vb/env.vb

   1 Imports System.Collections.Generic
   2 Imports Mal
   3 Imports MalVal = Mal.types.MalVal
   4 Imports MalSymbol = Mal.types.MalSymbol
   5 Imports MalList = Mal.types.MalList
   6
   7 Namespace Mal
   8     Public Class env
   9         Public Class Env
  10             Dim outer As Env = Nothing
  11             Dim data As Dictionary(Of String, MalVal) = New Dictionary(Of String, MalVal)
  12
  13             Public Sub New(new_outer As Env)
  14                 outer = new_outer
  15             End Sub
  16             Public Sub New(new_outer As Env, binds As MalList, exprs As MalList)
  17                 outer = new_outer
  18                 For i As Integer = 0 To binds.size()-1
  19                     Dim sym As String = DirectCast(binds.nth(i),MalSymbol).getName()
  20                     If sym = "&" Then
  21                         data(DirectCast(binds.nth(i+1),MalSymbol).getName()) = exprs.slice(i)
  22                         Exit For
  23                     Else
  24                         data(sym) = exprs.nth(i)
  25                     End If
  26                 Next
  27             End Sub
  28
  29             Public Function find(key As MalSymbol) As Env
  30                 If data.ContainsKey(key.getName()) Then
  31                     return Me
  32                 Else If outer IsNot Nothing Then
  33                     return outer.find(key)
  34                 Else
  35                     return Nothing
  36                 End If
  37             End Function
  38
  39             Public Function do_get(key As MalSymbol) As MalVal
  40                 Dim e As Env = find(key)
  41                 If e Is Nothing Then
  42                     throw New Mal.types.MalException(
  43                             "'" & key.getName() & "' not found")
  44                 Else
  45                     return e.data(key.getName())
  46                 End If
  47             End Function
  48
  49             Public Function do_set(key As MalSymbol, value As MalVal) As Env
  50                 data(key.getName()) = value
  51                 return Me
  52             End Function
  53         End Class
  54     End Class
  55 End Namespace