Add proverb (#301)

Author: BNAndras

config.json

@@ -219,6 +219,14 @@
           "math"
         ]
       },
+      {
+        "slug": "proverb",
+        "name": "Proverb",
+        "uuid": "a8a08760-d235-4544-b930-ded873f60e57",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 2
+      },
       {
         "slug": "raindrops",
         "name": "Raindrops",

exercises/practice/proverb/.docs/instructions.md

@@ -0,0 +1,19 @@
+# Instructions
+
+For want of a horseshoe nail, a kingdom was lost, or so the saying goes.
+
+Given a list of inputs, generate the relevant proverb.
+For example, given the list `["nail", "shoe", "horse", "rider", "message", "battle", "kingdom"]`, you will output the full text of this proverbial rhyme:
+
+```text
+For want of a nail the shoe was lost.
+For want of a shoe the horse was lost.
+For want of a horse the rider was lost.
+For want of a rider the message was lost.
+For want of a message the battle was lost.
+For want of a battle the kingdom was lost.
+And all for the want of a nail.
+```
+
+Note that the list of inputs may vary; your solution should be able to handle lists of arbitrary length and content.
+No line of the output text should be a static, unchanging string; all should vary according to the input given.

exercises/practice/proverb/.meta/config.json

@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "BNAndras"
+  ],
+  "files": {
+    "solution": [
+      "source/proverb.d"
+    ],
+    "test": [
+      "source/proverb.d"
+    ],
+    "example": [
+      "example/proverb.d"
+    ]
+  },
+  "blurb": "For want of a horseshoe nail, a kingdom was lost, or so the saying goes. Output the full text of this proverbial rhyme.",
+  "source": "Wikipedia",
+  "source_url": "https://en.wikipedia.org/wiki/For_Want_of_a_Nail"
+}

exercises/practice/proverb/.meta/tests.toml

@@ -0,0 +1,28 @@
+# 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.
+
+[e974b73e-7851-484f-8d6d-92e07fe742fc]
+description = "zero pieces"
+
+[2fcd5f5e-8b82-4e74-b51d-df28a5e0faa4]
+description = "one piece"
+
+[d9d0a8a1-d933-46e2-aa94-eecf679f4b0e]
+description = "two pieces"
+
+[c95ef757-5e94-4f0d-a6cb-d2083f5e5a83]
+description = "three pieces"
+
+[433fb91c-35a2-4d41-aeab-4de1e82b2126]
+description = "full proverb"
+
+[c1eefa5a-e8d9-41c7-91d4-99fab6d6b9f7]
+description = "four pieces modernized"

exercises/practice/proverb/dub.sdl

@@ -0,0 +1,2 @@
+name "proverb"
+buildRequirements "disallowDeprecations"

exercises/practice/proverb/example/proverb.d

@@ -0,0 +1,18 @@
+module proverb;
+
+import std.array;
+
+pure string recite(immutable string[] strings)
+{
+    if (strings.length == 0) return "";
+    
+    string[] fragments;
+    foreach (i, str; strings[0 .. strings.length - 1])
+    {
+        fragments ~= "For want of a " ~ str ~ " the " ~ strings[i+1] ~ " was lost.";
+    }
+    
+    fragments ~= "And all for the want of a " ~ strings[0] ~ ".";
+    
+    return fragments.join("\n");
+}

exercises/practice/proverb/source/proverb.d

@@ -0,0 +1,66 @@
+module proverb;
+
+pure string recite(immutable string[] strings)
+{
+    // implement this function
+}
+
+unittest
+{
+    immutable int allTestsEnabled = 0;
+
+    // Zero pieces
+    {
+        string expected = "";
+        assert(recite([]) == expected);
+    }
+
+    static if (allTestsEnabled)
+    {
+        // One piece
+        {
+            string expected = "And all for the want of a nail.";
+            assert(recite(["nail"]) == expected);
+        }
+
+        // Two pieces
+        {
+            string expected =   "For want of a nail the shoe was lost.\n"
+                              ~ "And all for the want of a nail.";
+            assert(recite(["nail", "shoe"]) == expected);
+        }
+
+        // Three pieces
+        {
+            string expected =   "For want of a nail the shoe was lost.\n"
+                              ~ "For want of a shoe the horse was lost.\n"
+                              ~ "And all for the want of a nail.";
+            assert(recite(["nail", "shoe", "horse"]) == expected);
+        }
+
+        // Full proverb
+        {
+            string expected =   "For want of a nail the shoe was lost.\n"
+                              ~ "For want of a shoe the horse was lost.\n"
+                              ~ "For want of a horse the rider was lost.\n"
+                              ~ "For want of a rider the message was lost.\n"
+                              ~ "For want of a message the battle was lost.\n"
+                              ~ "For want of a battle the kingdom was lost.\n"
+                              ~ "And all for the want of a nail.";
+            immutable string[] strings = [
+                "nail", "shoe", "horse", "rider",
+                "message", "battle", "kingdom"
+            ];
+            assert(recite(strings) == expected);
+        }
+
+        // Four pieces modernized
+        {
+            string expected =  "For want of a pin the gun was lost.\n"
+                             ~ "For want of a gun the soldier was lost.\n"
+                             ~ "For want of a soldier the battle was lost.\n"
+                             ~ "And all for the want of a pin.";
+            assert(recite(["pin", "gun", "soldier", "battle"]) == expected);
+        }
+    }
+}