Question

我想在运算符旁边的分流码算法中实现“函数”，并从生成的算法中做一个小解释器但是默认算法会忽略语法错误使用的标记。

有没有人写过翻译（或不）想帮助我？这将有助于很多人坚持这个问题！

这里列出了一些测试，shunting-yard函数忽略了函数调用中令牌的错误用法和/或缺少运算符/操作数：

func(,1)
func(2,)
func(,,,,,)
()
(((()))()())
func((),(,))
func(1,2(3,4))
etc...

我读过一些研究：

http://www.reedbeta.com/blog/2011/12/11/the-shunting-yard-algorithm/
http://en.wikipedia.org/wiki/Shunting-yard_algorithm
http://rosettacode.org/wiki/Parsing/Shunting-yard_algorithm

我的代码（vbscript）的解释，通过一些改进来测试它：

it allows usage of functions(beta)
it gives an error with most of the incorrect syntax
functions can be nested

如果有人想要分享改进或有任何好主意请告诉我！

我的代码：

Function Is_Empty(Stack)
If UBound(Stack) > - 1 Then
Is_Empty = False
Else
Is_Empty = True
End If
End Function
Function Peek(Stack)
If UBound(Stack) > - 1 Then
Peek = Stack(UBound(Stack))
End If
End Function
Function Pop(ByRef Stack)
If UBound(Stack) > - 1 Then
Pop = Stack(UBound(Stack))
ReDim Preserve Stack(UBound(Stack) - 1)
End If
End Function
Sub Push(Item, ByRef Stack)
If UBound(Stack) > - 1 Then
ReDim Preserve Stack(UBound(Stack) + 1)
Stack(UBound(Stack)) = Item
Else
Stack = Array(Item)
End If
End Sub
Set Prec = CreateObject("scripting.dictionary")
With Prec
.Add "+", 1
.Add "-", 1
.Add "*", 2
.Add "/", 2
End With
Function Is_Operator(Op)
Is_Operator = Prec.Exists(Op)
End Function

Set Re = New RegExp
Re.Pattern = "[a-z0-9]+|[+\-/*,()]"
Re.Global = True
Set X = Re.Execute("func (1,1(1,1))")'//here the test code

Stack = Array() : Queue = Array() : Level = 0

For Each Token In X
Select Case Token
Case "func"
Call Push(Token, Stack)
Case "("
If Peek(Stack) = "func" Then
Level = Level + 1
Call Push("#", Queue)
End If
Call Push(Token, Stack)
Case ")"
Do While Not(Peek(Stack) = "(")
If Is_Empty(Stack) Then MsgBox "error: (", 48 : WScript.Quit
Call Push(Pop(Stack), Queue)
Loop
Discard = Pop(Stack)
If Peek(Stack) = "func" Then
Level = Level - 1
If Peek(Queue) = "," Then MsgBox "error: ,", 48 : WScript.Quit
Call Push(Pop(Stack), Queue)
End If
Case ","
If Level = 0 Then MsgBox "error: ,", 48 : WScript.Quit
If Peek(Queue) = "#" Then MsgBox "error: ,", 48 : WScript.Quit
If Peek(Queue) = "," Then MsgBox "error: ,", 48 : WScript.Quit
Do While Not(Peek(Stack) = "(")
If Is_Empty(Stack) Then MsgBox "error: ( or ,", 48 : WScript.Quit
Call Push(Pop(Stack), Queue)
Loop
Call Push(Token, Queue)
Case "+", "-", "*", "/"
A = Token
Do While Is_Operator(Peek(Stack))
B = Peek(Stack)
If Prec(A) < Prec(B) Then
Call Push(Pop(Stack), Queue)
Else
Exit Do
End If
Loop
If Peek(Queue) = "," Then MsgBox "error: wrong operator", 48 : WScript.Quit
Call Push(A, Stack)
Case Else
Call Push(Token, Queue)
End Select
Next
For I = 0 To UBound(Stack)
If Peek(Stack) = "(" Then MsgBox "error: )", 48 : WScript.Quit
Call Push(Pop(Stack), Queue)
Next

MsgBox Join(Queue, "|"),, Level
stack = array()

For Counter = 0 To UBound(Queue)
select case queue(counter)
case "func"
do while not(peek(stack) = "#")
if peek(stack) = "," then
l = l + 1
discart = pop(stack)
elseif is_empty(stack) then
exit do
else
F = F + INT(pop(stack))
end if
loop
discart = pop(stack)
call push(F, stack)
case "+","-","*","/"
B = pop(stack)
if is_empty(stack) then MsgBox "error: not enough values", 48 : WScript.Quit
A = pop(stack)
if not(isnumeric(a) and isnumeric(b)) then MsgBox "error: not numeric", 48 : WScript.Quit
select case queue(Counter)
case "+"
C = int(a) + int(b)
case "-"
C = int(a) - int(b)
case "*"
C = int(a) * int(b)
case "/"
C = int(a) / int(b)
case else
MsgBox "error: " & queue(Counter), 48 : WScript.Quit
end select
call push(c, stack)
case else
Call Push(queue(Counter), Stack)
end select
next
If UBound(Stack) > 0 Then MsgBox "too many values", 48 : WScript.Quit
If is_empty(Stack) Then MsgBox "error: not enough values", 48 : WScript.Quit

msgbox stack(0),0,"result!"

[编辑] 我希望我的解释器的语法几乎与BASIC编程语言完全相同。

类似BASIC的表达示例： a + b *（c / func（x，y，func（z））） - d

语法错误表达式的示例： 1 + 2 + + 3 3 func（，1，（，2））（）

我的目标： 调车场算法的输出应该是正确的顺序，如果遇到语法问题，应该有一个错误：空括号“（）”或相互之后的多个运算符/函数/整数或函数调用中的错误括号不允许...

到目前为止，函数，整数和运算符的顺序是正确的如果你以正确的方式输入表达式！

如果它在vbscript本身中有效，它应该适用于这个算法，如果没有那么它不应该在这个脚本以太工作，你得到一个错误... 这就是我想在这里做的事情..

我希望语法如何:(在“[]”之间表示可选，“;”是注释，“##”之间是指向该标题的描述的链接...）

#function#:
func([#expression#[, #expression#[, #expression#...]]]) ; 

#number#:
(0-9)+ ; integers from 0 to ...

#operator#:
( ; open bracket, can be a function grouping or part of an expression
) ; closing bracket (see open bracket for details)
  ; bracket rules: must start with an open and stop with a closed bracket,
  ; can be nested but there must be something inside them!
, ; function argument seperator
+ ; plus
- ; minus
* ; multiply (higher prec than + and -)
/ ; divide (same prec as multiply)

#operand#:
#number# or #function#

#expression#:
#operand# [#operator# #operand#[ #operator# #operand#[ and so on...]]]

具有功能调试的分流码算法

0 个答案: