matlab/step2_eval.m

   1 function step2_eval(varargin), main(varargin), end
   2
   3 % read
   4 function ret = READ(str)
   5     ret = reader.read_str(str);
   6 end
   7
   8 % eval
   9 function ret = eval_ast(ast, env)
  10     switch class(ast)
  11     case 'types.Symbol'
  12         ret = env(ast.name);
  13     case 'types.List'
  14         ret = types.List();
  15         for i=1:length(ast)
  16             ret.append(EVAL(ast.get(i), env));
  17         end
  18     case 'types.Vector'
  19         ret = types.Vector();
  20         for i=1:length(ast)
  21             ret.append(EVAL(ast.get(i), env));
  22         end
  23     case 'types.HashMap'
  24         ret = types.HashMap();
  25         ks = ast.keys();
  26         for i=1:length(ks)
  27             k = ks{i};
  28             ret.set(EVAL(k, env), EVAL(ast.get(k), env));
  29         end
  30     otherwise
  31         ret = ast;
  32     end
  33 end
  34
  35 function ret = EVAL(ast, env)
  36     if ~types.list_Q(ast)
  37         ret = eval_ast(ast, env);
  38         return;
  39     end
  40
  41     % apply
  42     el = eval_ast(ast, env);
  43     f = el.get(1);
  44     args = el.data(2:end);
  45     ret = f(args{:});
  46 end
  47
  48 % print
  49 function ret = PRINT(ast)
  50     ret = printer.pr_str(ast, true);
  51 end
  52
  53 % REPL
  54 function ret = rep(str, env)
  55     ret = PRINT(EVAL(READ(str), env));
  56 end
  57
  58 function main(args)
  59     repl_env = containers.Map();
  60     repl_env('+') = @(a,b) a+b;
  61     repl_env('-') = @(a,b) a-b;
  62     repl_env('*') = @(a,b) a*b;
  63     repl_env('/') = @(a,b) floor(a/b);
  64
  65     %cleanObj = onCleanup(@() disp('*** here1 ***'));
  66     while (true)
  67         line = input('user> ', 's');
  68         if strcmp(strtrim(line),''), continue, end
  69         try
  70             fprintf('%s\n', rep(line, repl_env));
  71         catch err
  72             fprintf('Error: %s\n', err.message);
  73             fprintf('%s\n', getReport(err, 'extended'));
  74         end
  75     end
  76 end