External/json
8
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

POC for hex literal constants parsing

Browse Source
This commit is contained in:
Sfinktah Bungholio 2020-11-28 18:31:57 +11:00
parent 350ff4f7ce
commit 741d422fa6
1 changed files with 60 additions and 13 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
include/nlohmann/detail/input/lexer.hpp
View File

@ -929,17 +929,18 @@ class lexer : public lexer_base<BasicJsonType>
accepts the number. State "error" is a trap state to model errors. In the
table below, "anything" means any character but the ones listed before.
state | 0 | 1-9 | e E | + | - | . | anything
---------|----------|----------|----------|---------|---------|----------|-----------
init | zero | any1 | [error] | [error] | minus | [error] | [error]
minus | zero | any1 | [error] | [error] | [error] | [error] | [error]
zero | done | done | exponent | done | done | decimal1 | done
any1 | any1 | any1 | exponent | done | done | decimal1 | done
decimal1 | decimal2 | decimal2 | [error] | [error] | [error] | [error] | [error]
decimal2 | decimal2 | decimal2 | exponent | done | done | done | done
exponent | any2 | any2 | [error] | sign | sign | [error] | [error]
sign | any2 | any2 | [error] | [error] | [error] | [error] | [error]
any2 | any2 | any2 | done | done | done | done | done
state | 0 | 1-9 | e E | + | - | . | x | a-f A-F | anything
---------|----------|----------|----------|---------|---------|----------|-----------|-----------|-----------
init | zero | any1 | [error] | [error] | minus | [error] | [error] | [error] | [error]
minus | zero | any1 | [error] | [error] | [error] | [error] | [error] | [error] | [error]
zero | done | done | exponent | done | done | decimal1 | *hex1* | done | done
any1 | any1 | any1 | exponent | done | done | decimal1 | done | done | done
decimal1 | decimal2 | [error] | [error] | [error] | [error] | [error] | [error] | [error] | [error]
decimal2 | decimal2 | decimal2 | exponent | done | done | done | done | done | done
exponent | any2 | any2 | [error] | sign | sign | [error] | [error] | [error] | [error]
sign | any2 | any2 | [error] | [error] | [error] | [error] | [error] | [error] | [error]
any2 | any2 | any2 | done | done | done | done | done | done | done
hex1 | hex1 | hex1 | hex1 | [error] | [error] | [error] | [error] | hex1 | done
The state machine is realized with one label per state (prefixed with
"scan_number_") and `goto` statements between them. The state machine
@ -1090,6 +1091,52 @@ scan_number_any1:
goto scan_number_done;
}
scan_number_hex1:
// state: we are parsing a hex number having previously parsed '0x' or
// '0X' (however ugly that latter may be)
switch (get()) {
case '0': // in hex, we love padding with leading zeros
case '1':
case '2':
case '3':
case '4':
case '5':
case '6':
case '7':
case '8':
case '9':
case 'a':
case 'b':
case 'c':
case 'd':
case 'e':
case 'f':
case 'A':
case 'B':
case 'C':
case 'D':
case 'E':
case 'F':
{
add(current);
goto scan_number_hex1;
}
// omg, we are so not doing hex floating point
//case '.': {
// add(decimal_point_char);
// goto scan_number_decimal1;
//}
// safer to error while testing, but it would error on natural ends of numbers?
//default: {
// error_message = "invalid hexidecimal number; expected hex digit";
// return token_type::parse_error;
//}
default:
goto scan_number_done;
}
scan_number_decimal1:
// state: we just parsed a decimal point
number_type = token_type::value_float;
@ -1242,7 +1289,7 @@ scan_number_done:
// try to parse integers first and fall back to floats
if (number_type == token_type::value_unsigned)
{
const auto x = std::strtoull(token_buffer.data(), &endptr, 10);
const auto x = std::strtoull(token_buffer.data(), &endptr, 0);
// we checked the number format before
JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());
@ -1258,7 +1305,7 @@ scan_number_done:
}
else if (number_type == token_type::value_integer)
{
const auto x = std::strtoll(token_buffer.data(), &endptr, 10);
const auto x = std::strtoll(token_buffer.data(), &endptr, 0);
// we checked the number format before
JSON_ASSERT(endptr == token_buffer.data() + token_buffer.size());