llvm/flang/lib/parser/characters.cc

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#include "characters.h"
namespace Fortran {
namespace parser {
std::optional<int> UTF8CharacterBytes(const char *p) {
if ((*p & 0x80) == 0) {
return 1;
}
if ((*p & 0xf8) == 0xf0) {
if ((p[1] & 0xc0) == 0x80 && (p[2] & 0xc0) == 0x80 &&
(p[3] & 0xc0) == 0x80) {
return {4};
}
} else if ((*p & 0xf0) == 0xe0) {
if ((p[1] & 0xc0) == 0x80 && (p[2] & 0xc0) == 0x80) {
return {3};
}
} else if ((*p & 0xe0) == 0xc0) {
if ((p[1] & 0xc0) == 0x80) {
return {2};
}
}
return {};
}
std::optional<int> EUC_JPCharacterBytes(const char *p) {
int b1 = *p & 0xff;
if (b1 <= 0x7f) {
return {1};
}
if (b1 >= 0xa1 && b1 <= 0xfe) {
int b2 = p[1] & 0xff;
if (b2 >= 0xa1 && b2 <= 0xfe) {
// JIS X 0208 (code set 1)
return {2};
}
} else if (b1 == 0x8e) {
int b2 = p[1] & 0xff;
if (b2 >= 0xa1 && b2 <= 0xdf) {
// upper half JIS 0201 (half-width kana, code set 2)
return {2};
}
} else if (b1 == 0x8f) {
int b2 = p[1] & 0xff;
int b3 = p[2] & 0xff;
if (b2 >= 0xa1 && b2 <= 0xfe && b3 >= 0xa1 && b3 <= 0xfe) {
// JIS X 0212 (code set 3)
return {3};
}
}
return {};
}
std::optional<size_t> CountCharacters(
const char *p, size_t bytes, std::optional<int> (*cbf)(const char *)) {
size_t chars{0};
const char *limit{p + bytes};
while (p < limit) {
++chars;
if (std::optional<int> cb{cbf(p)}) {
p += *cb;
} else {
return {};
}
}
return {chars};
}
} // namespace parser
} // namespace Fortran