as10_s4b.py

from warnings import warn
def buildParseTree(fpexp):
    L,R,O,V = 1,2,3,4
    state = None
    fplist = fpexp.split()
    pStack = Stack()
    eTree = BinaryTree('')
    pStack.push(eTree)
    currentTree = eTree
    for i in fplist:
        if not state and i in ')+-*/': raise Exception(') ve islec olamaz')
        if i == '(':
            if state == V: raise Exception('islenen+(')
            if state == R: raise Exception(')+(')
	    currentTree.insertLeft('')
            pStack.push(currentTree)
            currentTree = currentTree.getLeftChild()
            state = L
        elif i not in '+-*/)':
            if state == V: raise Exception('islenen+islenen')
            if state == R: raise Exception(') + islenen')
	    currentTree.setRootVal(eval(i))
            parent = pStack.pop()
            currentTree = parent
            state = V
        elif i in '+-*/':
            if state == O: raise Exception('islec+islec')
            if state == L: raise Exception('(+islec')
	    currentTree.setRootVal(i)
	    currentTree.insertRight('')
	    pStack.push(currentTree)
	    currentTree = currentTree.getRightChild()
            state = O
        elif i == ')':
            if state == O: raise Exception('islec+)')
            if state == L: warn('(+)')
	    currentTree = pStack.pop()
            state = R
    return eTree