Cleaner and faster linear expressions

diff --git a/pypol/domains.py b/pypol/domains.py
index 12cf471..9187081 100644 (file)
--- a/pypol/domains.py
+++ b/pypol/domains.py
@@ -50,7 +50,7 @@ class Domain:
         symbols = set()
         for item in iterator:
             symbols.update(item.symbols)
-        return tuple(sorted(symbols))
+        return tuple(sorted(symbols, key=lambda symbol: symbol.name))
 
     @property
     def polyhedra(self):
@@ -139,7 +139,7 @@ class Domain:
 
     def simplify(self):
         #does not change anything in any of the examples
-        #isl seems to do this naturally 
+        #isl seems to do this naturally
         islset = self._toislset(self.polyhedra, self.symbols)
         islset = libisl.isl_set_remove_redundancies(islset)
         return self._fromislset(islset, self.symbols)
@@ -152,30 +152,21 @@ class Domain:
         islbset = libisl.isl_set_polyhedral_hull(islset)
         return Polyhedron._fromislbasicset(islbset, self.symbols)
 
-    def drop_dims(self, dims):
-        # use to remove certain variables use isl_set_drop_constraints_involving_dims instead?
-        from .polyhedra import Polyhedron 
-        n = 0 
-        dims = sorted(dims)
-        symbols = sorted(self.symbols)
+    def project_out(self, symbols):
+        # use to remove certain variables
         islset = self._toislset(self.polyhedra, self.symbols)
-        for dim in dims:
-            dim_index = dims.index(dim)
-            if dim in symbols:
-                first = symbols.index(dim) 
-                try:
-                    for dim in dims:
-                        if symbols[first+1] is dims[dim_index+1]: #check if next value in symbols is same as next value in dims
-                            n += 1
-                        islbset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, first, n) 
-                        symbols.remove(dim)
-                except:
-                    islbset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, first, 1) 
-                    symbols.remove(dim) 
-            else:
-                islbset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, 0, 0)     
-        return Polyhedron._fromislset(islbset, symbols)
-    
+        n = 0
+        for index, symbol in reversed(list(enumerate(self.symbols))):
+            if symbol in symbols:
+                n += 1
+            elif n > 0:
+                islset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, index + 1, n)
+                n = 0
+        if n > 0:
+            islset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, 0, n)
+        symbols = [symbol for symbol in self.symbols if symbol not in symbols]
+        return Domain._fromislset(islset, symbols)
+
     def sample(self):
         from .polyhedra import Polyhedron
         islset = self._toislset(self.polyhedra, self.symbols)

diff --git a/pypol/linexprs.py b/pypol/linexprs.py
index 10daf9d..ccd1564 100644 (file)
--- a/pypol/linexprs.py
+++ b/pypol/linexprs.py
@@ -3,13 +3,13 @@ import functools
 import numbers
 import re
 
-from collections import OrderedDict
+from collections import OrderedDict, defaultdict
 from fractions import Fraction, gcd
 
 
 __all__ = [
     'Expression',
-    'Symbol', 'symbols', 'symbolname', 'symbolnames',
+    'Symbol', 'symbols',
     'Constant',
 ]
 
@@ -36,37 +36,38 @@ class Expression:
         '_constant',
         '_symbols',
         '_dimension',
-        '_hash',
     )
 
