intern symbols using hash table

include/picconf.h

@@ -13,6 +13,7 @@
 #define PIC_STACK_SIZE 1024
 #define PIC_IREP_SIZE 256
 #define PIC_GLOBALS_SIZE 1024
+#define PIC_SYM_TBL_SIZE 128
 
 /* enable all debug flags */
 #define DEBUG 1

include/picrin.h

@@ -27,6 +27,8 @@ typedef struct {
   pic_value sADD, sSUB, sMUL, sDIV;
   struct pic_env *global_env;
 
+  struct sym_tbl *sym_tbl;
+
   pic_value *globals;
   size_t glen, gcapa;
   struct pic_irep **irep;

include/picrin/symbol.h

@@ -0,0 +1,12 @@
+#ifndef SYMBOL_H__
+#define SYMBOL_H__
+
+struct sym_tbl {
+  pic_value tbl[PIC_SYM_TBL_SIZE];
+  size_t size;
+};
+
+struct sym_tbl * sym_tbl_new();
+pic_value sym_tbl_get(struct sym_tbl *, const char *);
+
+#endif