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/*************************************************************************
** PDFParser.cpp **
** **
** This file is part of dvisvgm -- a fast DVI to SVG converter **
** Copyright (C) 2005-2018 Martin Gieseking <martin.gieseking@uos.de> **
** **
** This program is free software; you can redistribute it and/or **
** modify it under the terms of the GNU General Public License as **
** published by the Free Software Foundation; either version 3 of **
** the License, or (at your option) any later version. **
** **
** This program is distributed in the hope that it will be useful, but **
** WITHOUT ANY WARRANTY; without even the implied warranty of **
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the **
** GNU General Public License for more details. **
** **
** You should have received a copy of the GNU General Public License **
** along with this program; if not, see <http://www.gnu.org/licenses/>. **
*************************************************************************/
#include <cctype>
#include <istream>
#include <ostream>
#include <sstream>
#include <stdexcept>
#include "InputReader.hpp"
#include "PDFParser.hpp"
#include "utility.hpp"
using namespace std;
/** Parses PDF from an input stream and returns the corresponding object representation.
* @param[in] is input stream the PDF data is read from
* @param[in] opHandler handler used to treat PDF operators
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (std::istream &is, const PDFOperatorHandler &opHandler) {
StreamInputReader ir(is);
return parse(ir, opHandler);
}
/** Parses PDF from a string and returns the corresponding object representation.
* @param[in] str string that contains the PDF data
* @param[in] opHandler handler used to treat PDF operators
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (const std::string &str, const PDFOperatorHandler &opHandler) {
istringstream iss(str);
return parse(iss, opHandler);
}
/** Parses PDF from an InputReader object and returns the corresponding object representation.
* @param[in] ir InputReader the PDF data is read from
* @param[in] opHandler handler used to treat PDF operators
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (InputReader &ir, const PDFOperatorHandler &opHandler) {
vector<PDFObject> objects;
while (!ir.eof()) {
ir.skipSpace();
if (ir.peek() == '%') // comment?
while (ir.get() != '\n' && !ir.eof());
else if (!ir.eof())
parse(ir, objects, opHandler);
}
return objects;
}
/** Default handler for PDF operators. Just adds the operators to the
* object vector without evaluating them.
* @param[in] opname name of the operator
* @param[in,out] objects vector holding the parsed objects */
static void append_operator (const string &opname, vector<PDFObject> &objects) {
objects.emplace_back(PDFOperator(opname));
}
/** Parses PDF from an input stream and returns the corresponding object representation.
* @param[in] is input stream the PDF data is read from
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (std::istream &is) {
return parse(is, append_operator);
}
/** Parses PDF from a string and returns the corresponding object representation.
* @param[in] str string that contains the PDF data
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (const std::string &str) {
return parse(str, append_operator);
}
/** Parses PDF from an InputReader object and returns the corresponding object representation.
* @param[in] ir InputReader the PDF data is read from
* @return the parsed objects */
vector<PDFObject> PDFParser::parse (InputReader &ir) {
return parse(ir, append_operator);
}
/** Parses PDF from an InputReader object and appends the recognized objects to a vector.
* @param[in] ir InputReader the PDF data is read from
* @param[in,out] objects the parsed PDF objects are appended to this vector
* @return the parsed objects */
void PDFParser::parse (InputReader &ir, vector<PDFObject> &objects) {
parse(ir, objects, append_operator);
}
inline bool isoctaldigit (int c) {return c >= '0' && c <= '7';}
/** Parses a PDF escape sequence of the form \FOO, where FOO is a single
* character or a sequence of 1-3 octal digits
* @return pair (s,c), s=true if c contains a parsed character */
static pair<bool,int> parse_escape_seq (InputReader &ir) {
// leading backslash has already been read
if (isoctaldigit(ir.peek())) {
string str;
for (int i=0; i < 3 && isoctaldigit(ir.peek()); i++)
str += static_cast<char>(ir.get());
return pair<bool,int>{true, stoi(str, 0, 8)};
}
char c = static_cast<char>(ir.get());
switch (c) {
case 'n': c = '\n'; break;
case 'r': c = '\r'; break;
case 't': c = '\t'; break;
case 'b': c = '\b'; break;
case 'f': c = '\f'; break;
case '\n':
case '\r':
if ((c == '\n' && ir.peek() == '\r') || (c == '\r' && ir.peek() == '\n'))
ir.get();
return pair<bool,int>{false, 0};
}
return pair<bool,int>{true, c};
}
/** Parses a literal PDF string of the form (FOO). */
static string parse_literal_string (InputReader &ir) {
string str;
ir.get(); // skip initial '('
int open_parens=1;
while (ir.peek() >= 0 && open_parens > 0) {
if (ir.peek() == '\n' || ir.peek() == '\r')
break;
int c = ir.get();
switch (c) {
case '(': open_parens++; break;
case ')': open_parens--; break;
case '\\':
pair<bool,int> state = parse_escape_seq(ir);
c = state.first ? state.second : -1;
break;
}
if (open_parens > 0 && c >= 0)
str += static_cast<char>(c);
}
if (open_parens > 0)
throw PDFException("missing ')' at end of literal string");
return str;
}
/** Gets a single hex digit from the InputReader. */
static char get_hex_digit (InputReader &ir) {
int c = ir.get();
if (isxdigit(c))
return static_cast<char>(c);
ostringstream oss;
oss << "invalid hexadecimal digit '" << static_cast<char>(c) << "'";
throw PDFException(oss.str());
}
/** Parses a PDF hex string of the form <FOO>, where FOO is a sequence of
* hex digits optionally separated by whitespace. */
static string parse_hex_string (InputReader &ir) {
// initial '<' has already been read
string str;
ir.skipSpace();
while (ir.peek() > 0 && ir.peek() != '>') {
string hexpair;
hexpair += get_hex_digit(ir);
ir.skipSpace();
if (ir.peek() > 0 && ir.peek() != '>')
hexpair += get_hex_digit(ir);
else if (ir.peek() == '>')
hexpair += '0';
ir.skipSpace();
str += static_cast<char>(stoi(hexpair, 0, 16));
}
if (ir.peek() != '>')
throw PDFException("missing '>' at end of hexadecimal string");
ir.get(); // skip closing '>'
return str;
}
using NumberVariant = mpark::variant<int, double>;
/** Parses a PDF number from a string. The number is either integer or real.
