Add fuzzy tests

Author: rvanvelzen

doc/grammars/type.abnf

@@ -3,7 +3,7 @@
 ; ---------------------------------------------------------------------------- ;
 
 Type
-= Atomic [Union / Intersection]
+= Atomic [Union / Intersection / Conditional]
 / Nullable
 
 Union
@@ -12,6 +12,9 @@ Union
 Intersection
 = 1*(TokenIntersection Atomic)
 
+Conditional
+ = 1*ByteHorizontalWs "is" [1*ByteHorizontalWs "not"] 1*ByteHorizontalWs Atomic TokenNullable Atomic TokenColon Atomic
+
 Nullable
 = TokenNullable TokenIdentifier [Generic]
 

src/Parser/TokenIterator.php

@@ -7,6 +7,7 @@
 use function assert;
 use function count;
 use function in_array;
+use function strcasecmp;
 use function strlen;
 
 class TokenIterator
@@ -59,7 +60,7 @@ public function currentTokenOffset(): int
 
 public function isCurrentTokenValue(string $tokenValue): bool
 {
-return $this->tokens[$this->index][Lexer::VALUE_OFFSET] === $tokenValue;
+return strcasecmp($this->tokens[$this->index][Lexer::VALUE_OFFSET], $tokenValue) === 0;
 }