Improve Polyhedron.fromstring

[linpy.git] / pypol / linear.py

diff --git a/pypol/linear.py b/pypol/linear.py
index 8a61744..8fdece9 100644 (file)
--- a/pypol/linear.py
+++ b/pypol/linear.py
@@ -50,6 +50,13 @@ class Expression:
     This class implements linear expressions.
     """
 
+    __slots__ = (
+        '_coefficients',
+        '_constant',
+        '_symbols',
+        '_dimension',
+    )
+
     def __new__(cls, coefficients=None, constant=0):
         if isinstance(coefficients, str):
             if constant:
@@ -90,8 +97,7 @@ class Expression:
 
     @classmethod
     def _fromast(cls, node):
-        if isinstance(node, ast.Module):
-            assert len(node.body) == 1
+        if isinstance(node, ast.Module) and len(node.body) == 1:
             return cls._fromast(node.body[0])
         elif isinstance(node, ast.Expr):
             return cls._fromast(node.value)
@@ -99,9 +105,8 @@ class Expression:
             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.UnaryOp) and 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)
@@ -117,9 +122,7 @@ class Expression:
 
     @classmethod
     def fromstring(cls, string):
-        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()',
-                lambda m: '{}*{}'.format(m.group(1), m.group(2)),
-                string)
+        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()', r'\1*\2', string)
         tree = ast.parse(string, 'eval')
         return cls._fromast(tree)
 
@@ -357,6 +360,10 @@ class Constant(Expression):
 
 class Symbol(Expression):
 
+    __slots__ = Expression.__slots__ + (
+        '_name',
+    )
+
     def __new__(cls, name):
         if isinstance(name, Symbol):
             name = name.name
@@ -412,6 +419,13 @@ class Polyhedron:
     This class implements polyhedrons.
     """
 
+    __slots__ = (
+        '_equalities',
+        '_inequalities',
+        '_constraints',
+        '_symbols',
+    )
+
     def __new__(cls, equalities=None, inequalities=None):
         if isinstance(equalities, str):
             if inequalities is not None:
@@ -443,9 +457,54 @@ class Polyhedron:
         self._symbols = tuple(sorted(self._symbols))
         return self
 
+    @classmethod
+    def _fromast(cls, node):
+        if isinstance(node, ast.Module) and len(node.body) == 1:
+            return cls._fromast(node.body[0])
+        elif isinstance(node, ast.Expr):
+            return cls._fromast(node.value)
+        elif isinstance(node, ast.BinOp) and isinstance(node.op, ast.BitAnd):
+            equalities1, inequalities1 = cls._fromast(node.left)
+            equalities2, inequalities2 = cls._fromast(node.right)
+            equalities = equalities1 + equalities2
+            inequalities = inequalities1 + inequalities2
+            return equalities, inequalities
+        elif isinstance(node, ast.Compare):
+            equalities = []
+            inequalities = []
+            left = Expression._fromast(node.left)
+            for i in range(len(node.ops)):
+                op = node.ops[i]
+                right = Expression._fromast(node.comparators[i])
+                if isinstance(op, ast.Lt):
+                    inequalities.append(right - left - 1)
+                elif isinstance(op, ast.LtE):
+                    inequalities.append(right - left)
+                elif isinstance(op, ast.Eq):
+                    equalities.append(left - right)
+                elif isinstance(op, ast.GtE):
+                    inequalities.append(left - right)
+                elif isinstance(op, ast.Gt):
+                    inequalities.append(left - right - 1)
+                else:
+                    break
+                left = right
+            else:
+                return equalities, inequalities
+        raise SyntaxError('invalid syntax')
+
     @classmethod
     def fromstring(cls, string):
-        raise NotImplementedError
+        string = string.strip()
+        string = re.sub(r'^\{\s*|\s*\}$', '', string)
+        string = re.sub(r'([^<=>])=([^<=>])', r'\1==\2', string)
+        string = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()', r'\1*\2', string)
+        tokens = re.split(r',|;|and|&&|/\\|∧', string, flags=re.I)
+        tokens = ['({})'.format(token) for token in tokens]
+        string = ' & '.join(tokens)
+        tree = ast.parse(string, 'eval')
+        equalities, inequalities = cls._fromast(tree)
+        return cls(equalities, inequalities)
 
     @property
     def equalities(self):
@@ -612,7 +671,7 @@ class Polyhedron:
                 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 = str(inequality.constant).encode()
                 val = libisl.isl_val_read_from_str(_main_ctx, val)
                 cin = libisl.isl_constraint_set_constant_val(cin, val)
             bset = libisl.isl_basic_set_add_constraint(bset, cin)
@@ -632,12 +691,12 @@ class Polyhedron:
             { [i0, i1] : 2i1 >= -2 - i0 } '''
 
 Empty = eq(0,1)
+
 Universe = Polyhedron()
 
+
 if __name__ == '__main__':
-    e1 = Expression('2a + 2b + 1')
-    p1 = Polyhedron(equalities=[e1]) # empty
-    e2 = Expression('3x + 2y + 3')
-    p2 = Polyhedron(equalities=[e2]) # not empty
+    p1 = Polyhedron('2a + 2b + 1 == 0') # empty
     print(p1._toisl())
+    p2 = Polyhedron('3x + 2y + 3 == 0') # not empty
     print(p2._toisl())