     def __new__(cls, coefficients=None, constant=0):
         if isinstance(coefficients, str):
             if constant:
                 raise TypeError('too many arguments')
-            return cls.fromstring(coefficients)
-        if isinstance(coefficients, dict):
-            coefficients = coefficients.items()
+            return Expression.fromstring(coefficients)
         if coefficients is None:
             return Constant(constant)
+        if isinstance(coefficients, dict):
+            coefficients = coefficients.items()
+        for symbol, coefficient in coefficients:
+            if not isinstance(symbol, Symbol):
+                raise TypeError('symbols must be Symbol instances')
         coefficients = [(symbol, coefficient)
             for symbol, coefficient in coefficients if coefficient != 0]
         if len(coefficients) == 0:
             return Constant(constant)
-        elif len(coefficients) == 1 and constant == 0:
+        if len(coefficients) == 1 and constant == 0:
             symbol, coefficient = coefficients[0]
             if coefficient == 1:
-                return Symbol(symbol)
+                return symbol
         self = object().__new__(cls)
-        self._coefficients = {}
-        for symbol, coefficient in coefficients:
-            symbol = symbolname(symbol)
+        self._coefficients = OrderedDict()
+        for symbol, coefficient in sorted(coefficients,
+                key=lambda item: item[0].name):
             if isinstance(coefficient, Constant):
                 coefficient = coefficient.constant
             if not isinstance(coefficient, numbers.Rational):
                 raise TypeError('coefficients must be rational numbers '
                     'or Constant instances')
             self._coefficients[symbol] = coefficient
-        self._coefficients = OrderedDict(sorted(self._coefficients.items()))
         if isinstance(constant, Constant):
             constant = constant.constant
         if not isinstance(constant, numbers.Rational):
@@ -75,11 +76,11 @@ class Expression:
         self._constant = constant
         self._symbols = tuple(self._coefficients)
         self._dimension = len(self._symbols)
-        self._hash = hash((tuple(self._coefficients.items()), self._constant))
         return self
 
     def coefficient(self, symbol):
-        symbol = symbolname(symbol)
+        if not isinstance(symbol, Symbol):
+            raise TypeError('symbol must be a Symbol instance')
         try:
             return self._coefficients[symbol]
         except KeyError:
@@ -103,7 +104,7 @@ class Expression:
         return self._dimension
 
     def __hash__(self):
-        return self._hash
+        return hash((tuple(self._coefficients.items()), self._constant))
 
     def isconstant(self):
         return False
@@ -112,8 +113,7 @@ class Expression:
         return False
 
     def values(self):
-        for symbol in self.symbols:
-            yield self.coefficient(symbol)
+        yield from self._coefficients.values()
         yield self.constant
 
     def __bool__(self):
@@ -127,12 +127,9 @@ class Expression:
 
     @_polymorphic
     def __add__(self, other):
-        coefficients = dict(self.coefficients())
+        coefficients = defaultdict(Constant, self.coefficients())
         for symbol, coefficient in other.coefficients():
-            if symbol in coefficients:
-                coefficients[symbol] += coefficient
-            else:
-                coefficients[symbol] = coefficient
+            coefficients[symbol] += coefficient
         constant = self.constant + other.constant
         return Expression(coefficients, constant)
 
@@ -140,12 +137,9 @@ class Expression:
 
     @_polymorphic
     def __sub__(self, other):
-        coefficients = dict(self.coefficients())
+        coefficients = defaultdict(Constant, self.coefficients())
         for symbol, coefficient in other.coefficients():
-            if symbol in coefficients:
-                coefficients[symbol] -= coefficient
-            else:
-                coefficients[symbol] = -coefficient
+            coefficients[symbol] -= coefficient
         constant = self.constant - other.constant
         return Expression(coefficients, constant)
 
@@ -172,9 +166,8 @@ class Expression:
         if other.isconstant():
             coefficients = dict(self.coefficients())
             for symbol in coefficients:
-                coefficients[symbol] = \
-                        Fraction(coefficients[symbol], other.constant)
-            constant = Fraction(self.constant, other.constant)
+                coefficients[symbol] = Constant(coefficients[symbol], other.constant)
+            constant = Constant(self.constant, other.constant)
             return Expression(coefficients, constant)
         if isinstance(other, Expression):
             raise ValueError('non-linear expression: '
@@ -184,8 +177,7 @@ class Expression:
     def __rtruediv__(self, other):
         if isinstance(other, self):
             if self.isconstant():
-                constant = Fraction(other, self.constant)
-                return Expression(constant=constant)
+                return Constant(other, self.constant)
             else:
                 raise ValueError('non-linear expression: '
                         '{} / {}'.format(other._parenstr(), self._parenstr()))
@@ -196,8 +188,8 @@ class Expression:
         # "normal" equality
         # see http://docs.sympy.org/dev/tutorial/gotchas.html#equals-signs
         return isinstance(other, Expression) and \
-                self._coefficients == other._coefficients and \
-                self.constant == other.constant
+            self._coefficients == other._coefficients and \
+            self.constant == other.constant
 
