Speed up float parsing #110
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| } | ||
| None => { | ||
| if exponent >= 0 && significand != 0 { | ||
| f64::INFINITY |
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I don't think we should default to infinity. Not only does it break round tripping, it's also very confusing to get an infinity from a non-infinite number
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This matches the current behavior (as of 0.7.4). I filed #112 to change the behavior.
assert_eq!(f64::INFINITY, serde_json::from_str("1e1000").unwrap());
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Fixes #108 and fixes #109.
Parse floats as a u64 until the end, then use a lookup table to scale by the correct power of 10. This is faster and also more accurate. The old code used repeated division by 10 which is so inaccurate that
1.0 / 10.0 / 10.0 / 10.0 / 10.0 / 10.0 / 10.0 != 1e-6.This is about 40% improvement on the Canada benchmark (almost twice as fast).