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Base64: Add raw_ostream and SmallString interfaces. (#19)

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This commit is contained in:
Peter Johnson
2017-08-13 00:55:56 -07:00
committed by GitHub
parent 2fa41b23b9
commit 17b5cace5b
3 changed files with 107 additions and 32 deletions
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89
src/main/native/cpp/support/Base64.cpp
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@@ -64,6 +64,9 @@
#include "support/Base64.h"
#include "llvm/SmallVector.h"
#include "llvm/raw_ostream.h"
namespace wpi {
// aaaack but it's fast and const should make it shared text page.
@@ -88,65 +91,91 @@ static const unsigned char pr2six[256] =
64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64
};
std::size_t Base64Decode(llvm::StringRef encoded, std::string* plain) {
std::size_t Base64Decode(llvm::raw_ostream& os, llvm::StringRef encoded) {
const unsigned char *end = encoded.bytes_begin();
while (pr2six[*end] <= 63 && end != encoded.bytes_end()) ++end;
std::size_t nprbytes = end - encoded.bytes_begin();
plain->clear();
if (nprbytes == 0)
return 0;
plain->reserve(((nprbytes + 3) / 4) * 3);
if (nprbytes == 0) return 0;
const unsigned char *cur = encoded.bytes_begin();
while (nprbytes > 4) {
(*plain) += (pr2six[cur[0]] << 2 | pr2six[cur[1]] >> 4);
(*plain) += (pr2six[cur[1]] << 4 | pr2six[cur[2]] >> 2);
(*plain) += (pr2six[cur[2]] << 6 | pr2six[cur[3]]);
os << static_cast<unsigned char>(pr2six[cur[0]] << 2 | pr2six[cur[1]] >> 4);
os << static_cast<unsigned char>(pr2six[cur[1]] << 4 | pr2six[cur[2]] >> 2);
os << static_cast<unsigned char>(pr2six[cur[2]] << 6 | pr2six[cur[3]]);
cur += 4;
nprbytes -= 4;
}
// Note: (nprbytes == 1) would be an error, so just ignore that case
if (nprbytes > 1) (*plain) += (pr2six[cur[0]] << 2 | pr2six[cur[1]] >> 4);
if (nprbytes > 2) (*plain) += (pr2six[cur[1]] << 4 | pr2six[cur[2]] >> 2);
if (nprbytes > 3) (*plain) += (pr2six[cur[2]] << 6 | pr2six[cur[3]]);
if (nprbytes > 1)
os << static_cast<unsigned char>(pr2six[cur[0]] << 2 | pr2six[cur[1]] >> 4);
if (nprbytes > 2)
os << static_cast<unsigned char>(pr2six[cur[1]] << 4 | pr2six[cur[2]] >> 2);
if (nprbytes > 3)
os << static_cast<unsigned char>(pr2six[cur[2]] << 6 | pr2six[cur[3]]);
return (end - encoded.bytes_begin()) + ((4 - nprbytes) & 3);
}
std::size_t Base64Decode(llvm::StringRef encoded, std::string* plain) {
plain->resize(0);
llvm::raw_string_ostream os(*plain);
std::size_t rv = Base64Decode(os, encoded);
os.flush();
return rv;
}
llvm::StringRef Base64Decode(llvm::StringRef encoded, std::size_t* num_read,
llvm::SmallVectorImpl<char>& buf) {
buf.clear();
llvm::raw_svector_ostream os(buf);
*num_read = Base64Decode(os, encoded);
return os.str();
}
static const char basis_64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
void Base64Encode(llvm::StringRef plain, std::string* encoded) {
encoded->clear();
if (plain.empty())
return;
void Base64Encode(llvm::raw_ostream& os, llvm::StringRef plain) {
if (plain.empty()) return;
std::size_t len = plain.size();
encoded->reserve(((len + 2) / 3 * 4) + 1);
std::size_t i;
for (i = 0; (i + 2) < len; i += 3) {
(*encoded) += basis_64[(plain[i] >> 2) & 0x3F];
(*encoded) +=
basis_64[((plain[i] & 0x3) << 4) | ((int)(plain[i + 1] & 0xF0) >> 4)];
(*encoded) += basis_64[((plain[i + 1] & 0xF) << 2) |
((int)(plain[i + 2] & 0xC0) >> 6)];
(*encoded) += basis_64[plain[i + 2] & 0x3F];
os << basis_64[(plain[i] >> 2) & 0x3F];
os << basis_64[((plain[i] & 0x3) << 4) | ((int)(plain[i + 1] & 0xF0) >> 4)];
os << basis_64[((plain[i + 1] & 0xF) << 2) |
((int)(plain[i + 2] & 0xC0) >> 6)];
os << basis_64[plain[i + 2] & 0x3F];
}
if (i < len) {
(*encoded) += basis_64[(plain[i] >> 2) & 0x3F];
os << basis_64[(plain[i] >> 2) & 0x3F];
if (i == (len - 1)) {
(*encoded) += basis_64[((plain[i] & 0x3) << 4)];
(*encoded) += '=';
os << basis_64[((plain[i] & 0x3) << 4)];
os << '=';
} else {
(*encoded) +=
basis_64[((plain[i] & 0x3) << 4) | ((int)(plain[i + 1] & 0xF0) >> 4)];
(*encoded) += basis_64[((plain[i + 1] & 0xF) << 2)];
os << basis_64[((plain[i] & 0x3) << 4) |
((int)(plain[i + 1] & 0xF0) >> 4)];
os << basis_64[((plain[i + 1] & 0xF) << 2)];
}
(*encoded) += '=';
os << '=';
}
}
void Base64Encode(llvm::StringRef plain, std::string* encoded) {
encoded->resize(0);
llvm::raw_string_ostream os(*encoded);
Base64Encode(os, plain);
os.flush();
}
llvm::StringRef Base64Encode(llvm::StringRef plain,
llvm::SmallVectorImpl<char>& buf) {
buf.clear();
llvm::raw_svector_ostream os(buf);
Base64Encode(os, plain);
return os.str();
}
} // namespace wpi