vb/step6_file.vb

   1 Imports System
   2 Imports System.IO
   3 Imports System.Collections.Generic
   4 Imports Mal
   5 Imports MalVal = Mal.types.MalVal
   6 Imports MalInt = Mal.types.MalInt
   7 Imports MalString = Mal.types.MalString
   8 Imports MalSymbol = Mal.types.MalSymbol
   9 Imports MalList = Mal.types.MalList
  10 Imports MalVector = Mal.types.MalVector
  11 Imports MalHashMap = Mal.types.MalHashMap
  12 Imports MalFunc = Mal.types.MalFunc
  13 Imports MalEnv = Mal.env.Env
  14
  15 Namespace Mal
  16     Class step6_file
  17         ' read
  18         Shared Function READ(str As String) As MalVal
  19             Return reader.read_str(str)
  20         End Function
  21
  22         ' eval
  23         Shared Function eval_ast(ast As MalVal, env As MalEnv) As MalVal
  24             If TypeOf ast Is MalSymbol Then
  25                 return env.do_get(DirectCast(ast, MalSymbol))
  26             Else If TypeOf ast Is MalList Then
  27                 Dim old_lst As MalList = DirectCast(ast, MalList)
  28                 Dim new_lst As MalList
  29                 If ast.list_Q() Then
  30                     new_lst = New MalList
  31                 Else
  32                     new_lst = DirectCast(New MalVector, MalList)
  33                 End If
  34                 Dim mv As MalVal
  35                 For Each mv in old_lst.getValue()
  36                     new_lst.conj_BANG(EVAL(mv, env))
  37                 Next
  38                 return new_lst
  39             Else If TypeOf ast Is MalHashMap Then
  40                 Dim new_dict As New Dictionary(Of String, MalVal)
  41                 Dim entry As KeyValuePair(Of String, MalVal)
  42                 For Each entry in DirectCast(ast,MalHashMap).getValue()
  43                     new_dict.Add(entry.Key, EVAL(DirectCast(entry.Value,MalVal), env))
  44                 Next
  45                 return New MalHashMap(new_dict)
  46             Else
  47                 return ast
  48             End If
  49             return ast
  50         End Function
  51
  52         ' TODO: move to types.vb when it is ported
  53         Class FClosure
  54             Public ast As MalVal
  55             Public params As MalList
  56             Public env As MalEnv
  57             Function fn(args as MalList) As MalVal
  58                 return EVAL(ast, new MalEnv(env, params, args))
  59             End Function
  60         End Class
  61
  62         Shared Function EVAL(orig_ast As MalVal, env As MalEnv) As MalVal
  63             Do
  64
  65             'Console.WriteLine("EVAL: {0}", printer._pr_str(orig_ast, true))
  66             If not orig_ast.list_Q() Then
  67                 return eval_ast(orig_ast, env)
  68             End If
  69
  70             ' apply list
  71             Dim ast As MalList = DirectCast(orig_ast, MalList)
  72             If ast.size() = 0  Then
  73                 return ast
  74             End If
  75             Dim a0 As MalVal = ast(0)
  76             Dim a0sym As String
  77             If TypeOf a0 is MalSymbol Then
  78                 a0sym = DirectCast(a0,MalSymbol).getName()
  79             Else
  80                 a0sym = "__<*fn*>__"
