Alternative implementation of projection

[linpy.git] / pypol / domains.py

diff --git a/pypol/domains.py b/pypol/domains.py
index 20493fa..c844e55 100644 (file)
--- a/pypol/domains.py
+++ b/pypol/domains.py
@@ -138,10 +138,11 @@ class Domain:
         return self.complement()
 
     def simplify(self):
-        # see isl_set_coalesce, isl_set_detect_equalities,
-        # isl_set_remove_redundancies
-        # which ones? in which order?
-        raise NotImplementedError
+        #does not change anything in any of the examples
+        #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)
 
     def polyhedral_hull(self):
         # several types of hull are available
@@ -151,10 +152,16 @@ class Domain:
         islbset = libisl.isl_set_polyhedral_hull(islset)
         return Polyhedron._fromislbasicset(islbset, self.symbols)
 
-    def project(self, symbols):
-        # not sure what isl_set_project_out actually does…
-        # use isl_set_drop_constraints_involving_dims instead?
-        raise NotImplementedError
+    def project_out(self, symbols):
+        # use to remove certain variables
+        islset = self._toislset(self.polyhedra, self.symbols)
+        # the trick is to walk symbols in reverse order, to avoid index updates
+        for index, symbol in reversed(list(enumerate(self.symbols))):
+            if symbol in symbols:
+                islset = libisl.isl_set_project_out(islset, libisl.isl_dim_set, index, 1)
+        # remaining symbols
+        symbols = [symbol for symbol in self.symbols if symbol not in symbols]
+        return Domain._fromislset(islset, symbols)
 
     def sample(self):
         from .polyhedra import Polyhedron
@@ -287,25 +294,34 @@ class Domain:
                 return Polyhedron(equalities, inequalities)
         raise SyntaxError('invalid syntax')
 
+    _RE_BRACES = re.compile(r'^\{\s*|\s*\}$')
+    _RE_EQ = re.compile(r'([^<=>])=([^<=>])')
+    _RE_AND = re.compile(r'\band\b|,|&&|/\\|∧|∩')
+    _RE_OR = re.compile(r'\bor\b|;|\|\||\\/|∨|∪')
+    _RE_NOT = re.compile(r'\bnot\b|!|¬')
+    _RE_NUM_VAR = Expression._RE_NUM_VAR
+    _RE_OPERATORS = re.compile(r'(&|\||~)')
+
     @classmethod
     def fromstring(cls, string):
-        # remove brackets
-        string = re.sub(r'^\{\s*|\s*\}$', '', string)
+        # remove curly brackets
+        string = cls._RE_BRACES.sub(r'', string)
         # replace '=' by '=='
-        string = re.sub(r'([^<=>])=([^<=>])', r'\1==\2', string)
+        string = cls._RE_EQ.sub(r'\1==\2', string)
         # replace 'and', 'or', 'not'
-        string = re.sub(r'\band\b|,|&&|/\\|∧|∩', r' & ', string)
-        string = re.sub(r'\bor\b|;|\|\||\\/|∨|∪', r' | ', string)
-        string = re.sub(r'\bnot\b|!|¬', r' ~', string)
-        tokens = re.split(r'(&|\||~)', string)
+        string = cls._RE_AND.sub(r' & ', string)
+        string = cls._RE_OR.sub(r' | ', string)
+        string = cls._RE_NOT.sub(r' ~', string)
+        # add implicit multiplication operators, e.g. '5x' -> '5*x'
+        string = cls._RE_NUM_VAR.sub(r'\1*\2', string)
+        # add parentheses to force precedence
+        tokens = cls._RE_OPERATORS.split(string)
         for i, token in enumerate(tokens):
             if i % 2 == 0:
-                # add implicit multiplication operators, e.g. '5x' -> '5*x'
-                token = re.sub(r'(\d+|\))\s*([^\W\d_]\w*|\()', r'\1*\2', token)
                 token = '({})'.format(token)
                 tokens[i] = token
         string = ''.join(tokens)
-        tree = ast.parse(string)
+        tree = ast.parse(string, 'eval')
         return cls._fromast(tree)
 
     def __repr__(self):
@@ -320,7 +336,6 @@ class Domain:
     def tosympy(self):
         raise NotImplementedError
 
-
 def And(*domains):
     if len(domains) == 0:
         from .polyhedra import Universe