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use backtrace::BacktraceSymbol;
use std::fmt;
use std::hash::{Hash, Hasher};
use std::ptr;
/// A symbol in a backtrace.
///
/// This wrapper type serves two purposes. The first is that it provides a
/// representation of a symbol that can be inserted into hashmaps and hashsets;
/// the [`backtrace`] crate does not define [`Hash`], [`PartialEq`], or [`Eq`]
/// on [`BacktraceSymbol`], and recommends that users define their own wrapper
/// which implements these traits.
///
/// Second, this wrapper includes a `parent_hash` field that uniquely
/// identifies this symbol's position in its trace. Otherwise, e.g., our code
/// would not be able to distinguish between recursive calls of a function at
/// different depths.
#[derive(Clone)]
pub(super) struct Symbol {
pub(super) symbol: BacktraceSymbol,
pub(super) parent_hash: u64,
}
impl Hash for Symbol {
fn hash<H>(&self, state: &mut H)
where
H: Hasher,
{
if let Some(name) = self.symbol.name() {
name.as_bytes().hash(state);
}
if let Some(addr) = self.symbol.addr() {
ptr::hash(addr, state);
}
self.symbol.filename().hash(state);
self.symbol.lineno().hash(state);
self.symbol.colno().hash(state);
self.parent_hash.hash(state);
}
}
impl PartialEq for Symbol {
fn eq(&self, other: &Self) -> bool {
(self.parent_hash == other.parent_hash)
&& match (self.symbol.name(), other.symbol.name()) {
(None, None) => true,
(Some(lhs_name), Some(rhs_name)) => lhs_name.as_bytes() == rhs_name.as_bytes(),
_ => false,
}
&& match (self.symbol.addr(), other.symbol.addr()) {
(None, None) => true,
(Some(lhs_addr), Some(rhs_addr)) => ptr::eq(lhs_addr, rhs_addr),
_ => false,
}
&& (self.symbol.filename() == other.symbol.filename())
&& (self.symbol.lineno() == other.symbol.lineno())
&& (self.symbol.colno() == other.symbol.colno())
}
}
impl Eq for Symbol {}
impl fmt::Display for Symbol {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
if let Some(name) = self.symbol.name() {
let name = name.to_string();
let name = if let Some((name, _)) = name.rsplit_once("::") {
name
} else {
&name
};
fmt::Display::fmt(&name, f)?;
}
if let Some(filename) = self.symbol.filename() {
f.write_str(" at ")?;
filename.to_string_lossy().fmt(f)?;
if let Some(lineno) = self.symbol.lineno() {
f.write_str(":")?;
fmt::Display::fmt(&lineno, f)?;
if let Some(colno) = self.symbol.colno() {
f.write_str(":")?;
fmt::Display::fmt(&colno, f)?;
}
}
}
Ok(())
}
}