querystring: fix empty pairs and optimize parse()

This commit fixes handling of empty pairs that occur before the end
of the query string so that they are also ignored.

Additionally, some optimizations have been made, including:

* Avoid unnecessary code execution where possible
* Use a lookup table when checking for hex characters
* Avoid forced decoding when '+' characters are encountered and we
are using the default decoder

Fixes: https://github.com/nodejs/node/issues/10454
PR-URL: https://github.com/nodejs/node/pull/11234
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Nicu Micleușanu <micnic90@gmail.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/test/parallel/test-querystring.js b/test/parallel/test-querystring.js
index baa426094c..04034377fe 100644
--- a/test/parallel/test-querystring.js
+++ b/test/parallel/test-querystring.js
@@ -59,6 +59,15 @@ const qsTestCases = [
   ['&&&&', '', {}],
   ['&=&', '=', { '': '' }],
   ['&=&=', '=&=', { '': [ '', '' ]}],
+  ['a&&b', 'a=&b=', { 'a': '', 'b': '' }],
+  ['a=a&&b=b', 'a=a&b=b', { 'a': 'a', 'b': 'b' }],
+  ['&a', 'a=', { 'a': '' }],
+  ['&=', '=', { '': '' }],
+  ['a&a&', 'a=&a=', { a: [ '', '' ] }],
+  ['a&a&a&', 'a=&a=&a=', { a: [ '', '', '' ] }],
+  ['a&a&a&a&', 'a=&a=&a=&a=', { a: [ '', '', '', '' ] }],
+  ['a=&a=value&a=', 'a=&a=value&a=', { a: [ '', 'value', '' ] }],
+  ['foo+bar=baz+quux', 'foo%20bar=baz%20quux', { 'foo bar': 'baz quux' }],
   [null, '', {}],
   [undefined, '', {}]
 ];