Classes Symbol and Constant, rather than functions (à la SymPy)

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index 7544633..bd7037b 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -9,8 +9,7 @@ from .isl import libisl
 
 
 __all__ = [
 
 
 __all__ = [

-    'Expression',
-    'constant', 'symbol', 'symbols',
+    'Expression', 'Constant', 'Symbol', 'symbols',

     'eq', 'le', 'lt', 'ge', 'gt',
     'Polyhedron',
     'empty', 'universe'
     'eq', 'le', 'lt', 'ge', 'gt',
     'Polyhedron',
     'empty', 'universe'


@@ -23,7 +22,7 @@ def _polymorphic_method(func):
         if isinstance(b, Expression):
             return func(a, b)
         if isinstance(b, numbers.Rational):
         if isinstance(b, Expression):
             return func(a, b)
         if isinstance(b, numbers.Rational):

-            b = constant(b)
+            b = Constant(b)

             return func(a, b)
         return NotImplemented
     return wrapper
             return func(a, b)
         return NotImplemented
     return wrapper


@@ -34,7 +33,7 @@ def _polymorphic_operator(func):
     @functools.wraps(func)
     def wrapper(a, b):
         if isinstance(a, numbers.Rational):
     @functools.wraps(func)
     def wrapper(a, b):
         if isinstance(a, numbers.Rational):

-            a = constant(a)
+            a = Constant(a)

             return func(a, b)
         elif isinstance(a, Expression):
             return func(a, b)
             return func(a, b)
         elif isinstance(a, Expression):
             return func(a, b)


@@ -55,27 +54,43 @@ class Expression:
             if constant:
                 raise TypeError('too many arguments')
             return cls.fromstring(coefficients)
             if constant:
                 raise TypeError('too many arguments')
             return cls.fromstring(coefficients)

-        self = super().__new__(cls)
-        self._coefficients = {}

         if isinstance(coefficients, dict):
             coefficients = coefficients.items()
         if isinstance(coefficients, dict):
             coefficients = coefficients.items()

-        if coefficients is not None:
-            for symbol, coefficient in coefficients:
-                if isinstance(symbol, Expression) and symbol.issymbol():
-                    symbol = str(symbol)
-                elif not isinstance(symbol, str):
-                    raise TypeError('symbols must be strings')
-                if not isinstance(coefficient, numbers.Rational):
-                    raise TypeError('coefficients must be rational numbers')
-                if coefficient != 0:
-                    self._coefficients[symbol] = coefficient
+        if coefficients is None:
+            return Constant(constant)
+        coefficients = [(symbol, coefficient)
+                for symbol, coefficient in coefficients if coefficient != 0]
+        if len(coefficients) == 0:
+            return Constant(constant)
+        elif len(coefficients) == 1:
+            symbol, coefficient = coefficients[0]
+            if coefficient == 1:
+                return Symbol(symbol)
+        self = object().__new__(cls)
+        self._coefficients = {}
+        for symbol, coefficient in coefficients:
+            if isinstance(symbol, Symbol):
+                symbol = str(symbol)
+            elif not isinstance(symbol, str):
+                raise TypeError('symbols must be strings or Symbol instances')
+            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
+        if isinstance(constant, Constant):
+            constant = constant.constant

         if not isinstance(constant, numbers.Rational):
         if not isinstance(constant, numbers.Rational):

-            raise TypeError('constant must be a rational number')
+            raise TypeError('constant must be a rational number or a Constant instance')

         self._constant = constant
         self._symbols = tuple(sorted(self._coefficients))
         self._dimension = len(self._symbols)
         return self
 
         self._constant = constant
         self._symbols = tuple(sorted(self._coefficients))
         self._dimension = len(self._symbols)
         return self
 

+    @classmethod
+    def fromstring(cls, string):
+        raise NotImplementedError
+

     @property
     def symbols(self):
         return self._symbols
     @property
     def symbols(self):
         return self._symbols


@@ -85,10 +100,10 @@ class Expression:
         return self._dimension
 
     def coefficient(self, symbol):
         return self._dimension
 
     def coefficient(self, symbol):

-        if isinstance(symbol, Expression) and symbol.issymbol():
+        if isinstance(symbol, Symbol):

             symbol = str(symbol)
         elif not isinstance(symbol, str):
             symbol = str(symbol)
         elif not isinstance(symbol, str):

-            raise TypeError('symbol must be a string')
+            raise TypeError('symbol must be a string or a Symbol instance')

         try:
             return self._coefficients[symbol]
         except KeyError:
         try:
             return self._coefficients[symbol]
         except KeyError:


@@ -105,30 +120,22 @@ class Expression:
         return self._constant
 
     def isconstant(self):
         return self._constant
 
     def isconstant(self):

