Add micro-blog (#478)

Author: keiravillekode

config.json

@@ -574,6 +574,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "micro-blog",
+        "name": "Micro Blog",
+        "uuid": "0441593f-23d3-42b8-aa21-b47166c7c86d",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "perfect-numbers",
         "name": "Perfect Numbers",

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": [
+    "keiravillekode"
+  ],
+  "files": {
+    "solution": [
+      "micro_blog.zig"
+    ],
+    "test": [
+      "test_micro_blog.zig"
+    ],
+    "example": [
+      ".meta/example.zig"
+    ]
+  },
+  "blurb": "Given an input string, truncate it to 5 characters."
+}

exercises/practice/micro-blog/.meta/example.zig

@@ -0,0 +1,16 @@
+pub fn truncate(phrase: []const u8) []const u8 {
+    var index: usize = 0;
+    var remaining: usize = 6;
+    while (index < phrase.len) {
+        if (phrase[index] & 0xc0 != 0x80) {
+            remaining -= 1;
+            if (remaining == 0) {
+                // start of 6th character
+                break;
+            }
+        }
+        index += 1;
+    }
+
+    return phrase[0..index];
+}

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/micro_blog.zig

@@ -0,0 +1,4 @@
+pub fn truncate(phrase: []const u8) []const u8 {
+    _ = phrase;
+    @compileError("please implement the truncate function");
+}

exercises/practice/micro-blog/test_micro_blog.zig

@@ -0,0 +1,82 @@
+const std = @import("std");
+const testing = std.testing;
+
+const micro_blog = @import("micro_blog.zig");
+
+test "English language short" {
+    const expected: []const u8 = "Hi";
+    const actual = micro_blog.truncate("Hi");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "English language long" {
+    const expected: []const u8 = "Hello";
+    const actual = micro_blog.truncate("Hello there");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "German language short (broth)" {
+    const expected: []const u8 = "brühe";
+    const actual = micro_blog.truncate("brühe");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "German language long (bear carpet → beards)" {
+    const expected: []const u8 = "Bärte";
+    const actual = micro_blog.truncate("Bärteppich");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Bulgarian language short (good)" {
+    const expected: []const u8 = "Добър";
+    const actual = micro_blog.truncate("Добър");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Greek language short (health)" {
+    const expected: []const u8 = "υγειά";
+    const actual = micro_blog.truncate("υγειά");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Maths short" {
+    const expected: []const u8 = "a=πr²";
+    const actual = micro_blog.truncate("a=πr²");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Maths long" {
+    const expected: []const u8 = "∅⊊ℕ⊊ℤ";
+    const actual = micro_blog.truncate("∅⊊ℕ⊊ℤ⊊ℚ⊊ℝ⊊ℂ");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "English and emoji short" {
+    const expected: []const u8 = "Fly 🛫";
+    const actual = micro_blog.truncate("Fly 🛫");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Emoji short" {
+    const expected: []const u8 = "💇";
+    const actual = micro_blog.truncate("💇");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Emoji long" {
+    const expected: []const u8 = "❄🌡🤧🤒🏥";
+    const actual = micro_blog.truncate("❄🌡🤧🤒🏥🕰😀");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "Royal Flush?" {
+    const expected: []const u8 = "🃎🂸🃅🃋🃍";
+    const actual = micro_blog.truncate("🃎🂸🃅🃋🃍🃁🃊");
+    try testing.expectEqualStrings(expected, actual);
+}
+
+test "ideograms" {
+    const expected: []const u8 = "二兎を追う";
+    const actual = micro_blog.truncate("二兎を追う者は一兎をも得ず");
+    try testing.expectEqualStrings(expected, actual);
+}