     @_polymorphic
     def __le__(self, other):
@@ -219,11 +211,28 @@ class Expression:
         from .polyhedra import Gt
         return Gt(self, other)
 
-    def _toint(self):
+    def scaleint(self):
         lcm = functools.reduce(lambda a, b: a*b // gcd(a, b),
             [value.denominator for value in self.values()])
         return self * lcm
 
+    def subs(self, symbol, expression=None):
+        if expression is None:
+            if isinstance(symbol, dict):
+                symbol = symbol.items()
+            substitutions = symbol
+        else:
+            substitutions = [(symbol, expression)]
+        result = self
+        for symbol, expression in substitutions:
+            coefficients = [(othersymbol, coefficient)
+                for othersymbol, coefficient in result.coefficients()
+                if othersymbol != symbol]
+            coefficient = result.coefficient(symbol)
+            constant = result.constant
+            result = Expression(coefficients, constant) + coefficient*expression
+        return result
+
     @classmethod
     def _fromast(cls, node):
         if isinstance(node, ast.Module) and len(node.body) == 1:
@@ -249,46 +258,23 @@ class Expression:
                 return left / right
         raise SyntaxError('invalid syntax')
 
-    def subs(self, symbol, expression=None):
-        if expression is None:
-            if isinstance(symbol, dict):
-                symbol = symbol.items()
-            substitutions = symbol
-        else:
-            substitutions = [(symbol, expression)]
-        result = self
-        for symbol, expression in substitutions:
-            symbol = symbolname(symbol)
-            result = result._subs(symbol, expression)
-        return result
-
-    def _subs(self, symbol, expression):
-        coefficients = {name: coefficient
-            for name, coefficient in self.coefficients()
-            if name != symbol}
-        constant = self.constant
-        coefficient = self.coefficient(symbol)
-        result = Expression(coefficients, self.constant)
-        result += coefficient * expression
-        return result
-
     _RE_NUM_VAR = re.compile(r'(\d+|\))\s*([^\W\d_]\w*|\()')
 
     @classmethod
     def fromstring(cls, string):
         # add implicit multiplication operators, e.g. '5x' -> '5*x'
-        string = cls._RE_NUM_VAR.sub(r'\1*\2', string)
+        string = Expression._RE_NUM_VAR.sub(r'\1*\2', string)
         tree = ast.parse(string, 'eval')
         return cls._fromast(tree)
 
-    def __str__(self):
+    def __repr__(self):
         string = ''
         i = 0
         for symbol in self.symbols:
             coefficient = self.coefficient(symbol)
             if coefficient == 1:
                 if i == 0:
-                    string += symbol
+                    string += symbol.name
                 else:
                     string += ' + {}'.format(symbol)
             elif coefficient == -1:
@@ -325,30 +311,27 @@ class Expression:
         else:
             return '({})'.format(string)
 
-    def __repr__(self):
-        return '{}({!r})'.format(self.__class__.__name__, str(self))
-
     @classmethod
     def fromsympy(cls, expr):
         import sympy
-        coefficients = {}
+        coefficients = []
         constant = 0
         for symbol, coefficient in expr.as_coefficients_dict().items():
             coefficient = Fraction(coefficient.p, coefficient.q)
             if symbol == sympy.S.One:
                 constant = coefficient
             elif isinstance(symbol, sympy.Symbol):
-                symbol = symbol.name
-                coefficients[symbol] = coefficient
+                symbol = Symbol(symbol.name)
+                coefficients.append((symbol, coefficient))
             else:
                 raise ValueError('non-linear expression: {!r}'.format(expr))
-        return cls(coefficients, constant)
+        return Expression(coefficients, constant)
 
     def tosympy(self):
         import sympy
         expr = 0
         for symbol, coefficient in self.coefficients():
-            term = coefficient * sympy.Symbol(symbol)
+            term = coefficient * sympy.Symbol(symbol.name)
             expr += term
         expr += self.constant
         return expr
@@ -358,14 +341,13 @@ class Symbol(Expression):
 
     __slots__ = (
         '_name',
-        '_hash',
     )
 
     def __new__(cls, name):
-        name = symbolname(name)
+        if not isinstance(name, str):
+            raise TypeError('name must be a string')
         self = object().__new__(cls)
-        self._name = name
-        self._hash = hash(self._name)
+        self._name = name.strip()
         return self
 
