diff options
| -rw-r--r-- | Source/cmSystemTools.cxx | 77 | ||||
| -rw-r--r-- | Source/cmSystemTools.h | 10 |
2 files changed, 87 insertions, 0 deletions
diff --git a/Source/cmSystemTools.cxx b/Source/cmSystemTools.cxx index 7da9975..a0a9c50 100644 --- a/Source/cmSystemTools.cxx +++ b/Source/cmSystemTools.cxx @@ -2426,6 +2426,83 @@ bool cmSystemTools::VersionCompareGreaterEq(std::string const& lhs, lhs.c_str(), rhs.c_str()); } +static size_t cm_strverscmp_find_first_difference_or_end(const char* lhs, + const char* rhs) +{ + size_t i = 0; + /* Step forward until we find a difference or both strings end together. + The difference may lie on the null-terminator of one string. */ + while (lhs[i] == rhs[i] && lhs[i] != 0) { + ++i; + } + return i; +} + +static size_t cm_strverscmp_find_digits_begin(const char* s, size_t i) +{ + /* Step back until we are not preceded by a digit. */ + while (i > 0 && isdigit(s[i - 1])) { + --i; + } + return i; +} + +static size_t cm_strverscmp_find_digits_end(const char* s, size_t i) +{ + /* Step forward over digits. */ + while (isdigit(s[i])) { + ++i; + } + return i; +} + +static size_t cm_strverscmp_count_leading_zeros(const char* s, size_t b) +{ + size_t i = b; + /* Step forward over zeros that are followed by another digit. */ + while (s[i] == '0' && isdigit(s[i + 1])) { + ++i; + } + return i - b; +} + +static int cm_strverscmp(const char* lhs, const char* rhs) +{ + size_t const i = cm_strverscmp_find_first_difference_or_end(lhs, rhs); + if (lhs[i] != rhs[i]) { + /* The strings differ starting at 'i'. Check for a digit sequence. */ + size_t const b = cm_strverscmp_find_digits_begin(lhs, i); + if (b != i || (isdigit(lhs[i]) && isdigit(rhs[i]))) { + /* A digit sequence starts at 'b', preceding or at 'i'. */ + + /* Look for leading zeros, implying a leading decimal point. */ + size_t const lhs_zeros = cm_strverscmp_count_leading_zeros(lhs, b); + size_t const rhs_zeros = cm_strverscmp_count_leading_zeros(rhs, b); + if (lhs_zeros != rhs_zeros) { + /* The side with more leading zeros orders first. */ + return rhs_zeros > lhs_zeros ? 1 : -1; + } + if (lhs_zeros == 0) { + /* No leading zeros; compare digit sequence lengths. */ + size_t const lhs_end = cm_strverscmp_find_digits_end(lhs, i); + size_t const rhs_end = cm_strverscmp_find_digits_end(rhs, i); + if (lhs_end != rhs_end) { + /* The side with fewer digits orders first. */ + return lhs_end > rhs_end ? 1 : -1; + } + } + } + } + + /* Ordering was not decided by digit sequence lengths; compare bytes. */ + return lhs[i] - rhs[i]; +} + +int cmSystemTools::strverscmp(std::string const& lhs, std::string const& rhs) +{ + return cm_strverscmp(lhs.c_str(), rhs.c_str()); +} + bool cmSystemTools::RemoveRPath(std::string const& file, std::string* emsg, bool* removed) { diff --git a/Source/cmSystemTools.h b/Source/cmSystemTools.h index 3c1a9f4..aecf40e 100644 --- a/Source/cmSystemTools.h +++ b/Source/cmSystemTools.h @@ -306,6 +306,16 @@ public: std::string const& rhs); /** + * Compare two ASCII strings using natural versioning order. + * Non-numerical characters are compared directly. + * Numerical characters are first globbed such that, e.g. + * `test000 < test01 < test0 < test1 < test10`. + * Return a value less than, equal to, or greater than zero if lhs + * precedes, equals, or succeeds rhs in the defined ordering. + */ + static int strverscmp(std::string const& lhs, std::string const& rhs); + + /** * Determine the file type based on the extension */ static FileFormat GetFileFormat(const char* ext); |