QPDF_String.cc
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#include <qpdf/QPDF_String.hh>
#include <qpdf/QUtil.hh>
// DO NOT USE ctype -- it is locale dependent for some things, and
// it's not worth the risk of including it in case it may accidentally
// be used.
static bool
is_iso_latin1_printable(char ch)
{
return (
((ch >= 32) && (ch <= 126)) || (static_cast<unsigned char>(ch) >= 160));
}
QPDF_String::QPDF_String(std::string const& val) :
QPDFValue(::ot_string, "string"),
val(val)
{
}
std::shared_ptr<QPDFObject>
QPDF_String::create(std::string const& val)
{
return do_create(new QPDF_String(val));
}
std::shared_ptr<QPDFObject>
QPDF_String::create_utf16(std::string const& utf8_val)
{
std::string result;
if (!QUtil::utf8_to_pdf_doc(utf8_val, result, '?')) {
result = QUtil::utf8_to_utf16(utf8_val);
}
return do_create(new QPDF_String(result));
}
std::shared_ptr<QPDFObject>
QPDF_String::copy(bool shallow)
{
return create(val);
}
std::string
QPDF_String::unparse()
{
return unparse(false);
}
JSON
QPDF_String::getJSON(int json_version)
{
if (json_version == 1) {
return JSON::makeString(getUTF8Val());
}
// See if we can unambiguously represent as Unicode.
bool is_unicode = false;
std::string result;
std::string candidate = getUTF8Val();
if (QUtil::is_utf16(this->val) || QUtil::is_explicit_utf8(this->val)) {
is_unicode = true;
result = candidate;
} else if (!useHexString()) {
std::string test;
if (QUtil::utf8_to_pdf_doc(candidate, test, '?') &&
(test == this->val)) {
// This is a PDF-doc string that can be losslessly encoded
// as Unicode.
is_unicode = true;
result = candidate;
}
}
if (is_unicode) {
result = "u:" + result;
} else {
result = "b:" + QUtil::hex_encode(this->val);
}
return JSON::makeString(result);
}
bool
QPDF_String::useHexString() const
{
// Heuristic: use the hexadecimal representation of a string if
// there are any non-printable (in PDF Doc encoding) characters or
// if too large of a proportion of the string consists of
// non-ASCII characters.
unsigned int non_ascii = 0;
for (auto const ch: this->val) {
if (ch > 126) {
++non_ascii;
} else if (ch >= 32) {
continue;
} else if (ch < 0 || ch >= 24) {
++non_ascii;
} else if (!(ch == '\n' || ch == '\r' || ch == '\t' || ch == '\b' ||
ch == '\f')) {
return true;
}
}
return 5 * non_ascii > val.length();
}
std::string
QPDF_String::unparse(bool force_binary)
{
bool use_hexstring = force_binary || useHexString();
std::string result;
if (use_hexstring) {
static auto constexpr hexchars = "0123456789abcdef";
result.reserve(2 * this->val.length() + 2);
result += '<';
for (const char c: this->val) {
result += hexchars[static_cast<unsigned char>(c) >> 4];
result += hexchars[c & 0x0f];
}
result += '>';
} else {
result += "(";
for (unsigned int i = 0; i < this->val.length(); ++i) {
char ch = this->val.at(i);
switch (ch) {
case '\n':
result += "\\n";
break;
case '\r':
result += "\\r";
break;
case '\t':
result += "\\t";
break;
case '\b':
result += "\\b";
break;
case '\f':
result += "\\f";
break;
case '(':
result += "\\(";
break;
case ')':
result += "\\)";
break;
case '\\':
result += "\\\\";
break;
default:
if (is_iso_latin1_printable(ch)) {
result += this->val.at(i);
} else {
result +=
"\\" +
QUtil::int_to_string_base(
static_cast<int>(static_cast<unsigned char>(ch)),
8,
3);
}
break;
}
}
result += ")";
}
return result;
}
std::string
QPDF_String::getUTF8Val() const
{
if (QUtil::is_utf16(this->val)) {
return QUtil::utf16_to_utf8(this->val);
} else if (QUtil::is_explicit_utf8(this->val)) {
// PDF 2.0 allows UTF-8 strings when explicitly prefixed with
// the three-byte representation of U+FEFF.
return this->val.substr(3);
} else {
return QUtil::pdf_doc_to_utf8(this->val);
}
}