/rust/registry/src/github.com-1ecc6299db9ec823/addr2line-0.14.1/src/lazy.rs

Source (jump to first uncovered line)
use core::cell::UnsafeCell;

pub struct LazyCell<T> {
    contents: UnsafeCell<Option<T>>,
}
impl<T> LazyCell<T> {
    pub fn new() -> LazyCell<T> {
        LazyCell {
            contents: UnsafeCell::new(None),
        }
    }

    pub fn borrow_with(&self, closure: impl FnOnce() -> T) -> &T {
        unsafe {
            // First check if we're already initialized...
            let ptr = self.contents.get();
            if let Some(val) = &*ptr {
                return val;
            }
            // Note that while we're executing `closure` our `borrow_with` may
            // be called recursively. This means we need to check again after
            // the closure has executed. For that we use the `get_or_insert`
            // method which will only perform mutation if we aren't already
            // `Some`.
            let val = closure();
            (*ptr).get_or_insert(val)
        }
    }
}

Coverage Report

Created: 2021-03-22 08:29

Line	Count	Source (jump to first uncovered line)
1		use core::cell::UnsafeCell;
2
3		pub struct LazyCell<T> {
4		contents: UnsafeCell<Option<T>>,
5		}
6		impl<T> LazyCell<T> {
7		pub fn new() -> LazyCell<T> {
8		LazyCell {
9		contents: UnsafeCell::new(None),
10		}
11		}
12
13	0	pub fn borrow_with(&self, closure: impl FnOnce() -> T) -> &T {
14	0	unsafe {
15	0	// First check if we're already initialized...
16	0	let ptr = self.contents.get();
17	0	if let Some(val) = &*ptr {
18	0	return val;
19	0	}
20	0	// Note that while we're executing `closure` our `borrow_with` may
21	0	// be called recursively. This means we need to check again after
22	0	// the closure has executed. For that we use the `get_or_insert`
23	0	// method which will only perform mutation if we aren't already
24	0	// `Some`.
25	0	let val = closure();
26	0	(*ptr).get_or_insert(val)
27		}
28	0	} Unexecuted instantiation: <addr2line::lazy::LazyCell<core::result::Result<addr2line::Function<gimli::read::endian_slice::EndianSlice<gimli::endianity::LittleEndian>>, gimli::read::Error>>>::borrow_with::<<addr2line::ResUnit<gimli::read::endian_slice::EndianSlice<gimli::endianity::LittleEndian>>>::find_function_or_location::{closure#0}> Unexecuted instantiation: <addr2line::lazy::LazyCell<core::result::Result<addr2line::Lines, gimli::read::Error>>>::borrow_with::<<addr2line::ResUnit<gimli::read::endian_slice::EndianSlice<gimli::endianity::LittleEndian>>>::parse_lines::{closure#0}> Unexecuted instantiation: <addr2line::lazy::LazyCell<core::result::Result<addr2line::Functions<gimli::read::endian_slice::EndianSlice<gimli::endianity::LittleEndian>>, gimli::read::Error>>>::borrow_with::<<addr2line::ResUnit<gimli::read::endian_slice::EndianSlice<gimli::endianity::LittleEndian>>>::parse_functions::{closure#0}>
29		}