Extended LoopOverCoordinate.

The condition's comparison operator can now be set to any sp.Relational.
This allows for example to loop backwards.

pystencils/astnodes.py

@@ -345,7 +345,7 @@ class LoopOverCoordinate(Node):
     LOOP_COUNTER_NAME_PREFIX = "ctr"
     BlOCK_LOOP_COUNTER_NAME_PREFIX = "_blockctr"
 
-    def __init__(self, body, coordinate_to_loop_over, start, stop, step=1, is_block_loop=False):
+    def __init__(self, body, coordinate_to_loop_over, start, stop, step=1, is_block_loop=False, relational=sp.Lt):
         super(LoopOverCoordinate, self).__init__(parent=None)
         self.body = body
         body.parent = self
@@ -356,10 +356,11 @@ class LoopOverCoordinate(Node):
         self.body.parent = self
         self.prefix_lines = []
         self.is_block_loop = is_block_loop
+        self.relational = relational
 
     def new_loop_with_different_body(self, new_body):
         result = LoopOverCoordinate(new_body, self.coordinate_to_loop_over, self.start, self.stop,
-                                    self.step, self.is_block_loop)
+                                    self.step, self.is_block_loop, self.relational)
         result.prefix_lines = [l for l in self.prefix_lines]
         return result
 
@@ -452,14 +453,16 @@ class LoopOverCoordinate(Node):
         return len(self.atoms(LoopOverCoordinate)) == 0
 
     def __str__(self):
-        return 'for({!s}={!s}; {!s}<{!s}; {!s}+={!s})\n{!s}'.format(self.loop_counter_name, self.start,
-                                                                    self.loop_counter_name, self.stop,
-                                                                    self.loop_counter_name, self.step,
+        return 'for({!s}={!s}; {!s}; {!s}+={!s})\n{!s}'.format(self.loop_counter_name, self.start,
+                                                               sp.ccode(self.relational(self.loop_counter_name,
+                                                                                        self.stop)),
+                                                               self.loop_counter_name, self.step,
                                                                     ("\t" + "\t".join(str(self.body).splitlines(True))))
 
     def __repr__(self):
-        return 'for({!s}={!s}; {!s}<{!s}; {!s}+={!s})'.format(self.loop_counter_name, self.start,
-                                                              self.loop_counter_name, self.stop,
+        return 'for({!s}={!s}; {!s}; {!s}+={!s})'.format(self.loop_counter_name, self.start,
+                                                              sp.ccode(self.relational(self.loop_counter_name,
+                                                                                       self.stop)),
                                                               self.loop_counter_name, self.step)
 
 

pystencils/backends/cbackend.py

@@ -154,7 +154,8 @@ class CBackend:
     def _print_LoopOverCoordinate(self, node):
         counter_symbol = node.loop_counter_name
         start = "int %s = %s" % (counter_symbol, self.sympy_printer.doprint(node.start))
-        condition = "%s < %s" % (counter_symbol, self.sympy_printer.doprint(node.stop))
+        condition_expression = node.relational(node.loop_counter_symbol, node.stop)
+        condition = self.sympy_printer.doprint(condition_expression)
         update = "%s += %s" % (counter_symbol, self.sympy_printer.doprint(node.step),)
         loop_str = "for (%s; %s; %s)" % (start, condition, update)