279 lines
11 KiB
C++
279 lines
11 KiB
C++
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// ----------------------------------------------------------------------------
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// Copyright (C) 2009 Sebastian Redl
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//
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// Distributed under the Boost Software License, Version 1.0.
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// (See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt)
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//
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// For more information, see www.boost.org
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// ----------------------------------------------------------------------------
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#ifndef BOOST_PROPERTY_TREE_STRING_PATH_HPP_INCLUDED
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#define BOOST_PROPERTY_TREE_STRING_PATH_HPP_INCLUDED
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#include <boost/property_tree/ptree_fwd.hpp>
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#include <boost/property_tree/id_translator.hpp>
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#include <boost/property_tree/exceptions.hpp>
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#include <boost/property_tree/detail/ptree_utils.hpp>
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#include <boost/static_assert.hpp>
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#include <boost/assert.hpp>
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#include <boost/type_traits/is_same.hpp>
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#include <boost/optional.hpp>
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#include <boost/throw_exception.hpp>
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#include <algorithm>
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#include <string>
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#include <iterator>
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namespace boost { namespace property_tree
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{
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namespace detail
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{
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template <typename Sequence, typename Iterator>
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void append_and_preserve_iter(Sequence &s, const Sequence &r,
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Iterator &, std::forward_iterator_tag)
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{
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// Here we boldly assume that anything that is not random-access
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// preserves validity. This is valid for the STL sequences.
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s.insert(s.end(), r.begin(), r.end());
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}
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template <typename Sequence, typename Iterator>
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void append_and_preserve_iter(Sequence &s, const Sequence &r,
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Iterator &it,
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std::random_access_iterator_tag)
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{
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// Convert the iterator to an index, and later back.
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typename std::iterator_traits<Iterator>::difference_type idx =
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it - s.begin();
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s.insert(s.end(), r.begin(), r.end());
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it = s.begin() + idx;
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}
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template <typename Sequence>
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inline std::string dump_sequence(const Sequence &)
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{
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return "<undumpable sequence>";
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}
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inline std::string dump_sequence(const std::string &s)
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{
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return s;
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}
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#ifndef BOOST_NO_STD_WSTRING
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inline std::string dump_sequence(const std::wstring &s)
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{
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return narrow<std::string>(s.c_str());
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}
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#endif
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}
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/// Default path class. A path is a sequence of values. Groups of values
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/// are separated by the separator value, which defaults to '.' cast to
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/// the sequence's value type. The group of values is then passed to the
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/// translator to get a key.
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///
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/// If instantiated with std::string and id_translator\<std::string\>,
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/// it accepts paths of the form "one.two.three.four".
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///
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/// @tparam String Any Sequence. If the sequence does not support random-
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/// access iteration, concatenation of paths assumes that
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/// insertions at the end preserve iterator validity.
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/// @tparam Translator A translator with internal_type == String.
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template <typename String, typename Translator>
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class string_path
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{
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BOOST_STATIC_ASSERT((is_same<String,
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typename Translator::internal_type>::value));
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public:
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typedef typename Translator::external_type key_type;
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typedef typename String::value_type char_type;
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/// Create an empty path.
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explicit string_path(char_type separator = char_type('.'));
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/// Create a path by parsing the given string.
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/// @param value A sequence, possibly with separators, that describes
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/// the path, e.g. "one.two.three".
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/// @param separator The separator used in parsing. Defaults to '.'.
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/// @param tr The translator used by this path to convert the individual
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/// parts to keys.
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string_path(const String &value, char_type separator = char_type('.'),
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Translator tr = Translator());
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/// Create a path by parsing the given string.
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/// @param value A zero-terminated array of values. Only use if zero-
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/// termination makes sense for your type, and your
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/// sequence supports construction from it. Intended for
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/// string literals.
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/// @param separator The separator used in parsing. Defaults to '.'.
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/// @param tr The translator used by this path to convert the individual
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/// parts to keys.
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string_path(const char_type *value,
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char_type separator = char_type('.'),
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Translator tr = Translator());
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// Default copying doesn't do the right thing with the iterator
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string_path(const string_path &o);
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string_path& operator =(const string_path &o);
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/// Take a single element off the path at the front and return it.
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key_type reduce();
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/// Test if the path is empty.
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bool empty() const;
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/// Test if the path contains a single element, i.e. no separators.
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bool single() const;
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/// Get the separator used by this path.
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char_type separator() const { return m_separator; }
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std::string dump() const {
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return detail::dump_sequence(m_value);
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}
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/// Append a second path to this one.
