From 0ac7eef4b57966b99d3b86c1a12fe9964655752f Mon Sep 17 00:00:00 2001
From: Will McGugan <willmcgugan@gmail.com>
Date: Fri, 17 Feb 2023 18:11:55 +0000
Subject: [PATCH] docstrings and types

---
 src/textual/_spatial_map.py | 22 ++++++++++++++--------
 tests/test_spatial_map.py   |  2 +-
 2 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/src/textual/_spatial_map.py b/src/textual/_spatial_map.py
index 916602fbe..d31a7ee90 100644
--- a/src/textual/_spatial_map.py
+++ b/src/textual/_spatial_map.py
@@ -4,17 +4,23 @@ from collections import defaultdict
 from itertools import product
 from typing import Generic, Iterable, TypeVar
 
+from typing_extensions import TypeAlias
+
 from .geometry import Region
 
 ValueType = TypeVar("ValueType")
+GridCoordinate: TypeAlias = "tuple[int, int]"
 
 
 class SpatialMap(Generic[ValueType]):
     """A spatial map allows for data to be associated with rectangular regions
     in Euclidean space, and efficiently queried.
 
-    When the SpatialMap is populated, a reference to each value is placed in a bucket associated
-    with a regular grid that covers 2D space.
+    When the SpatialMap is populated, a reference to each value is placed into one or
+    more buckets associated with a regular grid that covers 2D space.
+
+    The SpatialMap is able to quickly retrieve the values under a given "window" region
+    by combining the values in the grid squares under the visible area.
 
     """
 
@@ -27,17 +33,17 @@ class SpatialMap(Generic[ValueType]):
         """
         self._grid_size = (grid_width, grid_height)
         self.total_region = Region()
-        self._map: defaultdict[tuple[int, int], list[ValueType]] = defaultdict(list)
+        self._map: defaultdict[GridCoordinate, list[ValueType]] = defaultdict(list)
         self._fixed: list[ValueType] = []
 
-    def _region_to_grid(self, region: Region) -> Iterable[tuple[int, int]]:
+    def _region_to_grid_coordinate(self, region: Region) -> Iterable[GridCoordinate]:
         """Get the grid squares under a region.
 
         Args:
             region: A region.
 
         Returns:
-            Iterable of grid squares (tuple of 2 values).
+            Iterable of grid coordinates (tuple of 2 values).
         """
         # (x1, y1) is the coordinate of the top left cell
         # (x2, y2) is the coordinate of the bottom right cell
@@ -64,7 +70,7 @@ class SpatialMap(Generic[ValueType]):
         """
         append_fixed = self._fixed.append
         get_grid_list = self._map.__getitem__
-        _region_to_grid = self._region_to_grid
+        _region_to_grid = self._region_to_grid_coordinate
         total_region = self.total_region
         for region, fixed, value in regions_and_values:
             total_region = total_region.union(region)
@@ -89,8 +95,8 @@ class SpatialMap(Generic[ValueType]):
         results: list[ValueType] = self._fixed.copy()
         add_results = results.extend
         get_grid_values = self._map.get
-        for grid in self._region_to_grid(region):
-            grid_values = get_grid_values(grid)
+        for grid_coordinate in self._region_to_grid_coordinate(region):
+            grid_values = get_grid_values(grid_coordinate)
             if grid_values is not None:
                 add_results(grid_values)
         unique_values = list(dict.fromkeys(results))
diff --git a/tests/test_spatial_map.py b/tests/test_spatial_map.py
index ddbf890fb..80a0eda1c 100644
--- a/tests/test_spatial_map.py
+++ b/tests/test_spatial_map.py
@@ -36,7 +36,7 @@ from textual.geometry import Region
 def test_region_to_grid(region, grid):
     spatial_map = SpatialMap(10, 10)
 
-    assert list(spatial_map._region_to_grid(region)) == grid
+    assert list(spatial_map._region_to_grid_coordinate(region)) == grid
 
 
 def test_get_values_in_region() -> None: