url: add urlSearchParams.sort()

Fixes: nodejs#10760
Ref: whatwg/url#26
Ref: whatwg/url#199
Ref: web-platform-tests/wpt#4531

doc/api/url.md

@@ -777,6 +777,21 @@ Returns an ES6 Iterator over the names of each name-value pair.
 Remove any existing name-value pairs whose name is `name` and append a new
 name-value pair.
 
+#### urlSearchParams.sort()
+
+Sort all existing name-value pairs in-place by their names. Sorting is done
+with a [stable sorting algorithm][], so relative order between name-value pairs
+with the same name is preserved.
+
+This method can be used, in particular, to increase cache hits.
+
+```js
+const params = new URLSearchParams('query[]=abc&type=search&query[]=123');
+params.sort();
+console.log(params.toString());
+  // Prints query%5B%5D=abc&query%5B%5D=123&type=search
+```
+
 #### urlSearchParams.toString()
 
 * Returns: {String}
@@ -872,3 +887,4 @@ console.log(myURL.origin);
 [`Map`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map
 [`array.toString()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/toString
 [WHATWG URL]: #url_the_whatwg_url_api
+[stable sorting algorithm]: https://en.wikipedia.org/wiki/Sorting_algorithm#Stability

lib/internal/url.js

@@ -766,6 +766,35 @@ class URLSearchParams {
   }
 }
 
+// for merge sort
+function merge(out, start, mid, end, lBuffer, rBuffer) {
+  const sizeLeft = mid - start;
+  const sizeRight = end - mid;
+  var l, r, o;
+
+  for (l = 0; l < sizeLeft; l++)
+    lBuffer[l] = out[start + l];
+  for (r = 0; r < sizeRight; r++)
+    rBuffer[r] = out[mid + r];
+
+  l = 0;
+  r = 0;
+  o = start;
+  while (l < sizeLeft && r < sizeRight) {
+    if (lBuffer[l] <= rBuffer[r]) {
+      out[o++] = lBuffer[l++];
+      out[o++] = lBuffer[l++];
+    } else {
+      out[o++] = rBuffer[r++];
+      out[o++] = rBuffer[r++];
+    }
+  }
+  while (l < sizeLeft)
+    out[o++] = lBuffer[l++];
+  while (r < sizeRight)
+    out[o++] = rBuffer[r++];
+}
+
 defineIDLClass(URLSearchParams.prototype, 'URLSearchParams', {
   append(name, value) {
     if (!this || !(this instanceof URLSearchParams)) {
@@ -897,6 +926,51 @@ defineIDLClass(URLSearchParams.prototype, 'URLSearchParams', {
     update(this[context], this);
   },
 
+  sort() {
+    const a = this[searchParams];
+    const len = a.length;
+    if (len <= 2) {
+      return;
+    }
+
+    // arbitrary number found through testing
+    if (len < 100) {
+      // Simple stable in-place insertion sort
+      // Derived from v8/src/js/array.js
+      for (var i = 2; i < len; i += 2) {
+        var curKey = a[i];
+        var curVal = a[i + 1];
+        var j;
+        for (j = i - 2; j >= 0; j -= 2) {
+          if (a[j] > curKey) {
+            a[j + 2] = a[j];
+            a[j + 3] = a[j + 1];
+          } else {
+            break;
+          }
+        }
+        a[j + 2] = curKey;
+        a[j + 3] = curVal;
+      }
+    } else {
+      // Bottom-up iterative stable merge sort
+      const lBuffer = new Array(len);
+      const rBuffer = new Array(len);
+      for (var step = 2; step < len; step *= 2) {
+        for (var start = 0; start < len - 2; start += 2 * step) {
+          var mid = start + step;
+          var end = mid + step;
+          end = end < len ? end : len;
+          if (mid > end)
+            continue;
+          merge(a, start, mid, end, lBuffer, rBuffer);
+        }
+      }
+    }
+
+    update(this[context], this);
+  },
+
   // https://heycam.github.io/webidl/#es-iterators
   // Define entries here rather than [Symbol.iterator] as the function name
   // must be set to `entries`.

test/parallel/test-whatwg-url-searchparams-sort.js

@@ -0,0 +1,84 @@
+'use strict';
+
+const common = require('../common');
+const {URL, URLSearchParams} = require('url');
+const { test, assert_array_equals } = common.WPT;
+
+/* eslint-disable */
+/* WPT Refs:
+   https://github.com/w3c/web-platform-tests/blob/5903e00e77e85f8bcb21c73d1d7819fcd04763bd/url/urlsearchparams-sort.html
+   License: http://www.w3.org/Consortium/Legal/2008/04-testsuite-copyright.html
+*/
+[
+  {
+    "input": "z=b&a=b&z=a&a=a",
+    "output": [["a", "b"], ["a", "a"], ["z", "b"], ["z", "a"]]
+  },
+  {
+    "input": "\uFFFD=x&\uFFFC&\uFFFD=a",
+    "output": [["\uFFFC", ""], ["\uFFFD", "x"], ["\uFFFD", "a"]]
+  },
+  {
+    "input": "ffi&🌈", // 🌈 > code point, but < code unit because two code units
+    "output": [["🌈", ""], ["ffi", ""]]
+  },
+  {
+    "input": "é&e\uFFFD&e\u0301",
+    "output": [["e\u0301", ""], ["e\uFFFD", ""], ["é", ""]]
+  },
+  {
+    "input": "z=z&a=a&z=y&a=b&z=x&a=c&z=w&a=d&z=v&a=e&z=u&a=f&z=t&a=g",
+    "output": [["a", "a"], ["a", "b"], ["a", "c"], ["a", "d"], ["a", "e"], ["a", "f"], ["a", "g"], ["z", "z"], ["z", "y"], ["z", "x"], ["z", "w"], ["z", "v"], ["z", "u"], ["z", "t"]]
+  }
+].forEach((val) => {
+  test(() => {
+    let params = new URLSearchParams(val.input),
+        i = 0
+    params.sort()
+    for(let param of params) {
+      assert_array_equals(param, val.output[i])
+      i++
+    }
+  }, "Parse and sort: " + val.input)
+
+  test(() => {
+    let url = new URL("?" + val.input, "https://example/")
+    url.searchParams.sort()
+    let params = new URLSearchParams(url.search),
+        i = 0
+    for(let param of params) {
+      assert_array_equals(param, val.output[i])
+      i++
+    }
+  }, "URL parse and sort: " + val.input)
+})
+/* eslint-enable */
+
+// Tests below are not from WPT.
+;[
+  {
+    'input': 'z=a&=b&c=d',
+    'output': [['', 'b'], ['c', 'd'], ['z', 'a']]
+  }
+].forEach((val) => {
+  test(() => {
+    const params = new URLSearchParams(val.input);
+    let i = 0;
+    params.sort();
+    for (const param of params) {
+      assert_array_equals(param, val.output[i]);
+      i++;
+    }
+  }, 'Parse and sort: ' + val.input);
+
+  test(() => {
+    const url = new URL(`?${val.input}`, 'https://example/');
+    url.searchParams.sort();
+    const params = new URLSearchParams(url.search);
+    let i = 0;
+    for (const param of params) {
+      assert_array_equals(param, val.output[i]);
+      i++;
+    }
+  }, 'URL parse and sort: ' + val.input);
+});