#1 - Randomization WiP.

CMakeLists.txt

@@ -1,7 +1,5 @@
 cmake_minimum_required(VERSION 3.6)
 
-set(OUTPUT_LOCATION ${CMAKE_CURRENT_LIST_DIR}/out/)
-
 add_subdirectory(libcron)
 add_subdirectory(test)
 

libcron/CMakeLists.txt

@@ -13,18 +13,20 @@ add_library(${PROJECT_NAME}
 		include/libcron/Cron.h
 		include/libcron/CronClock.h
 		include/libcron/CronData.h
+		include/libcron/CronRandomization.h
 		include/libcron/CronSchedule.h
 		include/libcron/DateTime.h
 		include/libcron/Task.h
 		include/libcron/TimeTypes.h
 		src/CronClock.cpp
 		src/CronData.cpp
+		src/CronRandomization.cpp
 		src/CronSchedule.cpp
 		src/Task.cpp)
 
 target_include_directories(${PROJECT_NAME}
 		PRIVATE ${CMAKE_CURRENT_LIST_DIR}/externals/date/include
-		PUBLIC ${CMAKE_CURRENT_LIST_DIR}/include)
+		PUBLIC include)
 
 set_target_properties(${PROJECT_NAME} PROPERTIES
         ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/out"

libcron/include/libcron/CronData.h

@@ -11,9 +11,12 @@ namespace libcron
     class CronData
     {
         public:
+            static const std::array<Months, 7> months_with_31;
+
             static CronData create(const std::string& cron_expression);
 
             CronData();
+
             CronData(const CronData&) = default;
 
             bool is_valid() const
@@ -61,6 +64,7 @@ namespace libcron
             static bool has_any_in_range(const std::set<T>& set, uint8_t low, uint8_t high)
             {
                 bool found = false;
+
                 for (auto i = low; !found && i <= high; ++i)
                 {
                     found |= set.find(static_cast<T>(i)) != set.end();
@@ -69,8 +73,10 @@ namespace libcron
                 return found;
             }
 
-        private:
+            template<typename T>
+            bool convert_from_string_range_to_number_range(const std::string& range, std::set<T>& numbers);
 
+        private:
             void parse(const std::string& cron_expression);
 
             template<typename T>
@@ -142,6 +148,7 @@ namespace libcron
         for (const auto& name : names)
         {
             std::regex m(name, std::regex_constants::ECMAScript | std::regex_constants::icase);
+
             for (auto& part : parts)
             {
                 std::string replaced;
@@ -155,7 +162,6 @@ namespace libcron
         }
 
         return process_parts(parts, numbers);
-
     }
 
     template<typename T>
@@ -163,60 +169,9 @@ namespace libcron
     {
         bool res = true;
 
-        T left;
-        T right;
-        uint8_t step_start;
-        uint8_t step;
-
         for (const auto& p : parts)
         {
-            if (p == "*" || p == "?")
+            res &= convert_from_string_range_to_number_range(p, numbers);
-            {
-                // We treat the ignore-character '?' the same as the full range being allowed.
-                add_full_range<T>(numbers);
-            }
-            else if (is_number(p))
-            {
-                res &= add_number<T>(numbers, std::stoi(p));
-            }
-            else if (get_range<T>(p, left, right))
-            {
-                // A range can be written as both 1-22 or 22-1, meaning totally different ranges.
-                // First case is 1...22 while 22-1 is only four hours: 22, 23, 0, 1.
-                if (left <= right)
-                {
-                    for (auto v = value_of(left); v <= value_of(right); ++v)
-                    {
-                        res &= add_number(numbers, v);
-                    }
-                }
-                else
-                {
-                    // 'left' and 'right' are not in value order. First, get values between 'left' and T::Last, inclusive
-                    for (auto v = value_of(left); v <= value_of(T::Last); ++v)
-                    {
-                        res &= add_number(numbers, v);
-                    }
-
-                    // Next, get values between T::First and 'right', inclusive.
-                    for (auto v = value_of(T::First); v <= value_of(right); ++v)
-                    {
-                        res &= add_number(numbers, v);
-                    }
-                }
-            }
-            else if (get_step<T>(p, step_start, step))
-            {
-                // Add from step_start to T::Last with a step of 'step'
-                for (auto v = step_start; v <= value_of(T::Last); v += step)
-                {
-                    res &= add_number(numbers, v);
-                }
-            }
-            else
-            {
-                res = false;
-            }
         }
 
