Off by one AST cache cleanup

[germainpigeon]

There is a behaviour that is unconsistent with the comment here:

jmespath.php/src/AstRuntime.php

Lines 37 to 42 in a2a865e

	// Clear the AST cache when it hits 1024 entries
	if (++$this->cachedCount > 1024) {
	$this->cache = [];
	$this->cachedCount = 0;
	}
	$this->cache[$expression] = $this->parser->parse($expression);

• After the first call cachedCount will be 1 and the cache will have 1 entry.
• After the 1024th call cachedCount will be 1024 and the cache will have 1024 entries.
  👉Note that while the cache has hit 1024 entries it is not cleared yet, so to me the comment is already a little misleading.
• After the 1025th call cachedCount will be 0 and the cache will have 1 entry.
  👉One could say that the state of the object is now invalid ?
• After the 2048th call cachedCount will be 1023 and the cache will have 1024 entry.
  👉Note that while the cache has hit 1024 entries it is not cleared yet, once again.
• After the 2049th call cachedCount will be 1024 and the cache will have 1025 entry.
  ❌This is more than 1024 and to me is not what was expected by the developper who wrote the comment.
• After the 2050th call cachedCount will be 0 and the cache will have 1 entry.
  👉Again, one could say that the state of the object is now invalid
• (Then it will repeat)

Please have a look to the code illustrating the current behaviour on 3v4l:
https://3v4l.org/MsW7e

Side proposition : rewrite the comment

-             // Clear the AST cache when it hits 1024 entries
+             // Clear the AST cache if it already holds 1024 entries 

Proposition 1 : fastest fix

-                 $this->cachedCount = 0;
+                 $this->cachedCount = 1;

Proposition 2 : cleaner code (as in "easier to review")

-             if (++$this->cachedCount > 1024) {
+             if ($this->cachedCount > 1024) {
                  $this->cache = [];
                  $this->cachedCount = 0;
              }
              $this->cache[$expression] = $this->parser->parse($expression);
+             $this->cachedCount++;