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275 lines
10 KiB
275 lines
10 KiB
// ---------------------------------------------------------------------------- |
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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(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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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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