HTML 5 Draft Standard - 30 July 2009 - Huihoo

44
The rules for parsing non-negative integers are as given in the following algorithm. When
invoked, the steps must be followed in the order given, aborting at the first step that returns a
value. This algorithm will either return zero, a positive integer, or an error. Leading spaces are
ignored. Trailing spaces and any trailing garbage characters are ignored.
1. Let input be the string being parsed.
2. Let position be a pointer into input, initially pointing at the start of the string.
3. Let value have the value 0.
4. Skip whitespace (page 42).
5. If position is past the end of input, return an error.
6. If the next character is a U+002B PLUS SIGN character (+), advance position to the next
character.
7. If position is past the end of input, return an error.
8. If the next character is not one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9),
then return an error.
9. Loop: If the next character is one of U+0030 DIGIT ZERO (0) .. U+0039 DIGIT NINE (9):
10. Return value.
1. Multiply value by ten.
2. Add the value of the current character (0..9) to value.
3. Advance position to the next character.
4. If position is not past the end of input, return to the top of the step labeled loop
in the overall algorithm (that's the step within which these substeps find
themselves).
2.4.4.2 Signed integers
A string is a valid integer if it consists of one or more characters in the range U+0030 DIGIT
ZERO (0) to U+0039 DIGIT NINE (9), optionally prefixed with a U+002D HYPHEN-MINUS ("-")
character.
A valid integer (page 44) without a U+002D HYPHEN-MINUS ("-") prefix represents the number
that is represented in base ten by that string of digits. A valid integer (page 44) with a U+002D
HYPHEN-MINUS ("-") prefix represents the number represented in base ten by the string of digits
that follows the U+002D HYPHEN-MINUS, subtracted from zero.
The rules for parsing integers are similar to the rules for non-negative integers (page 44),
and are as given in the following algorithm. When invoked, the steps must be followed in the
order given, aborting at the first step that returns a value. This algorithm will either return an