Changeset 16199 in josm for trunk/src/org/openstreetmap/josm/gui/mappaint

Timestamp:

2020-03-23T14:24:59+01:00 (4 years ago)

Author:

GerdP

Message:

fix #18964: MapCSS rules using index are slow
Avoid a sequential search through all nodes when index matches first or last node only

Location:

trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss

Files:

• ConditionFactory.java (modified) (2 diffs)
• Selector.java (modified) (3 diffs)

trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/ConditionFactory.java

@@ -448 +448 @@
         final String index;
         final Op op;
+        final boolean isFirstOrLast;
 
         /**
@@ -457 +458 @@
             this.index = index;
             this.op = op;
+            isFirstOrLast = op == Op.EQ && ("1".equals(index) || "-1".equals(index));
         }
 

trunk/src/org/openstreetmap/josm/gui/mappaint/mapcss/Selector.java

@@ -35 +35 @@
 import org.openstreetmap.josm.gui.mappaint.Environment;
 import org.openstreetmap.josm.gui.mappaint.Range;
+import org.openstreetmap.josm.gui.mappaint.mapcss.ConditionFactory.IndexCondition;
 import org.openstreetmap.josm.gui.mappaint.mapcss.ConditionFactory.OpenEndPseudoClassCondition;
 import org.openstreetmap.josm.tools.CheckParameterUtil;
@@ -220 +221 @@
                     return;
                 }
-                for (int i = 0; i < count; i++) {
-                    if (getter.apply(i).equals(e.osm) && link.matches(e.withParentAndIndexAndLinkContext(parent, i, count))) {
+                // see #18964
+                int step = firstAndLastOnly() ? count - 1 : 1;
+                for (int i = 0; i < count; i += step) {
+                    if (getter.apply(i).equals(e.osm)
+                            && link.matches(e.withParentAndIndexAndLinkContext(parent, i, count))) {
                         e.parent = parent;
                         e.index = i;
@@ -228 +232 @@
                     }
                 }
+            }
+
+            private boolean firstAndLastOnly() {
+                for (Condition c : link.conds) {
+                    if (!(c instanceof IndexCondition) || !((IndexCondition) c).isFirstOrLast) {
+                        return false;
+                    }
+                }
+                return true;
             }