implement fudge dices, complete with unit tests

lib/dice.c

@@ -22,6 +22,7 @@
 
 #include <stdlib.h>
 #include <string.h>
+#include <stdio.h>
 
 #include "config.h"
 
@@ -39,6 +40,7 @@ extern void yy_delete_buffer(void *b, void *scanner);
 struct dice_
 {
     int consumed;
+    bool fudge;
 
     uint32_t amount;
     uint32_t sides;
@@ -137,6 +139,7 @@ bool dice_set(dice_t d, dice_option_t opt, ...)
     switch (opt) {
     case DICEOPTION_AMOUNT: d->amount = va_arg(lst, uint32_t); break;
     case DICEOPTION_SIDES: d->sides = va_arg(lst, uint32_t); break;
+    case DICEOPTION_FUDGE: d->fudge = va_arg(lst, uint32_t); break;
     case DICEOPTION_ERROR:
     {
         char const *err = va_arg(lst, char const *);
@@ -175,6 +178,12 @@ bool dice_get(dice_t d, dice_option_t opt, ...)
         *ptr = d->error;
     } break;
 
+    case DICEOPTION_FUDGE:
+    {
+        bool *ptr = va_arg(lst, uint32_t*);
+        *ptr = d->fudge;
+    } break;
+
     default: return false;
     }
     va_end(lst);
@@ -182,13 +191,24 @@ bool dice_get(dice_t d, dice_option_t opt, ...)
     return true;
 }
 
+static int dice_roll_fudge(void)
+{
+    static int results[6] = {-1, -1, 0, 0, +1, +1};
+    int idx = arc4random_uniform(sizeof(results)/sizeof(int)) + 1;
+    return results[idx];
+}
+
 int64_t dice_roll(dice_t d)
 {
     int64_t result = 0;
     uint32_t i = 0;
 
     for (i = 0; i < d->amount; i++) {
-        result += arc4random_uniform(d->sides) + 1;
+        if (!d->fudge) {
+            result += arc4random_uniform(d->sides) + 1;
+        } else {
+            result += dice_roll_fudge();
+        }
     }
 
     return result;
@@ -211,7 +231,11 @@ bool dice_evaluate(dice_t d, dice_result_t **res, size_t *reslen)
     }
 
     for (i = 0; i < d->amount; i++) {
-        r[i].result = arc4random_uniform(d->sides) + 1;
+        if (!d->fudge) {
+            r[i].result = arc4random_uniform(d->sides) + 1;
+        } else {
+            r[i].result = dice_roll_fudge();
+        }
     }
 
     *reslen = len;

lib/dice.h

@@ -53,6 +53,12 @@ typedef enum {
      * set: char const *
      */
     DICEOPTION_ERROR,
+
+    /* Whether the dice has no amount but is a fudge dice instead.
+     * get: uint32_t *
+     * set: uint32_t
+     */
+    DICEOPTION_FUDGE,
 } dice_option_t;
 
 /* Creates a new dice object that is not initialised yet.

lib/dice_lexer.l

@@ -22,4 +22,11 @@ extern void dice_update_consumed(dice_t d, int off);
     dice_update_consumed(d, yyleng);
     return TOK_DICESEP;
 }
+
+[fF] {
+    dice_t d = yyget_extra(yyscanner);
+    dice_update_consumed(d, yyleng);
+    return TOK_FUDGE;
+}
+
 %%

lib/dice_parse.y

@@ -25,7 +25,7 @@ int yywrap(void)
     double number;
 }
 
-%token TOK_DICESEP
+%token TOK_DICESEP TOK_FUDGE
 %token  <integer>           TOK_INTEGER
 
 %%
@@ -42,6 +42,20 @@ dice:           TOK_INTEGER TOK_DICESEP TOK_INTEGER
                     dice_set(dice, DICEOPTION_AMOUNT, 1);
                     dice_set(dice, DICEOPTION_SIDES, $2);
 
+                    YYACCEPT;
+                }
+        |       TOK_DICESEP TOK_FUDGE
+                {
+                    dice_set(dice, DICEOPTION_AMOUNT, 1L);
+                    dice_set(dice, DICEOPTION_FUDGE, 1L);
+
+                    YYACCEPT;
+                }
+        |       TOK_INTEGER TOK_DICESEP TOK_FUDGE
+                {
+                    dice_set(dice, DICEOPTION_AMOUNT, $1);
+                    dice_set(dice, DICEOPTION_FUDGE, 1L);
+
                     YYACCEPT;
                 }
         ;