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https://github.com/pezkuwichain/serde.git
synced 2026-04-27 04:07:55 +00:00
David Tolnay
5e102c4da1
Let's keep crate::__private for only things that *need* to be accessible to the macro-generated code. Size_hint can be pub(crate).
30 lines
644 B
Rust
30 lines
644 B
Rust
use crate::lib::*;
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pub fn from_bounds<I>(iter: &I) -> Option<usize>
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where
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I: Iterator,
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{
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helper(iter.size_hint())
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}
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#[cfg(any(feature = "std", feature = "alloc"))]
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pub fn cautious<Element>(hint: Option<usize>) -> usize {
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const MAX_PREALLOC_BYTES: usize = 1024 * 1024;
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if mem::size_of::<Element>() == 0 {
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0
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} else {
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cmp::min(
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hint.unwrap_or(0),
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MAX_PREALLOC_BYTES / mem::size_of::<Element>(),
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)
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}
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}
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fn helper(bounds: (usize, Option<usize>)) -> Option<usize> {
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match bounds {
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(lower, Some(upper)) if lower == upper => Some(upper),
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_ => None,
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}
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}
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