-        return len(self._coefficients) == 0
+        return False

 
     def values(self):
         for symbol in self.symbols:
             yield self.coefficient(symbol)
         yield self.constant
 
 
     def values(self):
         for symbol in self.symbols:
             yield self.coefficient(symbol)
         yield self.constant
 

-    def values_int(self):
-        for symbol in self.symbols:
-            return self.coefficient(symbol)
-        return int(self.constant)
-

     @property
     def symbol(self):
     @property
     def symbol(self):

-        if not self.issymbol():
-            raise ValueError('not a symbol: {}'.format(self))
-        for symbol in self.symbols:
-            return symbol
+        raise ValueError('not a symbol: {}'.format(self))

 
     def issymbol(self):
 
     def issymbol(self):

-        return len(self._coefficients) == 1 and self._constant == 0
+        return False

 
     def __bool__(self):
 
     def __bool__(self):

-        return (not self.isconstant()) or bool(self.constant)
+        True

 
     def __pos__(self):
         return self
 
     def __pos__(self):
         return self


@@ -139,7 +146,7 @@ class Expression:
     @_polymorphic_method
     def __add__(self, other):
         coefficients = dict(self.coefficients())
     @_polymorphic_method
     def __add__(self, other):
         coefficients = dict(self.coefficients())

-        for symbol, coefficient in other.coefficients:
+        for symbol, coefficient in other.coefficients():

             if symbol in coefficients:
                 coefficients[symbol] += coefficient
             else:
             if symbol in coefficients:
                 coefficients[symbol] += coefficient
             else:


@@ -152,7 +159,7 @@ class Expression:
     @_polymorphic_method
     def __sub__(self, other):
         coefficients = dict(self.coefficients())
     @_polymorphic_method
     def __sub__(self, other):
         coefficients = dict(self.coefficients())

-        for symbol, coefficient in other.coefficients:
+        for symbol, coefficient in other.coefficients():

             if symbol in coefficients:
                 coefficients[symbol] -= coefficient
             else:
             if symbol in coefficients:
                 coefficients[symbol] -= coefficient
             else:


@@ -205,8 +212,8 @@ class Expression:
     def __str__(self):
         string = ''
         i = 0
     def __str__(self):
         string = ''
         i = 0

-        for symbol in symbols:
-            coefficient = self[symbol]
+        for symbol in self.symbols:
+            coefficient = self.coefficient(symbol)

             if coefficient == 1:
                 if i == 0:
                     string += symbol
             if coefficient == 1:
                 if i == 0:
                     string += symbol


@@ -255,10 +262,6 @@ class Expression:
         string += '}}, {!r})'.format(self.constant)
         return string
 
         string += '}}, {!r})'.format(self.constant)
         return string
 

-    @classmethod
-    def fromstring(cls, string):
-        raise NotImplementedError
-

     @_polymorphic_method
     def __eq__(self, other):
         # "normal" equality
     @_polymorphic_method
     def __eq__(self, other):
         # "normal" equality


@@ -296,16 +299,58 @@ class Expression:
         return Polyhedron(inequalities=[(self - other)._toint() - 1])
 
 
         return Polyhedron(inequalities=[(self - other)._toint() - 1])
 
 

-def constant(numerator=0, denominator=None):
-    if denominator is None and isinstance(numerator, numbers.Rational):
-        return Expression(constant=numerator)
-    else:
-        return Expression(constant=Fraction(numerator, denominator))
+class Constant(Expression):
+
+    def __new__(cls, numerator=0, denominator=None):
+        self = object().__new__(cls)
+        if denominator is None:
+            if isinstance(numerator, numbers.Rational):
+                self._constant = numerator
+            elif isinstance(numerator, Constant):
+                self._constant = numerator.constant
+            else:
+                raise TypeError('constant must be a rational number or a Constant instance')
+        else:
+            self._constant = Fraction(numerator, denominator)
+        self._coefficients = {}
+        self._symbols = ()
+        self._dimension = 0
+        return self
+
+    def isconstant(self):
+        return True

 
 

-def symbol(name):
-    if not isinstance(name, str):
-        raise TypeError('name must be a string')
-    return Expression(coefficients={name: 1})
+    def __bool__(self):
+        return bool(self.constant)
+
+    def __repr__(self):
+        return '{}({!r})'.format(self.__class__.__name__, self._constant)
+
+
+class Symbol(Expression):
+
+    def __new__(cls, name):
+        if isinstance(name, Symbol):
+            name = name.symbol
+        elif not isinstance(name, str):
+            raise TypeError('name must be a string or a Symbol instance')
+        self = object().__new__(cls)
+        self._coefficients = {name: 1}
+        self._constant = 0
+        self._symbols = tuple(name)
+        self._symbol = name
+        self._dimension = 1
+        return self
+
+    @property
+    def symbol(self):
+        return self._symbol
+
+    def issymbol(self):
+        return True
+
+    def __repr__(self):
+        return '{}({!r})'.format(self.__class__.__name__, self._symbol)

 
 def symbols(names):
     if isinstance(names, str):
 
 def symbols(names):
     if isinstance(names, str):


