sympy/core/ast_parser.py

   1 import compiler
   2 import parser
   3 from compiler.transformer import Transformer
   4 from compiler.visitor import ASTVisitor
   5 from compiler.ast import CallFunc, Name, Const, Tuple
   6 from compiler.pycodegen import ExpressionCodeGenerator
   7 import re
   8
   9 from basic import Basic
  10 from function import FunctionClass
  11 from symbol import Symbol
  12
  13 ###################################################3
  14 # HELPERS
  15 ###################################################3
  16
  17 _is_integer = re.compile(r'\A\d+(l|L)?\Z').match
  18
  19 int_types = (int, long)
  20 float_types = (float)
  21 complex_types = (complex)
  22 string_types = (str) # XXX: unicode?
  23 classes = Basic
  24
  25 ###################################################3
  26 # CODE
  27 ###################################################3
  28
  29 class SymPyTransformer(Transformer):
  30     def __init__(self, local_dict, global_dict):
  31         Transformer.__init__(self)
  32
  33         self.symbol_class = 'Symbol'
  34
  35         self.local_dict = local_dict
  36         self.global_dict = global_dict
  37
  38     def atom_number(self, nodelist):
  39         n = Transformer.atom_number(self, nodelist)
  40         number, lineno = nodelist[0][1:]
  41         if _is_integer(number):
  42             n = Const(long(number), lineno)
  43             return CallFunc(Name('Integer'), [n])
  44         if number.endswith('j'):
  45             n = Const(complex(number), lineno)
  46             return CallFunc(Name('sympify'), [n])
  47         n = Const(number, lineno)
  48         return CallFunc(Name('Real'), [n])
  49
  50     def atom_name(self, nodelist):
  51         name, lineno = nodelist[0][1:]
  52
  53         if self.local_dict.has_key(name):
  54             name_obj = self.local_dict[name]
  55             return Const(name_obj, lineno=lineno)
  56         elif self.global_dict.has_key(name):
  57             name_obj = self.global_dict[name]
  58
  59             if isinstance(name_obj, (Basic, type)) or callable(name_obj):
  60                 return Const(name_obj, lineno=lineno)
  61         elif name in ['True', 'False']:
  62             return Const(eval(name), lineno=lineno)
  63
  64         symbol_obj = Symbol(name)
  65         self.local_dict[name] = symbol_obj
  66
  67         return Const(symbol_obj, lineno=lineno)
  68
  69     def lambdef(self, nodelist):
  70         #this is python stdlib symbol, not SymPy symbol:
  71         from sympy import stdlib_symbol
  72         if nodelist[2][0] == stdlib_symbol.varargslist:
  73             names, defaults, flags = self.com_arglist(nodelist[2][1:])
  74         else:
  75             names = defaults = ()
  76             flags = 0
  77
  78         lineno = nodelist[1][2]
  79         code = self.com_node(nodelist[-1])
  80
  81         assert not defaults,`defaults` # sympy.Lambda does not support optional arguments
  82         assert len(names) <= 1
  83
  84         if len(names) > 0:
  85             argument = CallFunc( Name('Symbol'), [Const(names[0], lineno=lineno)])
  86         else:
  87             argument = CallFunc( Name('Symbol'), [Const('x')])
  88
  89         return CallFunc(Name('Lambda'),[argument, code])
  90
  91
  92 class SymPyParser:
  93     def __init__(self, local_dict={}): #Contents of local_dict change, but it has proper effect only in global scope
  94         global_dict = {}
  95         exec 'from sympy import *' in global_dict
  96
  97         self.r_transformer = SymPyTransformer(local_dict, global_dict)
  98         self.local_dict = local_dict
  99         self.global_dict = global_dict
 100
 101     def parse_expr(self, ws_expression):
 102         expression = ws_expression.strip() #in case of "   x"
 103         ast_tree = parser.expr(expression)
 104         ast_tree = self.r_transformer.transform(ast_tree)
 105
 106         compiler.misc.set_filename('<sympify>', ast_tree)
 107         code = ExpressionCodeGenerator(ast_tree).getCode()
 108
 109         parsed_expr = eval(code, self.local_dict, self.global_dict) #Changed order to prefer sympy objects to  user defined
 110
 111         return parsed_expr
 112