add max option

features/filter.feature

@@ -37,3 +37,37 @@ Feature: BibTeX
     And the "_site/scholar.html" file should exist
     And I should see "Programming Ruby" in "_site/scholar.html"
     And I should not see "The Ruby Programming Language" in "_site/scholar.html"
+
+  @tags @max
+  Scenario: Limit number of entries
+    Given I have a scholar configuration with:
+      | key    | value             |
+      | source | ./_bibliography   |
+    And I have a "_bibliography" directory
+    And I have a file "_bibliography/references.bib":
+      """
+      @book{ruby,
+        title     = {The Ruby Programming Language},
+        author    = {Flanagan, David and Matsumoto, Yukihiro},
+        year      = {2008},
+        publisher = {O'Reilly Media}
+      }
+      @book{pickaxe,
+        title     = {Programming Ruby 1.9: The Pragmatic Programmer's Guide},
+        author    = {Thomas, Dave and Fowler, Chad and Hunt, Andy},
+        year      = {2009},
+        edition   = 3,
+        publisher = {Pragmatic Bookshelf}
+      }
+      """
+    And I have a page "scholar.html":
+      """
+      ---
+      ---
+      {% bibliography --max 1 %}
+      """
+    When I run jekyll
+    Then the _site directory should exist
+    And the "_site/scholar.html" file should exist
+    And I should not see "Programming Ruby" in "_site/scholar.html"
+    And I should see "The Ruby Programming Language" in "_site/scholar.html"

lib/jekyll/scholar/tags/bibliography.rb

@@ -21,6 +21,8 @@ module Jekyll
           cited_references.include? e.key
         end if cited_only?
 
+        references = references.take(max.to_i) if limit_entries?
+
         bibliography = references.each_with_index.map { |entry, index|
           reference = bibliography_tag(entry, index + 1)
 

lib/jekyll/scholar/utilities.rb

@@ -15,7 +15,7 @@ module Jekyll
     module Utilities
 
       attr_reader :config, :site, :query,
-        :context, :prefix, :keys, :text
+        :context, :prefix, :keys, :text, :max
 
       def split_arguments(arguments)
 
@@ -56,6 +56,10 @@ module Jekyll
             locators << locator
           end
 
+          opts.on('-m', '--max MAX') do |max|
+            @max = max
+          end
+
           opts.on('-s', '--style STYLE') do |style|
             @style = style
           end
@@ -65,7 +69,7 @@ module Jekyll
           end
         end
 
-        argv = arguments.split(/(\B-[cfqptTsl]|\B--(?:cited|file|query|prefix|text|style|template|locator|))/)
+        argv = arguments.split(/(\B-[cfqptTslm]|\B--(?:cited|file|query|prefix|text|style|template|locator|max|))/)
 
         parser.parse argv.map(&:strip).reject(&:empty?)
       end
@@ -119,6 +123,10 @@ module Jekyll
         sort bibliography[query || config['query']]
       end
 
+      def limit_entries?
+        !max.nil?
+      end
+
       def sort(unsorted)
         return unsorted if config['sort_by'] == 'none'