Implement Struct#values_at and Array#values_at .

Add API `mrb_get_values_at()` to mruby/range.h .

include/mruby/range.h

@@ -27,6 +27,7 @@ struct RRange {
 
 mrb_value mrb_range_new(mrb_state*, mrb_value, mrb_value, mrb_bool);
 mrb_bool mrb_range_beg_len(mrb_state *mrb, mrb_value range, mrb_int *begp, mrb_int *lenp, mrb_int len);
+mrb_value mrb_get_values_at(mrb_state *mrb, mrb_value obj, mrb_int olen, mrb_int argc, const mrb_value *argv, mrb_value (*func)(mrb_state*, mrb_value, mrb_int));
 
 #if defined(__cplusplus)
 }  /* extern "C" { */

mrbgems/mruby-array-ext/src/array.c

 #include "mruby.h"
 #include "mruby/value.h"
 #include "mruby/array.h"
+#include "mruby/range.h"
 
 /*
  *  call-seq:
@@ -122,6 +123,17 @@ mrb_ary_at(mrb_state *mrb, mrb_value ary)
   return mrb_ary_entry(ary, pos);
 }
 
+static mrb_value
+mrb_ary_values_at(mrb_state *mrb, mrb_value self)
+{
+  mrb_int argc;
+  mrb_value *argv;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+
+  return mrb_get_values_at(mrb, self, MRB_INT_MAX, argc, argv, mrb_ary_ref);
+}
+
 void
 mrb_mruby_array_ext_gem_init(mrb_state* mrb)
 {
@@ -132,6 +144,7 @@ mrb_mruby_array_ext_gem_init(mrb_state* mrb)
   mrb_define_method(mrb, a, "assoc",  mrb_ary_assoc,  MRB_ARGS_REQ(1));
   mrb_define_method(mrb, a, "at",     mrb_ary_at,     MRB_ARGS_REQ(1));
   mrb_define_method(mrb, a, "rassoc", mrb_ary_rassoc, MRB_ARGS_REQ(1));
+  mrb_define_method(mrb, a, "values_at", mrb_ary_values_at, MRB_ARGS_ANY());
 }
 
 void

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

@@ -280,3 +280,13 @@ assert("Array#select!") do
   assert_equal [4, 5], a.select! { |val| val > 3 }
   assert_equal [4, 5], a
 end
+
+assert('Array#values_at') do
+  a = %w{red green purple white none}
+
+  assert_equal %w{red purple none}, a.values_at(0, 2, 4)
+  assert_equal ['green', 'white', nil, nil], a.values_at(1, 3, 5, 7)
+  assert_equal ['none', 'white', 'white', nil], a.values_at(-1, -2, -2, -7)
+  assert_equal ['none', nil, nil, 'red', 'green', 'purple'], a.values_at(4..6, 0...3)
+  assert_raise(TypeError) { a.values_at 'tt' }
+end

mrbgems/mruby-struct/src/struct.c

@@ -12,6 +12,7 @@
 #include "mruby/class.h"
 #include "mruby/variable.h"
 #include "mruby/hash.h"
+#include "mruby/range.h"
 
 #define RSTRUCT_LEN(st) RARRAY_LEN(st)
 #define RSTRUCT_PTR(st) RARRAY_PTR(st)
@@ -828,6 +829,23 @@ mrb_struct_to_h(mrb_state *mrb, mrb_value self)
   return ret;
 }
 
+static mrb_value
+struct_values_at_getter(mrb_state *mrb, mrb_value self, mrb_int idx)
+{
+  return mrb_struct_aref_n(mrb, self, mrb_fixnum_value(idx));
+}
+
+static mrb_value
+mrb_struct_values_at(mrb_state *mrb, mrb_value self)
+{
+  mrb_int argc;
+  mrb_value *argv;
+
+  mrb_get_args(mrb, "*", &argv, &argc);
+
+  return mrb_get_values_at(mrb, self, MRB_INT_MAX, argc, argv, struct_values_at_getter);
+}
+
 /*
  *  A <code>Struct</code> is a convenient way to bundle a number of
  *  attributes together, using accessor methods, without having to write
@@ -866,6 +884,7 @@ mrb_mruby_struct_gem_init(mrb_state* mrb)
   mrb_define_method(mrb, st,        "to_a",           mrb_struct_to_a,        MRB_ARGS_NONE());
   mrb_define_method(mrb, st,        "values",         mrb_struct_to_a,        MRB_ARGS_NONE());
   mrb_define_method(mrb, st,        "to_h",           mrb_struct_to_h,        MRB_ARGS_NONE());
+  mrb_define_method(mrb, st,        "values_at",      mrb_struct_values_at,   MRB_ARGS_NONE());
 }
 
 void

mrbgems/mruby-struct/test/struct.rb

@@ -123,3 +123,10 @@ assert('Struct#to_h') do
   s = Struct.new(:white, :red, :green).new('ruuko', 'yuzuki', 'hitoe')
   assert_equal(:white => 'ruuko', :red => 'yuzuki', :green => 'hitoe') { s.to_h }
 end
+
+assert('Struct#values_at') do
+  a = Struct.new(:blue, :purple).new('aki', 'io')
+  assert_equal ['aki'], a.values_at(0)
+  assert_equal ['io', 'aki'], a.values_at(1, 0)
+  assert_raise(IndexError) { a.values_at 2 }
+end

src/range.c

@@ -8,6 +8,7 @@
 #include "mruby/class.h"
 #include "mruby/range.h"
 #include "mruby/string.h"
+#include "mruby/array.h"
 
 #define RANGE_CLASS (mrb_class_get(mrb, "Range"))
 
@@ -395,6 +396,33 @@ range_initialize_copy(mrb_state *mrb, mrb_value copy)
   return copy;
 }
 
+mrb_value
+mrb_get_values_at(mrb_state *mrb, mrb_value obj, mrb_int olen, mrb_int argc, const mrb_value *argv, mrb_value (*func)(mrb_state*, mrb_value, mrb_int))
+{
+  mrb_int i, j, beg, len;
+  mrb_value result;
+  result = mrb_ary_new(mrb);
+
+  for (i = 0; i < argc; ++i) {
+    if (mrb_fixnum_p(argv[i])) {
+      mrb_ary_push(mrb, result, func(mrb, obj, mrb_fixnum(argv[i])));
+    } else if (mrb_range_beg_len(mrb, argv[i], &beg, &len, olen)) {
+      mrb_int const end = RARRAY_LEN(obj) < beg + len ? RARRAY_LEN(obj) : beg + len;
+      for (j = beg; j < end; ++j) {
+        mrb_ary_push(mrb, result, func(mrb, obj, j));
+      }
+
+      for (; j < beg + len; ++j) {
+        mrb_ary_push(mrb, result, mrb_nil_value());
+      }
+    } else {
+      mrb_raisef(mrb, E_ARGUMENT_ERROR, "invalid values selector: %S", argv[i]);
+    }
+  }
+
+  return result;
+}
+
 void
 mrb_init_range(mrb_state *mrb)
 {