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Implemented a parser and updated tiny_obj_loader.cc to use it unless a define is set.

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This commit is contained in:
Simon Otter
2015-03-03 01:37:28 +01:00
parent f020169c26
commit 4ea1cf0b77
2 changed files with 341 additions and 12 deletions
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200
float_parser_tests.cc
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@@ -1,41 +1,159 @@
#include <cstdio>
#include <cstddef>
#include <cstring>
#include <cmath>
#include <cctype>
// Tries to parse a floating point number located at s.
//
// s_end should be a location in the string where reading should absolutely
// stop. For example at the end of the string, to prevent buffer overflows.
//
// Parses the following EBNF grammar:
// sign = "+" | "-" ;
// END = ? anything not in digit ?
// digit = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ;
// integer = [sign] , digit , {digit} ;
// decimal = integer , ["." , {digit}] ;
// float = ( decimal , END ) | ( decimal , ("E" | "e") , decimal , END ) ;
// decimal = integer , ["." , integer] ;
// float = ( decimal , END ) | ( decimal , ("E" | "e") , integer , END ) ;
//
// Valid strings are for example:
// -0 +3.1417e+2 -0.E-3 1.0324 -1.41 11e2
// -0 +3.1417e+2 -0.0E-3 1.0324 -1.41 11e2
//
// If the parsing is a success, result is set to the parsed value and true
// is returned.
//
// The function is greedy, it will parse until it encounters a null-byte or
// a non-conforming character is encountered.
// The function is greedy and will parse until any of the following happens:
// - a non-conforming character is encountered.
// - s_end is reached.
//
// The following situations triggers a failure:
// - s >= s_end.
// - parse failure.
// - underflow/overflow.
//
bool tryParseFloat(const char *s, double *result)
bool tryParseDouble(const char *s, const char *s_end, double *result)
{
if (s >= s_end)
{
return false;
}
double mantissa = 0.0;
// This exponent is base 2 rather than 10.
// However the exponent we parse is supposed to be one of ten,
// thus we must take care to convert the exponent/and or the
// mantissa to a * 2^E, where a is the mantissa and E is the
// exponent.
// To get the final double we will use ldexp, it requires the
// exponent to be in base 2.
int exponent = 0;
// NOTE: THESE MUST BE DECLARED HERE SINCE WE ARE NOT ALLOWED
// TO JUMP OVER DEFINITIONS.
char sign = '+';
char exp_sign = '+';
char const *curr = s;
// How many characters were read in a loop.
int read = 0;
// Tells whether a loop terminated due to reaching s_end.
bool end_not_reached = false;
/*
BEGIN PARSING.
*/
// Find out what sign we've got.
if (*curr == '+' || *curr == '-')
{
sign = *curr;
curr++;
}
else if (isdigit(*curr)) { /* Pass through. */ }
else
{
goto fail;
}
// Read the integer part.
while ((end_not_reached = (curr != s_end)) && isdigit(*curr))
{
mantissa *= 10;
mantissa += static_cast<int>(*curr - 0x30);
curr++; read++;
}
// We must make sure we actually got something.
if (read == 0)
goto fail;
// We allow numbers of form "#", "###" etc.
if (!end_not_reached)
goto assemble;
// Read the decimal part.
if (*curr == '.')
{
curr++;
read = 1;
while ((end_not_reached = (curr != s_end)) && isdigit(*curr))
{
// NOTE: Don't use powf here, it will absolutely murder precision.
mantissa += static_cast<int>(*curr - 0x30) * pow(10, -read);
read++; curr++;
}
}
else if (*curr == 'e' || *curr == 'E') {}
else
{
goto assemble;
}
if (!end_not_reached)
goto assemble;
// Read the exponent part.
if (*curr == 'e' || *curr == 'E')
{
curr++;
// Figure out if a sign is present and if it is.
if ((end_not_reached = (curr != s_end)) && (*curr == '+' || *curr == '-'))
{
exp_sign = *curr;
curr++;
}
else if (isdigit(*curr)) { /* Pass through. */ }
else
{
// Empty E is not allowed.
