Use Lemire's fast check whether to escape a JSON string

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Dennis 2024-05-31 15:58:34 +02:00
parent 42fafdcdfe
commit 64f0b85dcf
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@ -10,26 +10,30 @@
namespace osrm::util namespace osrm::util
{ {
// implements Lemire's table-based escape needs check
// cf. https://lemire.me/blog/2024/05/31/quickly-checking-whether-a-string-needs-escaping/
inline static constexpr std::array<uint8_t, 256> json_quotable_character = []() constexpr
{
std::array<uint8_t, 256> result{};
for (size_t i = 0; i < 32; i++)
{
result[i] = 1;
}
for (size_t i : {'"', '\\'})
{
result[i] = 1;
}
return result;
}();
inline bool RequiresJSONStringEscaping(const std::string &string) inline bool RequiresJSONStringEscaping(const std::string &string)
{ {
for (const char letter : string) uint8_t needs = 0;
for (uint8_t c : string)
{ {
switch (letter) needs |= json_quotable_character[c];
{
case '\\':
case '"':
case '/':
case '\b':
case '\f':
case '\n':
case '\r':
case '\t':
return true;
default:
continue;
}
} }
return false; return needs;
} }
inline void EscapeJSONString(const std::string &input, std::string &output) inline void EscapeJSONString(const std::string &input, std::string &output)