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Merge pull request #2205 from grahame/floatstrfixes

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add inf/-inf/NaN parsing to float::from_str
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Brian Anderson 2012-04-14 12:25:45 -07:00
commit 4063802f64
1 changed files with 18 additions and 0 deletions
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18
src/libcore/float.rs
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@ -110,6 +110,7 @@ This function accepts strings such as
* '', or, equivalently, '.' (understood as 0) * '', or, equivalently, '.' (understood as 0)
* '5.' * '5.'
* '.5', or, equivalently, '0.5' * '.5', or, equivalently, '0.5'
* 'inf', '-inf', 'NaN'
Leading and trailing whitespace are ignored. Leading and trailing whitespace are ignored.
@ -123,6 +124,14 @@ Leading and trailing whitespace are ignored.
where `n` is the floating-point number represented by `[num]`. where `n` is the floating-point number represented by `[num]`.
"] "]
fn from_str(num: str) -> option<float> { fn from_str(num: str) -> option<float> {
if num == "inf" {
ret some(infinity);
} else if num == "-inf" {
ret some(neg_infinity);
} else if num == "NaN" {
ret some(NaN);
}
let mut pos = 0u; //Current byte position in the string. let mut pos = 0u; //Current byte position in the string.
//Used to walk the string in O(n). //Used to walk the string in O(n).
let len = str::len(num); //Length of the string, in bytes. let len = str::len(num); //Length of the string, in bytes.
@ -301,6 +310,15 @@ fn test_from_str() {
assert from_str("-.5") == some(-0.5); assert from_str("-.5") == some(-0.5);
assert from_str("-.5") == some(-0.5); assert from_str("-.5") == some(-0.5);
assert from_str("-5") == some(-5.); assert from_str("-5") == some(-5.);
assert from_str("-0") == some(-0.);
assert from_str("0") == some(0.);
assert from_str("inf") == some(infinity);
assert from_str("-inf") == some(neg_infinity);
// note: NaN != NaN, hence this slightly complex test
alt from_str("NaN") {
some(f) { assert is_NaN(f); }
none { fail; }
}
assert from_str("") == none; assert from_str("") == none;
assert from_str("x") == none; assert from_str("x") == none;