goto fail;
}
read = 0;
while ((end_not_reached = (curr != s_end)) && isdigit(*curr))
{
exponent *= 10;
exponent += static_cast<int>(*curr - 0x30);
curr++; read++;
}
exponent *= (exp_sign == '+'? 1 : -1);
if (read == 0)
goto fail;
}
assemble:
*result = (sign == '+'? 1 : -1) * ldexp(mantissa * pow(5, exponent), exponent);
return true;
fail:
return false;
}
void testParsing(const char *input, bool expectedRes, double expectedValue)
{
double val = 0.0;
bool res = tryParseFloat(input, &val);
if (res != expectedRes || val != expectedValue)
bool res = tryParseDouble(input, input + strlen(input), &val);
if (res != expectedRes || fabs(val - expectedValue) > 0.000001)
{
printf("% 20s failed, returned %d and value % 10.4f.\n", input, res, val);
printf("% 20s failed, returned %d and value % 10.5f.\n\t\tExpected value was % 10.5f\n------\n", input, res, val, expectedValue);
}
}
@@ -49,7 +167,65 @@ int main(int argc, char const *argv[])
testParsing("-1", true, -1.0);
testParsing("-1.08", true, -1.08);
testParsing("100.0823blabla", true, 100.0823);
testParsing("34.E-2\04", true, 34.0e-2);
testParsing("+34.23E2\02", true, 34.23E2);
testParsing("34.0E-2\04", true, 34.0e-2);
testParsing("+34.23E2\032", true, 34.23E2);
testParsing("10.023", true, 10.023);
testParsing("1.0e+23", true, 1.e+23);
testParsing("10e+23", true, 10e+23);
testParsing("20301.000", true, 20301.000);
testParsing("-41044.000", true, -41044.000);
testParsing("-93558.000", true, -93558.000);
testParsing("-79620.000", true, -79620.000);
testParsing("5257.000", true, 5257.000);
testParsing("-7145.000", true, -7145.000);
testParsing("-77314.000", true, -77314.000);
testParsing("-27131.000", true, -27131.000);
testParsing("52744.000", true, 52744.000);
testParsing("48106.000", true, 48106.000);
testParsing("42939.000", true, 42939.000);
testParsing("41187.000", true, 41187.000);
testParsing("70851.000", true, 70851.000);
testParsing("-90431.000", true, -90431.000);
testParsing("-13564.000", true, -13564.000);
testParsing("27150.000", true, 27150.000);
testParsing("71992.000", true, 71992.000);
testParsing("-42845.000", true, -42845.000);
testParsing("24806.000", true, 24806.000);
testParsing("30753.000", true, 30753.000);
testParsing("1.658500e+04", true, 1.658500e+04);
testParsing("9.572500e+04", true, 9.572500e+04);
testParsing("-5.888600e+04", true, -5.888600e+04);
testParsing("-2.998000e+04", true, -2.998000e+04);
testParsing("-4.842700e+04", true, -4.842700e+04);
testParsing("9.575400e+04", true, 9.575400e+04);
testParsing("-8.311500e+04", true, -8.311500e+04);
testParsing("-3.770800e+04", true, -3.770800e+04);
testParsing("-3.141600e+04", true, -3.141600e+04);
testParsing("-4.673700e+04", true, -4.673700e+04);
testParsing("-5.112400e+04", true, -5.112400e+04);
testParsing("7.111000e+03", true, 7.111000e+03);
testParsing("-3.727000e+03", true, -3.727000e+03);
testParsing("6.940700e+04", true, 6.940700e+04);
testParsing("-3.635100e+04", true, -3.635100e+04);
testParsing("2.762100e+04", true, 2.762100e+04);
testParsing("-1.512600e+04", true, -1.512600e+04);
testParsing("3.338000e+03", true, 3.338000e+03);
testParsing("7.598100e+04", true, 7.598100e+04);
testParsing("-8.198400e+04", true, -8.198400e+04);
testParsing("-", false, 0.0);
testParsing(" +", false, 0.0);
testParsing("", false, 0.0);
testParsing(".232", false, 0.0);
testParsing(".232E2", false, 0.0);
testParsing(".232", false, 0.0);
testParsing(".", false, 0.0);
testParsing(".E", false, 0.0);
testParsing("233.E", false, 0.0);
testParsing("233.323E-", false, 0.0);
testParsing("233.323E+", false, 0.0);
return 0;
}