☠☕ Decaffeinate src/text-utils.coffee

src/text-utils.js

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+const isHighSurrogate = (charCode) =>
+  charCode >= 0xD800 && charCode <= 0xDBFF
+
+const isLowSurrogate = (charCode) =>
+  charCode >= 0xDC00 && charCode <= 0xDFFF
+
+const isVariationSelector = (charCode) =>
+  charCode >= 0xFE00 && charCode <= 0xFE0F
+
+const isCombiningCharacter = charCode =>
+  (charCode >= 0x0300 && charCode <= 0x036F) ||
+  (charCode >= 0x1AB0 && charCode <= 0x1AFF) ||
+  (charCode >= 0x1DC0 && charCode <= 0x1DFF) ||
+  (charCode >= 0x20D0 && charCode <= 0x20FF) ||
+  (charCode >= 0xFE20 && charCode <= 0xFE2F)
+
+// Are the given character codes a high/low surrogate pair?
+//
+// * `charCodeA` The first character code {Number}.
+// * `charCode2` The second character code {Number}.
+//
+// Return a {Boolean}.
+const isSurrogatePair = (charCodeA, charCodeB) =>
+  isHighSurrogate(charCodeA) && isLowSurrogate(charCodeB)
+
+// Are the given character codes a variation sequence?
+//
+// * `charCodeA` The first character code {Number}.
+// * `charCode2` The second character code {Number}.
+//
+// Return a {Boolean}.
+const isVariationSequence = (charCodeA, charCodeB) =>
+  !isVariationSelector(charCodeA) && isVariationSelector(charCodeB)
+
+// Are the given character codes a combined character pair?
+//
+// * `charCodeA` The first character code {Number}.
+// * `charCode2` The second character code {Number}.
+//
+// Return a {Boolean}.
+const isCombinedCharacter = (charCodeA, charCodeB) =>
+  !isCombiningCharacter(charCodeA) && isCombiningCharacter(charCodeB)
+
+// Is the character at the given index the start of high/low surrogate pair
+// a variation sequence, or a combined character?
+//
+// * `string` The {String} to check for a surrogate pair, variation sequence,
+//            or combined character.
+// * `index`  The {Number} index to look for a surrogate pair, variation
+//            sequence, or combined character.
+//
+// Return a {Boolean}.
+const isPairedCharacter = (string, index = 0) => {
+  const charCodeA = string.charCodeAt(index)
+  const charCodeB = string.charCodeAt(index + 1)
+  return isSurrogatePair(charCodeA, charCodeB) ||
+    isVariationSequence(charCodeA, charCodeB) ||
+    isCombinedCharacter(charCodeA, charCodeB)
+}
+
+const IsJapaneseKanaCharacter = charCode =>
+  charCode >= 0x3000 && charCode <= 0x30FF
+
+const isCJKUnifiedIdeograph = charCode =>
+  charCode >= 0x4E00 && charCode <= 0x9FFF
+
+const isFullWidthForm = charCode =>
+  (charCode >= 0xFF01 && charCode <= 0xFF5E) ||
+  (charCode >= 0xFFE0 && charCode <= 0xFFE6)
+
+const isDoubleWidthCharacter = (character) => {
+  const charCode = character.charCodeAt(0)
+
+  return IsJapaneseKanaCharacter(charCode) ||
+  isCJKUnifiedIdeograph(charCode) ||
+  isFullWidthForm(charCode)
+}
+
+const isHalfWidthCharacter = (character) => {
+  const charCode = character.charCodeAt(0)
+
+  return (charCode >= 0xFF65 && charCode <= 0xFFDC) ||
+    (charCode >= 0xFFE8 && charCode <= 0xFFEE)
+}
+
+const isKoreanCharacter = (character) => {
+  const charCode = character.charCodeAt(0)
+
+  return (charCode >= 0xAC00 && charCode <= 0xD7A3) ||
+    (charCode >= 0x1100 && charCode <= 0x11FF) ||
+    (charCode >= 0x3130 && charCode <= 0x318F) ||
+    (charCode >= 0xA960 && charCode <= 0xA97F) ||
+    (charCode >= 0xD7B0 && charCode <= 0xD7FF)
+}
+
+const isCJKCharacter = (character) =>
+  isDoubleWidthCharacter(character) ||
+  isHalfWidthCharacter(character) ||
+  isKoreanCharacter(character)
+
+const isWordStart = (previousCharacter, character) =>
+  ((previousCharacter === ' ') || (previousCharacter === '\t')) &&
+  ((character !== ' ') && (character !== '\t'))
+
+const isWrapBoundary = (previousCharacter, character) =>
+  isWordStart(previousCharacter, character) || isCJKCharacter(character)
+
+// Does the given string contain at least surrogate pair, variation sequence,
+// or combined character?
+//
+// * `string` The {String} to check for the presence of paired characters.
+//
+// Returns a {Boolean}.
+const hasPairedCharacter = (string) => {
+  let index = 0
+  while (index < string.length) {
+    if (isPairedCharacter(string, index)) { return true }
+    index++
+  }
+  return false
+}
+
+module.exports = {
+  isPairedCharacter,
+  hasPairedCharacter,
+  isDoubleWidthCharacter,
+  isHalfWidthCharacter,
+  isKoreanCharacter,
+  isWrapBoundary
+}