Parses a byte slice as a number. This is meant to be a common base implementation for all numeric string conversion functions like from_str() or from_str_radix().

Arguments

• buf - The byte slice to parse.
• radix - Which base to parse the number as. Accepts 2-36.
• negative - Whether to accept negative numbers.
• fractional - Whether to accept numbers with fractional parts.
• special - Whether to accept special values like inf and NaN. Can conflict with radix, see Failure.
• exponent - Which exponent format to accept. Options are:
  • ExpNone: No Exponent, accepts just plain numbers like 42 or -8.2.
  • ExpDec: Accepts numbers with a decimal exponent like 42e5 or 8.2E-2. The exponent string itself is always base 10. Can conflict with radix, see Failure.
  • ExpBin: Accepts numbers with a binary exponent like 42P-8 or FFp128. The exponent string itself is always base 10. Can conflict with radix, see Failure.
• empty_zero - Whether to accept an empty buf as a 0 or not.
• ignore_underscores - Whether all underscores within the string should be ignored.

Return value

Returns Some(n) if buf parses to a number n without overflowing, and None otherwise, depending on the constraints set by the remaining arguments.

Failure

• Fails if radix < 2 or radix > 36.
• Fails if radix > 14 and exponent is ExpDec due to conflict between digit and exponent sign 'e'.
• Fails if radix > 25 and exponent is ExpBin due to conflict between digit and exponent sign 'p'.
• Fails if radix > 18 and special == true due to conflict between digit and lowest first character in inf and NaN, the 'i'.