         return res;
@@ -263,7 +218,8 @@ namespace libcron
         if (std::regex_match(s.begin(), s.end(), match, range))
         {
             int raw_start;
-            if(match[1].str() == "*")
+
+            if (match[1].str() == "*")
             {
                 raw_start = value_of(T::First);
             }
@@ -326,5 +282,64 @@ namespace libcron
                && is_between(high, value_of(T::First), value_of(T::Last));
     }
 
+    template<typename T>
+    bool CronData::convert_from_string_range_to_number_range(const std::string& range, std::set<T>& numbers)
+    {
+        T left;
+        T right;
+        uint8_t step_start;
+        uint8_t step;
 
+        bool res = true;
+
+        if (range == "*" || range == "?")
+        {
+            // We treat the ignore-character '?' the same as the full range being allowed.
+            add_full_range<T>(numbers);
+        }
+        else if (is_number(range))
+        {
+            res = add_number<T>(numbers, std::stoi(range));
+        }
+        else if (get_range<T>(range, left, right))
+        {
+            // A range can be written as both 1-22 or 22-1, meaning totally different ranges.
+            // First case is 1...22 while 22-1 is only four hours: 22, 23, 0, 1.
+            if (left <= right)
+            {
+                for (auto v = value_of(left); v <= value_of(right); ++v)
+                {
+                    res &= add_number(numbers, v);
+                }
+            }
+            else
+            {
+                // 'left' and 'right' are not in value order. First, get values between 'left' and T::Last, inclusive
+                for (auto v = value_of(left); v <= value_of(T::Last); ++v)
+                {
+                    res = add_number(numbers, v);
+                }
+
+                // Next, get values between T::First and 'right', inclusive.
+                for (auto v = value_of(T::First); v <= value_of(right); ++v)
+                {
+                    res = add_number(numbers, v);
+                }
+            }
+        }
+        else if (get_step<T>(range, step_start, step))
+        {
+            // Add from step_start to T::Last with a step of 'step'
+            for (auto v = step_start; v <= value_of(T::Last); v += step)
+            {
+                res = add_number(numbers, v);
+            }
+        }
+        else
+        {
+            res = false;
+        }
+
+        return res;
+    }
 }

