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| #include <string> | |
| #include <stdlib.h> | |
| namespace { | |
| static const char * const DIGITS = "0123456789"; | |
| } | |
| /// Use with std::sort(start, end, NaturalComparator()) | |
| class NaturalComparator | |
| { | |
| public: | |
| bool operator()(const std::string& a, const std::string& b) | |
| { | |
| size_t offsetA = 0; | |
| size_t offsetB = 0; | |
| while (offsetA < a.length() && offsetB < b.length()) { | |
| size_t posA = a.find_first_of(DIGITS, offsetA); | |
| size_t posB = b.find_first_of(DIGITS, offsetB); | |
| if (posA == offsetA && posB == offsetB) { | |
| char* endA; | |
| char* endB; | |
| unsigned long valA = strtoul(a.c_str() + offsetA, &endA, 10); | |
| unsigned long valB = strtoul(b.c_str() + offsetB, &endB, 10); | |
| if (valA != valB) { | |
| return valA < valB; | |
| } | |
| offsetA = endA - a.c_str(); | |
| offsetB = endB - b.c_str(); | |
| } else { | |
| int comp = a.compare(offsetA, posA - offsetA, b, offsetB, posB - offsetB); | |
| if (comp != 0) { | |
| return comp < 0; | |
| } | |
| offsetA = posA; | |
| offsetB = posB; | |
| } | |
| } | |
| return (offsetA >= a.length()); | |
| } | |
| }; |
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