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/*
Ousía
Copyright (C) 2014, 2015 Benjamin Paaßen, Andreas Stöckel
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 <cassert>
#include <sstream>
#include <core/Utils.hpp>
#include "Reader.hpp"
namespace ousia {
namespace variant {
static const char *ERR_UNEXPECTED_CHARACTER = "Unexpected character";
static const char *ERR_UNEXPECTED_END = "Unexpected end";
static const char *ERR_UNTERMINATED = "Unterminated literal";
static const char *ERR_INVALID_ESCAPE = "Invalid escape sequence";
static const int STATE_INIT = 0;
static const int STATE_IN_STRING = 1;
static const int STATE_ESCAPE = 2;
static const int STATE_WHITESPACE = 3;
template <class T>
static std::pair<bool, T> error(BufferedCharReader &reader, Logger &logger,
const char *err, T res)
{
logger.errorAt(err, reader);
return std::make_pair(false, std::move(res));
}
std::pair<bool, std::string> Reader::parseString(
BufferedCharReader &reader, Logger &logger,
const std::unordered_set<char> *delims)
{
// Initialize the internal state
int state = STATE_INIT;
char quote = 0;
std::stringstream res;
// Consume all whitespace
reader.consumeWhitespace();
// Statemachine whic iterates over each character in the stream
// TODO: Combination of peeking and consumePeek is stupid as consumePeek is
// the default (read and putBack would obviously be better, yet the latter
// is not trivial to implement in the current BufferedCharReader).
char c;
while (reader.peek(&c)) {
switch (state) {
case STATE_INIT:
if (c == '"' || c == '\'') {
quote = c;
state = STATE_IN_STRING;
break;
} else if (delims && delims->count(c)) {
return error(reader, logger, ERR_UNEXPECTED_END, res.str());
}
return error(reader, logger, ERR_UNEXPECTED_CHARACTER,
res.str());
case STATE_IN_STRING:
if (c == quote) {
reader.consumePeek();
return std::make_pair(true, res.str());
} else if (c == '\\') {
state = STATE_ESCAPE;
reader.consumePeek();
break;
} else if (c == '\n') {
return error(reader, logger, ERR_UNTERMINATED, res.str());
}
res << c;
reader.consumePeek();
break;
case STATE_ESCAPE:
// Handle all possible special escape characters
switch (c) {
case 'b':
res << '\b';
break;
case 'f':
res << '\f';
break;
case 'n':
res << '\n';
break;
case 'r':
res << '\r';
break;
case 't':
res << '\t';
break;
case 'v':
res << '\v';
break;
case '\'':
res << '\'';
break;
case '"':
res << '"';
break;
case '\\':
res << '\\';
break;
case '\n':
break;
case 'x':
// TODO: Parse Latin-1 sequence hex XX
break;
case 'u':
// TODO: Parse 16-Bit unicode character hex XXXX
break;
default:
if (Utils::isNumeric(c)) {
// TODO: Parse octal 000 sequence
} else {
logger.errorAt(ERR_INVALID_ESCAPE, reader);
}
break;
}
// Switch back to the "normal" state
state = STATE_IN_STRING;
reader.consumePeek();
break;
}
}
return error(reader, logger, ERR_UNEXPECTED_END, res.str());
}
std::pair<bool, std::string> Reader::parseUnescapedString(
BufferedCharReader &reader, Logger &logger,
const std::unordered_set<char> &delims)
{
std::stringstream res;
std::stringstream buf;
char c;
// Consume all whitespace
reader.consumeWhitespace();
// Copy all characters, skip whitespace at the end
int state = STATE_IN_STRING;
while (reader.peek(&c)) {
if (delims.count(c)) {
reader.resetPeek();
return std::make_pair(true, res.str());
} else if (Utils::isWhitespace(c)) {
// Do not add whitespace to the output buffer
state = STATE_WHITESPACE;
buf << c;
} else {
// If we just hat a sequence of whitespace, append it to the output
// buffer and continue
if (state == STATE_WHITESPACE) {
res << buf.str();
buf.str(std::string{});
buf.clear();
state = STATE_IN_STRING;
}
res << c;
}
reader.consumePeek();
}
return std::make_pair(true, res.str());
}
std::pair<bool, Variant> Reader::parseGeneric(
BufferedCharReader &reader, Logger &logger,
const std::unordered_set<char> &delims)
{
char c;
// Skip all whitespace characters
reader.consumeWhitespace();
while (reader.peek(&c)) {
// Stop if a delimiter is reached
if (delims.count(c)) {
return error(reader, logger, ERR_UNEXPECTED_END, nullptr);
}
// Parse a string if a quote is reached
if (c == '"' || c == '\'') {
auto res = parseString(reader, logger);
return std::make_pair(res.first, res.second.c_str());
}
if (c == '[') {
// TODO: Parse struct descriptor
}
if (Utils::isNumeric(c)) {
// TODO: Parse integer/double
}
// Parse an unescaped string in any other case
auto res = parseUnescapedString(reader, logger, delims);
return std::make_pair(res.first, res.second.c_str());
}
return error(reader, logger, ERR_UNEXPECTED_END, nullptr);
}
}
}
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