Add twelve-days practice exercise

config.json

@@ -1287,6 +1287,14 @@
           "comparisons"
         ],
         "difficulty": 6
+      },
+      {
+        "slug": "twelve-days",
+        "name": "Twelve Days",
+        "uuid": "0daec3e8-a0d1-49e8-9de5-0ad73f9c3243",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
       }
     ],
     "foregone": [

exercises/practice/twelve-days/.docs/instructions.md

@@ -0,0 +1,36 @@
+# Instructions
+
+Your task in this exercise is to write code that returns the lyrics of the song: "The Twelve Days of Christmas."
+
+"The Twelve Days of Christmas" is a common English Christmas carol.
+Each subsequent verse of the song builds on the previous verse.
+
+The lyrics your code returns should _exactly_ match the full song text shown below.
+
+## Lyrics
+
+```text
+On the first day of Christmas my true love gave to me: a Partridge in a Pear Tree.
+
+On the second day of Christmas my true love gave to me: two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the third day of Christmas my true love gave to me: three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fourth day of Christmas my true love gave to me: four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the fifth day of Christmas my true love gave to me: five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the sixth day of Christmas my true love gave to me: six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the seventh day of Christmas my true love gave to me: seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eighth day of Christmas my true love gave to me: eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the ninth day of Christmas my true love gave to me: nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the tenth day of Christmas my true love gave to me: ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the eleventh day of Christmas my true love gave to me: eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+
+On the twelfth day of Christmas my true love gave to me: twelve Drummers Drumming, eleven Pipers Piping, ten Lords-a-Leaping, nine Ladies Dancing, eight Maids-a-Milking, seven Swans-a-Swimming, six Geese-a-Laying, five Gold Rings, four Calling Birds, three French Hens, two Turtle Doves, and a Partridge in a Pear Tree.
+```

exercises/practice/twelve-days/.meta/config.json

@@ -0,0 +1,21 @@
+{
+  "authors": [
+    "alienx5499"
+  ],
+  "files": {
+    "solution": [
+      "twelve_days.cpp",
+      "twelve_days.h"
+    ],
+    "test": [
+      "twelve_days_test.cpp"
+    ],
+    "example": [
+      ".meta/example.cpp",
+      ".meta/example.h"
+    ]
+  },
+  "blurb": "Output the lyrics to 'The Twelve Days of Christmas'.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/The_Twelve_Days_of_Christmas_(song)"
+}

exercises/practice/twelve-days/.meta/example.cpp

@@ -0,0 +1,73 @@
+#include <array>
+#include <string>
+
+#include "twelve_days.h"
+
+namespace twelve_days {
+
+std::string recite(int start_day, int end_day) {
+    constexpr std::array ordinals = {
+        "",        "first",  "second", "third", "fourth",   "fifth",  "sixth",
+        "seventh", "eighth", "ninth",  "tenth", "eleventh", "twelfth"};
+
+    constexpr std::array gifts = {"",
+                                  "a Partridge in a Pear Tree",
+                                  "two Turtle Doves",
+                                  "three French Hens",
+                                  "four Calling Birds",
+                                  "five Gold Rings",
+                                  "six Geese-a-Laying",
+                                  "seven Swans-a-Swimming",
+                                  "eight Maids-a-Milking",
+                                  "nine Ladies Dancing",
+                                  "ten Lords-a-Leaping",
+                                  "eleven Pipers Piping",
+                                  "twelve Drummers Drumming"};
+
+    if (start_day == end_day) {
+        // Single verse case
+        auto result = std::string{"On the "} +
+                      std::string{ordinals[start_day]} +
+                      " day of Christmas my true love gave to me: ";
+
+        for (int i = start_day; i >= 1; --i) {
+            if (i == start_day) {
+                result += std::string{gifts[i]};
+            } else if (i == 1) {
+                result += std::string{", and "} + std::string{gifts[i]};
+            } else {
+                result += std::string{", "} + std::string{gifts[i]};
+            }
+        }
+
+        result += ".\n";
+        return result;
+    } else {
+        // Multiple verses case
+        std::string result = "";
+        for (int i = start_day; i <= end_day; ++i) {
+            if (i > start_day) {
+                result += "\n";
+            }
+
+            auto verse = std::string{"On the "} + std::string{ordinals[i]} +
+                         " day of Christmas my true love gave to me: ";
+
+            for (int j = i; j >= 1; --j) {
+                if (j == i) {
+                    verse += std::string{gifts[j]};
+                } else if (j == 1) {
+                    verse += std::string{", and "} + std::string{gifts[j]};
+                } else {
+                    verse += std::string{", "} + std::string{gifts[j]};
+                }
+            }
+
+            verse += ".\n";
+            result += verse;
+        }
+        return result;
+    }
+}
+
+}  // namespace twelve_days

exercises/practice/twelve-days/.meta/example.h

@@ -0,0 +1,9 @@
+#pragma once
+
+#include <string>
+
+namespace twelve_days {
+
+std::string recite(int start_day, int end_day);
+
+}  // namespace twelve_days

