pagy.rb in pagy-4.3.0

- old
+ new

@@ -3,11 +3,11 @@
 
 require 'pathname'
 
 # main class
 class Pagy
-  VERSION = '4.2.0'
+  VERSION = '4.3.0'
 
   # Root pathname to get the path of Pagy files like templates or dictionaries
   def self.root
     @root ||= Pathname.new(__dir__).freeze
   end
@@ -27,40 +27,44 @@
     INSTANCE_VARS_MIN.each do |name,min|
       raise VariableError.new(self), "expected :#{name} >= #{min}; got #{@vars[name].inspect}" \
             unless @vars[name] && instance_variable_set(:"@#{name}", @vars[name].to_i) >= min
     end
     @pages = @last = [(@count.to_f / @items).ceil, 1].max
-    raise OverflowError.new(self), "expected :page in 1..#{@last}; got #{@page.inspect}" if @page > @last
+    raise OverflowError.new(self), "expected :page in 1..#{@last}; got #{@page.inspect}" \
+          if @page > @last
 
     @offset = @items * (@page - 1) + @outset
-    @items  = @count - ((@pages-1) * @items) if @page == @last && @count.positive?
+    @items  = @count - ((@pages - 1) * @items) if @page == @last && @count.positive?
     @from   = @count.zero? ? 0 : @offset + 1 - @outset
     @to     = @count.zero? ? 0 : @offset + @items - @outset
-    @prev   = (@page-1 unless @page == 1)
+    @prev   = (@page - 1 unless @page == 1)
     @next   = @page == @last ? (1 if @vars[:cycle]) : @page + 1
   end
 
   # Return the array of page numbers and :gap items e.g. [1, :gap, 7, 8, "9", 10, 11, :gap, 36]
   def series(size=@vars[:size])
     return [] if size.empty?
     raise VariableError.new(self), "expected 4 items >= 0 in :size; got #{size.inspect}" \
-          unless size.size == 4 && size.all?{ |num| num >= 0 rescue false }  # rubocop:disable Style/RescueModifier
-
+          unless size.size == 4 && size.all?{ |num| !num.negative? rescue false }  # rubocop:disable Style/RescueModifier
+    # This algorithm is up to ~5x faster and ~2.3x lighter than the previous one (pagy < 4.3)
+    left_gap_start  =     1 + size[0]
+    left_gap_end    = @page - size[1] - 1
+    right_gap_start = @page + size[2] + 1
+    right_gap_end   = @last - size[3]
+    left_gap_end    = right_gap_end  if left_gap_end   > right_gap_end
+    right_gap_start = left_gap_start if left_gap_start > right_gap_start
     series = []
-    [ *0..size[0],                                   # initial pages from 0
-      *@page-size[1]..@page+size[2],                 # around current page
-      *@last-size[3]+1..@last+1                      # final pages till @last+1
-    ].sort!.each_cons(2) do |left, right|            # sort and loop by 2
-      next if left.negative? || left == right        # skip out of range and duplicates
-      break if left > @last                          # break if out of @last boundary
-      case right
-      when left+1 then series.push(left)             # no gap     -> no additions
-      when left+2 then series.push(left, left+1)     # 1 page gap -> fill with missing page
-      else             series.push(left, :gap)       # n page gap -> add gap
-      end
+    start  = 1
+    if (left_gap_end - left_gap_start).positive?
+      series.push(*start..(left_gap_start - 1), :gap)
+      start = left_gap_end + 1
     end
-    series.shift                                     # shift the start boundary (0)
-    series[series.index(@page)] = @page.to_s         # convert the current page to String
+    if (right_gap_end - right_gap_start).positive?
+      series.push(*start..(right_gap_start - 1), :gap)
+      start = right_gap_end + 1
+    end
+    series.push(*start..@last)
+    series[series.index(@page)] = @page.to_s
     series
   end
 
 end
 