes it is required to set certain parameters of the assembler such as the base address (represented by the $@ symbol in expressions).
+
+Valid directives:
+
+  \.org <expression>  
+    Sets the base address
+
 .SH EXAMPLES
  
 .SH SEE ALSO
diff --git a/include/ulas.h b/include/ulas.h
index f026f2e..1798b3f 100644
--- a/include/ulas.h
+++ b/include/ulas.h
@@ -218,7 +218,7 @@ struct ulas_sym {
  * -1 denotes a NULL value
  */
 
-enum ulas_exprs { ULAS_EXPUNARY, ULAS_EXPBINARY, ULAS_EXPLITERAL };
+enum ulas_exprs { ULAS_EXPUN, ULAS_EXPBIN, ULAS_EXPLIT, ULAS_EXPGRP };
 
 struct ulas_expun {
   long expr;
@@ -235,10 +235,19 @@ struct ulas_explit {
   long tok;
 };
 
+struct ulas_expgrp {
+  // points to the first expression 
+  // in this group 
+  long expr;
+  // how many expressions belong to the group
+  long len;
+};
+
 union ulas_expval {
   struct ulas_expun un;
   struct ulas_expbin bin;
   struct ulas_explit lit;
+  struct ulas_expgrp grp;
 };
 
 struct ulas_expr {
-- 
2.30.2