mirror of
https://github.com/minetest/minetest.git
synced 2024-12-27 16:37:30 +01:00
Optimize JSON string (de)serialization routines
stringstreams were shown to be slow when reading/writing single characters and there is lots of potential by having functions perform on existing buffers whenever possible.
This commit is contained in:
parent
70dc23f996
commit
9ee3dc71f1
@ -18,15 +18,14 @@ with this program; if not, write to the Free Software Foundation, Inc.,
|
||||
*/
|
||||
|
||||
#include "serialize.h"
|
||||
#include "pointer.h"
|
||||
#include "porting.h"
|
||||
#include "util/string.h"
|
||||
#include "util/hex.h"
|
||||
#include "exceptions.h"
|
||||
#include "irrlichttypes.h"
|
||||
|
||||
#include <sstream>
|
||||
#include <iomanip>
|
||||
#include <vector>
|
||||
#include <iostream>
|
||||
#include <cassert>
|
||||
|
||||
FloatType g_serialize_f32_type = FLOATTYPE_UNKNOWN;
|
||||
|
||||
@ -120,118 +119,148 @@ std::string deSerializeString32(std::istream &is)
|
||||
}
|
||||
|
||||
////
|
||||
//// JSON
|
||||
//// JSON-like strings
|
||||
////
|
||||
|
||||
std::string serializeJsonString(const std::string &plain)
|
||||
{
|
||||
std::ostringstream os(std::ios::binary);
|
||||
os << "\"";
|
||||
std::string tmp;
|
||||
|
||||
tmp.reserve(plain.size() + 2);
|
||||
tmp.push_back('"');
|
||||
|
||||
for (char c : plain) {
|
||||
switch (c) {
|
||||
case '"':
|
||||
os << "\\\"";
|
||||
tmp.append("\\\"");
|
||||
break;
|
||||
case '\\':
|
||||
os << "\\\\";
|
||||
tmp.append("\\\\");
|
||||
break;
|
||||
case '\b':
|
||||
os << "\\b";
|
||||
tmp.append("\\b");
|
||||
break;
|
||||
case '\f':
|
||||
os << "\\f";
|
||||
tmp.append("\\f");
|
||||
break;
|
||||
case '\n':
|
||||
os << "\\n";
|
||||
tmp.append("\\n");
|
||||
break;
|
||||
case '\r':
|
||||
os << "\\r";
|
||||
tmp.append("\\r");
|
||||
break;
|
||||
case '\t':
|
||||
os << "\\t";
|
||||
tmp.append("\\t");
|
||||
break;
|
||||
default: {
|
||||
if (c >= 32 && c <= 126) {
|
||||
os << c;
|
||||
tmp.push_back(c);
|
||||
} else {
|
||||
u32 cnum = (u8)c;
|
||||
os << "\\u" << std::hex << std::setw(4)
|
||||
<< std::setfill('0') << cnum;
|
||||
// We pretend that Unicode codepoints map to bytes (they don't)
|
||||
u8 cnum = static_cast<u8>(c);
|
||||
tmp.append("\\u00");
|
||||
tmp.push_back(hex_chars[cnum >> 4]);
|
||||
tmp.push_back(hex_chars[cnum & 0xf]);
|
||||
}
|
||||
break;
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
os << "\"";
|
||||
return os.str();
|
||||
tmp.push_back('"');
|
||||
return tmp;
|
||||
}
|
||||
|
||||
static void deSerializeJsonString(std::string &s)
|
||||
{
|
||||
assert(s.size() >= 2);
|
||||
assert(s.front() == '"' && s.back() == '"');
|
||||
|
||||
size_t w = 0; // write index
|
||||
size_t i = 1; // read index
|
||||
const size_t len = s.size() - 1; // string length with trailing quote removed
|
||||
|
||||
while (i < len) {
|
||||
char c = s[i++];
|
||||
assert(c != '"');
|
||||
|
||||
if (c != '\\') {
|
||||
s[w++] = c;
|
||||
continue;
|
||||
}
|
||||
|
||||
if (i >= len)
|
||||
throw SerializationError("JSON string ended prematurely");
|
||||
char c2 = s[i++];
|
||||
switch (c2) {
|
||||
case 'b':
|
||||
s[w++] = '\b';
|
||||
break;
|
||||
case 'f':
|
||||
s[w++] = '\f';
|
||||
break;
|
||||
case 'n':
|
||||
s[w++] = '\n';
|
||||
break;
|
||||
case 'r':
|
||||
s[w++] = '\r';
|
||||
break;
|
||||
case 't':
|
||||
s[w++] = '\t';
|
||||
break;
|
||||
case 'u': {
|
||||
if (i + 3 >= len)
|
||||
throw SerializationError("JSON string ended prematurely");
|
||||
unsigned char v[4] = {};
|
||||
for (int j = 0; j < 4; j++)
|
||||
hex_digit_decode(s[i+j], v[j]);
|
||||
i += 4;
|
||||
u32 hexnumber = (v[0] << 12) | (v[1] << 8) | (v[2] << 4) | v[3];
|
||||
// Note that this does not work for anything other than ASCII
|
||||
// but these functions do not actually interact with real JSON input.
