Пример #1
0
        static eValue ParseAST(eValue ast, Env env)
        {
            if (ast is eSymbol)
            {
                return(env.get((eSymbol)ast));
            }
            else if (ast is eList)
            {
                eList oldList = (eList)ast;
                eList newList = ast.list_Q() ? new eList() : (eList) new eVector();

                foreach (eValue mv in oldList.getValue())
                {
                    newList.conj_BANG(Eval(mv, env));
                }

                return(newList);
            }
            else if (ast is eHashMap)
            {
                var hashMap = new Dictionary <string, eValue>();

                foreach (var entry in ((eHashMap)ast).getValue())
                {
                    hashMap.Add(entry.Key, Eval((eValue)entry.Value, env));
                }

                return(new eHashMap(hashMap));
            }
            else
            {
                return(ast);
            }
        }
Пример #2
0
 public eFunction(eValue ast, Evil.Env env, eList fparams,
                  Func <eList, eValue> fn)
 {
     this.fn      = fn;
     this.ast     = ast;
     this.env     = env;
     this.fparams = fparams;
 }
Пример #3
0
 public static eValue macroexpand(eValue ast, Env env)
 {
     while (is_macro_call(ast, env))
     {
         eSymbol   a0  = (eSymbol)((eList)ast) [0];
         eFunction mac = (eFunction)env.get(a0);
         ast = mac.apply(((eList)ast).rest());
     }
     return(ast);
 }
Пример #4
0
 public static bool is_macro_call(eValue ast, Env env)
 {
     if (ast is eList)
     {
         eValue a0 = ((eList)ast) [0];
         if (a0 is eSymbol &&
             env.find((eSymbol)a0) != null)
         {
             eValue mac = env.get((eSymbol)a0);
             if (mac is eFunction &&
                 ((eFunction)mac).isMacro())
             {
                 return(true);
             }
         }
     }
     return(false);
 }
Пример #5
0
        static eValue Eval(eValue orig_ast, Env env)
        {
            eValue a0, a1, a2, res;
            eList  el;

            while (true)
            {
                if (!orig_ast.list_Q())
                {
                    return(ParseAST(orig_ast, env));
                }

                eValue expanded = macroexpand(orig_ast, env);
                if (!expanded.list_Q())
                {
                    return(ParseAST(expanded, env));
                }

                eList ast = (eList)expanded;
                if (ast.size() == 0)
                {
                    return(ast);
                }

                a0 = ast[0];

                String a0sym = a0 is eSymbol ? ((eSymbol)a0).getName() : "__<*fn*>__";

                switch (a0sym)
                {
                case "def": // define vareable
                    res = Eval(ast[2] /* vareable value */, env);
                    env.set((eSymbol)ast[1] /* vareable name */, res);
                    return(res);

                case "let":
                    a1 = ast[1];
                    a2 = ast[2];
                    eSymbol key;
                    eValue  val;
                    Env     let_env = new Env(env);
                    for (int i = 0; i < ((eList)a1).size(); i += 2)
                    {
                        key = (eSymbol)((eList)a1) [i];
                        val = ((eList)a1) [i + 1];
                        let_env.set(key, Eval(val, let_env));
                    }
                    orig_ast = a2;
                    env      = let_env;
                    break;

                case "quote":
                    return(ast[1]);

                case "quasiquote":
                    orig_ast = quasiquote(ast[1]);
                    break;

                case "defmacro": // define macros
                    res = Eval(ast[2] /* macros value */, env);
                    ((eFunction)res).setMacro();
                    env.set(((eSymbol)ast[1] /* macros name */), res);
                    return(res);

                case "macroexpand": // return macros body
                    return(macroexpand(ast[1] /* macros name */, env));

                case "try*":
                    try
                    {
                        return(Eval(ast[1], env));
                    }
                    catch (Exception e)
                    {
                        if (ast.size() > 2)
                        {
                            eValue exc;
                            a2 = ast[2];
                            eValue a20 = ((eList)a2) [0];
                            if (((eSymbol)a20).getName() == "catch*")
                            {
                                if (e is Evil.Types.eException)
                                {
                                    exc = ((Evil.Types.eException)e).getValue();
                                }
                                else
                                {
                                    exc = new eString(e.StackTrace);
                                }
                                return(Eval(((eList)a2) [2],
                                            new Env(env, ((eList)a2).slice(1, 2),
                                                    new eList(exc))));
                            }
                        }
                        throw e;
                    }

                case "do": // simple block construction
                    ParseAST(ast.slice(1, ast.size() - 1), env);
                    orig_ast = ast[ast.size() - 1];
                    break;

                case "if":
                    a1 = ast[1];
                    eValue cond = Eval(a1, env);
                    if (cond == Evil.Types.Nil || cond == Evil.Types.False)
                    {
                        // eval false slot form
                        if (ast.size() > 3)
                        {
                            orig_ast = ast[3];
                        }
                        else
                        {
                            return(Evil.Types.Nil);
                        }
                    }
                    else
                    {
                        // eval true slot form
                        orig_ast = ast[2];
                    }
                    break;

                case "fn":
                    eList  a1f     = (eList)ast[1];
                    eValue a2f     = ast[2];
                    Env    cur_env = env;
                    return(new eFunction(a2f, env, a1f,
                                         args => Eval(a2f, new Env(cur_env, a1f, args))));

                default:
                    el = (eList)ParseAST(ast, env);
                    var    f     = (eFunction)el[0];
                    eValue fnast = f.getAst();
                    if (fnast != null)
                    {
                        orig_ast = fnast;
                        env      = f.genEnv(el.rest());
                    }
                    else
                    {
                        return(f.apply(el.rest()));
                    }
                    break;
                }
            }
        }