     @property
@@ -373,17 +355,18 @@ class Symbol(Expression):
         return self._name
 
     def __hash__(self):
-        return self._hash
+        return hash(self._name)
 
     def coefficient(self, symbol):
-        symbol = symbolname(symbol)
-        if symbol == self.name:
+        if not isinstance(symbol, Symbol):
+            raise TypeError('symbol must be a Symbol instance')
+        if symbol == self:
             return 1
         else:
             return 0
 
     def coefficients(self):
-        yield self.name, 1
+        yield self, 1
 
     @property
     def constant(self):
@@ -391,7 +374,7 @@ class Symbol(Expression):
 
     @property
     def symbols(self):
-        return self.name,
+        return self,
 
     @property
     def dimension(self):
@@ -400,6 +383,9 @@ class Symbol(Expression):
     def issymbol(self):
         return True
 
+    def values(self):
+        yield 1
+
     def __eq__(self, other):
         return isinstance(other, Symbol) and self.name == other.name
 
@@ -413,14 +399,11 @@ class Symbol(Expression):
             return Symbol(node.id)
         raise SyntaxError('invalid syntax')
 
-    def __repr__(self):
-        return '{}({!r})'.format(self.__class__.__name__, self._name)
-
     @classmethod
     def fromsympy(cls, expr):
         import sympy
         if isinstance(expr, sympy.Symbol):
-            return cls(expr.name)
+            return Symbol(expr.name)
         else:
             raise TypeError('expr must be a sympy.Symbol instance')
 
@@ -428,27 +411,13 @@ class Symbol(Expression):
 def symbols(names):
     if isinstance(names, str):
         names = names.replace(',', ' ').split()
-    return (Symbol(name) for name in names)
-
-def symbolname(symbol):
-    if isinstance(symbol, str):
-        return symbol.strip()
-    elif isinstance(symbol, Symbol):
-        return symbol.name
-    else:
-        raise TypeError('symbol must be a string or a Symbol instance')
-
-def symbolnames(symbols):
-    if isinstance(symbols, str):
-        return symbols.replace(',', ' ').split()
-    return tuple(symbolname(symbol) for symbol in symbols)
+    return tuple(Symbol(name) for name in names)
 
 
 class Constant(Expression):
 
     __slots__ = (
         '_constant',
-        '_hash',
     )
 
     def __new__(cls, numerator=0, denominator=None):
@@ -457,18 +426,18 @@ class Constant(Expression):
             self._constant = numerator.constant
         else:
             self._constant = Fraction(numerator, denominator)
-        self._hash = hash(self._constant)
         return self
 
     def __hash__(self):
-        return self._hash
+        return hash(self.constant)
 
     def coefficient(self, symbol):
-        symbol = symbolname(symbol)
+        if not isinstance(symbol, Symbol):
+            raise TypeError('symbol must be a Symbol instance')
         return 0
 
     def coefficients(self):
-        yield from []
+        yield from ()
 
     @property
     def symbols(self):
@@ -481,6 +450,9 @@ class Constant(Expression):
     def isconstant(self):
         return True
 
+    def values(self):
+        yield self._constant
+
     @_polymorphic
     def __eq__(self, other):
         return isinstance(other, Constant) and self.constant == other.constant
@@ -490,25 +462,16 @@ class Constant(Expression):
 
     @classmethod
     def fromstring(cls, string):
-        if isinstance(string, str):
-            return Constant(Fraction(string))
-        else:
+        if not isinstance(string, str):
             raise TypeError('string must be a string instance')
-
-    def __repr__(self):
-        if self.constant.denominator == 1:
-            return '{}({!r})'.format(self.__class__.__name__,
-                self.constant.numerator)
-        else:
-            return '{}({!r}, {!r})'.format(self.__class__.__name__,
-                self.constant.numerator, self.constant.denominator)
+        return Constant(Fraction(string))
 
