[New exercise] Markdown (#2401)

* Adding autogenerated files

* Adding tests

* Added code to be refactored

* Update markdown.spec.js

* Added a working solution

* Formatting

config.json

@@ -2578,6 +2578,17 @@
           "strings"
         ]
       },
+      {
+        "slug": "markdown",
+        "name": "Markdown",
+        "uuid": "cd666b3a-7114-4ba9-9b2a-7622a2c8c12c",
+        "practices": [
+          "strings",
+          "string-formatting"
+        ],
+        "prerequisites": [],
+        "difficulty": 5
+      },
       {
         "slug": "micro-blog",
         "name": "Micro Blog",

exercises/practice/markdown/.docs/instructions.md

@@ -0,0 +1,13 @@
+# Instructions
+
+Refactor a Markdown parser.
+
+The markdown exercise is a refactoring exercise.
+There is code that parses a given string with [Markdown syntax][markdown] and returns the associated HTML for that string.
+Even though this code is confusingly written and hard to follow, somehow it works and all the tests are passing!
+Your challenge is to re-write this code to make it easier to read and maintain while still making sure that all the tests keep passing.
+
+It would be helpful if you made notes of what you did in your refactoring in comments so reviewers can see that, but it isn't strictly necessary.
+The most important thing is to make the code better!
+
+[markdown]: https://guides.github.com/features/mastering-markdown/

exercises/practice/markdown/.eslintrc

@@ -0,0 +1,14 @@
+{
+  "root": true,
+  "extends": "@exercism/eslint-config-javascript",
+  "env": {
+    "jest": true
+  },
+  "overrides": [
+    {
+      "files": [".meta/proof.ci.js", ".meta/exemplar.js", "*.spec.js"],
+      "excludedFiles": ["custom.spec.js"],
+      "extends": "@exercism/eslint-config-javascript/maintainers"
+    }
+  ]
+}

exercises/practice/markdown/.gitignore

@@ -0,0 +1,5 @@
+/node_modules
+/bin/configlet
+/bin/configlet.exe
+/pnpm-lock.yaml
+/yarn.lock

exercises/practice/markdown/.meta/config.json

@@ -0,0 +1,17 @@
+{
+  "authors": [
+    "Cool-Katt"
+  ],
+  "files": {
+    "solution": [
+      "markdown.js"
+    ],
+    "test": [
+      "markdown.spec.js"
+    ],
+    "example": [
+      ".meta/proof.ci.js"
+    ]
+  },
+  "blurb": "Refactor a Markdown parser."
+}

exercises/practice/markdown/.meta/proof.ci.js

@@ -0,0 +1,55 @@
+const wrapInTag = (tag, text) => `<${tag}>${text}</${tag}>`;
+
+const REPLACERS = {
+  paragraph: {
+    operationNumber: 1,
+    regexPattern: /^(.+)$/gim,
+    replacer: (match, p1) =>
+      match.startsWith('*') || match.startsWith('#')
+        ? match
+        : wrapInTag('p', p1),
+  },
+  heading: {
+    operationNumber: 2,
+    regexPattern: /^(#{1,7})\s*(.+)/gim,
+    replacer: (match, p1, p2) =>
+      p1.length > 6 ? wrapInTag('p', match) : wrapInTag(`h${p1.length}`, p2),
+  },
+  bold: {
+    operationNumber: 3,
+    regexPattern: /__(.+)__/gim,
+    replacer: (match, p1) => wrapInTag('strong', p1),
+  },
+  italic: {
+    operationNumber: 4,
+    regexPattern: /_(.+)_/gim,
+    replacer: (match, p1) => wrapInTag('em', p1),
+  },
+  listItem: {
+    operationNumber: 5,
+    regexPattern: /^\*\s(.+)/gim,
+    replacer: (match, p1) => wrapInTag('li', p1),
+  },
+  newLine: {
+    operationNumber: 6,
+    regexPattern: /\n/gim,
+    replacer: () => '',
+  },
+  list: {
+    operationNumber: 7,
+    regexPattern: /(<li>.+<\/li>)/gim,
+    replacer: (match, p1) => wrapInTag('ul', p1),
+  },
+};
+
+const sortedOperations = Object.values(REPLACERS).sort(
+  (a, b) => a.operationNumber - b.operationNumber,
+);
+
+export function parse(markdown) {
+  return sortedOperations.reduce(
+    (text, { regexPattern, replacer }) =>
+      text.replaceAll(new RegExp(regexPattern), replacer),
+    markdown,
+  );
+}

