Shell: Cache PATH for faster tab completion

This patch reduces the O(n) tab completion to something like O(log(n)).
The cache is just a sorted vector of strings and we binary search it to
get a string matching our input, and then check the surrounding strings
to see if we need to remove any characters. Also we no longer stat each
file every time.

Also added an #include in BinarySearch since it was using size_t. Oops.

If `export` is called, we recache. Need to implement the `hash` builtin
for when an executable has been added to a directory in PATH.

1 files changed, 2 insertions, 0 deletions

diff --git a/AK/BinarySearch.h b/AK/BinarySearch.h
index 16cd9784dc..c3f00ce04d 100644
--- a/AK/BinarySearch.h
+++ b/AK/BinarySearch.h
@@ -1,5 +1,7 @@
 #pragma once
 
+#include <AK/Types.h>
+
 namespace AK {
 
 template<typename T>