Implement micro-blog

config.json

@@ -762,6 +762,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 1
+      },
+      {
+        "slug": "micro-blog",
+        "name": "Micro Blog",
+        "uuid": "f03e4e99-97ff-4ac7-8975-bbafa38c9088",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 1
       }
     ]
   },

exercises/practice/micro-blog/.docs/instructions.md

@@ -0,0 +1,37 @@
+# Instructions
+
+You have identified a gap in the social media market for very very short posts.
+Now that Twitter allows 280 character posts, people wanting quick social media updates aren't being served.
+You decide to create your own social media network.
+
+To make your product noteworthy, you make it extreme and only allow posts of 5 or less characters.
+Any posts of more than 5 characters should be truncated to 5.
+
+To allow your users to express themselves fully, you allow Emoji and other Unicode.
+
+The task is to truncate input strings to 5 characters.
+
+## Text Encodings
+
+Text stored digitally has to be converted to a series of bytes.
+There are 3 ways to map characters to bytes in common use.
+
+- **ASCII** can encode English language characters.
+  All characters are precisely 1 byte long.
+- **UTF-8** is a Unicode text encoding.
+  Characters take between 1 and 4 bytes.
+- **UTF-16** is a Unicode text encoding.
+  Characters are either 2 or 4 bytes long.
+
+UTF-8 and UTF-16 are both Unicode encodings which means they're capable of representing a massive range of characters including:
+
+- Text in most of the world's languages and scripts
+- Historic text
+- Emoji
+
+UTF-8 and UTF-16 are both variable length encodings, which means that different characters take up different amounts of space.
+
+Consider the letter 'a' and the emoji '😛'.
+In UTF-16 the letter takes 2 bytes but the emoji takes 4 bytes.
+
+The trick to this exercise is to use APIs designed around Unicode characters (codepoints) instead of Unicode codeunits.

exercises/practice/micro-blog/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "m-dango"
+  ],
+  "files": {
+    "solution": [
+      "lib/MicroBlog.pm"
+    ],
+    "test": [
+      "t/micro-blog.t"
+    ],
+    "example": [
+      ".meta/solutions/lib/MicroBlog.pm"
+    ]
+  },
+  "blurb": "Given an input string, truncate it to 5 characters."
+}

exercises/practice/micro-blog/.meta/solutions/lib/MicroBlog.pm

@@ -0,0 +1,16 @@
+package MicroBlog;
+
+use strict;
+use warnings;
+use experimental qw<signatures postderef postderef_qq>;
+
+use Exporter qw<import>;
+our @EXPORT_OK = qw<truncate_post>;
+
+use Encode;
+
+sub truncate_post ($utf8_bytes) {
+    return substr( Encode::decode( 'UTF-8', $utf8_bytes ), 0, 5 );
+}
+
+1;

exercises/practice/micro-blog/.meta/solutions/t/micro-blog.t

@@ -0,0 +1 @@
+../../../t/micro-blog.t

exercises/practice/micro-blog/.meta/template-data.yaml

@@ -0,0 +1,28 @@
+subs: truncate_post
+
+properties:
+  truncate:
+    test: |-
+      use Data::Dmp;
+      use Encode;
+
+      sprintf(<<'END', dmp(Encode::encode('UTF-8', $case->{input}{phrase})), $case->{expected}, $case->{description});
+      is(
+          truncate_post(%s),
+          '%s',
+          '%s',
+      );
+      END
+
+
+example: |-
+  use Encode;
+
+  sub truncate_post ($utf8_bytes) {
+      return substr(Encode::decode('UTF-8', $utf8_bytes), 0, 5);
+  }
+
+stub: |-
+  sub truncate_post ($utf8_bytes) {
+      return undef;
+  }

exercises/practice/micro-blog/.meta/tests.toml

@@ -0,0 +1,46 @@
+# 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.
+
+[b927b57f-7c98-42fd-8f33-fae091dc1efc]
+description = "English language short"
+
+[a3fcdc5b-0ed4-4f49-80f5-b1a293eac2a0]
+description = "English language long"
+
+[01910864-8e15-4007-9c7c-ac956c686e60]
+description = "German language short (broth)"
+
+[f263e488-aefb-478f-a671-b6ba99722543]
+description = "German language long (bear carpet → beards)"
+
+[0916e8f1-41d7-4402-a110-b08aa000342c]
+description = "Bulgarian language short (good)"
+
+[bed6b89c-03df-4154-98e6-a61a74f61b7d]
+description = "Greek language short (health)"
+
+[485a6a70-2edb-424d-b999-5529dbc8e002]
+description = "Maths short"
+
+[8b4b7b51-8f48-4fbe-964e-6e4e6438be28]
+description = "Maths long"
+
+[71f4a192-0566-4402-a512-fe12878be523]
+description = "English and emoji short"
+
+[6f0f71f3-9806-4759-a844-fa182f7bc203]
+description = "Emoji short"
+
+[ce71fb92-5214-46d0-a7f8-d5ba56b4cc6e]
+description = "Emoji long"
+
+[5dee98d2-d56e-468a-a1f2-121c3f7c5a0b]
+description = "Royal Flush?"

