Here is a chunk from Alice's Adventures in Wonderland:
They had not gone far before they saw the Mock Turtle in the distance, sitting sad and lonely on a little ledge of rock, and, as they came nearer, Alice could hear him sighing as if his heart would break.
I wonder what would means here. Is it the same as were willing? I know that will and would can be used in if-clauses (there is a question on ELU), but does as if obey the same rules?