     @classmethod
     def fromsympy(cls, expr):
         import sympy
         if isinstance(expr, sympy.Rational):
-            return cls(expr.p, expr.q)
+            return Constant(expr.p, expr.q)
         elif isinstance(expr, numbers.Rational):
-            return cls(expr)
+            return Constant(expr)
         else:
             raise TypeError('expr must be a sympy.Rational instance')

diff --git a/pypol/polyhedra.py b/pypol/polyhedra.py
index ac67cf8..6ef7cc1 100644 (file)
--- a/pypol/polyhedra.py
+++ b/pypol/polyhedra.py
@@ -44,14 +44,14 @@ class Polyhedron(Domain):
             for i, equality in enumerate(equalities):
                 if not isinstance(equality, Expression):
                     raise TypeError('equalities must be linear expressions')
-                equalities[i] = equality._toint()
+                equalities[i] = equality.scaleint()
         if inequalities is None:
             inequalities = []
         else:
             for i, inequality in enumerate(inequalities):
                 if not isinstance(inequality, Expression):
                     raise TypeError('inequalities must be linear expressions')
-                inequalities[i] = inequality._toint()
+                inequalities[i] = inequality.scaleint()
         symbols = cls._xsymbols(equalities + inequalities)
         islbset = cls._toislbasicset(equalities, inequalities, symbols)
         return cls._fromislbasicset(islbset, symbols)
@@ -95,7 +95,8 @@ class Polyhedron(Domain):
             constant = islhelper.isl_val_to_int(constant)
             coefficients = {}
             for index, symbol in enumerate(symbols):
-                coefficient = libisl.isl_constraint_get_coefficient_val(islconstraint, libisl.isl_dim_set, index)
+                coefficient = libisl.isl_constraint_get_coefficient_val(islconstraint,
+                    libisl.isl_dim_set, index)
                 coefficient = islhelper.isl_val_to_int(coefficient)
                 if coefficient != 0:
                     coefficients[symbol] = coefficient

diff --git a/pypol/tests/test_domains.py b/pypol/tests/test_domains.py
index 55853fd..e9dd1cd 100644 (file)
--- a/pypol/tests/test_domains.py
+++ b/pypol/tests/test_domains.py
@@ -1,7 +1,7 @@
 import unittest
 
 from ..domains import *
-from ..linexprs import symbols
+from ..linexprs import Symbol, symbols
 from ..polyhedra import *
 
 
@@ -78,10 +78,10 @@ class TestDomain(unittest.TestCase):
         self.assertEqual(self.square1.polyhedral_hull(), self.hull)
 
     def test_project_out(self):
-        self.assertEqual(self.square1.project_out('x'), self.dropped)
-        self.assertEqual(self.square1.project_out('x y'), self.universe)
-        self.assertEqual(self.universe.project_out(' '), self.universe)
-        self.assertEqual(self.empty.project_out(' '), Empty)
+        self.assertEqual(self.square1.project_out(symbols('x')), self.dropped)
+        self.assertEqual(self.square1.project_out(symbols('x y')), self.universe)
+        self.assertEqual(self.universe.project_out([]), self.universe)
+        self.assertEqual(self.empty.project_out([]), Empty)
 
     def test_simplify(self):
         self.assertEqual(self.universe.simplify(), self.universe)

diff --git a/pypol/tests/test_linexprs.py b/pypol/tests/test_linexprs.py
index bc062b6..8dfd13e 100644 (file)
--- a/pypol/tests/test_linexprs.py
+++ b/pypol/tests/test_linexprs.py
@@ -10,9 +10,9 @@ from .libhelper import requires_sympy
 class TestExpression(unittest.TestCase):
 
     def setUp(self):
-        self.x = Expression({'x': 1})
-        self.y = Expression({'y': 1})
-        self.z = Expression({'z': 1})
+        self.x = Symbol('x')
+        self.y = Symbol('y')
+        self.z = Symbol('z')
         self.zero = Expression(constant=0)
         self.one = Expression(constant=1)
         self.pi = Expression(constant=Fraction(22, 7))
@@ -23,11 +23,10 @@ class TestExpression(unittest.TestCase):
         self.assertIsInstance(self.pi, Constant)
         self.assertNotIsInstance(self.x + self.pi, Symbol)
         self.assertNotIsInstance(self.x + self.pi, Constant)
-        xx = Expression({'x': 2})
+        xx = Expression({self.x: 2})
         self.assertNotIsInstance(xx, Symbol)
         with self.assertRaises(TypeError):
             Expression('x + y', 2)
-        self.assertEqual(Expression({'x': 2}), Expression({self.x: 2}))
         with self.assertRaises(TypeError):
             Expression({0: 2})
         with self.assertRaises(TypeError):
@@ -38,27 +37,29 @@ class TestExpression(unittest.TestCase):
             Expression(constant='a')
 
