clsparsers.cls

vb写的网络蜘蛛程序

VERSION 1.0 CLASS
BEGIN
  MultiUse = -1  'True
END
Attribute VB_Name = "clsParsers"
Attribute VB_Creatable = False
Attribute VB_Exposed = False
Option Explicit

Public NextWord As String
Public Remainder As String

Public Sub Advance()
    NextWord = ""
    Do While (Remainder <> "") And (Left(Remainder, 1) = " ")
        Remainder = Mid(Remainder, 2)
        Loop
    If Remainder <> "" Then
        If (Left(Remainder, 1) = "(") Or (Left(Remainder, 1) = ")") Then
            NextWord = Left(Remainder, 1)
            Remainder = Mid(Remainder, 2)
          ElseIf Left(Remainder, 1) = """" Then
            Remainder = Mid(Remainder, 2)
            Do While (Remainder <> "") And (Left(Remainder, 1) <> """")
                NextWord = NextWord + Left(Remainder, 1)
                Remainder = Mid(Remainder, 2)
                Loop
            Remainder = Mid(Remainder, 2)
          Else
            Do While (Remainder <> "") And Not _
                     ((Left(Remainder, 1) = "(") Or _
                      (Left(Remainder, 1) = ")") Or _
                      (Left(Remainder, 1) = " "))
                NextWord = NextWord + Left(Remainder, 1)
                Remainder = Mid(Remainder, 2)
                Loop
          End If
      End If
    End Sub

Public Sub Init(Source As String)
    Remainder = Source
    Advance
    End Sub

Public Function CanRead(S As String) As Boolean
    If NextWord = S Then
        Advance
        CanRead = True
      Else
        CanRead = False
      End If

    End Function

Public Sub Expect(S As String)
    If Not CanRead(S) Then
        MsgBox "Expected " & S & vbCrLf & _
                " but found " & NextWord & ".", _
                vbOKOnly + vbCritical, _
                "Invalid Search String"
      End If
    End Sub