[GR-20329] Implement rb_fstring.

PullRequest: truffleruby/1641

CHANGELOG.md

@@ -22,6 +22,7 @@ Compatibility:
 * Fix detection of `#find_type` in FFI to ignore `MakeMakefile#find_type` from `mkmf` (#1896, #2010).
 * Implemented `rb_uv_to_utf8` (#1998).
 * Implemented `rb_str_cat_cstr`.
+* Implemented `rb_fstring`.
 
 Performance:
 

spec/ruby/optional/capi/ext/string_spec.c

@@ -49,6 +49,12 @@ VALUE string_spec_rb_str_set_len_RSTRING_LEN(VALUE self, VALUE str, VALUE len) {
   return INT2FIX(RSTRING_LEN(str));
 }
 
+VALUE rb_fstring(VALUE str); /* internal.h, used in ripper */
+
+VALUE string_spec_rb_str_fstring(VALUE self, VALUE str) {
+  return rb_fstring(str);
+}
+
 VALUE string_spec_rb_str_buf_new(VALUE self, VALUE len, VALUE str) {
   VALUE buf;
 
@@ -460,6 +466,7 @@ void Init_string_spec(void) {
   VALUE cls = rb_define_class("CApiStringSpecs", rb_cObject);
   rb_define_method(cls, "rb_cstr2inum", string_spec_rb_cstr2inum, 2);
   rb_define_method(cls, "rb_cstr_to_inum", string_spec_rb_cstr_to_inum, 3);
+  rb_define_method(cls, "rb_fstring", string_spec_rb_str_fstring, 1);
   rb_define_method(cls, "rb_str2inum", string_spec_rb_str2inum, 2);
   rb_define_method(cls, "rb_str_append", string_spec_rb_str_append, 2);
   rb_define_method(cls, "rb_str_buf_new", string_spec_rb_str_buf_new, 2);

spec/ruby/optional/capi/string_spec.rb

@@ -464,6 +464,25 @@ def inspect
     end
   end
 
+  describe "rb_fstring" do
+    it 'returns self if the String is frozen' do
+      input  = 'foo'.freeze
+      output = @s.rb_fstring(input)
+
+      output.should equal(input)
+      output.should.frozen?
+    end
+
+    it 'returns a frozen copy if the String is not frozen' do
+      input  = 'foo'
+      output = @s.rb_fstring(input)
+
+      output.should.frozen?
+      output.should_not equal(input)
+      output.should == 'foo'
+    end
+  end
+
   describe "rb_str_subseq" do
     it "returns a byte-indexed substring" do
       str = "\x00\x01\x02\x03\x04".force_encoding("binary")

src/main/c/cext/string.c

@@ -121,6 +121,10 @@ VALUE rb_str_to_str(VALUE string) {
   return rb_convert_type(string, T_STRING, "String", "to_str");
 }
 
+VALUE rb_fstring(VALUE str) {
+  return RUBY_INVOKE(str, "-@");
+}
+
 VALUE rb_str_buf_new(long capacity) {
   VALUE str = rb_str_new(NULL, capacity);
   rb_str_set_len(str, 0);