ich es geschaffen, den folgenden Pseudo-Code auf Wikipedia zu finden, die einen Postfix-Ausdruck erstellen zeigt, wie den Rangierbahnhof Algorithmus verwenden:Wie erstellt man einen abstrakten Baum anstelle eines Postfix-Ausdrucks mit dem Shunting Yard-Algorithmus?
While there are tokens to be read:
Read a token.
If the token is a number, then push it to the output queue.
If the token is a function token, then push it onto the stack.
If the token is a function argument separator (e.g., a comma):
Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue. If no left parentheses are encountered, either the separator was misplaced or parentheses were mismatched.
If the token is an operator, o1, then:
while there is an operator token o2, at the top of the operator stack and either
o1 is left-associative and its precedence is less than or equal to that of o2, or
o1 is right associative, and has precedence less than that of o2,
pop o2 off the operator stack, onto the output queue;
at the end of iteration push o1 onto the operator stack.
If the token is a left parenthesis (i.e. "("), then push it onto the stack.
If the token is a right parenthesis (i.e. ")"):
Until the token at the top of the stack is a left parenthesis, pop operators off the stack onto the output queue.
Pop the left parenthesis from the stack, but not onto the output queue.
If the token at the top of the stack is a function token, pop it onto the output queue.
If the stack runs out without finding a left parenthesis, then there are mismatched parentheses.
When there are no more tokens to read:
While there are still operator tokens in the stack:
If the operator token on the top of the stack is a parenthesis, then there are mismatched parentheses.
Pop the operator onto the output queue.
Exit.
wie ich diesen Algorithmus ändern Sie einen abstrakten Syntaxbaum zu erzeugen, was sollte ich tun, anstatt Operatoren oder Operanden zu einer Ausgabe zu drücken?
Werfen Sie einen Blick [hier] (http://softwareengineering.stackexchange.com/questions/254074/how-exactly-is-anabstract-syntax-tree-created?rq=1). –
Danke, also mache ich nur das Gleiche, aber drücke Operanden zu einem Ausdrucksstapel statt zu einem Ausgang. Und die beiden Ausdrücke an der Spitze des Stapels mit einem Operator verbinden, wenn dieser zu einer Ausgabe geschoben würde? – user3102599