// scan_keyword.hpp --------------------------------------------------------------//
//===----------------------------------------------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is dual licensed under the MIT and the University of Illinois Open
// Source Licenses. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Adaptation to Boost of the libcxx
// Copyright 2010 Vicente J. Botet Escriba
// Distributed under the Boost Software License, Version 1.0.
// See http://www.boost.org/LICENSE_1_0.txt
#ifndef BOOST_CHRONO_DETAIL_SCAN_KEYWORD_HPP
#define BOOST_CHRONO_DETAIL_SCAN_KEYWORD_HPP
#include <boost/chrono/config.hpp>
#include <boost/interprocess/smart_ptr/unique_ptr.hpp>
#include <ios>
#include <exception>
#include <stdlib.h>
namespace boost {
using interprocess::unique_ptr;
namespace chrono {
namespace chrono_detail {
inline void free_aux(void* ptr) { free(ptr); }
// scan_keyword
// Scans [b, e) until a match is found in the basic_strings range
// [kb, ke) or until it can be shown that there is no match in [kb, ke).
// b will be incremented (visibly), consuming CharT until a match is found
// or proved to not exist. A keyword may be "", in which will match anything.
// If one keyword is a prefix of another, and the next CharT in the input
// might match another keyword, the algorithm will attempt to find the longest
// matching keyword. If the longer matching keyword ends up not matching, then
// no keyword match is found. If no keyword match is found, ke is returned
// and failbit is set in err.
// Else an iterator pointing to the matching keyword is found. If more than
// one keyword matches, an iterator to the first matching keyword is returned.
// If on exit b == e, eofbit is set in err.
// Examples:
// Keywords: "a", "abb"
// If the input is "a", the first keyword matches and eofbit is set.
// If the input is "abc", no match is found and "ab" are consumed.
template <class InputIterator, class ForwardIterator>
ForwardIterator
scan_keyword(InputIterator& b, InputIterator e,
ForwardIterator kb, ForwardIterator ke,
std::ios_base::iostate& err
)
{
typedef typename std::iterator_traits<InputIterator>::value_type CharT;
size_t nkw = std::distance(kb, ke);
const unsigned char doesnt_match = '\0';
const unsigned char might_match = '\1';
const unsigned char does_match = '\2';
unsigned char statbuf[100];
unsigned char* status = statbuf;
// Change free by free_aux to avoid
// Error: Could not find a match for boost::interprocess::unique_ptr<unsigned char, void(*)(void*)>::unique_ptr(int, extern "C" void(void*))
unique_ptr<unsigned char, void(*)(void*)> stat_hold(0, free_aux);
if (nkw > sizeof(statbuf))
{
status = (unsigned char*)malloc(nkw);
if (status == 0)
throw std::bad_alloc();
stat_hold.reset(status);
}
size_t n_might_match = nkw; // At this point, any keyword might match
size_t n_does_match = 0; // but none of them definitely do
// Initialize all statuses to might_match, except for "" keywords are does_match
unsigned char* st = status;
for (ForwardIterator ky = kb; ky != ke; ++ky, ++st)
{
if (!ky->empty())
*st = might_match;
else
{
*st = does_match;
--n_might_match;
++n_does_match;
}
}
// While there might be a match, test keywords against the next CharT
for (size_t indx = 0; b != e && n_might_match > 0; ++indx)
{
// Peek at the next CharT but don't consume it
CharT c = *b;
bool consume = false;
// For each keyword which might match, see if the indx character is c
// If a match if found, consume c
// If a match is found, and that is the last character in the keyword,
// then that keyword matches.
// If the keyword doesn't match this character, then change the keyword
// to doesn't match
st = status;
for (ForwardIterator ky = kb; ky != ke; ++ky, ++st)
{
if (*st == might_match)
{
CharT kc = (*ky)[indx];
if (c == kc)
{
consume = true;
if (ky->size() == indx+1)
{
*st = does_match;
--n_might_match;
++n_does_match;
}
}
else
{
*st = doesnt_match;
--n_might_match;
}
}
}
// consume if we matched a character
if (consume)
{
++b;
// If we consumed a character and there might be a matched keyword that
// was marked matched on a previous iteration, then such keywords
// which are now marked as not matching.
if (n_might_match + n_does_match > 1)
{
st = status;
for (ForwardIterator ky = kb; ky != ke; ++ky, ++st)
{
if (*st == does_match && ky->size() != indx+1)
{
*st = doesnt_match;
--n_does_match;
}
}
}
}
}
// We've exited the loop because we hit eof and/or we have no more "might matches".
if (b == e)
err |= std::ios_base::eofbit;
// Return the first matching result
for (st = status; kb != ke; ++kb, ++st)
if (*st == does_match)
break;
if (kb == ke)
err |= std::ios_base::failbit;
return kb;
}
}
}
}
#endif // BOOST_CHRONO_DETAIL_SCAN_KEYWORD_HPP
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