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#pragma once
#include <util/system/types.h>
// Whether to ensure strict ASCII compatibility
// Turns UTF-8 strings into unreadable garbage for no known reason
//#define CESCAPE_STRICT_ASCII
namespace NYsonPull {
namespace NDetail {
namespace NCEscape {
namespace NImpl {
inline ui8 hex_digit(ui8 value) {
constexpr ui8 hex_digits[] = "0123456789ABCDEF";
return hex_digits[value];
}
inline ui8 oct_digit(ui8 value) {
return '0' + value;
}
inline bool is_printable(ui8 c) {
#ifdef CESCAPE_STRICT_ASCII
return c >= 32 && c <= 126;
#else
return c >= 32;
#endif
}
inline bool is_hex_digit(ui8 c) {
return (c >= '0' && c <= '9') || (c >= 'A' && c <= 'F') || (c >= 'a' && c <= 'f');
}
inline bool is_oct_digit(ui8 c) {
return c >= '0' && c <= '7';
}
constexpr size_t ESCAPE_C_BUFFER_SIZE = 4;
inline size_t escape_char(
ui8 c,
ui8 next,
ui8 r[ESCAPE_C_BUFFER_SIZE]) {
// (1) Printable characters go as-is, except backslash and double quote.
// (2) Characters \r, \n, \t and \0 ... \7 replaced by their simple escape characters (if possible).
// (3) Otherwise, character is encoded using hexadecimal escape sequence (if possible), or octal.
if (c == '\"') {
r[0] = '\\';
r[1] = '\"';
return 2;
} else if (c == '\\') {
r[0] = '\\';
r[1] = '\\';
return 2;
} else if (is_printable(c)) {
r[0] = c;
return 1;
} else if (c == '\r') {
r[0] = '\\';
r[1] = 'r';
return 2;
} else if (c == '\n') {
r[0] = '\\';
r[1] = 'n';
return 2;
} else if (c == '\t') {
r[0] = '\\';
r[1] = 't';
return 2;
} else if (c < 8 && !is_oct_digit(next)) {
r[0] = '\\';
r[1] = oct_digit(c);
return 2;
} else if (!is_hex_digit(next)) {
r[0] = '\\';
r[1] = 'x';
r[2] = hex_digit((c & 0xF0) >> 4);
r[3] = hex_digit((c & 0x0F) >> 0);
return 4;
} else {
r[0] = '\\';
r[1] = oct_digit((c & 0700) >> 6);
r[2] = oct_digit((c & 0070) >> 3);
r[3] = oct_digit((c & 0007) >> 0);
return 4;
}
}
template <typename T>
inline void escape_impl(const ui8* str, size_t len, T&& consume) {
ui8 buffer[ESCAPE_C_BUFFER_SIZE];
size_t i, j;
for (i = 0, j = 0; i < len; ++i) {
auto next_char = i + 1 < len ? str[i + 1] : 0;
size_t rlen = escape_char(str[i], next_char, buffer);
if (rlen > 1) {
consume(str + j, i - j);
j = i + 1;
consume(buffer, rlen);
}
}
if (j > 0) {
consume(str + j, len - j);
} else {
consume(str, len);
}
}
}
} // namespace NCEscape
} // namespace NDetail
}
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