grammar and small changes

Wyst.g4

@@ -1,9 +1,28 @@
 grammar Wyst;
 
-WS : [ \t\r\n]+ -> skip;
+WS: [ \t\r\n]+ -> skip;
+NUMBER: [1-9][0-9]* | '0';
+HEX: '0x' [a-fA-F0-9]*;
+IDENTIFIER: [a-zA-Z_] ([a-zA-Z0-9] | '::')*;
+MATH: '+' | '-' | '*' | '/';
+fragment ESC: '\\' ['"\\] ;
+STRING: '"' (ESC | ~["\\])* '"';
+round_def: '(' (var_def (',' var_def)* ','?)? ')';
+func_def: IDENTIFIER IDENTIFIER round_def code_block;
+var_def: IDENTIFIER IDENTIFIER;
+var_def_set: var_def '=' expr;
+asm: '%' IDENTIFIER expr (',' expr)* ';';
 
-expr: IDENTIFIER
-    ;
+expr:
+    (   NUMBER |
+        HEX |
+        IDENTIFIER |
+        STRING
+    ) (MATH expr)*;
 
-INT: [0-9]+;
-IDENTIFIER: [a-zA-Z_] ([a-zA-Z0-9] | '::')*;
+code_block: '{' ((
+    expr |
+    var_def |
+    var_def_set
+) ';')* '}';
+top: (asm|func_def)*;