strawberry-audio-player-win.../ext/libstrawberry-tagreader/fmpsparser.cpp

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2018-02-27 18:06:05 +01:00
/* This file is part of Strawberry.
Copyright 2010, David Sansome <me@davidsansome.com>
Strawberry 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.
Strawberry 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 Strawberry. If not, see <http://www.gnu.org/licenses/>.
*/
#include "fmpsparser.h"
#include <functional>
#include <QStringList>
#include <QtDebug>
using std::placeholders::_1;
using std::placeholders::_2;
FMPSParser::FMPSParser() :
// The float regex ends with (?:$|(?=::|;;)) to ensure it matches all the way
// up to the end of the value. Without it, it would match a string that
// starts with a number, like "123abc".
float_re_("\\s*([+-]?\\d+(?:\\.\\d+)?)\\s*(?:$|(?=::|;;))"),
// Matches any character except unescaped slashes, colons and semicolons.
string_re_("((?:[^\\\\;:]|(?:\\\\[\\\\:;]))+)(?:$|(?=::|;;))"),
// Used for replacing escaped characters.
escape_re_("\\\\([\\\\:;])") {}
// Parses a list of things (of type T) that are separated by two consecutive
// Separator characters. Each individual thing is parsed by the F function.
// For example, to parse this data:
// foo::bar::baz
// Use:
// QVariantList ret;
// ParseContainer<':'>(data, ParseValue, &ret);
// ret will then contain "foo", "bar", and "baz".
// Returns the number of characters that were consumed from data.
//
// You can parse lists of lists by using different separator characters:
// ParseContainer<';'>(data, ParseContainer<':'>, &ret);
template <char Separator, typename F, typename T>
static int ParseContainer(const QStringRef& data, F f, QList<T>* ret) {
ret->clear();
T value;
int pos = 0;
while (pos < data.length()) {
const int len = data.length() - pos;
int matched_len = f(QStringRef(data.string(), data.position() + pos, len), &value);
if (matched_len == -1 || matched_len > len)
break;
ret->append(value);
pos += matched_len;
// Expect two separators in a row
if (pos + 2 <= data.length() && data.at(pos) == Separator && data.at(pos+1) == Separator) {
pos += 2;
} else {
break;
}
}
return pos;
}
bool FMPSParser::Parse(const QString &data) {
result_ = Result();
// Only return success if we matched the whole string
return ParseListList(data, &result_) == data.length();
}
int FMPSParser::ParseValueRef(const QStringRef& data, QVariant* ret) const {
// Try to match a float
int pos = float_re_.indexIn(*data.string(), data.position());
if (pos == data.position()) {
*ret = float_re_.cap(1).toDouble();
return float_re_.matchedLength();
}
// Otherwise try to match a string
pos = string_re_.indexIn(*data.string(), data.position());
if (pos == data.position()) {
// Replace escape sequences with their actual characters
QString value = string_re_.cap(1);
value.replace(escape_re_, "\\1");
*ret = value;
return string_re_.matchedLength();
}
return -1;
}
// Parses an inner list - a list of values
int FMPSParser::ParseListRef(const QStringRef &data, QVariantList *ret) const {
return ParseContainer<':'>(data, std::bind(&FMPSParser::ParseValueRef, this, _1, _2), ret);
}
// Parses an outer list - a list of lists
int FMPSParser::ParseListListRef(const QStringRef &data, Result *ret) const {
return ParseContainer<';'>(data, std::bind(&FMPSParser::ParseListRef, this, _1, _2), ret);
}
// Convenience functions that take QStrings instead of QStringRefs. Use the
// QStringRef versions if possible, they're faster.
int FMPSParser::ParseValue(const QString &data, QVariant *ret) const {
return ParseValueRef(QStringRef(&data), ret);
}
int FMPSParser::ParseList(const QString &data, QVariantList *ret) const {
return ParseListRef(QStringRef(&data), ret);
}
int FMPSParser::ParseListList(const QString &data, Result *ret) const {
return ParseListListRef(QStringRef(&data), ret);
}