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25 lines
625 B
Rust
25 lines
625 B
Rust
#![allow(bare_trait_objects)]
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// check-pass
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pub struct FormatWith<'a, I, F> {
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sep: &'a str,
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/// FormatWith uses interior mutability because Display::fmt takes &self.
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inner: RefCell<Option<(I, F)>>,
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}
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use std::cell::RefCell;
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use std::fmt;
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struct Layout;
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pub fn new_format<'a, I, F>(iter: I, separator: &'a str, f: F) -> FormatWith<'a, I, F>
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where
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I: Iterator,
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F: FnMut(I::Item, &mut FnMut(&fmt::Display) -> fmt::Result) -> fmt::Result,
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{
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FormatWith { sep: separator, inner: RefCell::new(Some((iter, f))) }
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}
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fn main() {
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let _ = new_format(0..32, " | ", |i, f| f(&format_args!("0x{:x}", i)));
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}
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