cs/step2_eval.cs

   1 using System;
   2 using System.IO;
   3 using System.Collections;
   4 using System.Collections.Generic;
   5 using Mal;
   6 using MalVal = Mal.types.MalVal;
   7 using MalSymbol = Mal.types.MalSymbol;
   8 using MalInt = Mal.types.MalInt;
   9 using MalList = Mal.types.MalList;
  10 using MalVector = Mal.types.MalVector;
  11 using MalHashMap = Mal.types.MalHashMap;
  12 using MalFunc = Mal.types.MalFunc;
  13
  14 namespace Mal {
  15     class step2_eval {
  16         // read
  17         static MalVal READ(string str) {
  18             return reader.read_str(str);
  19         }
  20
  21         // eval
  22         static MalVal eval_ast(MalVal ast, Dictionary<string, MalVal> env) {
  23             if (ast is MalSymbol) {
  24                 MalSymbol sym = (MalSymbol)ast;
  25                 return (MalVal)env[sym.getName()];
  26             } else if (ast is MalList) {
  27                 MalList old_lst = (MalList)ast;
  28                 MalList new_lst = ast.list_Q() ? new MalList()
  29                                             : (MalList)new MalVector();
  30                 foreach (MalVal mv in old_lst.getValue()) {
  31                     new_lst.conj_BANG(EVAL(mv, env));
  32                 }
  33                 return new_lst;
  34             } else if (ast is MalHashMap) {
  35                 var new_dict = new Dictionary<string, MalVal>();
  36                 foreach (var entry in ((MalHashMap)ast).getValue()) {
  37                     new_dict.Add(entry.Key, EVAL((MalVal)entry.Value, env));
  38                 }
  39                 return new MalHashMap(new_dict);
  40             } else {
  41                 return ast;
  42             }
  43         }
  44
  45
  46         static MalVal EVAL(MalVal orig_ast, Dictionary<string, MalVal> env) {
  47             MalVal a0;
  48             //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
  49             if (!orig_ast.list_Q()) {
  50                 return eval_ast(orig_ast, env);
  51             }
  52
  53             // apply list
  54             MalList ast = (MalList)orig_ast;
  55             if (ast.size() == 0) { return ast; }
  56             a0 = ast[0];
  57             if (!(a0 is MalSymbol)) {
  58                 throw new Mal.types.MalError("attempt to apply on non-symbol '"
  59                         + Mal.printer._pr_str(a0,true) + "'");
  60             }
  61             var el = (MalList)eval_ast(ast, env);
  62             var f = (MalFunc)el[0];
  63             return f.apply(el.rest());
  64
  65         }
  66
  67         // print
  68         static string PRINT(MalVal exp) {
  69             return printer._pr_str(exp, true);
  70         }
  71
  72         // repl
  73         static void Main(string[] args) {
  74             var repl_env = new Dictionary<string, MalVal> {
  75                 {"+", new MalFunc(a => (MalInt)a[0] + (MalInt)a[1]) },
  76                 {"-", new MalFunc(a => (MalInt)a[0] - (MalInt)a[1]) },
  77                 {"*", new MalFunc(a => (MalInt)a[0] * (MalInt)a[1]) },
  78                 {"/", new MalFunc(a => (MalInt)a[0] / (MalInt)a[1]) },
  79             };
  80             Func<string, MalVal> RE = (string str) => EVAL(READ(str), repl_env);
  81
  82             if (args.Length > 0 && args[0] == "--raw") {
  83                 Mal.readline.mode = Mal.readline.Mode.Raw;
  84             }
  85
  86             // repl loop
  87             while (true) {
  88                 string line;
  89                 try {
  90                     line = Mal.readline.Readline("user> ");
  91                     if (line == null) { break; }
  92                     if (line == "") { continue; }
  93                 } catch (IOException e) {
  94                     Console.WriteLine("IOException: " + e.Message);
  95                     break;
  96                 }
  97                 try {
  98                     Console.WriteLine(PRINT(RE(line)));
  99                 } catch (Mal.types.MalContinue) {
 100                     continue;
 101                 } catch (Exception e) {
 102                     Console.WriteLine("Error: " + e.Message);
 103                     Console.WriteLine(e.StackTrace);
 104                     continue;
 105                 }
 106             }
 107         }
 108     }
 109 }