Merge pull request #23 from eddyb/master
Support demangling the new Rust mangling scheme.
diff --git a/src/legacy.rs b/src/legacy.rs
new file mode 100644
index 0000000..1e1824c
--- /dev/null
+++ b/src/legacy.rs
@@ -0,0 +1,370 @@
+use core::fmt;
+
+/// Representation of a demangled symbol name.
+pub struct Demangle<'a> {
+ inner: &'a str,
+ /// The number of ::-separated elements in the original name.
+ elements: usize,
+}
+
+/// De-mangles a Rust symbol into a more readable version
+///
+/// All Rust symbols by default are mangled as they contain characters that
+/// cannot be represented in all object files. The mangling mechanism is similar
+/// to C++'s, but Rust has a few specifics to handle items like lifetimes in
+/// symbols.
+///
+/// This function will take a **mangled** symbol and return a value. When printed,
+/// the de-mangled version will be written. If the symbol does not look like
+/// a mangled symbol, the original value will be written instead.
+///
+/// # Examples
+///
+/// ```
+/// use rustc_demangle::demangle;
+///
+/// assert_eq!(demangle("_ZN4testE").to_string(), "test");
+/// assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar");
+/// assert_eq!(demangle("foo").to_string(), "foo");
+/// ```
+
+// All Rust symbols are in theory lists of "::"-separated identifiers. Some
+// assemblers, however, can't handle these characters in symbol names. To get
+// around this, we use C++-style mangling. The mangling method is:
+//
+// 1. Prefix the symbol with "_ZN"
+// 2. For each element of the path, emit the length plus the element
+// 3. End the path with "E"
+//
+// For example, "_ZN4testE" => "test" and "_ZN3foo3barE" => "foo::bar".
+//
+// We're the ones printing our backtraces, so we can't rely on anything else to
+// demangle our symbols. It's *much* nicer to look at demangled symbols, so
+// this function is implemented to give us nice pretty output.
+//
+// Note that this demangler isn't quite as fancy as it could be. We have lots
+// of other information in our symbols like hashes, version, type information,
+// etc. Additionally, this doesn't handle glue symbols at all.
+pub fn demangle(s: &str) -> Result<Demangle, ()> {
+ // First validate the symbol. If it doesn't look like anything we're
+ // expecting, we just print it literally. Note that we must handle non-Rust
+ // symbols because we could have any function in the backtrace.
+ let inner;
+ if s.len() > 4 && s.starts_with("_ZN") && s.ends_with('E') {
+ inner = &s[3..s.len() - 1];
+ } else if s.len() > 3 && s.starts_with("ZN") && s.ends_with('E') {
+ // On Windows, dbghelp strips leading underscores, so we accept "ZN...E"
+ // form too.
+ inner = &s[2..s.len() - 1];
+ } else if s.len() > 5 && s.starts_with("__ZN") && s.ends_with('E') {
+ // On OSX, symbols are prefixed with an extra _
+ inner = &s[4..s.len() - 1];
+ } else {
+ return Err(());
+ }
+
+ // only work with ascii text
+ if inner.bytes().any(|c| c & 0x80 != 0) {
+ return Err(());
+ }
+
+ let mut elements = 0;
+ let mut chars = inner.chars().peekable();
+ loop {
+ let mut i = 0usize;
+ while let Some(&c) = chars.peek() {
+ if !c.is_digit(10) {
+ break
+ }
+ chars.next();
+ let next = i.checked_mul(10)
+ .and_then(|i| i.checked_add(c as usize - '0' as usize));
+ i = match next {
+ Some(i) => i,
+ None => {
+ return Err(());
+ }
+ };
+ }
+
+ if i == 0 {
+ if !chars.next().is_none() {
+ return Err(());
+ }
+ break;
+ } else if chars.by_ref().take(i).count() != i {
+ return Err(());
+ } else {
+ elements += 1;
+ }
+ }
+
+ Ok(Demangle {
+ inner: inner,
+ elements: elements,
+ })
+}
+
+// Rust hashes are hex digits with an `h` prepended.
+fn is_rust_hash(s: &str) -> bool {
+ s.starts_with('h') && s[1..].chars().all(|c| c.is_digit(16))
+}
+
+impl<'a> fmt::Display for Demangle<'a> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ // Alright, let's do this.
+ let mut inner = self.inner;
+ for element in 0..self.elements {
+ let mut rest = inner;
+ while rest.chars().next().unwrap().is_digit(10) {
+ rest = &rest[1..];
+ }
+ let i: usize = inner[..(inner.len() - rest.len())].parse().unwrap();
+ inner = &rest[i..];
+ rest = &rest[..i];
+ // Skip printing the hash if alternate formatting
+ // was requested.