libcron/include/libcron/CronRandomization.h

@@ -0,0 +1,96 @@
+#pragma once
+
+#include <tuple>
+#include <random>
+#include <regex>
+#include <functional>
+#include "CronData.h"
+
+namespace libcron
+{
+    class CronRandomization
+    {
+        public:
+            std::tuple<bool, std::string> parse(const std::string& cron_schedule);
+
+            CronRandomization();
+
+            CronRandomization(const CronRandomization&) = delete;
+
+            CronRandomization & operator=(const CronRandomization &) = delete;
+
+        private:
+            template<typename T>
+            std::pair<bool, std::string> get_random_in_range(const std::string& section,
+                                                             int& selected_value,
+                                                             std::pair<int, int> limit = std::make_pair(-1, -1));
+
+            std::pair<int, int> day_limiter(const std::set<Months>& month);
+            int cap(int value, int lower, int upper);
+
+            std::regex const rand_expression{ R"#([rR]\((\d+)\-(\d+)\))#", std::regex_constants::ECMAScript };
+            std::random_device rd{};
+            std::mt19937 twister;
+    };
+
+    template<typename T>
+    std::pair<bool, std::string> CronRandomization::get_random_in_range(const std::string& section,
+                                                                        int& selected_value,
+                                                                        std::pair<int, int> limit)
+    {
+        auto res = std::make_pair(true, std::string{});
+        selected_value = -1;
+
+        std::smatch random_match;
+
+        if (std::regex_match(section.begin(), section.end(), random_match, rand_expression))
+        {
+            // Random range, get left and right numbers.
+            auto left = std::stoi(random_match[1].str());
+            auto right = std::stoi(random_match[2].str());
+
+            if (limit.first != -1 && limit.second != -1)
+            {
+                left = cap(left, limit.first, limit.second);
+                right = cap(right, limit.first, limit.second);
+            }
+
+            libcron::CronData cd;
+            std::set<T> numbers;
+            res.first = cd.convert_from_string_range_to_number_range<T>(
+                    std::to_string(left) + "-" + std::to_string(right), numbers);
+
+            // Remove items outside limits.
+//            for(auto it = numbers.begin(); it != numbers.end();)
+//            {
+//                if(CronData::value_of(*it) < limit.first || CronData::value_of(*it) > limit.second)
+//                {
+//                    it = numbers.erase(it);
+//                }
+//                else
+//                {
+//                    ++it;
+//                }
+//            }
+
+            if (res.first)
+            {
+                // Generate random indexes to select one of the numbers in the range.
+                std::uniform_int_distribution<> dis(0, static_cast<int>(numbers.size() - 1));
+
+                // Select the random number to use as the schedule
+                auto it = numbers.begin();
+                std::advance(it, dis(twister));
+                selected_value = CronData::value_of(*it);
+                res.second = std::to_string(selected_value);
+            }
+        }
+        else
+        {
+            // Not random, just append input to output.
+            res.second = section;
+        }
+
+        return res;
+    }
+}

libcron/include/libcron/TimeTypes.h

@@ -31,7 +31,19 @@ namespace libcron
     enum class Months : uint8_t
     {
         First = 1,
-            Last = 12
+        January = First,
+        February,
+        March,
+        April,
+        May,
+        June,
+        July,
+        August,
+        September,
+        October,
+        November,
+        December = 12,
+        Last = December
     };
 
     enum class DayOfWeek : uint8_t

libcron/src/CronData.cpp

@@ -5,6 +5,13 @@ using namespace date;
 
 namespace libcron
 {
+    const constexpr std::array<Months, 7> CronData::months_with_31{ Months::January,
+                                                                    Months::March,
+                                                                    Months::May,
+                                                                    Months::July,
+                                                                    Months::August,
+                                                                    Months::October,
+                                                                    Months::December };
 
     CronData CronData::create(const std::string& cron_expression)
     {
@@ -15,16 +22,16 @@ namespace libcron
     }
 
     CronData::CronData()
-            : month_names({"JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC"}),
+            : month_names({ "JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC" }),
-              day_names({"SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT"})
+              day_names({ "SUN", "MON", "TUE", "WED", "THU", "FRI", "SAT" })
     {
     }
 
     void CronData::parse(const std::string& cron_expression)
     {
         // First, split on white-space. We expect six parts.
-        std::regex split{R"#(^\s*(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s*$)#",
+        std::regex split{ R"#(^\s*(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s*$)#",
-                         std::regex_constants::ECMAScript};
+                          std::regex_constants::ECMAScript };
 
         std::smatch match;
 
@@ -48,13 +55,12 @@ namespace libcron
         std::string r = "[";
         r += token;
         r += "]";
-        std::regex splitter{r, std::regex_constants::ECMAScript};
+        std::regex splitter{ r, std::regex_constants::ECMAScript };
 
         std::copy(std::sregex_token_iterator(s.begin(), s.end(), splitter, -1),
                   std::sregex_token_iterator(),
                   std::back_inserter(res));
 
