Initial commit: 11ty website with Fire/Frost branding

node_modules/bcp-47-match/index.js

@@ -0,0 +1,234 @@
+/**
+ * See <https://tools.ietf.org/html/rfc4647#section-3.1>
+ * for more info on the algorithms.
+ */
+
+/**
+ * @typedef {string} Tag
+ *   BCP-47 tag.
+ * @typedef {Array<Tag>} Tags
+ *   List of BCP-47 tags.
+ * @typedef {string} Range
+ *   RFC 4647 range.
+ * @typedef {Array<Range>} Ranges
+ *   List of RFC 4647 range.
+ *
+ * @callback Check
+ *   An internal check.
+ * @param {Tag} tag
+ *   BCP-47 tag.
+ * @param {Range} range
+ *   RFC 4647 range.
+ * @returns {boolean}
+ *   Whether the range matches the tag.
+ *
+ * @typedef {FilterOrLookup<true>} Filter
+ *   Filter: yields all tags that match a range.
+ * @typedef {FilterOrLookup<false>} Lookup
+ *   Lookup: yields the best tag that matches a range.
+ */
+
+/**
+ * @template {boolean} IsFilter
+ *   Whether to filter or perform a lookup.
+ * @callback FilterOrLookup
+ *   A check.
+ * @param {Tag|Tags} tags
+ *   One or more BCP-47 tags.
+ * @param {Range|Ranges|undefined} [ranges='*']
+ *   One or more RFC 4647 ranges.
+ * @returns {IsFilter extends true ? Tags : Tag|undefined}
+ *   Result.
+ */
+
+/**
+ * Factory to perform a filter or a lookup.
+ *
+ * This factory creates a function that accepts a list of tags and a list of
+ * ranges, and contains logic to exit early for lookups.
+ * `check` just has to deal with one tag and one range.
+ * This match function iterates over ranges, and for each range,
+ * iterates over tags.
+ * That way, earlier ranges matching any tag have precedence over later ranges.
+ *
+ * @template {boolean} IsFilter
+ * @param {Check} check
+ *   A check.
+ * @param {IsFilter} filter
+ *   Whether to filter or perform a lookup.
+ * @returns {FilterOrLookup<IsFilter>}
+ *   Filter or lookup.
+ */
+function factory(check, filter) {
+  /**
+   * @param {Tag|Tags} tags
+   *   One or more BCP-47 tags.
+   * @param {Range|Ranges|undefined} [ranges='*']
+   *   One or more RFC 4647 ranges.
+   * @returns {IsFilter extends true ? Tags : Tag|undefined}
+   *   Result.
+   */
+  return function (tags, ranges) {
+    let left = cast(tags, 'tag')
+    const right = cast(
+      ranges === null || ranges === undefined ? '*' : ranges,
+      'range'
+    )
+    /** @type {Tags} */
+    const matches = []
+    let rightIndex = -1
+
+    while (++rightIndex < right.length) {
+      const range = right[rightIndex].toLowerCase()
+
+      // Ignore wildcards in lookup mode.
+      if (!filter && range === '*') continue
+
+      let leftIndex = -1
+      /** @type {Tags} */
+      const next = []
+
+      while (++leftIndex < left.length) {
+        if (check(left[leftIndex].toLowerCase(), range)) {
+          // Exit if this is a lookup and we have a match.
+          if (!filter) {
+            return /** @type {IsFilter extends true ? Tags : Tag|undefined} */ (
+              left[leftIndex]
+            )
+          }
+
+          matches.push(left[leftIndex])
+        } else {
+          next.push(left[leftIndex])
+        }
+      }
+
+      left = next
+    }
+
+    // If this is a filter, return the list.  If it’s a lookup, we didn’t find
+    // a match, so return `undefined`.
+    return /** @type {IsFilter extends true ? Tags : Tag|undefined} */ (
+      filter ? matches : undefined
+    )
+  }
+}
+
+/**
+ * Basic Filtering (Section 3.3.1) matches a language priority list consisting
+ * of basic language ranges (Section 2.1) to sets of language tags.
+ *
+ * @param {Tag|Tags} tags
+ *   One or more BCP-47 tags.
+ * @param {Range|Ranges|undefined} [ranges='*']
+ *   One or more RFC 4647 ranges.
+ * @returns {Tags}
+ *   List of BCP-47 tags.
+ */
+export const basicFilter = factory(function (tag, range) {
+  return range === '*' || tag === range || tag.includes(range + '-')
+}, true)
+
+/**
+ * Extended Filtering (Section 3.3.2) matches a language priority list
+ * consisting of extended language ranges (Section 2.2) to sets of language
+ * tags.
+ *
+ * @param {Tag|Tags} tags
+ *   One or more BCP-47 tags.
+ * @param {Range|Ranges|undefined} [ranges='*']
+ *   One or more RFC 4647 ranges.
+ * @returns {Tags}
+ *   List of BCP-47 tags.
+ */
+export const extendedFilter = factory(function (tag, range) {
+  // 3.3.2.1
+  const left = tag.split('-')
+  const right = range.split('-')
+  let leftIndex = 0
+  let rightIndex = 0
+
+  // 3.3.2.2
+  if (right[rightIndex] !== '*' && left[leftIndex] !== right[rightIndex]) {
+    return false
+  }
+
+  leftIndex++
+  rightIndex++
+
+  // 3.3.2.3
+  while (rightIndex < right.length) {
+    // 3.3.2.3.A
+    if (right[rightIndex] === '*') {
+      rightIndex++
+      continue
+    }
+
+    // 3.3.2.3.B
+    if (!left[leftIndex]) return false
+
+    // 3.3.2.3.C
+    if (left[leftIndex] === right[rightIndex]) {
+      leftIndex++
+      rightIndex++
+      continue
+    }
+
+    // 3.3.2.3.D
+    if (left[leftIndex].length === 1) return false
+
+    // 3.3.2.3.E
+    leftIndex++
+  }
+
+  // 3.3.2.4
+  return true
+}, true)
+
+/**
+ * Lookup (Section 3.4) matches a language priority list consisting of basic
+ * language ranges to sets of language tags to find the one exact language tag
+ * that best matches the range.
+ *
+ * @param {Tag|Tags} tags
+ *   One or more BCP-47 tags.
+ * @param {Range|Ranges|undefined} [ranges='*']
+ *   One or more RFC 4647 ranges.
+ * @returns {Tag|undefined}
+ *   BCP-47 tag.
+ */
+export const lookup = factory(function (tag, range) {
+  let right = range
+
+  /* eslint-disable-next-line no-constant-condition */
+  while (true) {
+    if (right === '*' || tag === right) return true
+
+    let index = right.lastIndexOf('-')
+
+    if (index < 0) return false
+
+    if (right.charAt(index - 2) === '-') index -= 2
+
+    right = right.slice(0, index)
+  }
+}, false)
+
+/**
+ * Validate tags or ranges, and cast them to arrays.
+ *
+ * @param {string|Array<string>} values
+ * @param {string} name
+ * @returns {Array<string>}
+ */
+function cast(values, name) {
+  const value = values && typeof values === 'string' ? [values] : values
+
+  if (!value || typeof value !== 'object' || !('length' in value)) {
+    throw new Error(
+      'Invalid ' + name + ' `' + value + '`, expected non-empty string'
+    )
+  }
+
+  return value
+}