Automatic table of contents generation for Markdown

Adds table of contents for any Markdown note or
Markdown snippet.
Consequent generations update existing TOC.
Generated TOC is case sensitive to handle #2067

Shortcut : CommandOrControl+Alt+T
Menu : Edit/Generate/Update Markdown TOC

browser/lib/markdown-toc-generator.js

@@ -0,0 +1,52 @@
+/**
+ * @fileoverview Markdown table of contents generator
+ */
+
+import toc from 'markdown-toc'
+import diacritics from 'diacritics-map'
+import stripColor from 'strip-color'
+
+/**
+ * @caseSensitiveSlugify Custom slugify function
+ * Same implementation that the original used by markdown-toc (node_modules/markdown-toc/lib/utils.js),
+ * but keeps original case to properly handle https://github.com/BoostIO/Boostnote/issues/2067
+ */
+function caseSensitiveSlugify (str) {
+  function replaceDiacritics (str) {
+    return str.replace(/[À-ž]/g, function (ch) {
+      return diacritics[ch] || ch
+    })
+  }
+  function getTitle (str) {
+    if (/^\[[^\]]+\]\(/.test(str)) {
+      var m = /^\[([^\]]+)\]/.exec(str)
+      if (m) return m[1]
+    }
+    return str
+  }
+  str = getTitle(str)
+  str = stripColor(str)
+  // str = str.toLowerCase() //let's be case sensitive
+
+  // `.split()` is often (but not always) faster than `.replace()`
+  str = str.split(' ').join('-')
+  str = str.split(/\t/).join('--')
+  str = str.split(/<\/?[^>]+>/).join('')
+  str = str.split(/[|$&`~=\\\/@+*!?({[\]})<>=.,;:'"^]/).join('')
+  str = str.split(/[。？！，、；：“”【】（）〔〕［］﹃﹄“ ”‘’﹁﹂—…－～《》〈〉「」]/).join('')
+  str = replaceDiacritics(str)
+  return str
+}
+
+export function generate (currentValue, updateCallback) {
+  const TOC_MARKER = '<!-- toc -->'
+  if (!currentValue.includes(TOC_MARKER)) {
+    currentValue = TOC_MARKER + currentValue
+  }
+  updateCallback(toc.insert(currentValue, {slugify: caseSensitiveSlugify}))
+}
+
+export default {
+  generate
+}
+