From 9b38690e69a9f195688121feebff1078dfa83ae4 Mon Sep 17 00:00:00 2001
From: Konstantin Pastbin <konstantin.pastbin@gmail.com>
Date: Tue, 31 Jan 2023 18:07:26 +0000
Subject: [PATCH] Optimize choosers by discarding non-matching rules

Signed-off-by: Konstantin Pastbin <konstantin.pastbin@gmail.com>
---
 src/mapcss/Rule.py         |  8 +-------
 src/mapcss/StyleChooser.py | 17 +++++++----------
 src/mapcss/__init__.py     | 21 ++++++++++++++++++---
 3 files changed, 26 insertions(+), 20 deletions(-)

diff --git a/src/mapcss/Rule.py b/src/mapcss/Rule.py
index 0966310..db516c1 100644
--- a/src/mapcss/Rule.py
+++ b/src/mapcss/Rule.py
@@ -38,13 +38,7 @@ class Rule():
     def __repr__(self):
         return "%s|z%s-%s %s %s" % (self.subject, self.minZoom, self.maxZoom, self.conditions, self.runtime_conditions)
 
-    def test(self, obj, tags, zoom):
-        if (zoom < self.minZoom) or (zoom > self.maxZoom):
-            return False
-
-        if (obj not in self.type_matches):
-            return False
-
+    def test(self, tags):
         subpart = "::default"
         for condition in self.conditions:
             res = condition.test(tags)
diff --git a/src/mapcss/StyleChooser.py b/src/mapcss/StyleChooser.py
index b27b550..a386599 100644
--- a/src/mapcss/StyleChooser.py
+++ b/src/mapcss/StyleChooser.py
@@ -109,14 +109,11 @@ class StyleChooser:
         self.cached_tags = a
         return a
 
-    def get_runtime_conditions(self, ftype, tags, zoom):
+    def get_runtime_conditions(self, tags):
         if not self.has_runtime_conditions:
             return None
 
-        if zoom < self.selzooms[0] or zoom > self.selzooms[1]:
-            return None
-
-        rule_and_object_id = self.testChain(self.ruleChains, ftype, tags, zoom)
+        rule_and_object_id = self.testChains(tags)
 
         if not rule_and_object_id:
             return None
@@ -125,9 +122,9 @@ class StyleChooser:
 
         return rule.runtime_conditions
 
-    def updateStyles(self, sl, ftype, tags, zoom, xscale, zscale, filter_by_runtime_conditions):
+    def updateStyles(self, sl, tags, xscale, zscale, filter_by_runtime_conditions):
         # Are any of the ruleChains fulfilled?
-        rule_and_object_id = self.testChain(self.ruleChains, ftype, tags, zoom)
+        rule_and_object_id = self.testChains(tags)
 
         if not rule_and_object_id:
             return sl
@@ -181,12 +178,12 @@ class StyleChooser:
 
         return sl
 
-    def testChain(self, chain, obj, tags, zoom):
+    def testChains(self, tags):
         """
         Tests an object against a chain
         """
-        for r in chain:
-            tt = r.test(obj, tags, zoom)
+        for r in self.ruleChains:
+            tt = r.test(tags)
             if tt:
                 return r, tt
         return False
diff --git a/src/mapcss/__init__.py b/src/mapcss/__init__.py
index feff12a..d52e8a5 100644
--- a/src/mapcss/__init__.py
+++ b/src/mapcss/__init__.py
@@ -130,11 +130,26 @@ class MapCSS():
                             self.choosers_by_type_zoom_tag[type][zoom][clname]['set'].add(chooser)
 
     def finalize_choosers_tree(self):
-        # Remove unneeded unique sets of choosers
         for ftype in self.choosers_by_type_zoom_tag.keys():
             for zoom in self.choosers_by_type_zoom_tag[ftype].keys():
                 for clname in self.choosers_by_type_zoom_tag[ftype][zoom].keys():
+                    # Discard unneeded unique set of choosers.
                     self.choosers_by_type_zoom_tag[ftype][zoom][clname] = self.choosers_by_type_zoom_tag[ftype][zoom][clname]['arr']
+                    for i in range(0, len(self.choosers_by_type_zoom_tag[ftype][zoom][clname])):
+                        chooser = self.choosers_by_type_zoom_tag[ftype][zoom][clname][i]
+                        optimized = StyleChooser(chooser.scalepair)
+                        optimized.styles = chooser.styles
+                        optimized.eval_type = chooser.eval_type
+                        optimized.has_evals = chooser.has_evals
+                        optimized.has_runtime_conditions = chooser.has_runtime_conditions
+                        optimized.selzooms = [zoom, zoom]
+                        optimized.ruleChains = []
+                        for rule in chooser.ruleChains:
+                            # Discard chooser's rules that don't match type or zoom.
+                            if ftype in rule.type_matches and zoom >= rule.minZoom and zoom <= rule.maxZoom:
+                                optimized.ruleChains.append(rule)
+                        self.choosers_by_type_zoom_tag[ftype][zoom][clname][i] = optimized
+
 
     def get_runtime_rules(self, clname, type, tags, zoom):
         """
@@ -143,7 +158,7 @@ class MapCSS():
         runtime_rules = []
         if type in self.choosers_by_type_zoom_tag:
             for chooser in self.choosers_by_type_zoom_tag[type][zoom][clname]:
-                runtime_conditions = chooser.get_runtime_conditions(type, tags, zoom)
+                runtime_conditions = chooser.get_runtime_conditions(tags)
                 if runtime_conditions:
                     runtime_rules.append(runtime_conditions)
         return runtime_rules
@@ -152,7 +167,7 @@ class MapCSS():
         style = []
         if type in self.choosers_by_type_zoom_tag:
             for chooser in self.choosers_by_type_zoom_tag[type][zoom][clname]:
-                style = chooser.updateStyles(style, type, tags, zoom, xscale, zscale, filter_by_runtime_conditions)
+                style = chooser.updateStyles(style, tags, xscale, zscale, filter_by_runtime_conditions)
         style = [x for x in style if x["object-id"] != "::*"]
         for x in style:
             for k, v in [('width', 0), ('casing-width', 0)]: