Throw error if a quantifier is quantified eg. 'a**'; throw error if start of character range is greater than the end eg. '[b-a]'

compile.go

@@ -469,6 +469,10 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 						outQueue = append(outQueue, newPostfixNode(to_append))
 						topStack, _ = peek(opStack)
 					}
+					outQueueFinalElement, _ := peek(outQueue)
+					if (c == '*' && outQueueFinalElement.nodetype == KLEENE) || (c == '+' && outQueueFinalElement.nodetype == PLUS) { // You cannot apply a quantifier to a quantifier in this way
+						return nil, fmt.Errorf("illegal use of token '%c'", c)
+					}
 					opStack = append(opStack, c)
 				}
 			}
@@ -654,6 +658,9 @@ func shuntingYard(re string, flags ...ReFlag) ([]postfixNode, error) {
 						// We have established that they both have a length of 1
 						startRangeRune := startRangePostfixNode.contents[0]
 						endRangeRune := endRangePostfixNode.contents[0]
+						if startRangeRune > endRangeRune {
+							return nil, fmt.Errorf("character range syntax is [a-b], not [b-a]")
+						}
 						chars = append(chars, newPostfixCharNode(genRange(startRangeRune, endRangeRune+1)...))
 					}