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         if len(ast) == 0: return ast
  46         el = eval_ast(ast, env)
  47         f = el.values[0]
  48         if isinstance(f, MalFunc):
  49             return f.apply(el.values[1:])
  50         else:
  51             raise Exception("%s is not callable" % f)
  52
  53 # print
  54 def PRINT(exp):
  55     return printer._pr_str(exp)
  56
  57 # repl
  58 repl_env = {}
  59 def REP(str, env):
  60     return PRINT(EVAL(READ(str), env))
  61
  62 def plus(args):
  63     a, b = args[0], args[1]
  64     assert isinstance(a, MalInt)
  65     assert isinstance(b, MalInt)
  66     return MalInt(a.value+b.value)
  67 def minus(args):
  68     a, b = args[0], args[1]
  69     assert isinstance(a, MalInt)
  70     assert isinstance(b, MalInt)
  71     return MalInt(a.value-b.value)
  72 def multiply(args):
  73     a, b = args[0], args[1]
  74     assert isinstance(a, MalInt)
  75     assert isinstance(b, MalInt)
  76     return MalInt(a.value*b.value)
  77 def divide(args):
  78     a, b = args[0], args[1]
  79     assert isinstance(a, MalInt)
  80     assert isinstance(b, MalInt)
  81     return MalInt(int(a.value/b.value))
  82 repl_env[u'+'] = MalFunc(plus)
  83 repl_env[u'-'] = MalFunc(minus)
  84 repl_env[u'*'] = MalFunc(multiply)
  85 repl_env[u'/'] = MalFunc(divide)
  86
  87 def entry_point(argv):
  88     while True:
  89         try:
  90             line = mal_readline.readline("user> ")
  91             if line == "": continue
  92             print(REP(line, repl_env))
  93         except EOFError as e:
  94             break
  95         except reader.Blank:
  96             continue
  97         except types.MalException as e:
  98             print(u"Error: %s" % printer._pr_str(e.object, False))
  99         except Exception as e:
 100             print("Error: %s" % e)
 101             #print("".join(traceback.format_exception(*sys.exc_info())))
 102     return 0
 103
 104 # _____ Define and setup target ___
 105 def target(*args):
 106     return entry_point
 107
 108 # Just run entry_point if not RPython compilation
 109 import sys
 110 if not sys.argv[0].endswith('rpython'):
 111     entry_point(sys.argv)