New methods for MiGA::Taxonomy

- `#reset`
- `#delete_alternative`
- New option `replace` in `#add_alternative`

lib/miga/taxonomy.rb

@@ -21,13 +21,21 @@ class MiGA::Taxonomy < MiGA::MiGA
   # String, Array, or Hash entries as defined above (except +ranks+ are not
   # allowed).
   def initialize(str, ranks = nil, alt = [])
+    reset(str, ranks)
+    @alt = (alt || []).map { |i| Taxonomy.new(i) }
+  end
+
+  ##
+  # Reset ranks (including namespace) while leaving alternatives untouched.
+  # See #initialize for +str+ and +ranks+.
+  def reset(str, ranks = nil)
     @ranks = {}
     if ranks.nil?
       initialize_by_str(str)
     else
       initialize_by_ranks(str, ranks)
     end
-    @alt = (alt || []).map { |i| Taxonomy.new(i) }
+    initialize_by_str(str)
   end
 
   ##
@@ -76,10 +84,24 @@ def alternative(which = nil)
   end
 
   ##
-  # Add an alternative taxonomy.
-  def add_alternative(tax)
+  # Add an alternative taxonomy. If the namespace matches an existing namespace,
+  # the alternative (or master) is replaced instead if +replace+ is true.
+  def add_alternative(tax, replace = true)
     raise 'Unsupported taxonomy class.' unless tax.is_a? MiGA::Taxonomy
-    @alt << tax
+    alt_ns = alternative(tax.namespace)
+    if !replace || tax.namespace.nil? || alt_ns.nil?
+      @alt << tax
+    else
+      alt_ns.reset(tax.to_s)
+    end
+  end
+
+  ##
+  # Removes (and returns) all alternative taxonomies. 
+  def delete_alternative
+    alt = @alt.dup
+    @alt = []
+    alt
   end
 
   ##

test/taxonomy_test.rb

@@ -1,5 +1,5 @@
-require "test_helper"
-require "miga/taxonomy"
+require 'test_helper'
+require 'miga/taxonomy'
 
 class TaxonomyTest < Test::Unit::TestCase
 
@@ -83,6 +83,33 @@ def test_alternative
     # Add
     tx.add_alternative(tx.alternative(3))
     assert_equal(4, tx.alternative.size)
+    tx.add_alternative(tx.alternative(2))
+    assert_equal(4, tx.alternative.size)
+    # Delete
+    alt = tx.delete_alternative
+    assert_equal(4, alt.size)
+    assert(tx.alternative.empty?)
+  end
+
+  def test_reset
+    tx = MiGA::Taxonomy.new('ns:Letters d:Latin s:A', nil,
+      ['ns:Words d:English s:A', 'ns:Music d:Tone s:A'])
+    # Reset
+    assert_equal(2, tx.alternative.size)
+    assert_equal('Letters', tx.namespace)
+    tx.reset('g:A')
+    assert_equal(2, tx.alternative.size)
+    assert_nil(tx.namespace)
+    tx.reset('ns:Letters d:Latin s:A')
+    assert_equal('Letters', tx.namespace)
+    # Change of alternative
+    assert_equal('ns:Words d:English s:A', tx.alternative('Words').to_s)
+    tx.add_alternative(MiGA::Taxonomy.new('ns:Words d:Spanish s:A'))
+    assert_equal('ns:Words d:Spanish s:A', tx.alternative('Words').to_s)
+    # Change of master
+    assert_equal('ns:Letters d:Latin s:A', tx.to_s)
+    tx.add_alternative(MiGA::Taxonomy.new('ns:Letters d:Unicode s:A'))
+    assert_equal('ns:Letters d:Unicode s:A', tx.to_s)
   end
 
 end