javacc笔记3

void Input() :
	{}
	{
	  "a" BC() "c"
	}

	void BC() :
	{}
	{
	  "b" [ "c" ]
	}

有两种输出可能，如果：

	void BC() :
	{}
	{
	  "b"
	  [ LOOKAHEAD( { getToken(1).kind == C && getToken(2).kind != C } )
	    <C:"c">
	  ]
	}

则

	if (next token is "c" and following token is not "c") {
	  choose the nested expansion (i.e., go into the [...] construct)
	} else {
	  go beyond the [...] construct without entering it.
	}

rewritten 则：

	void BC() :
	{}
	{
	  "b"
	  [ LOOKAHEAD( "c", { getToken(2).kind != C } )
	    <C:"c">
	  ]
	}