Extended Module#const_get to support class paths

include/mruby/string.h

@@ -89,6 +89,7 @@ MRB_API void mrb_str_modify(mrb_state*, struct RString*);
  * Finds the index of a substring in a string
  */
 MRB_API mrb_int mrb_str_index(mrb_state*, mrb_value, const char*, mrb_int, mrb_int);
+#define mrb_str_index_lit(mrb, str, lit, off) mrb_str_index(mrb, str, lit, mrb_strlen_lit(lit), off);
 
 /*
  * Appends self to other. Returns self as a concatnated string.

src/class.c

@@ -2161,15 +2161,45 @@ mrb_mod_const_defined(mrb_state *mrb, mrb_value mod)
 }
 
 static mrb_value
-mrb_mod_const_get(mrb_state *mrb, mrb_value mod)
+mrb_const_get_sym(mrb_state *mrb, mrb_value mod, mrb_sym id)
 {
-  mrb_sym id;
-
-  mrb_get_args(mrb, "n", &id);
   check_const_name_sym(mrb, id);
   return mrb_const_get(mrb, mod, id);
 }
 
+static mrb_value
+mrb_mod_const_get(mrb_state *mrb, mrb_value mod)
+{
+  mrb_value path;
+  mrb_sym id;
+  char *ptr;
+  mrb_int off, end, len;
+
+  mrb_get_args(mrb, "o", &path);
+
+  if (mrb_symbol_p(path)) {
+    /* const get with symbol */
+    id = mrb_symbol(path);
+    return mrb_const_get_sym(mrb, mod, id);
+  }
+
+  /* const get with class path string */
+  path = mrb_string_type(mrb, path);
+  ptr = RSTRING_PTR(path);
+  len = RSTRING_LEN(path);
+  off = 0;
+
+  while (off < len) {
+    end = mrb_str_index_lit(mrb, path, "::", off);
+    end = (end == -1) ? len : end;
+    id = mrb_intern(mrb, ptr+off, end-off);
+    mod = mrb_const_get_sym(mrb, mod, id);
+    off = (end == len) ? end : end+2;
+  }
+
+  return mod;
+}
+
 static mrb_value
 mrb_mod_const_set(mrb_state *mrb, mrb_value mod)
 {

test/t/module.rb

@@ -268,6 +268,12 @@ assert('Module#const_get', '15.2.2.4.21') do
   end
 
   assert_equal 42, Test4ConstGet.const_get(:Const4Test4ConstGet)
+  assert_equal 42, Test4ConstGet.const_get("Const4Test4ConstGet")
+  assert_equal 42, Object.const_get("Test4ConstGet::Const4Test4ConstGet")
+
+  assert_raise(TypeError){ Test4ConstGet.const_get(123) }
+  assert_raise(NameError){ Test4ConstGet.const_get(:I_DO_NOT_EXIST) }
+  assert_raise(NameError){ Test4ConstGet.const_get("I_DO_NOT_EXIST::ME_NEITHER") }
 end
 
 assert('Module#const_missing', '15.2.2.4.22') do
@@ -280,7 +286,7 @@ assert('Module#const_missing', '15.2.2.4.22') do
   assert_equal 42, Test4ConstMissing.const_get(:ConstDoesntExist)
 end
 
-assert('Module#const_get', '15.2.2.4.23') do
+assert('Module#const_set', '15.2.2.4.23') do
   module Test4ConstSet
     Const4Test4ConstSet = 42
   end