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[josuexyz/.git] / node_modules / negotiator / lib / encoding.js

diff --git a/node_modules/negotiator/lib/encoding.js b/node_modules/negotiator/lib/encoding.js
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+/**
+ * negotiator
+ * Copyright(c) 2012 Isaac Z. Schlueter
+ * Copyright(c) 2014 Federico Romero
+ * Copyright(c) 2014-2015 Douglas Christopher Wilson
+ * MIT Licensed
+ */
+
+'use strict';
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = preferredEncodings;
+module.exports.preferredEncodings = preferredEncodings;
+
+/**
+ * Module variables.
+ * @private
+ */
+
+var simpleEncodingRegExp = /^\s*([^\s;]+)\s*(?:;(.*))?$/;
+
+/**
+ * Parse the Accept-Encoding header.
+ * @private
+ */
+
+function parseAcceptEncoding(accept) {
+  var accepts = accept.split(',');
+  var hasIdentity = false;
+  var minQuality = 1;
+
+  for (var i = 0, j = 0; i < accepts.length; i++) {
+    var encoding = parseEncoding(accepts[i].trim(), i);
+
+    if (encoding) {
+      accepts[j++] = encoding;
+      hasIdentity = hasIdentity || specify('identity', encoding);
+      minQuality = Math.min(minQuality, encoding.q || 1);
+    }
+  }
+
+  if (!hasIdentity) {
+    /*
+     * If identity doesn't explicitly appear in the accept-encoding header,
+     * it's added to the list of acceptable encoding with the lowest q
+     */
+    accepts[j++] = {
+      encoding: 'identity',
+      q: minQuality,
+      i: i
+    };
+  }
+
+  // trim accepts
+  accepts.length = j;
+
+  return accepts;
+}
+
+/**
+ * Parse an encoding from the Accept-Encoding header.
+ * @private
+ */
+
+function parseEncoding(str, i) {
+  var match = simpleEncodingRegExp.exec(str);
+  if (!match) return null;
+
+  var encoding = match[1];
+  var q = 1;
+  if (match[2]) {
+    var params = match[2].split(';');
+    for (var j = 0; j < params.length; j++) {
+      var p = params[j].trim().split('=');
+      if (p[0] === 'q') {
+        q = parseFloat(p[1]);
+        break;
+      }
+    }
+  }
+
+  return {
+    encoding: encoding,
+    q: q,
+    i: i
+  };
+}
+
+/**
+ * Get the priority of an encoding.
+ * @private
+ */
+
+function getEncodingPriority(encoding, accepted, index) {
+  var priority = {o: -1, q: 0, s: 0};
+
+  for (var i = 0; i < accepted.length; i++) {
+    var spec = specify(encoding, accepted[i], index);
+
+    if (spec && (priority.s - spec.s || priority.q - spec.q || priority.o - spec.o) < 0) {
+      priority = spec;
+    }
+  }
+
+  return priority;
+}
+
+/**
+ * Get the specificity of the encoding.
+ * @private
+ */
+
+function specify(encoding, spec, index) {
+  var s = 0;
+  if(spec.encoding.toLowerCase() === encoding.toLowerCase()){
+    s |= 1;
+  } else if (spec.encoding !== '*' ) {
+    return null
+  }
+
+  return {
+    i: index,
+    o: spec.i,
+    q: spec.q,
+    s: s
+  }
+};
+
+/**
+ * Get the preferred encodings from an Accept-Encoding header.
+ * @public
+ */
+
+function preferredEncodings(accept, provided) {
+  var accepts = parseAcceptEncoding(accept || '');
+
+  if (!provided) {
+    // sorted list of all encodings
+    return accepts
+      .filter(isQuality)
+      .sort(compareSpecs)
+      .map(getFullEncoding);
+  }
+
+  var priorities = provided.map(function getPriority(type, index) {
+    return getEncodingPriority(type, accepts, index);
+  });
+
+  // sorted list of accepted encodings
+  return priorities.filter(isQuality).sort(compareSpecs).map(function getEncoding(priority) {
+    return provided[priorities.indexOf(priority)];
+  });
+}
+
+/**
+ * Compare two specs.
+ * @private
+ */
+
+function compareSpecs(a, b) {
+  return (b.q - a.q) || (b.s - a.s) || (a.o - b.o) || (a.i - b.i) || 0;
+}
+
+/**
+ * Get full encoding string.
+ * @private
+ */
+
+function getFullEncoding(spec) {
+  return spec.encoding;
+}
+
+/**
+ * Check if a spec has any quality.
+ * @private
+ */
+
+function isQuality(spec) {
+  return spec.q > 0;
+}