* @param[in] str string to parse
* @param[out] nv variant holding the numeric value
* @return true if entire string has been parsed succesfully */
static bool parse_number (const string &str, NumberVariant &nv) {
if (str.empty())
return false;
try {
size_t dotpos = str.find('.');
if (dotpos == string::npos) { // not a real number?
size_t count;
nv = NumberVariant(stoi(str, &count, 10)); // then try to convert str to int
return count == str.length(); // successful only if all characters have been processed
}
string postdot = str.substr(dotpos+1);
// ensure signless integer after dot to exclude exponental notation
// which is not allowed in PDF real number constants
if (!postdot.empty() && isdigit(postdot[0])) {
size_t count;
stoi(postdot, &count, 10);
if (count != postdot.length())
return false;
}
size_t count;
nv = NumberVariant(stod(str, &count));
return count == str.length();
}
catch (invalid_argument &e) {
return false;
}
}
/** Parses a PDF array from the input stream and returns a corresponding object. */
PDFArray PDFParser::parseArray (InputReader &ir, const PDFOperatorHandler &opHandler) {
ir.get(); // skip '['
vector<PDFObject> localObjects;
while (!ir.eof() && ir.peek() != ']')
parse(ir, localObjects, opHandler);
ir.skipSpace();
if (ir.peek() != ']')
throw PDFException("missing ']' at end of array");
ir.get();
PDFArray arr;
std::move(localObjects.begin(), localObjects.end(), back_inserter(arr));
return arr;
}
/** Parses a PDF dictionary from the input stream and returns a corresponding object.
* The function expects that the first opening angle bracket denoting the start of an
* dictionary has already been swallowed from the stream. */
PDFDict PDFParser::parseDict (InputReader &ir, const PDFOperatorHandler &opHandler) {
ir.get(); // skip second "<"
vector<PDFObject> localObjects;
while (!ir.eof() && ir.peek() != '>')
parse(ir, localObjects, opHandler);
if (ir.getString(2) != ">>")
throw PDFException("missing '>>' at end of dictionary");
PDFDict dict;
for (auto it=localObjects.begin(); it != localObjects.end(); ++it) {
if (!it->get<PDFName>())
throw PDFException("name key expected in dictionary");
const PDFName &key = *it->get<PDFName>();
if (++it == localObjects.end())
throw PDFException(string("missing dictionary value for key '")+key.str+"'");
dict.emplace(key.str, std::move(*it));
}
return dict;
}
static PDFStream parse_stream (InputReader &ir, const char *delim) {
do
ir.skipUntil("endstream");
while (ir.peek() >= 0 && !strchr(delim, ir.peek())); // ensure delimiter after "endstream"
return PDFStream();
}
static PDFIndirectObject parse_indirect_object (InputReader &ir, const char *delim, vector<PDFObject> &objects) {
do
ir.skipUntil("endobj");
while (ir.peek() >= 0 && !strchr(delim, ir.peek())); // ensure delimiter after "endobj"
if (objects.size() >= 2) {
const int *genno = objects.back().get<int>();
objects.pop_back();
const int *objno = objects.back().get<int>();
objects.pop_back();
if (objno && genno)
return PDFIndirectObject(*objno, *genno);
}
throw PDFException("object and generation number expected before 'obj'");
}
static PDFObjectRef parse_object_ref (vector<PDFObject> &objects) {
if (objects.size() >= 2) {
const int *genno = objects.back().get<int>();
objects.pop_back();
const int *objno = objects.back().get<int>();
objects.pop_back();
if (objno && genno)
return PDFObjectRef(*objno, *genno);
}
throw PDFException("object and generation number expected before 'R'");
}
/** Replaces all occurences of "#XX" (XX are two hex digits) with the corresponding character. */
static string& subst_numeric_chars (string &str) {
for (size_t pos=str.find('#'); pos != string::npos; pos=str.find('#', pos+1)) {
if (pos > str.length()-3)
throw PDFException("sign character # must be followed by two hexadecimal digits");
if (isxdigit(str[pos+1]) && isxdigit(str[pos+2])) {
int c = stoi(str.substr(pos+1, 2), 0, 16);
if (c == 0)
throw PDFException("null character not permitted in name");
str.replace(pos, 3, 1, static_cast<char>(c));
}
else
throw PDFException("sign character # must be followed by two hexadecimal digits");
}
return str;
}
/** Parses a single PDF object from an InputReader object.
