Add a number implementation struct to libab.

include/libabacus.h

@@ -7,6 +7,7 @@
 #include "parser.h"
 #include "result.h"
 #include "table.h"
+#include "number.h"
 
 /**
  * The main struct of libabacus,
@@ -29,6 +30,10 @@ struct libab_s {
      * things like functions and operators.
      */
     libab_table table;
+    /**
+     * The number implementation used by this instance.
+     */
+    libab_number_impl impl;
 };
 
 typedef struct libab_s libab;

include/number.h

@@ -0,0 +1,37 @@
+#ifndef LIBABACUS_NUMBER_H
+#define LIBABACUS_NUMBER_H
+
+typedef void (*libab_num_function)(void*, void*, void*);
+typedef void (*libab_num_function_unary)(void*, void*);
+
+/**
+ * Struct that holds information
+ * about the implementation of numbers
+ * that is being used by libab. This is not
+ * assumed or inferred, and it's necessary to
+ * provide all of these definitions.
+ */
+struct libab_number_impl_s {
+    /**
+     * The function used to allocate a number.
+     */
+    void* (*allocate)();
+    /**
+     * The function used to free a number.
+     */
+    void (*free)(void*);
+    /**
+     * The function used to construct a number
+     * out of a string.
+     */
+    void* (*parse)(const char*);
+    /**
+     * A function to copy the value of one number
+     * into the value of another.
+     */
+    void (*copy)(void*, void*);
+};
+
+typedef struct libab_number_impl_s libab_number_impl;
+
+#endif