rpython/step2_eval.py

   1 #import sys, traceback
   2 import mal_readline
   3 import mal_types as types
   4 from mal_types import (MalSym, MalInt, MalStr,
   5                        _keywordu,
   6                        MalList, _list, MalVector, MalHashMap, MalFunc)
   7 import reader, printer
   8
   9 # read
  10 def READ(str):
  11     return reader.read_str(str)
  12
  13 # eval
  14 def eval_ast(ast, env):
  15     if types._symbol_Q(ast):
  16         assert isinstance(ast, MalSym)
  17         if ast.value in env:
  18             return env[ast.value]
  19         else:
  20             raise Exception(u"'" + ast.value + u"' not found")
  21     elif types._list_Q(ast):
  22         res = []
  23         for a in ast.values:
  24             res.append(EVAL(a, env))
  25         return MalList(res)
  26     elif types._vector_Q(ast):
  27         res = []
  28         for a in ast.values:
  29             res.append(EVAL(a, env))
  30         return MalVector(res)
  31     elif types._hash_map_Q(ast):
  32         new_dct = {}
  33         for k in ast.dct.keys():
  34             new_dct[k] = EVAL(ast.dct[k], env)
  35         return MalHashMap(new_dct)
  36     else:
  37         return ast  # primitive value, return unchanged
  38
  39 def EVAL(ast, env):
  40         #print("EVAL %s" % printer._pr_str(ast))
  41         if not types._list_Q(ast):
  42             return eval_ast(ast, env)
  43
  44         # apply list
  45         el = eval_ast(ast, env)
  46         f = el.values[0]
  47         if isinstance(f, MalFunc):
  48             return f.apply(el.values[1:])
  49         else:
  50             raise Exception("%s is not callable" % f)
  51
  52 # print
  53 def PRINT(exp):
  54     return printer._pr_str(exp)
  55
  56 # repl
  57 repl_env = {}
  58 def REP(str, env):
  59     return PRINT(EVAL(READ(str), env))
  60
  61 def plus(args):
  62     a, b = args[0], args[1]
  63     assert isinstance(a, MalInt)
  64     assert isinstance(b, MalInt)
  65     return MalInt(a.value+b.value)
  66 def minus(args):
  67     a, b = args[0], args[1]
  68     assert isinstance(a, MalInt)
  69     assert isinstance(b, MalInt)
  70     return MalInt(a.value-b.value)
  71 def multiply(args):
  72     a, b = args[0], args[1]
  73     assert isinstance(a, MalInt)
  74     assert isinstance(b, MalInt)
  75     return MalInt(a.value*b.value)
  76 def divide(args):
  77     a, b = args[0], args[1]
  78     assert isinstance(a, MalInt)
  79     assert isinstance(b, MalInt)
  80     return MalInt(int(a.value/b.value))
  81 repl_env[u'+'] = MalFunc(plus)
  82 repl_env[u'-'] = MalFunc(minus)
  83 repl_env[u'*'] = MalFunc(multiply)
  84 repl_env[u'/'] = MalFunc(divide)
  85
  86 def entry_point(argv):
  87     while True:
  88         try:
  89             line = mal_readline.readline("user> ")
  90             if line == "": continue
  91             print(REP(line, repl_env))
  92         except EOFError as e:
  93             break
  94         except reader.Blank:
  95             continue
  96         except types.MalException as e:
  97             print(u"Error: %s" % printer._pr_str(e.object, False))
  98         except Exception as e:
  99             print("Error: %s" % e)
 100             #print("".join(traceback.format_exception(*sys.exc_info())))
 101     return 0
 102
 103 # _____ Define and setup target ___
 104 def target(*args):
 105     return entry_point
 106
 107 # Just run entry_point if not RPython compilation
 108 import sys
 109 if not sys.argv[0].endswith('rpython'):
 110     entry_point(sys.argv)