* @param[in,out] ir reader object to read the PDF data from
* @param[out] objects the parsed object is appended to this vector
* @param[in] opHandler handler used to treat PDF operators
* @throws PDFException on failure */
void PDFParser::parse (InputReader &ir, vector<PDFObject> &objects, const PDFOperatorHandler &opHandler) {
static const char *delim = "()<>[]{}/% \t\n\r\f";
ir.skipSpace();
if (ir.peek() < 0)
return;
switch (ir.peek()) {
case '(':
objects.emplace_back(parse_literal_string(ir)); break;
case '[':
objects.emplace_back(util::make_unique<PDFArray>(parseArray(ir, opHandler))); break;
case '<':
ir.get();
if (ir.peek() != '<')
objects.emplace_back(parse_hex_string(ir));
else
objects.emplace_back(util::make_unique<PDFDict>(parseDict(ir, opHandler)));
break;
case '/': {
ir.get();
string name = ir.getString(delim);
objects.emplace_back(PDFName(subst_numeric_chars(name)));
break;
}
default: {
string str = ir.getString(delim);
if (str.empty())
break;
if (str == "null")
objects.emplace_back(PDFNull());
else if (str == "true")
objects.emplace_back(true);
else if (str == "false")
objects.emplace_back(false);
else if (str == "stream")
objects.emplace_back(parse_stream(ir, delim));
else if (str == "obj")
objects.emplace_back(parse_indirect_object(ir, delim, objects));
else if (str == "R")
objects.emplace_back(parse_object_ref(objects));
else {
NumberVariant number;
if (!parse_number(str, number))
opHandler(str, objects);
else {
if (mpark::get_if<int>(&number))
objects.emplace_back(mpark::get<int>(number));
else
objects.emplace_back(mpark::get<double>(number));
}
}
}
}
}
//////////////////////////////////////////////////////////////////////////
struct ToDoubleVisitor {
template <typename V>
double operator () (const V &val) {return 0;}
};
template<> double ToDoubleVisitor::operator () (const int &val) {return static_cast<double>(val);}
template<> double ToDoubleVisitor::operator () (const double &val) {return val;}
template<> double ToDoubleVisitor::operator () (const string &val) {
try {
return stod(val);
}
catch (exception &e) {
return 0;
}
}
PDFObject::operator double () const {
return mpark::visit(ToDoubleVisitor(), _value);
}
PDFObject::operator std::string () const {
ostringstream oss;
oss << *this;
return oss.str();
}
static std::ostream& operator << (std::ostream &os, const PDFName &name) {return os << name.str;}
static ostream& operator << (ostream &os, const PDFNull&) {return os << "null";}
static ostream& operator << (ostream &os, const PDFStream&) {return os << "stream";}
static ostream& operator << (ostream &os, const PDFOperator &op) {return os << op.opname;}
static ostream& operator << (ostream &os, const PDFIndirectObject &obj) {
return os << "obj(" << obj.objnum << ", " << obj.gennum << ')';
}
static ostream& operator << (ostream &os, const PDFObjectRef &ref) {
return os << "obj(" << ref.objnum << ", " << ref.gennum << ')';
}
static ostream& operator << (ostream &os, const unique_ptr<vector<PDFObject>> &val) {
os << '[';
for (auto it=val->begin(); it != val->end(); ++it) {
if (it != val->begin())
os << ", ";
it->write(os);
}
os << ']';
return os;
}
static ostream& operator << (ostream &os, const unique_ptr<Dictionary<string,PDFObject>> &val) {
os << "<<";
for (auto it=val->begin(); it != val->end(); ++it) {
if (it != val->begin())
os << ", ";
os << it->first << ':' << it->second;
}
os << ">>";
return os;
}
struct WriteVisitor {
WriteVisitor (ostream &os) : _os(os) {}
template <typename T> void operator () (const T &val) {_os << val;}
ostream &_os;
};
void PDFObject::write (ostream &os) const {
mpark::visit(WriteVisitor(os), _value);
}
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