  81             End If
  82
  83             Select a0sym
  84             Case "def!"
  85                 Dim a1 As MalVal = ast(1)
  86                 Dim a2 As MalVal = ast(2)
  87                 Dim res As MalVal = EVAL(a2, env)
  88                 env.do_set(DirectCast(a1,MalSymbol), res)
  89                 return res
  90             Case "let*"
  91                 Dim a1 As MalVal = ast(1)
  92                 Dim a2 As MalVal = ast(2)
  93                 Dim key As MalSymbol
  94                 Dim val as MalVal
  95                 Dim let_env As new MalEnv(env)
  96                 For i As Integer = 0 To (DirectCast(a1,MalList)).size()-1 Step 2
  97                     key = DirectCast(DirectCast(a1,MalList)(i),MalSymbol)
  98                     val = DirectCast(a1,MalList)(i+1)
  99                     let_env.do_set(key, EVAL(val, let_env))
 100                 Next
 101                 orig_ast = a2
 102                 env = let_env
 103             Case "do"
 104                 eval_ast(ast.slice(1, ast.size()-1), env)
 105                 orig_ast = ast(ast.size()-1)
 106             Case "if"
 107                 Dim a1 As MalVal = ast(1)
 108                 Dim cond As MalVal = EVAL(a1, env)
 109                 If cond Is Mal.types.Nil or cond Is Mal.types.MalFalse Then
 110                     ' eval false slot form
 111                     If ast.size() > 3 Then
 112                         orig_ast = ast(3)
 113                     Else
 114                         return Mal.types.Nil
 115                     End If
 116                 Else
 117                     ' eval true slot form
 118                     orig_ast = ast(2)
 119
 120                 End If
 121             Case "fn*"
 122                 Dim fc As New FClosure()
 123                 fc.ast = ast(2)
 124                 fc.params = DirectCast(ast(1),MalLIst)
 125                 fc.env = env
 126                 Dim f As Func(Of MalList, MalVal) = AddressOf fc.fn
 127                 Dim mf As new MalFunc(ast(2), env,
 128                                       DirectCast(ast(1),MalList), f)
 129                 return DirectCast(mf,MalVal)
 130             Case Else
 131                 Dim el As MalList = DirectCast(eval_ast(ast, env), MalList)
 132                 Dim f As MalFunc = DirectCast(el(0), MalFunc)
 133                 Dim fnast As MalVal = f.getAst()
 134                 If not fnast Is Nothing
 135                     orig_ast = fnast
 136                     env = f.genEnv(el.rest())
 137                 Else
 138                     Return f.apply(el.rest())
 139                 End If
 140             End Select
 141
 142             Loop While True
 143         End Function
 144
 145         ' print
 146         Shared Function PRINT(exp As MalVal) As String
 147             return printer._pr_str(exp, TRUE)
 148         End Function
 149
 150         ' repl
 151         Shared repl_env As MalEnv
 152
 153         Shared Function REP(str As String) As String
 154             Return PRINT(EVAL(READ(str), repl_env))
 155         End Function
 156
 157         Shared Function do_eval(args As MalList) As MalVal
 158             Return EVAL(args(0), repl_env)
 159         End Function
 160
 161         Shared Function Main As Integer
 162             Dim args As String() = Environment.GetCommandLineArgs()
 163
 164             repl_env = New MalEnv(Nothing)
 165
 166             ' core.vb: defined using VB.NET
 167             For Each entry As KeyValuePair(Of String,MalVal) In core.ns()
 168                 repl_env.do_set(new MalSymbol(entry.Key), entry.Value)
 169             Next
 170             repl_env.do_set(new MalSymbol("eval"), new MalFunc(AddressOf do_eval))
 171             Dim fileIdx As Integer = 1
 172             If args.Length > 1 AndAlso args(1) = "--raw" Then
 173                 Mal.readline.SetMode(Mal.readline.Modes.Raw)
 174                 fileIdx = 2
 175             End If
 176             Dim argv As New MalList()
 177             For i As Integer = fileIdx+1 To args.Length-1
 178                 argv.conj_BANG(new MalString(args(i)))
 179             Next
 180             repl_env.do_set(new MalSymbol("*ARGV*"), argv)
 181
 182             ' core.mal: defined using the language itself
 183             REP("(def! not (fn* (a) (if a false true)))")
 184             REP("(def! load-file (fn* (f) (eval (read-string (str ""(do "" (slurp f) "")"")))))")
 185
 186             If args.Length > fileIdx Then
 187                 REP("(load-file """ & args(fileIdx) & """)")
 188                 return 0
 189             End If
 190
 191             ' repl loop
 192             Dim line As String
 193             Do
 194                 Try
 195                     line = Mal.readline.Readline("user> ")
 196                     If line is Nothing Then
 197                         Exit Do
 198                     End If
 199                     If line = "" Then
 200                         Continue Do
 201                     End If
 202                 Catch e As IOException
 203                     Console.WriteLine("IOException: " & e.Message)
 204                 End Try
 205                 Try
 206                     Console.WriteLine(REP(line))
 207                 Catch e as Exception
 208                     Console.WriteLine("Error: " & e.Message)
 209                     Console.WriteLine(e.StackTrace)
 210                     Continue Do
 211                 End Try
 212             Loop While True
 213         End function
 214     End Class
 215 End Namespace