X-Git-Url: http://git.veekun.com/pseudoku.git/blobdiff_plain/bf40f463be2e8809afbaed42abdd00105053a19d..8a045b780490790e8d69f929562a8d4befaf6283:/pseudoku/grid/constraints.py

diff --git a/pseudoku/grid/constraints.py b/pseudoku/grid/constraints.py
new file mode 100644
index 0000000..91f8287
--- /dev/null
+++ b/pseudoku/grid/constraints.py
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+from __future__ import division
+
+from weakref import ref
+
+class Constraint(object):
+    """Represents any group of cells in a grid that cannot repeat a digit."""
+
+    ### Accessors
+
+    # NOTE: _cells is a list of refs; _grid is a ref
+    # XXX document this
+    cells = property(lambda self: [ x() for x in self._cells ])
+    grid = property(lambda self: self._grid())
+
+    ### Methods
+    # XXX inherited __init__ to init _grid/_cells
+
+    def find_value(self, value):
+        """Returns the cells that can be a specific value."""
+        possible_cells = []
+        for cell in self.cells:
+            if value in cell._values:
+                possible_cells.append(cell)
+
+        if len(possible_cells) == 0:
+            raise Exception  # XXX
+
+        return possible_cells
+
+    def resolve_uniques(self):
+        for value in xrange(self.grid._size):
+            # XXX cache values that are taken care of
+            possible_cells = self.find_value(value)
+
+            if len(possible_cells) > 1:
+                # Not unique
+                continue
+
+            target_cell = possible_cells[0]
+            if target_cell.solved:
+                # Already seen this
+                # XXX this is what cache is for
+                continue
+
+            # Only cell in the group that can be value
+            target_cell.set(value)
+
+
+class Box(Constraint):
+    def _get_box_row(self):
+        return self._pos // self.grid._box_width
+    box_row = property(_get_box_row)
+
+    def _get_box_column(self):
+        return self._pos % self.grid._box_height
+    box_column = property(_get_box_column)
+
+    def __init__(self, grid, position):
+        self._grid = ref(grid)
+        self._pos = position
+
+        self._cells = []
+        for row in xrange(self.grid._box_height):
+            for col in xrange(self.grid._box_width):
+                cell_row = row + self.box_row * self.grid._box_height
+                cell_col = col + self.box_column * self.grid._box_width
+                self._cells.append(ref(self.grid.cell(cell_row, cell_col)))
+
+
+class Row(Constraint):
+    def __init__(self, grid, position):
+        self._grid = ref(grid)
+        self._pos = position
+
+        self._cells = []
+        for col in xrange(self.grid._size):
+            self._cells.append(ref(self.grid.cell(self._pos, col)))
+
+class Column(Constraint):
+    def __init__(self, grid, position):
+        self._grid = ref(grid)
+        self._pos = position
+
+        self._cells = []
+        for row in xrange(self.grid._size):
+            self._cells.append(ref(self.grid.cell(row, self._pos)))
+
+class Diagonal(Constraint):
+    def __init__(self, grid, direction='down', offset=0):
+        self._grid = ref(grid)
+        self._direction = direction
+        self._offset = offset
+
+        if direction == 'down':
+            coords = {'row': 0, 'column': 0}
+            increment = 1
+        elif direction == 'up':
+            coords = {'row': 0, 'column': grid.size - 1}
+            increment = -1
+        else:
+            raise Exception # XXX
+
+        # XXX
+        if offset != 0:
+            raise NotImplementedError
+
+        self._cells = []
+        for i in xrange(self.grid.size):
+            self._cells.append(ref(self.grid.cell(coords['row'], coords['column'])))
+            coords['row'] += 1
+            coords['column'] += increment