     def test_coefficient(self):
-        self.assertEqual(self.expr.coefficient('x'), 1)
-        self.assertEqual(self.expr.coefficient('y'), -2)
+        self.assertEqual(self.expr.coefficient(self.x), 1)
         self.assertEqual(self.expr.coefficient(self.y), -2)
-        self.assertEqual(self.expr.coefficient('z'), 0)
+        self.assertEqual(self.expr.coefficient(self.z), 0)
+        with self.assertRaises(TypeError):
+            self.expr.coefficients('x')
         with self.assertRaises(TypeError):
             self.expr.coefficient(0)
         with self.assertRaises(TypeError):
             self.expr.coefficient(self.expr)
 
     def test_getitem(self):
-        self.assertEqual(self.expr['x'], 1)
-        self.assertEqual(self.expr['y'], -2)
+        self.assertEqual(self.expr[self.x], 1)
         self.assertEqual(self.expr[self.y], -2)
-        self.assertEqual(self.expr['z'], 0)
+        self.assertEqual(self.expr[self.z], 0)
+        with self.assertRaises(TypeError):
+            self.assertEqual(self.expr['x'], 1)
         with self.assertRaises(TypeError):
             self.expr[0]
         with self.assertRaises(TypeError):
             self.expr[self.expr]
 
     def test_coefficients(self):
-        self.assertCountEqual(self.expr.coefficients(), [('x', 1), ('y', -2)])
+        self.assertCountEqual(self.expr.coefficients(), [(self.x, 1), (self.y, -2)])
 
     def test_constant(self):
         self.assertEqual(self.x.constant, 0)
@@ -66,9 +67,9 @@ class TestExpression(unittest.TestCase):
         self.assertEqual(self.expr.constant, 3)
 
     def test_symbols(self):
-        self.assertCountEqual(self.x.symbols, ['x'])
+        self.assertCountEqual(self.x.symbols, [self.x])
         self.assertCountEqual(self.pi.symbols, [])
-        self.assertCountEqual(self.expr.symbols, ['x', 'y'])
+        self.assertCountEqual(self.expr.symbols, [self.x, self.y])
 
     def test_dimension(self):
         self.assertEqual(self.x.dimension, 1)
@@ -127,21 +128,29 @@ class TestExpression(unittest.TestCase):
         self.assertNotEqual(self.x, self.y)
         self.assertEqual(self.zero, 0)
 
-    def test__toint(self):
-        self.assertEqual((self.x + self.y/2 + self.z/3)._toint(),
+    def test_scaleint(self):
+        self.assertEqual((self.x + self.y/2 + self.z/3).scaleint(),
                 6*self.x + 3*self.y + 2*self.z)
 
     def test_subs(self):
-        self.assertEqual(self.x.subs('x', 3), 3)
-        self.assertEqual(self.x.subs('x', self.x), self.x)
-        self.assertEqual(self.x.subs('x', self.y), self.y)
-        self.assertEqual(self.x.subs('x', self.x + self.y), self.x + self.y)
-        self.assertEqual(self.x.subs('y', 3), self.x)
-        self.assertEqual(self.pi.subs('x', 3), self.pi)
-        self.assertEqual(self.expr.subs('x', -3), -2 * self.y)
-        self.assertEqual(self.expr.subs([('x', self.y), ('y', self.x)]), 3 - self.x)
-        self.assertEqual(self.expr.subs({'x': self.z, 'y': self.z}), 3 - self.z)
+        self.assertEqual(self.x.subs(self.x, 3), 3)
+        self.assertEqual(self.x.subs(self.x, self.x), self.x)
+        self.assertEqual(self.x.subs(self.x, self.y), self.y)
+        self.assertEqual(self.x.subs(self.x, self.x + self.y), self.x + self.y)
+        self.assertEqual(self.x.subs(self.y, 3), self.x)
+        self.assertEqual(self.pi.subs(self.x, 3), self.pi)
+        self.assertEqual(self.expr.subs(self.x, -3), -2 * self.y)
+        self.assertEqual(self.expr.subs([(self.x, self.y), (self.y, self.x)]), 3 - self.x)
         self.assertEqual(self.expr.subs({self.x: self.z, self.y: self.z}), 3 - self.z)
+        self.assertEqual(self.expr.subs({self.x: self.z, self.y: self.z}), 3 - self.z)
+        with self.assertRaises(TypeError):
+            self.x.subs('x', 3)
+        with self.assertRaises(TypeError):
+            self.expr.subs([('x', self.z), ('y', self.z)])
+        with self.assertRaises(TypeError):
+            self.expr.subs({'x': self.z, 'y': self.z})
+        with self.assertRaises(TypeError):
+            self.expr.subs(self.x, 'x')
 