-
         return res;
     }
 
@@ -90,17 +96,15 @@ namespace libcron
             // Make sure that if the days contains only 31, at least one month allows that date.
             if (day_of_month.size() == 1 && day_of_month.find(DayOfMonth::Last) != day_of_month.end())
             {
-                constexpr std::array<uint32_t, 7> months_with_31{1, 3, 5, 7, 8, 10, 12};
-
                 res = false;
+
                 for (size_t i = 0; !res && i < months_with_31.size(); ++i)
                 {
-                    res = months.find(static_cast<Months>(months_with_31[i])) != months.end();
+                    res = months.find(months_with_31[i]) != months.end();
                 }
             }
         }
 
-
         return res;
     }
 

libcron/src/CronRandomization.cpp

@@ -0,0 +1,110 @@
+#include <libcron/CronRandomization.h>
+
+#include <regex>
+#include <map>
+#include <array>
+#include <algorithm>
+#include <iterator>
+#include <libcron/TimeTypes.h>
+#include <libcron/CronData.h>
+
+namespace libcron
+{
+    CronRandomization::CronRandomization()
+            : twister(rd())
+    {
+    }
+
+    std::tuple<bool, std::string> CronRandomization::parse(const std::string& cron_schedule)
+    {
+        // Split on space to get each separate part, six parts expected
+        std::regex split{ R"#(^\s*(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s+(.*?)\s*$)#",
+                          std::regex_constants::ECMAScript };
+
+        std::smatch all_sections;
+
+        std::string final_cron_schedule;
+
+        auto res = std::regex_match(cron_schedule.begin(), cron_schedule.end(), all_sections, split);
+
+        if (res)
+        {
+            int selected_value = -1;
+            auto second = get_random_in_range<Seconds>(all_sections[1].str(), selected_value);
+            res = second.first;
+            final_cron_schedule = second.second;
+
+            auto minute = get_random_in_range<Minutes>(all_sections[2].str(), selected_value);
+            res &= minute.first;
+            final_cron_schedule += " " + minute.second;
+
+            auto hour = get_random_in_range<Hours>(all_sections[3].str(), selected_value);
+            res &= hour.first;
+            final_cron_schedule += " " + hour.second;
+
+            // Do Month before DayOfMonth to allow capping the allowed range.
+            auto month = get_random_in_range<Months>(all_sections[5].str(), selected_value);
+            res &= month.first;
+
+            std::set<Months> month_range{};
+            if (selected_value == -1)
+            {
+                // Month is not specific, we need to get the 'max minimum' day of month to use.
+                CronData cr;
+                res &= cr.convert_from_string_range_to_number_range<Months>(all_sections[5].str(), month_range);
+            }
+            else
+            {
+                month_range.emplace(static_cast<Months>(selected_value));
+            }
+
+            auto limits = day_limiter(month_range);
+
+            auto day_of_month = get_random_in_range<DayOfMonth>(all_sections[4].str(),
+                    selected_value,
+                    limits);
+
+            res &= day_of_month.first;
+            final_cron_schedule += " " + day_of_month.second + " " + month.second;
+
+            auto day_of_week = get_random_in_range<DayOfWeek>(all_sections[6].str(), selected_value);
+            res &= day_of_week.first;
+            final_cron_schedule += " " + day_of_week.second;
+        }
+
+        return { res, final_cron_schedule };
+    }
+
+    std::pair<int, int> CronRandomization::day_limiter(const std::set<Months>& months)
+    {
+        auto max = 31;
+
+        for (auto month : months)
+        {
+            if (month == Months::February)
+            {
+                // Limit to 29 days, possibly causing delaying schedule until next leap year.
+                max = std::min(max, 29);
+            }
+            else if (std::find(CronData::months_with_31.begin(),
+                               CronData::months_with_31.end(),
+                               month) == CronData::months_with_31.end())
+            {
+                max = std::min(max, 30);
+            }
+            else
+            {
+                max = std::min(max, 31);
+            }
+        }
+
+        auto res = std::pair<int, int>{ CronData::value_of(DayOfMonth::First), max };
+
+        return res;
+    }
+
+    int CronRandomization::cap(int value, int lower, int upper)
+    {
+        return std::max(std::min(value, upper), lower);
+    }
+}

