js/step6_file.js

   1 if (typeof module !== 'undefined') {
   2     var types = require('./types');
   3     var readline = require('./node_readline');
   4     var reader = require('./reader');
   5     var printer = require('./printer');
   6     var Env = require('./env').Env;
   7     var core = require('./core');
   8 }
   9
  10 // read
  11 function READ(str) {
  12     return reader.read_str(str);
  13 }
  14
  15 // eval
  16 function eval_ast(ast, env) {
  17     if (types._symbol_Q(ast)) {
  18         return env.get(ast);
  19     } else if (types._list_Q(ast)) {
  20         return ast.map(function(a) { return EVAL(a, env); });
  21     } else if (types._vector_Q(ast)) {
  22         var v = ast.map(function(a) { return EVAL(a, env); });
  23         v.__isvector__ = true;
  24         return v;
  25     } else if (types._hash_map_Q(ast)) {
  26         var new_hm = {};
  27         for (k in ast) {
  28             new_hm[EVAL(k, env)] = EVAL(ast[k], env);
  29         }
  30         return new_hm;
  31     } else {
  32         return ast;
  33     }
  34 }
  35
  36 function _EVAL(ast, env) {
  37     while (true) {
  38
  39     //printer.println("EVAL:", printer._pr_str(ast, true));
  40     if (!types._list_Q(ast)) {
  41         return eval_ast(ast, env);
  42     }
  43     if (ast.length === 0) {
  44         return ast;
  45     }
  46
  47     // apply list
  48     var a0 = ast[0], a1 = ast[1], a2 = ast[2], a3 = ast[3];
  49     switch (a0.value) {
  50     case "def!":
  51         var res = EVAL(a2, env);
  52         return env.set(a1, res);
  53     case "let*":
  54         var let_env = new Env(env);
  55         for (var i=0; i < a1.length; i+=2) {
  56             let_env.set(a1[i], EVAL(a1[i+1], let_env));
  57         }
  58         ast = a2;
  59         env = let_env;
  60         break;
  61     case "do":
  62         eval_ast(ast.slice(1, -1), env);
  63         ast = ast[ast.length-1];
  64         break;
  65     case "if":
  66         var cond = EVAL(a1, env);
  67         if (cond === null || cond === false) {
  68             ast = (typeof a3 !== "undefined") ? a3 : null;
  69         } else {
  70             ast = a2;
  71         }
  72         break;
  73     case "fn*":
  74         return types._function(EVAL, Env, a2, env, a1);
  75     default:
  76         var el = eval_ast(ast, env), f = el[0];
  77         if (f.__ast__) {
  78             ast = f.__ast__;
  79             env = f.__gen_env__(el.slice(1));
  80         } else {
  81             return f.apply(f, el.slice(1));
  82         }
  83     }
  84
  85     }
  86 }
  87
  88 function EVAL(ast, env) {
  89     var result = _EVAL(ast, env);
  90     return (typeof result !== "undefined") ? result : null;
  91 }
  92
  93 // print
  94 function PRINT(exp) {
  95     return printer._pr_str(exp, true);
  96 }
  97
  98 // repl
  99 var repl_env = new Env();
 100 var rep = function(str) { return PRINT(EVAL(READ(str), repl_env)); };
 101
 102 // core.js: defined using javascript
 103 for (var n in core.ns) { repl_env.set(types._symbol(n), core.ns[n]); }
 104 repl_env.set(types._symbol('eval'), function(ast) {
 105     return EVAL(ast, repl_env); });
 106 repl_env.set(types._symbol('*ARGV*'), []);
 107
 108 // core.mal: defined using the language itself
 109 rep("(def! not (fn* (a) (if a false true)))");
 110 rep("(def! load-file (fn* (f) (eval (read-string (str \"(do \" (slurp f) \"\nnil)\")))))");
 111
 112 if (typeof process !== 'undefined' && process.argv.length > 2) {
 113     repl_env.set(types._symbol('*ARGV*'), process.argv.slice(3));
 114     rep('(load-file "' + process.argv[2] + '")');
 115     process.exit(0);
 116 }
 117
 118 // repl loop
 119 if (typeof require !== 'undefined' && require.main === module) {
 120     // Synchronous node.js commandline mode
 121     while (true) {
 122         var line = readline.readline("user> ");
 123         if (line === null) { break; }
 124         try {
 125             if (line) { printer.println(rep(line)); }
 126         } catch (exc) {
 127             if (exc instanceof reader.BlankException) { continue }
 128             if (exc instanceof Error) { console.warn(exc.stack) }
 129             else { console.warn("Error: " + printer._pr_str(exc, true)) }
 130         }
 131     }
 132 }