ADD file via upload

AST.py

@@ -0,0 +1,135 @@
+#!/usr/bin/env python3
+
+from queryParse import *
+import os
+import numpy as mp
+import sys
+import tensorflow as tf
+
+'''
+This modult aimed to transfer the infix expression to AST
+
+For example:
+Given a [WHERE] subsequence: 
+'''
+class TreeNode:
+    '''
+    Define the AST's tree node, each node has three parts:
+
+    1. content: the node's content, e.g. 'deposit', 'op5', 50000
+    2. left: left node
+    3. right: right node
+    '''
+
+    '''
+    Construct function
+    '''
+    def __init__(self, exp):
+        self.content = exp
+        self.left = NULL
+        self.right = NULL
+
+def priority(a):
+    '''
+    This function will return the priority of each operator, if priority greater, the return value will bigger
+        Operator   ReplaceCode
+        >          op0
+        <          op1
+        ==         op2
+        >=         op3
+        <=         op4
+        <>         op5
+        +          op6
+        -          op7
+        *          op8
+        /          op9
+    '''
+    if a in ['ALL', 'ANY', 'BETWEEN', 'LIKE', 'IN', 'OR', 'SOME']:
+        return 1
+    if a in ['AND']:
+        return 2
+    if a in ['NOT']:
+        return 3
+    if a in ['op0', 'op1', 'op2', 'op3', 'op4', 'op5']:
+        return 4
+    if a in ['op6', 'op7']:
+        return 5
+    if a in ['op8', 'op9']:
+        return 6
+
+def infix2postfix(exp):
+    '''
+    This function will transfer the infix expression to postfix expression
+
+    For example: 
+    ['deposit', 'op5', '20000', 'AND', '(', 'credit', 'op3', '3', 'OR', 'credit', 'op4', '7', ')']
+    |   |   |   |   |
+    After transform:
+    ['deposit', '20000', 'credit', '3', 'op3', 'credit', '7', 'op4', 'op5', 'AND']
+    '''
+
+    '''
+    tuple: Store the infix form for WHERE subquery
+    '''
+    op = ['ALL', 'ANY', 'BETWEEN', 'LIKE', 'IN', 'OR', 'SOME', 'AND', 'NOT', 'op0', 'op1', 'op2', 'op3', 'op4', 'op5', 'op6', 'op7', 'op8', 'op9', '(', ')']
+    tuples = []
+    for subexp in exp:
+        for element in subexp:
+            if element != '':
+                tuples.append(element.replace(' ', ''))
+    
+    '''
+    Define two stacks: stack, postfix
+
+    stack-store the operator
+    postfix-store the postfix
+    '''
+    stack = []
+    postfix = []
+    for tuple in tuples:
+        if tuple not in op:
+            '''
+            If tuple not in operator, push to the stack
+            '''
+            postfix.append(tuple)
+        else:
+            if tuple != ')' and (not stack or tuple == '(' or stack[-1] == '('
+                             or priority(tuple) > priority(stack[-1])):
+                '''
+                If stack not empty, stack's top is '('
+                '''
+                stack.append(tuple)
+            elif tuple == ')':
+                '''
+                If tuple is ')', push into the stack
+                '''
+                while True:
+                    temp = stack.pop()
+                    if temp != '(':
+                        postfix.append(temp)
+                    else:
+                        break
+            else:
+                '''
+                Compare the priority of operators to decide whether to push or pop the stack
+                '''
+                while True:
+                    if stack and stack[-1] != '(' and priority(tuple) <= priority(stack[-1]):
+                        postfix.append(stack.pop())
+                    else:
+                        stack.append(tuple)
+                        break
+    
+    while stack:
+        '''
+        If stack is not empty, all remaining elements are pushed into the postfix stack
+        '''
+        postfix.append(stack.pop())
+    return postfix
+    
+
+def AST():
+    '''
+    This function will build the expression AST according to postfix expression
+    '''
+    node = TreeNode("")