exercises/practice/twelve-days/.meta/tests.toml

@@ -0,0 +1,55 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[c0b5a5e6-c89d-49b1-a6b2-9f523bff33f7]
+description = "verse -> first day a partridge in a pear tree"
+
+[1c64508a-df3d-420a-b8e1-fe408847854a]
+description = "verse -> second day two turtle doves"
+
+[a919e09c-75b2-4e64-bb23-de4a692060a8]
+description = "verse -> third day three french hens"
+
+[9bed8631-ec60-4894-a3bb-4f0ec9fbe68d]
+description = "verse -> fourth day four calling birds"
+
+[cf1024f0-73b6-4545-be57-e9cea565289a]
+description = "verse -> fifth day five gold rings"
+
+[50bd3393-868a-4f24-a618-68df3d02ff04]
+description = "verse -> sixth day six geese-a-laying"
+
+[8f29638c-9bf1-4680-94be-e8b84e4ade83]
+description = "verse -> seventh day seven swans-a-swimming"
+
+[7038d6e1-e377-47ad-8c37-10670a05bc05]
+description = "verse -> eighth day eight maids-a-milking"
+
+[37a800a6-7a56-4352-8d72-0f51eb37cfe8]
+description = "verse -> ninth day nine ladies dancing"
+
+[10b158aa-49ff-4b2d-afc3-13af9133510d]
+description = "verse -> tenth day ten lords-a-leaping"
+
+[08d7d453-f2ba-478d-8df0-d39ea6a4f457]
+description = "verse -> eleventh day eleven pipers piping"
+
+[0620fea7-1704-4e48-b557-c05bf43967f0]
+description = "verse -> twelfth day twelve drummers drumming"
+
+[da8b9013-b1e8-49df-b6ef-ddec0219e398]
+description = "lyrics -> recites first three verses of the song"
+
+[c095af0d-3137-4653-ad32-bfb899eda24c]
+description = "lyrics -> recites three verses from the middle of the song"
+
+[20921bc9-cc52-4627-80b3-198cbbfcf9b7]
+description = "lyrics -> recites the whole song"

exercises/practice/twelve-days/CMakeLists.txt

@@ -0,0 +1,67 @@
+# Get the exercise name from the current directory
+get_filename_component(exercise ${CMAKE_CURRENT_SOURCE_DIR} NAME)
+
+# Basic CMake project
+cmake_minimum_required(VERSION 3.5.1)
+
+# Name the project after the exercise
+project(${exercise} CXX)
+
+# Get a source filename from the exercise name by replacing -'s with _'s
+string(REPLACE "-" "_" file ${exercise})
+
+# Implementation could be only a header
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/${file}.cpp)
+    set(exercise_cpp ${file}.cpp)
+else()
+    set(exercise_cpp "")
+endif()
+
+# Use the common Catch library?
+if(EXERCISM_COMMON_CATCH)
+    # For Exercism track development only
+    add_executable(${exercise} ${file}_test.cpp ${exercise_cpp} ${file}.h $<TARGET_OBJECTS:catchlib>)
+elseif(EXERCISM_TEST_SUITE)
+    # The Exercism test suite is being run, the Docker image already
+    # includes a pre-built version of Catch.
+    find_package(Catch2 REQUIRED)
+    add_executable(${exercise} ${file}_test.cpp ${exercise_cpp} ${file}.h)
+    target_link_libraries(${exercise} PRIVATE Catch2::Catch2WithMain)
+    # When Catch is installed system wide we need to include a different
+    # header, we need this define to use the correct one.
+    target_compile_definitions(${exercise} PRIVATE EXERCISM_TEST_SUITE)
+else()
+    # Build executable from sources and headers
+    add_executable(${exercise} ${file}_test.cpp ${exercise_cpp} ${file}.h test/tests-main.cpp)
+endif()
+
+set_target_properties(${exercise} PROPERTIES
+    CXX_STANDARD 17
+    CXX_STANDARD_REQUIRED OFF
+    CXX_EXTENSIONS OFF
+)
+
+set(CMAKE_BUILD_TYPE Debug)
+
+if("${CMAKE_CXX_COMPILER_ID}" MATCHES "(GNU|Clang)")
+    set_target_properties(${exercise} PROPERTIES
+        COMPILE_FLAGS "-Wall -Wextra -Wpedantic -Werror"
+    )
+endif()
+
+# Configure to run all the tests?
+if(${EXERCISM_RUN_ALL_TESTS})
+    target_compile_definitions(${exercise} PRIVATE EXERCISM_RUN_ALL_TESTS)
+endif()
+
+# Tell MSVC not to warn us about unchecked iterators in debug builds
+# Treat warnings as errors
+# Treat type conversion warnings C4244 and C4267 as level 4 warnings, i.e. ignore them in level 3
+if(${MSVC})
+    set_target_properties(${exercise} PROPERTIES
+        COMPILE_DEFINITIONS_DEBUG _SCL_SECURE_NO_WARNINGS
+        COMPILE_FLAGS "/WX /w44244 /w44267")
+endif()
+
+# Run the tests on every build
+add_custom_target(test_${exercise} ALL DEPENDS ${exercise} COMMAND ${exercise})