@@ -370,6 +415,10 @@ class Polyhedron:
         self._symbols = tuple(sorted(self._symbols))
         return self
 
         self._symbols = tuple(sorted(self._symbols))
         return self
 

+    @classmethod
+    def fromstring(cls, string):
+        raise NotImplementedError
+

     @property
     def equalities(self):
         return self._equalities
     @property
     def equalities(self):
         return self._equalities


@@ -378,16 +427,6 @@ class Polyhedron:
     def inequalities(self):
         return self._inequalities
 
     def inequalities(self):
         return self._inequalities
 

-    @property
-    def constant(self):
-        return self._constant
-
-    def isconstant(self):
-        return len(self._coefficients) == 0
-
-    def isempty(self):
-        return bool(libisl.isl_basic_set_is_empty(self._bset))
-

     @property
     def constraints(self):
         return self._constraints
     @property
     def constraints(self):
         return self._constraints


@@ -411,10 +450,11 @@ class Polyhedron:
         raise NotImplementedError
 
     def isempty(self):
         raise NotImplementedError
 
     def isempty(self):

-        return self == empty
+        bset = self._toisl()
+        return bool(libisl.isl_basic_set_is_empty(bset))

 
     def isuniverse(self):
 
     def isuniverse(self):

-        return self == universe
+        raise NotImplementedError

 
     def isdisjoint(self, other):
         # return true if the polyhedron has no elements in common with other
 
     def isdisjoint(self, other):
         # return true if the polyhedron has no elements in common with other


@@ -484,17 +524,13 @@ class Polyhedron:
         return '{}(equalities={!r}, inequalities={!r})' \
                 ''.format(self.__class__.__name__, equalities, inequalities)
 
         return '{}(equalities={!r}, inequalities={!r})' \
                 ''.format(self.__class__.__name__, equalities, inequalities)
 

-    @classmethod
-    def fromstring(cls, string):
-        raise NotImplementedError
-

     def _symbolunion(self, *others):
         symbols = set(self.symbols)
         for other in others:
             symbols.update(other.symbols)
         return sorted(symbols)
 
     def _symbolunion(self, *others):
         symbols = set(self.symbols)
         for other in others:
             symbols.update(other.symbols)
         return sorted(symbols)
 

-    def _to_isl(self, symbols=None):
+    def _toisl(self, symbols=None):

         if symbols is None:
             symbols = self.symbols
         num_coefficients = len(symbols)
         if symbols is None:
             symbols = self.symbols
         num_coefficients = len(symbols)


@@ -530,16 +566,16 @@ class Polyhedron:
         return bset
 
     @classmethod
         return bset
 
     @classmethod

-    def from_isl(cls, bset):
-        '''takes basic set in isl form and puts back into python version of polyhedron
-        isl example code gives isl form as:
-            "{[i] : exists (a : i = 2a and i >= 10 and i <= 42)}")
-            our printer is giving form as:
-            b'{ [i0] : 1 = 0 }' '''
+    def _fromisl(cls, bset):

         raise NotImplementedError
         equalities = ...
         inequalities = ...
         return cls(equalities, inequalities)
         raise NotImplementedError
         equalities = ...
         inequalities = ...
         return cls(equalities, inequalities)

+        '''takes basic set  in isl form and puts back into python version of polyhedron
+        isl example code gives isl form as:
+            "{[i] : exists (a : i = 2a and i >= 10 and i <= 42)}")
+            our printer is giving form as:
+            b'{ [i0] : 1 = 0 }' '''

         #bset = self
         # if self._equalities:
         #     constraints = libisl.isl_basic_set_equalities_matrix(bset, 3)
         #bset = self
         # if self._equalities:
         #     constraints = libisl.isl_basic_set_equalities_matrix(bset, 3)


@@ -556,5 +592,7 @@ if __name__ == '__main__':
     ex1 = Expression(coefficients={'a': 1, 'x': 2}, constant=2)
     ex2 = Expression(coefficients={'a': 3  , 'b': 2}, constant=3)
     p = Polyhedron(inequalities=[ex1, ex2])
     ex1 = Expression(coefficients={'a': 1, 'x': 2}, constant=2)
     ex2 = Expression(coefficients={'a': 3  , 'b': 2}, constant=3)
     p = Polyhedron(inequalities=[ex1, ex2])

-    bs = p._to_isl()
+    bs = p._toisl()

     print(bs)
     print(bs)

+    print('empty ?', p.isempty())
+    print('empty ?', eq(0, 1).isempty())