Use C++ stdlib for random number generation

test/helpers/random_helpers.cc

@@ -1,22 +1,40 @@
 #include <string>
 #include <vector>
-#include <stdlib.h>
+#include <random>
+#include <time.h>
 
 using std::string;
 using std::vector;
 
+static std::default_random_engine engine;
+
+unsigned get_time_as_seed() {
+  return time(nullptr);
+}
+
+void random_reseed(unsigned seed) {
+  engine.seed(seed);
+}
+
+unsigned random_unsigned() {
+  return std::uniform_int_distribution<unsigned>()(engine);
+}
+
+unsigned random_unsigned(unsigned max) {
+  return std::uniform_int_distribution<unsigned>(0, max - 1)(engine);
+}
+
 static string random_string(char min, char max) {
   string result;
-  size_t length = random() % 12;
+  size_t length = random_unsigned(12);
   for (size_t i = 0; i < length; i++) {
-    char inserted_char = min + (random() % (max - min));
-    result += inserted_char;
+    result += (min + random_unsigned(max - min));
   }
   return result;
 }
 
 static string random_char(string characters) {
-  size_t index = random() % characters.size();
+  size_t index = random_unsigned(characters.size());
   return string() + characters[index];
 }
 
@@ -24,7 +42,7 @@ string random_words(size_t count) {
   string result;
   bool just_inserted_word = false;
   for (size_t i = 0; i < count; i++) {
-    if (random() % 10 < 6) {
+    if (random_unsigned(10) < 6) {
       result += random_char("!(){}[]<>+-=");
     } else {
       if (just_inserted_word)
@@ -37,5 +55,5 @@ string random_words(size_t count) {
 }
 
 string select_random(const vector<string> &list) {
-  return list[random() % list.size()];
+  return list[random_unsigned(list.size())];
 }

test/helpers/random_helpers.h

@@ -4,6 +4,10 @@
 #include <string>
 #include <vector>
 
+unsigned get_time_as_seed();
+void random_reseed(unsigned);
+unsigned random_unsigned();
+unsigned random_unsigned(unsigned max);
 std::string random_words(size_t count);
 std::string select_random(const std::vector<std::string> &);
 

test/integration/real_grammars.cc

@@ -75,9 +75,9 @@ for (auto &language_name : test_languages) {
       set<pair<size_t, string>> insertions;
 
       for (size_t i = 0; i < 60; i++) {
-        size_t edit_position = random() % utf8_char_count(entry.input);
-        size_t deletion_size = random() % (utf8_char_count(entry.input) - edit_position);
-        string inserted_text = random_words(random() % 4 + 1);
+        size_t edit_position = random_unsigned(utf8_char_count(entry.input));
+        size_t deletion_size = random_unsigned(utf8_char_count(entry.input) - edit_position);
+        string inserted_text = random_words(random_unsigned(4) + 1);
 
         if (insertions.insert({edit_position, inserted_text}).second) {
           string description = "\"" + inserted_text + "\" at " + to_string(edit_position);

test/tests.cc

@@ -1,4 +1,5 @@
 #include "test_helper.h"
+#include "helpers/random_helpers.h"
 
 int main(int argc, char *argv[]) {
   int seed;
@@ -6,11 +7,11 @@ int main(int argc, char *argv[]) {
   if (seed_env) {
     seed = atoi(seed_env);
   } else {
-    seed = time(nullptr);
+    seed = get_time_as_seed();
   }
 
   printf("Random seed: %d\n", seed);
-  srandom(seed);
+  random_reseed(seed);
 
   return bandit::run(argc, argv);
 }