istringstream_nocopy: Implement in a standards-compliant way.

Fixes the problem mentioned in e6a61b8da7

See #1135
This commit is contained in:
Shea Levy 2017-03-06 13:03:02 -05:00
parent 1cf4801108
commit 4fc30922cf
4 changed files with 89 additions and 15 deletions

View file

@ -152,7 +152,7 @@ static StringSet parseStrings(std::istream & str, bool arePaths)
static Derivation parseDerivation(const string & s) static Derivation parseDerivation(const string & s)
{ {
Derivation drv; Derivation drv;
std::istringstream str(s); istringstream_nocopy str(s);
expect(str, "Derive(["); expect(str, "Derive([");
/* Parse the list of outputs. */ /* Parse the list of outputs. */

View file

@ -117,17 +117,6 @@ S3Helper::DownloadResult S3Helper::getObject(
return res; return res;
} }
#if __linux__
struct istringstream_nocopy : public std::stringstream
{
istringstream_nocopy(const std::string & s)
{
rdbuf()->pubsetbuf(
(char *) s.data(), s.size());
}
};
struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore struct S3BinaryCacheStoreImpl : public S3BinaryCacheStore
{ {
std::string bucketName; std::string bucketName;
@ -313,8 +302,6 @@ static RegisterStoreImplementation regStore([](
return store; return store;
}); });
#endif
} }
#endif #endif

View file

@ -104,7 +104,7 @@ Hash parseHash(HashType ht, const string & s)
string s2(s, i * 2, 2); string s2(s, i * 2, 2);
if (!isxdigit(s2[0]) || !isxdigit(s2[1])) if (!isxdigit(s2[0]) || !isxdigit(s2[1]))
throw BadHash(format("invalid hash %1%") % s); throw BadHash(format("invalid hash %1%") % s);
std::istringstream str(s2); istringstream_nocopy str(s2);
int n; int n;
str >> std::hex >> n; str >> std::hex >> n;
hash.hash[i] = n; hash.hash[i] = n;

View file

@ -449,4 +449,91 @@ struct ReceiveInterrupts
}; };
template <class CharT, class Traits = std::char_traits<CharT>, class Allocator = std::allocator<CharT>>
class basic_istringbuf_nocopy : public std::basic_streambuf<CharT, Traits>
{
public:
typedef std::basic_string<CharT, Traits, Allocator> string_type;
typedef typename std::basic_streambuf<CharT, Traits>::off_type off_type;
typedef typename std::basic_streambuf<CharT, Traits>::pos_type pos_type;
typedef typename std::basic_streambuf<CharT, Traits>::int_type int_type;
typedef typename std::basic_streambuf<CharT, Traits>::traits_type traits_type;
private:
const string_type & s;
off_type off;
public:
basic_istringbuf_nocopy(const string_type & s) : s{s}, off{0}
{
}
private:
pos_type seekoff(off_type off, std::ios_base::seekdir dir, std::ios_base::openmode which)
{
if (which & std::ios_base::in) {
this->off = dir == std::ios_base::beg
? off
: (dir == std::ios_base::end
? s.size() + off
: this->off + off);
}
return pos_type(this->off);
}
pos_type seekpos(pos_type pos, std::ios_base::openmode which)
{
return seekoff(pos, std::ios_base::beg, which);
}
std::streamsize showmanyc()
{
return s.size() - off;
}
int_type underflow()
{
if (typename string_type::size_type(off) == s.size())
return traits_type::eof();
return traits_type::to_int_type(s[off]);
}
int_type uflow()
{
if (typename string_type::size_type(off) == s.size())
return traits_type::eof();
return traits_type::to_int_type(s[off++]);
}
int_type pbackfail(int_type ch)
{
if (off == 0 || (ch != traits_type::eof() && ch != s[off - 1]))
return traits_type::eof();
return traits_type::to_int_type(s[--off]);
}
};
template <class CharT, class Traits = std::char_traits<CharT>, class Allocator = std::allocator<CharT>>
class basic_istringstream_nocopy : public std::basic_iostream<CharT, Traits>
{
typedef basic_istringbuf_nocopy<CharT, Traits, Allocator> buf_type;
buf_type buf;
public:
basic_istringstream_nocopy(const typename buf_type::string_type & s) :
std::basic_iostream<CharT, Traits>(&buf), buf(s) {};
};
/* A variant of std::istringstream that doesn't its string
argument. This is useful for large strings. The caller must ensure
that the string object is not destroyed while it's referenced by
this object. */
typedef basic_istringstream_nocopy<char> istringstream_nocopy;
} }