Implement Expression.fromstring

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index 75ae166..8a61744 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -1,5 +1,7 @@
+import ast

 import functools
 import numbers
 import functools
 import numbers

+import re

 
 from fractions import Fraction, gcd
 
 
 from fractions import Fraction, gcd
 


@@ -11,7 +13,7 @@ __all__ = [
     'Expression', 'Constant', 'Symbol', 'symbols',
     'eq', 'le', 'lt', 'ge', 'gt',
     'Polyhedron',
     'Expression', 'Constant', 'Symbol', 'symbols',
     'eq', 'le', 'lt', 'ge', 'gt',
     'Polyhedron',

-    'empty', 'universe'
+    'Empty', 'Universe'

 ]
 
 
 ]
 
 


@@ -69,7 +71,7 @@ class Expression:
         self._coefficients = {}
         for symbol, coefficient in coefficients:
             if isinstance(symbol, Symbol):
         self._coefficients = {}
         for symbol, coefficient in coefficients:
             if isinstance(symbol, Symbol):

-                symbol = str(symbol)
+                symbol = symbol.name

             elif not isinstance(symbol, str):
                 raise TypeError('symbols must be strings or Symbol instances')
             if isinstance(coefficient, Constant):
             elif not isinstance(symbol, str):
                 raise TypeError('symbols must be strings or Symbol instances')
             if isinstance(coefficient, Constant):


@@ -86,9 +88,40 @@ class Expression:
         self._dimension = len(self._symbols)
         return self
 
         self._dimension = len(self._symbols)
         return self
 

+    @classmethod
+    def _fromast(cls, node):
+        if isinstance(node, ast.Module):
+            assert len(node.body) == 1
+            return cls._fromast(node.body[0])
+        elif isinstance(node, ast.Expr):
+            return cls._fromast(node.value)
+        elif isinstance(node, ast.Name):
+            return Symbol(node.id)
+        elif isinstance(node, ast.Num):
+            return Constant(node.n)
+        elif isinstance(node, ast.UnaryOp):
+            if isinstance(node.op, ast.USub):
+                return -cls._fromast(node.operand)
+        elif isinstance(node, ast.BinOp):
+            left = cls._fromast(node.left)
+            right = cls._fromast(node.right)
+            if isinstance(node.op, ast.Add):
+                return left + right
+            elif isinstance(node.op, ast.Sub):
+                return left - right
+            elif isinstance(node.op, ast.Mult):
+                return left * right
+            elif isinstance(node.op, ast.Div):
+                return left / right
+        raise SyntaxError('invalid syntax')
+

     @classmethod
     def fromstring(cls, string):
     @classmethod
     def fromstring(cls, string):

-        raise NotImplementedError
+        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()',
+                lambda m: '{}*{}'.format(m.group(1), m.group(2)),
+                string)
+        tree = ast.parse(string, 'eval')
+        return cls._fromast(tree)

 
     @property
     def symbols(self):
 
     @property
     def symbols(self):


@@ -126,10 +159,6 @@ class Expression:
             yield self.coefficient(symbol)
         yield self.constant
 
             yield self.coefficient(symbol)
         yield self.constant
 

-    @property
-    def symbol(self):
-        raise ValueError('not a symbol: {}'.format(self))
-

     def issymbol(self):
         return False
 
     def issymbol(self):
         return False
 


@@ -330,26 +359,26 @@ class Symbol(Expression):
 
     def __new__(cls, name):
         if isinstance(name, Symbol):
 
     def __new__(cls, name):
         if isinstance(name, Symbol):

-            name = name.symbol
+            name = name.name

         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)
         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._name = name

         self._dimension = 1
         return self
 
     @property
         self._dimension = 1
         return self
 
     @property

-    def symbol(self):
-        return self._symbol
+    def name(self):
+        return self._name

 
     def issymbol(self):
         return True
 
     def __repr__(self):
 
     def issymbol(self):
         return True
 
     def __repr__(self):

-        return '{}({!r})'.format(self.__class__.__name__, self._symbol)
+        return '{}({!r})'.format(self.__class__.__name__, self._name)

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


@@ -527,7 +556,6 @@ class Polyhedron:
         other = other._toisl(symbols)
         difference = libisl.isl_set_subtract(bset, other)
         return difference
         other = other._toisl(symbols)
         difference = libisl.isl_set_subtract(bset, other)
         return difference

-    

 
     def __sub__(self, other):
         return self.difference(other)
 
     def __sub__(self, other):
         return self.difference(other)


@@ -541,10 +569,15 @@ class Polyhedron:
         return '{{{}}}'.format(', '.join(constraints))
 
     def __repr__(self):
         return '{{{}}}'.format(', '.join(constraints))
 
     def __repr__(self):

-        equalities = list(self.equalities)
-        inequalities = list(self.inequalities)
-        return '{}(equalities={!r}, inequalities={!r})' \
-                ''.format(self.__class__.__name__, equalities, inequalities)
+        if self.isempty():
+            return 'Empty'
+        elif self.isuniverse():
+            return 'Universe'
+        else:
+            equalities = list(self.equalities)
+            inequalities = list(self.inequalities)
+            return '{}(equalities={!r}, inequalities={!r})' \
+                    ''.format(self.__class__.__name__, equalities, inequalities)

 
     def _symbolunion(self, *others):
         symbols = set(self.symbols)
 
     def _symbolunion(self, *others):
         symbols = set(self.symbols)


