* array.c: Add Array#to_h [Feature #7292]

* enum.c: Add Enumerable#to_h

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43401 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

6 files changed, 117 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 4908c6b15a..f677d271c1 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Thu Oct 24 00:10:22 2013  Marc-Andre Lafortune  <ruby-core@marc-andre.ca>
+
+	* array.c: Add Array#to_h [Feature #7292]
+
+	* enum.c: Add Enumerable#to_h
+
 Wed Oct 23 23:48:28 2013  Aman Gupta <ruby@tmm1.net>
 
 	* gc.c: Rename free_min to min_free_slots and free_min_page to
diff --git a/NEWS b/NEWS
index fe4ae53cd5..3e68c40df3 100644
--- a/NEWS
+++ b/NEWS
@@ -31,12 +31,20 @@ with all sufficient information, see the ChangeLog file.
 
 === Core classes updates (outstanding ones only)
 
+* Array
+  * New methods
+    * Array#to_h converts an array of key-value pairs into a Hash.
+
 * Binding
   * New methods
     * Binding#local_variable_get(symbol)
     * Binding#local_variable_set(symbol, obj)
     * Binding#local_variable_defined?(symbol)
 
+* Enumerable
+  * New methods
+    * Enumerable#to_h converts a list of key-value pairs into a Hash.
+
 * GC
   * added environment variable:
     * RUBY_HEAP_SLOTS_GROWTH_FACTOR: growth rate of the heap.
diff --git a/array.c b/array.c
index 54ddff47e6..7e4d4185ae 100644
--- a/array.c
+++ b/array.c
@@ -2126,6 +2126,32 @@ rb_ary_to_a(VALUE ary)
 
 /*
  *  call-seq:
+ *     ary.to_h     -> hash
+ *
+ *  Returns the result of interpreting <i>ary</i> as an array of
+ *  <tt>[key, value]</tt> pairs. Elements other than pairs of
+ *  values are ignored.
+ *
+ *     [[:foo, :bar], [1, 2]].to_h
+ *       # => {:foo => :bar, 1 => 2}
+ */
+
+static VALUE
+rb_ary_to_h(VALUE ary)
+{
+    long i;
+    VALUE hash = rb_hash_new();
+    for (i=0; i<RARRAY_LEN(ary); i++) {
+	VALUE key_value_pair = rb_check_array_type(rb_ary_elt(ary, i));
+	if (!NIL_P(key_value_pair) && (RARRAY_LEN(key_value_pair) == 2)) {
+	    rb_hash_aset(hash, RARRAY_AREF(key_value_pair, 0), RARRAY_AREF(key_value_pair, 1));
+	}
+    }
+    return hash;
+}
+
+/*
+ *  call-seq:
  *     ary.to_ary -> ary
  *
  *  Returns +self+.
@@ -5564,6 +5590,7 @@ Init_Array(void)
     rb_define_method(rb_cArray, "inspect", rb_ary_inspect, 0);
     rb_define_alias(rb_cArray,  "to_s", "inspect");
     rb_define_method(rb_cArray, "to_a", rb_ary_to_a, 0);
+    rb_define_method(rb_cArray, "to_h", rb_ary_to_h, 0);
     rb_define_method(rb_cArray, "to_ary", rb_ary_to_ary_m, 0);
     rb_define_method(rb_cArray, "frozen?",  rb_ary_frozen_p, 0);
 
diff --git a/enum.c b/enum.c
index df3c5636ec..ce7d22434b 100644
--- a/enum.c
+++ b/enum.c
@@ -510,6 +510,39 @@ enum_to_a(int argc, VALUE *argv, VALUE obj)
 }
 
 static VALUE
+enum_to_h_i(VALUE i, VALUE hash, int argc, VALUE *argv)
+{
+    ENUM_WANT_SVALUE();
+    rb_thread_check_ints();
+    i = rb_check_array_type(i);
+    if (!NIL_P(i) && RARRAY_LEN(i) == 2) {
+	rb_hash_aset(hash, RARRAY_AREF(i, 0), RARRAY_AREF(i, 1));
+    }
+    return Qnil;
+}
+
+/*
+ *  call-seq:
+ *     enum.to_h(*args)  -> hash
+ *
+ *  Returns the result of interpreting <i>enum</i> as a list of
+ *  <tt>[key, value]</tt> pairs. Elements other than pairs of
+ *  values are ignored.
+ *
+ *     %i[hello world].each_with_index.to_h
+ *       # => {:hello => 0, :world => 1}
+ */
+
+static VALUE
+enum_to_h(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE hash = rb_hash_new();
+    rb_block_call(obj, id_each, argc, argv, enum_to_h_i, hash);
+    OBJ_INFECT(hash, obj);
+    return hash;
+}
+
+static VALUE
 inject_i(VALUE i, VALUE p, int argc, VALUE *argv)
 {
     NODE *memo = RNODE(p);
@@ -2758,6 +2791,7 @@ Init_Enumerable(void)
 
     rb_define_method(rb_mEnumerable, "to_a", enum_to_a, -1);
     rb_define_method(rb_mEnumerable, "entries", enum_to_a, -1);
+    rb_define_method(rb_mEnumerable, "to_h", enum_to_h, -1);
 
     rb_define_method(rb_mEnumerable, "sort", enum_sort, 0);
     rb_define_method(rb_mEnumerable, "sort_by", enum_sort_by, 0);
diff --git a/test/ruby/test_array.rb b/test/ruby/test_array.rb
index f4faa9bedc..d7e1c365dd 100644
--- a/test/ruby/test_array.rb
+++ b/test/ruby/test_array.rb
@@ -1456,6 +1456,21 @@ class TestArray < Test::Unit::TestCase
     $, = nil
   end
 
+  def test_to_h
+    kvp = Object.new
+    def kvp.to_ary
+      [:obtained, :via_to_ary]
+    end
+    array = [
+      [:key, :value],
+      [:ignore_me],
+      [:ignore, :me, :too],
+      :ignore_me,
+      kvp,
+    ]
+    assert_equal({key: :value, obtained: :via_to_ary}, array.to_h)
+  end
+
   def test_uniq
     a = []
     b = a.uniq
diff --git a/test/ruby/test_enum.rb b/test/ruby/test_enum.rb
index ea873a4069..b86ae274d1 100644
--- a/test/ruby/test_enum.rb
+++ b/test/ruby/test_enum.rb
@@ -103,6 +103,33 @@ class TestEnumerable < Test::Unit::TestCase
     assert_equal([1, 2, 3, 1, 2], @obj.to_a)
   end
 
+  def test_to_h
+    assert_equal({}, @obj.to_h)
+    obj = Object.new
+    def obj.each(*args)
+      yield args
+      yield [:key, :value]
+      yield [:ignore_me]
+      yield [:ignore, :me, :too]
+      yield :other_key, :other_value
+      yield :ignore_me
+      yield :ignore, :me, :too
+      yield
+      kvp = Object.new
+      def kvp.to_ary
+        [:obtained, :via_to_ary]
+      end
+      yield kvp
+    end
+    obj.extend Enumerable
+    assert_equal({
+      :hello => :world,
+      :key => :value,
+      :other_key => :other_value,
+      :obtained => :via_to_ary,
+    }, obj.to_h(:hello, :world))
+  end
+
   def test_inject
     assert_equal(12, @obj.inject {|z, x| z * x })
     assert_equal(48, @obj.inject {|z, x| z * 2 + x })