Implement endless zoom ranges

.rubocop_todo.yml

@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2025-11-28 15:41:06 UTC using RuboCop version 1.81.7.
+# on 2025-12-01 11:50:08 UTC using RuboCop version 1.81.7.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -9,34 +9,34 @@
 # Offense count: 4
 # Configuration parameters: AllowedMethods, AllowedPatterns, CountRepeatedAttributes.
 Metrics/AbcSize:
-  Max: 49
+  Max: 53
 
 # Offense count: 2
 # Configuration parameters: CountComments, CountAsOne.
 Metrics/ClassLength:
-  Max: 200
+  Max: 206
 
 # Offense count: 3
 # Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/CyclomaticComplexity:
-  Max: 17
+  Max: 18
 
 # Offense count: 4
 # Configuration parameters: CountComments, CountAsOne, AllowedMethods, AllowedPatterns.
 Metrics/MethodLength:
-  Max: 31
+  Max: 35
 
 # Offense count: 2
 # Configuration parameters: AllowedMethods, AllowedPatterns.
 Metrics/PerceivedComplexity:
-  Max: 19
+  Max: 21
 
 # Offense count: 1
 Naming/AccessorMethodName:
   Exclude:
     - 'lib/glug/layer.rb'
 
-# Offense count: 1
+# Offense count: 5
 # Configuration parameters: CountAsOne.
 RSpec/ExampleLength:
   Max: 53

README.md

@@ -81,7 +81,7 @@ You create a layer like this:
 
 The layer call begins with the layer id (`:water`) and then any additional layer-wide properties (source, source_layer, metadata, interactive). If no source is specified, the default will be used. If no source_layer is specified, the layer id will be used - so in this case, Glug would assume a source_layer of 'water'.
 
-Zoom levels are always specified as Ruby ranges (`5..13`) rather than separate minzoom/maxzoom properties.
+Zoom levels are always specified as Ruby ranges (`5..13`) rather than separate minzoom/maxzoom properties. "Beginless" and "Endless" ranges (e.g. `..5` or `13..`) are supported.
 
 ### Style definitions
 

lib/glug/layer.rb

@@ -253,8 +253,12 @@ def to_hash
 
       # Convert zoom level
       if (v = hash['zoom'])
-        hash['minzoom'] = v.is_a?(Range) ? v.first : v
-        hash['maxzoom'] = v.is_a?(Range) ? v.last : v
+        if v.is_a?(Range)
+          hash['minzoom'] = v.first unless v.begin.nil?
+          hash['maxzoom'] = v.last unless v.end.nil?
+        else
+          hash['minzoom'] = hash['maxzoom'] = v
+        end
         hash.delete('zoom')
       end
 

spec/lib/glug/layer_spec.rb

@@ -25,5 +25,33 @@
       expect(h['minzoom']).to be(1)
       expect(h['maxzoom']).to be(5)
     end
+
+    context 'with endless ranges' do
+      it 'does not set a max zoom' do
+        stylesheet = Glug::Stylesheet.new do
+          source :osm_data, type: 'vector', url: 'http://example.com/osm.tilejson', default: true
+        end
+        l = described_class.new(stylesheet, { zoom: 1.. })
+        l.line_width 1
+
+        h = l.to_hash
+        expect(h).to have_key('minzoom')
+        expect(h['minzoom']).to be(1)
+        expect(h).not_to have_key('maxzoom')
+      end
+
+      it 'does not set a min zoom' do
+        stylesheet = Glug::Stylesheet.new do
+          source :osm_data, type: 'vector', url: 'http://example.com/osm.tilejson', default: true
+        end
+        l = described_class.new(stylesheet, { zoom: ..5 })
+        l.line_width 1
+
+        h = l.to_hash
+        expect(h).not_to have_key('minzoom')
+        expect(h).to have_key('maxzoom')
+        expect(h['maxzoom']).to be(5)
+      end
+    end
   end
 end