exercises/practice/markdown/.meta/tests.toml

@@ -0,0 +1,66 @@
+# 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.
+
+[e75c8103-a6b8-45d9-84ad-e68520545f6e]
+description = "parses normal text as a paragraph"
+
+[69a4165d-9bf8-4dd7-bfdc-536eaca80a6a]
+description = "parsing italics"
+
+[ec345a1d-db20-4569-a81a-172fe0cad8a1]
+description = "parsing bold text"
+
+[51164ed4-5641-4909-8fab-fbaa9d37d5a8]
+description = "mixed normal, italics and bold text"
+
+[ad85f60d-0edd-4c6a-a9b1-73e1c4790d15]
+description = "with h1 header level"
+
+[d0f7a31f-6935-44ac-8a9a-1e8ab16af77f]
+description = "with h2 header level"
+
+[9df3f500-0622-4696-81a7-d5babd9b5f49]
+description = "with h3 header level"
+
+[50862777-a5e8-42e9-a3b8-4ba6fcd0ed03]
+description = "with h4 header level"
+
+[ee1c23ac-4c86-4f2a-8b9c-403548d4ab82]
+description = "with h5 header level"
+
+[13b5f410-33f5-44f0-a6a7-cfd4ab74b5d5]
+description = "with h6 header level"
+
+[6dca5d10-5c22-4e2a-ac2b-bd6f21e61939]
+description = "with h7 header level"
+include = false
+
+[81c0c4db-435e-4d77-860d-45afacdad810]
+description = "h7 header level is a paragraph"
+reimplements = "6dca5d10-5c22-4e2a-ac2b-bd6f21e61939"
+
+[25288a2b-8edc-45db-84cf-0b6c6ee034d6]
+description = "unordered lists"
+
+[7bf92413-df8f-4de8-9184-b724f363c3da]
+description = "With a little bit of everything"
+
+[0b3ed1ec-3991-4b8b-8518-5cb73d4a64fe]
+description = "with markdown symbols in the header text that should not be interpreted"
+
+[113a2e58-78de-4efa-90e9-20972224d759]
+description = "with markdown symbols in the list item text that should not be interpreted"
+
+[e65e46e2-17b7-4216-b3ac-f44a1b9bcdb4]
+description = "with markdown symbols in the paragraph text that should not be interpreted"
+
+[f0bbbbde-0f52-4c0c-99ec-be4c60126dd4]
+description = "unordered lists close properly with preceding and following lines"

exercises/practice/markdown/.npmrc

@@ -0,0 +1 @@
+audit=false

exercises/practice/markdown/LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2021 Exercism
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

exercises/practice/markdown/babel.config.js

@@ -0,0 +1,4 @@
+module.exports = {
+  presets: ['@exercism/babel-preset-javascript'],
+  plugins: [],
+};

exercises/practice/markdown/markdown.js

@@ -0,0 +1,101 @@
+function wrap(text, tag) {
+  return `<${tag}>${text}</${tag}>`;
+}
+
+function isTag(text, tag) {
+  return text.startsWith(`<${tag}>`);
+}
+
+function parser(markdown, delimiter, tag) {
+  const pattern = new RegExp(`${delimiter}(.+)${delimiter}`);
+  const replacement = `<${tag}>$1</${tag}>`;
+  return markdown.replace(pattern, replacement);
+}
+
+function parse__(markdown) {
+  return parser(markdown, '__', 'strong');
+}
+
+function parse_(markdown) {
+  return parser(markdown, '_', 'em');
+}
+
+function parseText(markdown, list) {
+  const parsedText = parse_(parse__(markdown));
+  if (list) {
+    return parsedText;
+  } else {
+    return wrap(parsedText, 'p');
+  }
+}
+
+function parseHeader(markdown, list) {
+  let count = 0;
+  for (let i = 0; i < markdown.length; i++) {
+    if (markdown[i] === '#') {
+      count += 1;
+    } else {
+      break;
+    }
+  }
+  if (count === 0 || count > 6) {
+    return [null, list];
+  }
+  const headerTag = `h${count}`;
+  const headerHtml = wrap(markdown.substring(count + 1), headerTag);
+  if (list) {
+    return [`</ul>${headerHtml}`, false];
+  } else {
+    return [headerHtml, false];
+  }
+}
+
+function parseLineItem(markdown, list) {
+  if (markdown.startsWith('*')) {
+    const innerHtml = wrap(parseText(markdown.substring(2), true), 'li');
+    if (list) {
+      return [innerHtml, true];
+    } else {
+      return [`<ul>${innerHtml}`, true];
+    }
+  }
+  return [null, list];
+}
+
+function parseParagraph(markdown, list) {
+  if (!list) {
+    return [parseText(markdown, false), false];
+  } else {
+    return [`</ul>${parseText(markdown, false)}`, false];
+  }
+}
+
+function parseLine(markdown, list) {
+  let [result, inListAfter] = parseHeader(markdown, list);
+  if (result === null) {
+    [result, inListAfter] = parseLineItem(markdown, list);
+  }
+  if (result === null) {
+    [result, inListAfter] = parseParagraph(markdown, list);
+  }
+  if (result === null) {
+    throw new Error('Invalid markdown');
+  }
+  return [result, inListAfter];
+}
+
+export function parse(markdown) {
+  const lines = markdown.split('\n');
+  let result = '';
+  let list = false;
+  for (let i = 0; i < lines.length; i++) {
+    let [lineResult, newList] = parseLine(lines[i], list);
+    result += lineResult;
+    list = newList;
+  }
+  if (list) {
+    return result + '</ul>';
+  } else {
+    return result;
+  }
+}