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take-cheeze wants to merge 3 commits into from
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Support StringIO#ungetc #14

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1990d9f
Add partial ungetc support
take-cheeze Aug 10, 2020
fe77d63
Make ungetc more compatible to CRuby
take-cheeze Aug 12, 2020
92c0632
Check ungetc data
take-cheeze Aug 12, 2020
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31 changes: 31 additions & 0 deletions src/stringio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -468,6 +468,36 @@ stringio_getc(mrb_state *mrb, mrb_value self)
return ret;
}

static mrb_value
stringio_ungetc(mrb_state *mrb, mrb_value self)
{
struct StringIO *ptr = StringIO(self);
mrb_value string = stringio_iv_get("@string");
mrb_int in_len;
const char* in_data;
mrb_get_args(mrb, "s", &in_data, &in_len);

mrb_int flags = mrb_fixnum(stringio_iv_get("@flags"));
if ((flags & FMODE_READABLE) == 0) {
mrb_raise(mrb, E_IOERROR, "not opened for reading");
}

if (in_len == 0) {
return mrb_nil_value();
}

if (in_len != 1) {
mrb_raisef(mrb, E_IOERROR, "mruby-ext: ungetc is only supported for single byte string. len: %S", mrb_fixnum_value(in_len));
}
if (ptr->pos <= 0) {
mrb_raise(mrb, E_IOERROR, "mruby-ext: ungetc not supported in beginning of stream");
}
ptr->pos -= 1;

mrb_assert(RSTRING_PTR(string)[ptr->pos] == *in_data);
return mrb_nil_value();
}

static mrb_value
stringio_gets(mrb_state *mrb, mrb_value self)
{
Expand Down Expand Up @@ -653,6 +683,7 @@ mrb_mruby_stringio_gem_init(mrb_state* mrb)
mrb_define_alias(mrb, stringio, "syswrite", "write");
mrb_define_method(mrb, stringio, "getc", stringio_getc, MRB_ARGS_ANY());
mrb_define_method(mrb, stringio, "gets", stringio_gets, MRB_ARGS_ANY());
mrb_define_method(mrb, stringio, "ungetc", stringio_ungetc, MRB_ARGS_REQ(1));
mrb_define_method(mrb, stringio, "seek", stringio_seek, MRB_ARGS_ANY());
mrb_define_method(mrb, stringio, "size", stringio_size, MRB_ARGS_NONE());
mrb_define_alias(mrb, stringio, "length", "size");
Expand Down
13 changes: 13 additions & 0 deletions test/stringio.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -206,6 +206,19 @@ def o.to_s; "baz"; end
assert_equal nil, strio.getc
end

assert 'StringIO#ungetc' do
strio = StringIO.new("abc")
strio.ungetc ''
assert_equal 'abc', strio.string
assert_raise(IOError) { strio.ungetc 'a' }
assert_equal 'a', strio.getc
assert_nil strio.ungetc 'a'
assert_equal 'a', strio.getc

strio = StringIO.new("abc", 'w')
assert_raise(IOError) { strio.ungetc 'a' }
end

assert 'StringIO#gets' do
io = StringIO.new("this>is>an>example")
assert_equal "this>", io.gets(">")
Expand Down
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