complete redesign: use nodejs on server instead of php - documentation to be updated

nodejs/node_modules/stylus/lib/cache/memory.js

@@ -0,0 +1,116 @@
+/**
+ * Module dependencies.
+ */
+
+var crypto = require('crypto')
+  , nodes = require('../nodes');
+
+var MemoryCache = module.exports = function(options) {
+  options = options || {};
+  this.limit = options['cache limit'] || 256;
+  this._cache = {};
+  this.length = 0;
+  this.head = this.tail = null;
+};
+
+/**
+ * Set cache item with given `key` to `value`.
+ *
+ * @param {String} key
+ * @param {Object} value
+ * @api private
+ */
+
+MemoryCache.prototype.set = function(key, value) {
+  var clone = value.clone()
+    , item;
+
+  clone.filename = nodes.filename;
+  clone.lineno = nodes.lineno;
+  clone.column = nodes.column;
+  item = { key: key, value: clone };
+  this._cache[key] = item;
+
+  if (this.tail) {
+    this.tail.next = item;
+    item.prev = this.tail;
+  } else {
+    this.head = item;
+  }
+
+  this.tail = item;
+  if (this.length++ == this.limit) this.purge();
+};
+
+/**
+ * Get cache item with given `key`.
+ *
+ * @param {String} key
+ * @return {Object}
+ * @api private
+ */
+
+MemoryCache.prototype.get = function(key) {
+  var item = this._cache[key]
+    , val = item.value.clone();
+
+  if (item == this.tail) return val;
+  if (item.next) {
+    if (item == this.head) this.head = item.next;
+    item.next.prev = item.prev;
+  }
+  if (item.prev) item.prev.next = item.next;
+
+  item.next = null;
+  item.prev = this.tail;
+
+  if (this.tail) this.tail.next = item;
+  this.tail = item;
+
+  return val;
+};
+
+/**
+ * Check if cache has given `key`.
+ *
+ * @param {String} key
+ * @return {Boolean}
+ * @api private
+ */
+
+MemoryCache.prototype.has = function(key) {
+  return !!this._cache[key];
+};
+
+/**
+ * Generate key for the source `str` with `options`.
+ *
+ * @param {String} str
+ * @param {Object} options
+ * @return {String}
+ * @api private
+ */
+
+MemoryCache.prototype.key = function(str, options) {
+  var hash = crypto.createHash('sha1');
+  hash.update(str + options.prefix);
+  return hash.digest('hex');
+};
+
+/**
+ * Remove the oldest item from the cache.
+ *
+ * @api private
+ */
+
+MemoryCache.prototype.purge = function() {
+  var item = this.head;
+
+  if (this.head.next) {
+    this.head = this.head.next;
+    this.head.prev = null;
+  }
+
+  this._cache[item.key] = item.prev = item.next = null;
+  this.length--;
+};