test/CMakeLists.txt

@@ -18,11 +18,13 @@ include_directories(
 add_executable(
         ${PROJECT_NAME}
         CronDataTest.cpp
-        CronScheduleTest.cpp CronTest.cpp)
+        CronRandomizationTest.cpp
+		CronScheduleTest.cpp
+		CronTest.cpp)
 
 target_link_libraries(${PROJECT_NAME} libcron)
 
 set_target_properties(${PROJECT_NAME} PROPERTIES
-        ARCHIVE_OUTPUT_DIRECTORY "${OUTPUT_LOCATION}"
+        ARCHIVE_OUTPUT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/out"
-        LIBRARY_OUTPUT_DIRECTORY "${OUTPUT_LOCATION}"
+        LIBRARY_OUTPUT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/out"
-        RUNTIME_OUTPUT_DIRECTORY "${OUTPUT_LOCATION}")
+        RUNTIME_OUTPUT_DIRECTORY "${CMAKE_CURRENT_LIST_DIR}/out")

test/CronRandomizationTest.cpp

@@ -0,0 +1,88 @@
+#include <catch.hpp>
+#include <string>
+#include <unordered_map>
+#include <algorithm>
+#include <libcron/CronRandomization.h>
+#include <libcron/Cron.h>
+#include <iostream>
+
+using namespace libcron;
+
+SCENARIO("Randomize all the things")
+{
+    const char* full_random = "R(0-59) R(0-59) R(0-23) R(1-31) R(1-12) ?";
+    Cron<> cron;
+
+    GIVEN(full_random)
+    {
+        THEN("Only valid schedules generated")
+        {
+            libcron::CronRandomization cr;
+            std::unordered_map<int, std::unordered_map<int, int>> results{};
+
+            for (int i = 0; i < 1000; ++i)
+            {
+                auto res = cr.parse(full_random);
+                REQUIRE(std::get<0>(res));
+                auto schedule = std::get<1>(res);
+
+                auto start = schedule.begin();
+                auto space = std::find(schedule.begin(), schedule.end(), ' ');
+
+                for (int section = 0; start != schedule.end() && section < 5; ++section)
+                {
+                    auto& map = results[section];
+                    auto s = std::string{start, space};
+                    auto value = std::stoi(s);
+                    map[value]++;
+                    start = space + 1;
+                    space = std::find(start, schedule.end(), ' ');
+                }
+
+                REQUIRE(results.size() == 5);
+                INFO("schedule:" << schedule);
+                REQUIRE(cron.add_schedule("validate schedule", schedule, []() {}));
+            }
+        }
+    }
+}
+
+SCENARIO("Randomize all the things with reverse ranges")
+{
+    // Only generate DayOfMonth up to 28 to prevent failing tests where the month doesn't have more days.
+    const char* full_random = "R(45-15) R(30-0) R(18-2) R(28-15) 2 ?";
+    Cron<> cron;
+
+    GIVEN(full_random)
+    {
+        THEN("Only valid schedules generated")
+        {
+            libcron::CronRandomization cr;
+            std::unordered_map<int, std::unordered_map<int, int>> results{};
+
+            for (int i = 0; i < 1000; ++i)
+            {
+                auto res = cr.parse(full_random);
+                REQUIRE(std::get<0>(res));
+                auto schedule = std::get<1>(res);
+
+                auto start = schedule.begin();
+                auto space = std::find(schedule.begin(), schedule.end(), ' ');
+
+                for (int section = 0; start != schedule.end() && section < 5; ++section)
+                {
+                    auto& map = results[section];
+                    auto s = std::string{start, space};
+                    auto value = std::stoi(s);
+                    map[value]++;
+                    start = space + 1;
+                    space = std::find(start, schedule.end(), ' ');
+                }
+
+                REQUIRE(results.size() == 5);
+                INFO("schedule:" << schedule);
+                REQUIRE(cron.add_schedule("validate schedule", schedule, []() {}));
+            }
+        }
+    }
+}