cs/step3_env.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 using Env = Mal.env.Env;
  14
  15 namespace Mal {
  16     class step3_env {
  17         // read
  18         static MalVal READ(string str) {
  19             return reader.read_str(str);
  20         }
  21
  22         // eval
  23         static MalVal eval_ast(MalVal ast, Env env) {
  24             if (ast is MalSymbol) {
  25                 return env.get((MalSymbol)ast);
  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, Env env) {
  47             MalVal a0, a1, a2, res;
  48             MalList el;
  49             //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
  50             if (!orig_ast.list_Q()) {
  51                 return eval_ast(orig_ast, env);
  52             }
  53
  54             // apply list
  55             MalList ast = (MalList)orig_ast;
  56             if (ast.size() == 0) { return ast; }
  57             a0 = ast[0];
  58             if (!(a0 is MalSymbol)) {
  59                 throw new Mal.types.MalError("attempt to apply on non-symbol '"
  60                         + Mal.printer._pr_str(a0,true) + "'");
  61             }
  62
  63             switch (((MalSymbol)a0).getName()) {
  64             case "def!":
  65                 a1 = ast[1];
  66                 a2 = ast[2];
  67                 res = EVAL(a2, env);
  68                 env.set((MalSymbol)a1, res);
  69                 return res;
  70             case "let*":
  71                 a1 = ast[1];
  72                 a2 = ast[2];
  73                 MalSymbol key;
  74                 MalVal val;
  75                 Env let_env = new Env(env);
  76                 for(int i=0; i<((MalList)a1).size(); i+=2) {
  77                     key = (MalSymbol)((MalList)a1)[i];
  78                     val = ((MalList)a1)[i+1];
  79                     let_env.set(key, EVAL(val, let_env));
  80                 }
  81                 return EVAL(a2, let_env);
  82             default:
  83                 el = (MalList)eval_ast(ast, env);
  84                 var f = (MalFunc)el[0];
  85                 return f.apply(el.rest());
  86             }
  87         }
  88
  89         // print
  90         static string PRINT(MalVal exp) {
  91             return printer._pr_str(exp, true);
  92         }
  93
  94         // repl
  95         static void Main(string[] args) {
  96             var repl_env = new Mal.env.Env(null);
  97             Func<string, MalVal> RE = (string str) => EVAL(READ(str), repl_env);
  98             repl_env.set(new MalSymbol("+"), new MalFunc(
  99                         a => (MalInt)a[0] + (MalInt)a[1]) );
 100             repl_env.set(new MalSymbol("-"), new MalFunc(
 101                         a => (MalInt)a[0] - (MalInt)a[1]) );
 102             repl_env.set(new MalSymbol("*"), new MalFunc(
 103                         a => (MalInt)a[0] * (MalInt)a[1]) );
 104             repl_env.set(new MalSymbol("/"), new MalFunc(
 105                         a => (MalInt)a[0] / (MalInt)a[1]) );
 106
 107             if (args.Length > 0 && args[0] == "--raw") {
 108                 Mal.readline.mode = Mal.readline.Mode.Raw;
 109             }
 110
 111             // repl loop
 112             while (true) {
 113                 string line;
 114                 try {
 115                     line = Mal.readline.Readline("user> ");
 116                     if (line == null) { break; }
 117                     if (line == "") { continue; }
 118                 } catch (IOException e) {
 119                     Console.WriteLine("IOException: " + e.Message);
 120                     break;
 121                 }
 122                 try {
 123                     Console.WriteLine(PRINT(RE(line)));
 124                 } catch (Mal.types.MalContinue) {
 125                     continue;
 126                 } catch (Exception e) {
 127                     Console.WriteLine("Error: " + e.Message);
 128                     Console.WriteLine(e.StackTrace);
 129                     continue;
 130                 }
 131             }
 132         }
 133     }
 134 }