cs/step5_tco.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 step5_tco {
  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
  50             while (true) {
  51
  52             //Console.WriteLine("EVAL: " + printer._pr_str(orig_ast, true));
  53             if (!orig_ast.list_Q()) {
  54                 return eval_ast(orig_ast, env);
  55             }
  56
  57             // apply list
  58             MalList ast = (MalList)orig_ast;
  59             if (ast.size() == 0) { return ast; }
  60             a0 = ast[0];
  61
  62             String a0sym = a0 is MalSymbol ? ((MalSymbol)a0).getName()
  63                                            : "__<*fn*>__";
  64
  65             switch (a0sym) {
  66             case "def!":
  67                 a1 = ast[1];
  68                 a2 = ast[2];
  69                 res = EVAL(a2, env);
  70                 env.set((MalSymbol)a1, res);
  71                 return res;
  72             case "let*":
  73                 a1 = ast[1];
  74                 a2 = ast[2];
  75                 MalSymbol key;
  76                 MalVal val;
  77                 Env let_env = new Env(env);
  78                 for(int i=0; i<((MalList)a1).size(); i+=2) {
  79                     key = (MalSymbol)((MalList)a1)[i];
  80                     val = ((MalList)a1)[i+1];
  81                     let_env.set(key, EVAL(val, let_env));
  82                 }
  83                 orig_ast = a2;
  84                 env = let_env;
  85                 break;
  86             case "do":
  87                 eval_ast(ast.slice(1, ast.size()-1), env);
  88                 orig_ast = ast[ast.size()-1];
  89                 break;
  90             case "if":
  91                 a1 = ast[1];
  92                 MalVal cond = EVAL(a1, env);
  93                 if (cond == Mal.types.Nil || cond == Mal.types.False) {
  94                     // eval false slot form
  95                     if (ast.size() > 3) {
  96                         orig_ast = ast[3];
  97                     } else {
  98                         return Mal.types.Nil;
  99                     }
 100                 } else {
 101                     // eval true slot form
 102                     orig_ast = ast[2];
 103                 }
 104                 break;
 105             case "fn*":
 106                 MalList a1f = (MalList)ast[1];
 107                 MalVal a2f = ast[2];
 108                 Env cur_env = env;
 109                 return new MalFunc(a2f, env, a1f,
 110                     args => EVAL(a2f, new Env(cur_env, a1f, args)) );
 111             default:
 112                 el = (MalList)eval_ast(ast, env);
 113                 var f = (MalFunc)el[0];
 114                 MalVal fnast = f.getAst();
 115                 if (fnast != null) {
 116                     orig_ast = fnast;
 117                     env = f.genEnv(el.rest());
 118                 } else {
 119                     return f.apply(el.rest());
 120                 }
 121                 break;
 122             }
 123
 124             }
 125         }
 126
 127         // print
 128         static string PRINT(MalVal exp) {
 129             return printer._pr_str(exp, true);
 130         }
 131
 132         // repl
 133         static void Main(string[] args) {
 134             var repl_env = new Mal.env.Env(null);
 135             Func<string, MalVal> RE = (string str) => EVAL(READ(str), repl_env);
 136
 137             // core.cs: defined using C#
 138             foreach (var entry in core.ns) {
 139                 repl_env.set(new MalSymbol(entry.Key), entry.Value);
 140             }
 141
 142             // core.mal: defined using the language itself
 143             RE("(def! not (fn* (a) (if a false true)))");
 144
 145             if (args.Length > 0 && args[0] == "--raw") {
 146                 Mal.readline.mode = Mal.readline.Mode.Raw;
 147             }
 148
 149             // repl loop
 150             while (true) {
 151                 string line;
 152                 try {
 153                     line = Mal.readline.Readline("user> ");
 154                     if (line == null) { break; }
 155                     if (line == "") { continue; }
 156                 } catch (IOException e) {
 157                     Console.WriteLine("IOException: " + e.Message);
 158                     break;
 159                 }
 160                 try {
 161                     Console.WriteLine(PRINT(RE(line)));
 162                 } catch (Mal.types.MalContinue) {
 163                     continue;
 164                 } catch (Exception e) {
 165                     Console.WriteLine("Error: " + e.Message);
 166                     Console.WriteLine(e.StackTrace);
 167                     continue;
 168                 }
 169             }
 170         }
 171     }
 172 }