|
||||
s[w++] = (int) hexnumber;
|
||||
break;
|
||||
}
|
||||
default:
|
||||
s[w++] = c2;
|
||||
break;
|
||||
}
|
||||
}
|
||||
|
||||
assert(w <= i && i <= len);
|
||||
// Truncate string to current write index
|
||||
s.resize(w);
|
||||
}
|
||||
|
||||
std::string deSerializeJsonString(std::istream &is)
|
||||
{
|
||||
std::ostringstream os(std::ios::binary);
|
||||
char c, c2;
|
||||
std::string tmp;
|
||||
char c;
|
||||
bool was_backslash = false;
|
||||
|
||||
// Parse initial doublequote
|
||||
is >> c;
|
||||
c = is.get();
|
||||
if (c != '"')
|
||||
throw SerializationError("JSON string must start with doublequote");
|
||||
tmp.push_back(c);
|
||||
|
||||
// Parse characters
|
||||
// Grab the entire json string
|
||||
for (;;) {
|
||||
c = is.get();
|
||||
if (is.eof())
|
||||
throw SerializationError("JSON string ended prematurely");
|
||||
|
||||
if (c == '"') {
|
||||
return os.str();
|
||||
}
|
||||
|
||||
if (c == '\\') {
|
||||
c2 = is.get();
|
||||
if (is.eof())
|
||||
throw SerializationError("JSON string ended prematurely");
|
||||
switch (c2) {
|
||||
case 'b':
|
||||
os << '\b';
|
||||
break;
|
||||
case 'f':
|
||||
os << '\f';
|
||||
break;
|
||||
case 'n':
|
||||
os << '\n';
|
||||
break;
|
||||
case 'r':
|
||||
os << '\r';
|
||||
break;
|
||||
case 't':
|
||||
os << '\t';
|
||||
break;
|
||||
case 'u': {
|
||||
int hexnumber;
|
||||
char hexdigits[4 + 1];
|
||||
|
||||
is.read(hexdigits, 4);
|
||||
if (is.eof())
|
||||
throw SerializationError("JSON string ended prematurely");
|
||||
hexdigits[4] = 0;
|
||||
|
||||
std::istringstream tmp_is(hexdigits, std::ios::binary);
|
||||
tmp_is >> std::hex >> hexnumber;
|
||||
os << (char)hexnumber;
|
||||
break;
|
||||
}
|
||||
default:
|
||||
os << c2;
|
||||
break;
|
||||
}
|
||||
} else {
|
||||
os << c;
|
||||
}
|
||||
tmp.push_back(c);
|
||||
if (was_backslash)
|
||||
was_backslash = false;
|
||||
else if (c == '\\')
|
||||
was_backslash = true;
|
||||
else if (c == '"')
|
||||
break; // found end of string
|
||||
}
|
||||
|
||||
return os.str();
|
||||
deSerializeJsonString(tmp);
|
||||
return tmp;
|
||||
}
|
||||
|
||||
std::string serializeJsonStringIfNeeded(const std::string &s)
|
||||
@ -245,41 +274,21 @@ std::string serializeJsonStringIfNeeded(const std::string &s)
|
||||
|
||||
std::string deSerializeJsonStringIfNeeded(std::istream &is)
|
||||
{
|
||||
std::stringstream tmp_os(std::ios_base::binary | std::ios_base::in | std::ios_base::out);
|
||||
bool expect_initial_quote = true;
|
||||
bool is_json = false;
|
||||
bool was_backslash = false;
|
||||
for (;;) {
|
||||
char c = is.get();
|
||||
if (is.eof())
|
||||
break;
|
||||
// Check for initial quote
|
||||
char c = is.peek();
|
||||
if (is.eof())
|
||||
return "";
|
||||
|
||||
if (expect_initial_quote && c == '"') {
|
||||
tmp_os << c;
|
||||
is_json = true;
|
||||
} else if(is_json) {
|
||||
tmp_os << c;
|
||||
if (was_backslash)
|
||||
was_backslash = false;
|
||||
else if (c == '\\')
|
||||
was_backslash = true;
|
||||
else if (c == '"')
|
||||
break; // Found end of string
|
||||
} else {
|
||||
if (c == ' ') {
|
||||
// Found end of word
|
||||
is.unget();
|
||||
break;
|
||||
}
|
||||
|
||||
tmp_os << c;
|
||||
}
|
||||
expect_initial_quote = false;
|
||||
}
|
||||
if (is_json) {
|
||||
return deSerializeJsonString(tmp_os);
|
||||
if (c == '"') {
|
||||
// json string: defer to the right implementation
|
||||
return deSerializeJsonString(is);
|
||||
}
|
||||
|
||||
return tmp_os.str();
|
||||
// not a json string:
|
||||
std::string tmp;
|
||||
std::getline(is, tmp, ' ');
|
||||
if (!is.eof())
|
||||
is.unget(); // we hit a space, put it back
|
||||
return tmp;
|
||||
}
|
||||
|
||||
|
Loading…
Reference in New Issue
Block a user