Add Hash#delete_if

mrbgems/mruby-hash-ext/mrblib/hash.rb

@@ -27,4 +27,27 @@ class Hash
       self[key]
     end
   end
+
+  ##
+  #  call-seq:
+  #     hsh.delete_if {| key, value | block }  -> hsh
+  #     hsh.delete_if                          -> an_enumerator
+  #
+  #  Deletes every key-value pair from <i>hsh</i> for which <i>block</i>
+  #  evaluates to <code>true</code>.
+  #
+  #  If no block is given, an enumerator is returned instead.
+  #
+  #     h = { "a" => 100, "b" => 200, "c" => 300 }
+  #     h.delete_if {|key, value| key >= "b" }   #=> {"a"=>100}
+  #
+
+  def delete_if(&block)
+    return to_enum :delete_if unless block_given?
+
+    self.each do |k, v|
+      self.delete(k) if block.call(k, v)
+    end 
+    self
+  end
 end

mrbgems/mruby-hash-ext/test/hash.rb

@@ -39,3 +39,37 @@ assert('Hash#fetch') do
     assert_kind_of(StandardError, e);
   end
 end
+
+assert("Hash#delete_if") do
+  base = { 1 => 'one', 2 => false, true => 'true', 'cat' => 99 }
+  h1   = { 1 => 'one', 2 => false, true => 'true' }
+  h2   = { 2 => false, 'cat' => 99 }
+  h3   = { 2 => false }
+
+  h = base.dup
+  assert_equal(h, h.delete_if { false })
+  assert_equal({}, h.delete_if { true })
+
+  h = base.dup
+  assert_equal(h1, h.delete_if {|k,v| k.instance_of?(String) })
+  assert_equal(h1, h)
+
+  h = base.dup
+  assert_equal(h2, h.delete_if {|k,v| v.instance_of?(String) })
+  assert_equal(h2, h)
+
+  h = base.dup
+  assert_equal(h3, h.delete_if {|k,v| v })
+  assert_equal(h3, h)
+
+  h = base.dup
+  n = 0
+  h.delete_if {|*a|
+    n += 1
+    assert_equal(2, a.size)
+    assert_equal(base[a[0]], a[1])
+    h.shift
+    true
+  }
+  assert_equal(base.size, n)
+end