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/// @pre o's separator is the same as this one's, or o has no separators
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string_path& operator /=(const string_path &o) {
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// If it's single, there's no separator. This allows to do
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// p /= "piece";
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// even for non-default separators.
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BOOST_ASSERT((m_separator == o.m_separator
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|| o.empty()
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|| o.single())
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&& "Incompatible paths.");
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if(!o.empty()) {
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String sub;
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if(!this->empty()) {
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sub.push_back(m_separator);
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}
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sub.insert(sub.end(), o.cstart(), o.m_value.end());
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detail::append_and_preserve_iter(m_value, sub, m_start,
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typename std::iterator_traits<s_iter>::iterator_category());
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}
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return *this;
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}
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private:
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typedef typename String::iterator s_iter;
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typedef typename String::const_iterator s_c_iter;
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String m_value;
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char_type m_separator;
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Translator m_tr;
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s_iter m_start;
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s_c_iter cstart() const { return m_start; }
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};
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template <typename String, typename Translator> inline
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string_path<String, Translator>::string_path(char_type separator)
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: m_separator(separator), m_start(m_value.begin())
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{}
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template <typename String, typename Translator> inline
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string_path<String, Translator>::string_path(const String &value,
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char_type separator,
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Translator tr)
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: m_value(value), m_separator(separator),
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m_tr(tr), m_start(m_value.begin())
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{}
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template <typename String, typename Translator> inline
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string_path<String, Translator>::string_path(const char_type *value,
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char_type separator,
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Translator tr)
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: m_value(value), m_separator(separator),
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m_tr(tr), m_start(m_value.begin())
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{}
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template <typename String, typename Translator> inline
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string_path<String, Translator>::string_path(const string_path &o)
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: m_value(o.m_value), m_separator(o.m_separator),
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m_tr(o.m_tr), m_start(m_value.begin())
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{
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std::advance(m_start, std::distance(o.m_value.begin(), o.cstart()));
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}
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template <typename String, typename Translator> inline
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string_path<String, Translator>&
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string_path<String, Translator>::operator =(const string_path &o)
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{
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m_value = o.m_value;
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m_separator = o.m_separator;
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m_tr = o.m_tr;
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m_start = m_value.begin();
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std::advance(m_start, std::distance(o.m_value.begin(), o.cstart()));
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return *this;
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}
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template <typename String, typename Translator>
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typename Translator::external_type string_path<String, Translator>::reduce()
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{
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BOOST_ASSERT(!empty() && "Reducing empty path");
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s_iter next_sep = std::find(m_start, m_value.end(), m_separator);
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String part(m_start, next_sep);
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m_start = next_sep;
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if(!empty()) {
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// Unless we're at the end, skip the separator we found.
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++m_start;
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}
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if(optional<key_type> key = m_tr.get_value(part)) {
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return *key;
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}
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BOOST_PROPERTY_TREE_THROW(ptree_bad_path("Path syntax error", *this));
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}
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template <typename String, typename Translator> inline
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bool string_path<String, Translator>::empty() const
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{
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return m_start == m_value.end();
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}
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template <typename String, typename Translator> inline
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bool string_path<String, Translator>::single() const
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{
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return std::find(static_cast<s_c_iter>(m_start),
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m_value.end(), m_separator)
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== m_value.end();
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}
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// By default, this is the path for strings. You can override this by
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// specializing path_of for a more specific form of std::basic_string.
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template <typename Ch, typename Traits, typename Alloc>
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struct path_of< std::basic_string<Ch, Traits, Alloc> >
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{
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typedef std::basic_string<Ch, Traits, Alloc> _string;
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typedef string_path< _string, id_translator<_string> > type;
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};
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template <typename String, typename Translator> inline
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string_path<String, Translator> operator /(
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string_path<String, Translator> p1,
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const string_path<String, Translator> &p2)
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{
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p1 /= p2;
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return p1;
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}
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// These shouldn't be necessary, but GCC won't find the one above.
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template <typename String, typename Translator> inline
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string_path<String, Translator> operator /(
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string_path<String, Translator> p1,
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const typename String::value_type *p2)
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{
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p1 /= p2;
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return p1;
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}
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template <typename String, typename Translator> inline
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string_path<String, Translator> operator /(
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const typename String::value_type *p1,
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const string_path<String, Translator> &p2)
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{
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string_path<String, Translator> t(p1);
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t /= p2;
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return t;
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}
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}}
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#endif
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