exercises/practice/micro-blog/lib/MicroBlog.pm

@@ -0,0 +1,12 @@
+package MicroBlog;
+
+use v5.40;
+
+use Exporter qw<import>;
+our @EXPORT_OK = qw<truncate_post>;
+
+sub truncate_post ($utf8_bytes) {
+    return undef;
+}
+
+1;

exercises/practice/micro-blog/t/micro-blog.t

@@ -0,0 +1,81 @@
+#!/usr/bin/env perl
+use Test2::V0;
+
+use FindBin qw<$Bin>;
+use lib "$Bin/../lib", "$Bin/../local/lib/perl5";
+
+use MicroBlog qw<truncate_post>;
+
+is( # begin: b927b57f-7c98-42fd-8f33-fae091dc1efc
+    truncate_post("Hi"),
+    'Hi',
+    'English language short',
+); # end: b927b57f-7c98-42fd-8f33-fae091dc1efc
+
+is( # begin: a3fcdc5b-0ed4-4f49-80f5-b1a293eac2a0
+    truncate_post("Hello there"),
+    'Hello',
+    'English language long',
+); # end: a3fcdc5b-0ed4-4f49-80f5-b1a293eac2a0
+
+is( # begin: 01910864-8e15-4007-9c7c-ac956c686e60
+    truncate_post("br\xC3\xBChe"),
+    'brühe',
+    'German language short (broth)',
+); # end: 01910864-8e15-4007-9c7c-ac956c686e60
+
+is( # begin: f263e488-aefb-478f-a671-b6ba99722543
+    truncate_post("B\xC3\xA4rteppich"),
+    'Bärte',
+    'German language long (bear carpet → beards)',
+); # end: f263e488-aefb-478f-a671-b6ba99722543
+
+is( # begin: 0916e8f1-41d7-4402-a110-b08aa000342c
+    truncate_post("\xD0\x94\xD0\xBE\xD0\xB1\xD1\x8A\xD1\x80"),
+    'Добър',
+    'Bulgarian language short (good)',
+); # end: 0916e8f1-41d7-4402-a110-b08aa000342c
+
+is( # begin: bed6b89c-03df-4154-98e6-a61a74f61b7d
+    truncate_post("\xCF\x85\xCE\xB3\xCE\xB5\xCE\xB9\xCE\xAC"),
+    'υγειά',
+    'Greek language short (health)',
+); # end: bed6b89c-03df-4154-98e6-a61a74f61b7d
+
+is( # begin: 485a6a70-2edb-424d-b999-5529dbc8e002
+    truncate_post("a=\xCF\x80r\xC2\xB2"),
+    'a=πr²',
+    'Maths short',
+); # end: 485a6a70-2edb-424d-b999-5529dbc8e002
+
+is( # begin: 8b4b7b51-8f48-4fbe-964e-6e4e6438be28
+    truncate_post("\xE2\x88\x85\xE2\x8A\x8A\xE2\x84\x95\xE2\x8A\x8A\xE2\x84\xA4\xE2\x8A\x8A\xE2\x84\x9A\xE2\x8A\x8A\xE2\x84\x9D\xE2\x8A\x8A\xE2\x84\x82"),
+    '∅⊊ℕ⊊ℤ',
+    'Maths long',
+); # end: 8b4b7b51-8f48-4fbe-964e-6e4e6438be28
+
+is( # begin: 71f4a192-0566-4402-a512-fe12878be523
+    truncate_post("Fly \xF0\x9F\x9B\xAB"),
+    'Fly 🛫',
+    'English and emoji short',
+); # end: 71f4a192-0566-4402-a512-fe12878be523
+
+is( # begin: 6f0f71f3-9806-4759-a844-fa182f7bc203
+    truncate_post("\xF0\x9F\x92\x87"),
+    '💇',
+    'Emoji short',
+); # end: 6f0f71f3-9806-4759-a844-fa182f7bc203
+
+is( # begin: ce71fb92-5214-46d0-a7f8-d5ba56b4cc6e
+    truncate_post("\xE2\x9D\x84\xF0\x9F\x8C\xA1\xF0\x9F\xA4\xA7\xF0\x9F\xA4\x92\xF0\x9F\x8F\xA5\xF0\x9F\x95\xB0\xF0\x9F\x98\x80"),
+    '❄🌡🤧🤒🏥',
+    'Emoji long',
+); # end: ce71fb92-5214-46d0-a7f8-d5ba56b4cc6e
+
+is( # begin: 5dee98d2-d56e-468a-a1f2-121c3f7c5a0b
+    truncate_post("\xF0\x9F\x83\x8E\xF0\x9F\x82\xB8\xF0\x9F\x83\x85\xF0\x9F\x83\x8B\xF0\x9F\x83\x8D\xF0\x9F\x83\x81\xF0\x9F\x83\x8A"),
+    '🃎🂸🃅🃋🃍',
+    'Royal Flush?',
+); # end: 5dee98d2-d56e-468a-a1f2-121c3f7c5a0b
+
+done_testing;