     def test_fromstring(self):
         self.assertEqual(Expression.fromstring('x'), self.x)
@@ -151,20 +160,13 @@ class TestExpression(unittest.TestCase):
         self.assertEqual(Expression.fromstring('x - (3-1)y + 3'), self.expr)
         self.assertEqual(Expression.fromstring('x - 2*y + 3'), self.expr)
 
-    def test_str(self):
+    def test_repr(self):
         self.assertEqual(str(Expression()), '0')
         self.assertEqual(str(self.x), 'x')
         self.assertEqual(str(-self.x), '-x')
         self.assertEqual(str(self.pi), '22/7')
         self.assertEqual(str(self.expr), 'x - 2*y + 3')
 
-    def test_repr(self):
-        self.assertEqual(repr(self.x), "Symbol('x')")
-        self.assertEqual(repr(self.one), 'Constant(1)')
-        self.assertEqual(repr(self.pi), 'Constant(22, 7)')
-        self.assertEqual(repr(self.x + self.one), "Expression('x + 1')")
-        self.assertEqual(repr(self.expr), "Expression('x - 2*y + 3')")
-
     @requires_sympy
     def test_fromsympy(self):
         import sympy
@@ -192,7 +194,8 @@ class TestSymbol(unittest.TestCase):
 
     def test_new(self):
         self.assertEqual(Symbol(' x '), self.x)
-        self.assertEqual(Symbol(self.x), self.x)
+        with self.assertRaises(TypeError):
+            Symbol(self.x)
         with self.assertRaises(TypeError):
             Symbol(1)
 
@@ -207,11 +210,8 @@ class TestSymbol(unittest.TestCase):
         with self.assertRaises(SyntaxError):
             Symbol.fromstring('1')
 
-    def test_str(self):
-        self.assertEqual(str(self.x), 'x')
-
     def test_repr(self):
-        self.assertEqual(repr(self.x), "Symbol('x')")
+        self.assertEqual(str(self.x), 'x')
 
     @requires_sympy
     def test_fromsympy(self):
@@ -259,9 +259,9 @@ class TestConstant(unittest.TestCase):
             Constant.fromstring(1)
 
     def test_repr(self):
-        self.assertEqual(repr(self.zero), 'Constant(0)')
-        self.assertEqual(repr(self.one), 'Constant(1)')
-        self.assertEqual(repr(self.pi), 'Constant(22, 7)')
+        self.assertEqual(repr(self.zero), '0')
+        self.assertEqual(repr(self.one), '1')
+        self.assertEqual(repr(self.pi), '22/7')
 
     @requires_sympy
     def test_fromsympy(self):

diff --git a/pypol/tests/test_polyhedra.py b/pypol/tests/test_polyhedra.py
index c7a58a4..cb2015f 100644 (file)
--- a/pypol/tests/test_polyhedra.py
+++ b/pypol/tests/test_polyhedra.py
@@ -13,7 +13,7 @@ class TestPolyhedron(unittest.TestCase):
         self.square = Polyhedron(inequalities=[x, 1 - x, y, 1 - y])
 
     def test_symbols(self):
-        self.assertCountEqual(self.square.symbols, ['x', 'y'])
+        self.assertCountEqual(self.square.symbols, symbols('x y'))
 
     def test_dimension(self):
         self.assertEqual(self.square.dimension, 2)