@@ -555,42 +588,39 @@ class Polyhedron:
     def _toisl(self, symbols=None):
         if symbols is None:
             symbols = self.symbols
     def _toisl(self, symbols=None):
         if symbols is None:
             symbols = self.symbols

-        num_coefficients = len(symbols)
-        space = libisl.isl_space_set_alloc(_main_ctx, 0, num_coefficients)
+        dimension = len(symbols)
+        space = libisl.isl_space_set_alloc(_main_ctx, 0, dimension)

         bset = libisl.isl_basic_set_universe(libisl.isl_space_copy(space))
         ls = libisl.isl_local_space_from_space(space)
         bset = libisl.isl_basic_set_universe(libisl.isl_space_copy(space))
         ls = libisl.isl_local_space_from_space(space)

-        #if there are equalities/inequalities, take each constant and coefficient and add as a constraint to the basic set
-        for eq in self.equalities:
+        for equality in self.equalities:

             ceq = libisl.isl_equality_alloc(libisl.isl_local_space_copy(ls))
             ceq = libisl.isl_equality_alloc(libisl.isl_local_space_copy(ls))

-            coeff_eq = dict(eq.coefficients())
-            if eq.constant:
-                value = str(eq.constant).encode()
-                val = libisl.isl_val_read_from_str(_main_ctx, value)
+            for symbol, coefficient in equality.coefficients():
+                val = str(coefficient).encode()
+                val = libisl.isl_val_read_from_str(_main_ctx, val)
+                dim = symbols.index(symbol)
+                ceq = libisl.isl_constraint_set_coefficient_val(ceq, libisl.isl_dim_set, dim, val)
+            if equality.constant != 0:
+                val = str(equality.constant).encode()
+                val = libisl.isl_val_read_from_str(_main_ctx, val)

                 ceq = libisl.isl_constraint_set_constant_val(ceq, val)
                 ceq = libisl.isl_constraint_set_constant_val(ceq, val)

-            for eq in coeff_eq:
-                number = str(coeff_eq.get(eq)).encode()
-                num = libisl.isl_val_read_from_str(_main_ctx, number)
-                iden = symbols.index(eq)
-                ceq = libisl.isl_constraint_set_coefficient_val(ceq, libisl.isl_dim_set, iden, num)  #use 3 for type isl_dim_set
-            bset = libisl.isl_basic_set_add_constraint(bset, ceq)  
-        for ineq in self.inequalities:
+            bset = libisl.isl_basic_set_add_constraint(bset, ceq)
+        for inequality in self.inequalities:

             cin = libisl.isl_inequality_alloc(libisl.isl_local_space_copy(ls))
             cin = libisl.isl_inequality_alloc(libisl.isl_local_space_copy(ls))

-            coeff_in = dict(ineq.coefficients())
-            if ineq.constant:
-                value = str(ineq.constant).encode()
-                val = libisl.isl_val_read_from_str(_main_ctx, value)
+            for symbol, coefficient in inequality.coefficients():
+                val = str(coefficient).encode()
+                val = libisl.isl_val_read_from_str(_main_ctx, val)
+                dim = symbols.index(symbol)
+                cin = libisl.isl_constraint_set_coefficient_val(cin, libisl.isl_dim_set, dim, val)
+            if inequality.constant != 0:
+                val = str(ineq.constant).encode()
+                val = libisl.isl_val_read_from_str(_main_ctx, val)

                 cin = libisl.isl_constraint_set_constant_val(cin, val)
                 cin = libisl.isl_constraint_set_constant_val(cin, val)

-            for ineq in coeff_in:
-                number = str(coeff_in.get(ineq)).encode()
-                num = libisl.isl_val_read_from_str(_main_ctx, number)
-                iden = symbols.index(ineq)
-                cin = libisl.isl_constraint_set_coefficient_val(cin, libisl.isl_dim_set, iden, num)  #use 3 for type isl_dim_set
-            bset = libisl.isl_basic_set_add_constraint(bset, cin)   
+            bset = libisl.isl_basic_set_add_constraint(bset, cin)

         bset = isl.BasicSet(bset)
         return bset
 
     @classmethod
         bset = isl.BasicSet(bset)
         return bset
 
     @classmethod

-    def _fromisl(cls, bset):
+    def _fromisl(cls, bset, symbols):

         raise NotImplementedError
         equalities = ...
         inequalities = ...
         raise NotImplementedError
         equalities = ...
         inequalities = ...


@@ -601,12 +631,13 @@ class Polyhedron:
             our printer is giving form as:
             { [i0, i1] : 2i1 >= -2 - i0 } '''
 
             our printer is giving form as:
             { [i0, i1] : 2i1 >= -2 - i0 } '''
 

-empty = None #eq(0,1)
-universe = None #Polyhedron()
+Empty = eq(0,1)
+Universe = Polyhedron()

 
 if __name__ == '__main__':
 
 if __name__ == '__main__':

-    ex1 = Expression(coefficients={'a': 6, 'b': 6}, constant= 3) #this is the expression that does not work (even without adding values)
-    ex2 = Expression(coefficients={'x': 4, 'y': 2}, constant= 3)
-    p = Polyhedron(equalities=[ex2])
-    p2 = Polyhedron(equalities=[ex2])
-    print(p._toisl()) # checking is values works for toisl
+    e1 = Expression('2a + 2b + 1')
+    p1 = Polyhedron(equalities=[e1]) # empty
+    e2 = Expression('3x + 2y + 3')
+    p2 = Polyhedron(equalities=[e2]) # not empty
+    print(p1._toisl())
+    print(p2._toisl())