+ if f.alternate() && element+1 == self.elements && is_rust_hash(&rest) {
+ break;
+ }
+ if element != 0 {
+ try!(f.write_str("::"));
+ }
+ if rest.starts_with("_$") {
+ rest = &rest[1..];
+ }
+ while !rest.is_empty() {
+ if rest.starts_with('.') {
+ if let Some('.') = rest[1..].chars().next() {
+ try!(f.write_str("::"));
+ rest = &rest[2..];
+ } else {
+ try!(f.write_str("."));
+ rest = &rest[1..];
+ }
+ } else if rest.starts_with('$') {
+ macro_rules! demangle {
+ ($($pat:expr => $demangled:expr,)*) => ({
+ $(if rest.starts_with($pat) {
+ try!(f.write_str($demangled));
+ rest = &rest[$pat.len()..];
+ } else)*
+ {
+ try!(f.write_str(rest));
+ break;
+ }
+
+ })
+ }
+
+ // see src/librustc/back/link.rs for these mappings
+ demangle! {
+ "$SP$" => "@",
+ "$BP$" => "*",
+ "$RF$" => "&",
+ "$LT$" => "<",
+ "$GT$" => ">",
+ "$LP$" => "(",
+ "$RP$" => ")",
+ "$C$" => ",",
+
+ // in theory we can demangle any Unicode code point, but
+ // for simplicity we just catch the common ones.
+ "$u7e$" => "~",
+ "$u20$" => " ",
+ "$u27$" => "'",
+ "$u3d$" => "=",
+ "$u5b$" => "[",
+ "$u5d$" => "]",
+ "$u7b$" => "{",
+ "$u7d$" => "}",
+ "$u3b$" => ";",
+ "$u2b$" => "+",
+ "$u21$" => "!",
+ "$u22$" => "\"",
+ }
+ } else {
+ let idx = match rest.char_indices().find(|&(_, c)| c == '$' || c == '.') {
+ None => rest.len(),
+ Some((i, _)) => i,
+ };
+ try!(f.write_str(&rest[..idx]));
+ rest = &rest[idx..];
+ }
+ }
+ }
+
+ Ok(())
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ use std::prelude::v1::*;
+
+ macro_rules! t {
+ ($a:expr, $b:expr) => (assert!(ok($a, $b)))
+ }
+
+ macro_rules! t_err {
+ ($a:expr) => (assert!(ok_err($a)))
+ }
+
+ macro_rules! t_nohash {
+ ($a:expr, $b:expr) => ({
+ assert_eq!(format!("{:#}", ::demangle($a)), $b);
+ })
+ }
+
+ fn ok(sym: &str, expected: &str) -> bool {
+ match ::try_demangle(sym) {
+ Ok(s) => {
+ if s.to_string() == expected {
+ true
+ } else {
+ println!("\n{}\n!=\n{}\n", s, expected);
+ false
+ }
+ }
+ Err(_) => {
+ println!("error demangling");
+ false
+ }
+ }
+ }
+
+ fn ok_err(sym: &str) -> bool {
+ match ::try_demangle(sym) {
+ Ok(_) => {
+ println!("succeeded in demangling");
+ false
+ }
+ Err(_) => ::demangle(sym).to_string() == sym,
+ }
+ }
+
+ #[test]
+ fn demangle() {
+ t_err!("test");
+ t!("_ZN4testE", "test");
+ t_err!("_ZN4test");
+ t!("_ZN4test1a2bcE", "test::a::bc");
+ }
+
+ #[test]
+ fn demangle_dollars() {
+ t!("_ZN4$RP$E", ")");
+ t!("_ZN8$RF$testE", "&test");
+ t!("_ZN8$BP$test4foobE", "*test::foob");
+ t!("_ZN9$u20$test4foobE", " test::foob");
+ t!("_ZN35Bar$LT$$u5b$u32$u3b$$u20$4$u5d$$GT$E", "Bar<[u32; 4]>");
+ }
+
+ #[test]
+ fn demangle_many_dollars() {
+ t!("_ZN13test$u20$test4foobE", "test test::foob");
+ t!("_ZN12test$BP$test4foobE", "test*test::foob");
+ }
+
+
+ #[test]
+ fn demangle_osx() {
+ t!("__ZN5alloc9allocator6Layout9for_value17h02a996811f781011E", "alloc::allocator::Layout::for_value::h02a996811f781011");
+ t!("__ZN38_$LT$core..option..Option$LT$T$GT$$GT$6unwrap18_MSG_FILE_LINE_COL17haf7cb8d5824ee659E", "<core::option::Option<T>>::unwrap::_MSG_FILE_LINE_COL::haf7cb8d5824ee659");
+ t!("__ZN4core5slice89_$LT$impl$u20$core..iter..traits..IntoIterator$u20$for$u20$$RF$$u27$a$u20$$u5b$T$u5d$$GT$9into_iter17h450e234d27262170E", "core::slice::<impl core::iter::traits::IntoIterator for &'a [T]>::into_iter::h450e234d27262170");
+ }
+
+ #[test]
+ fn demangle_windows() {
+ t!("ZN4testE", "test");
+ t!("ZN13test$u20$test4foobE", "test test::foob");
+ t!("ZN12test$RF$test4foobE", "test&test::foob");
+ }
+
+ #[test]
+ fn demangle_elements_beginning_with_underscore() {
+ t!("_ZN13_$LT$test$GT$E", "<test>");
+ t!("_ZN28_$u7b$$u7b$closure$u7d$$u7d$E", "{{closure}}");
+ t!("_ZN15__STATIC_FMTSTRE", "__STATIC_FMTSTR");
+ }
+
+ #[test]
+ fn demangle_trait_impls() {
+ t!("_ZN71_$LT$Test$u20$$u2b$$u20$$u27$static$u20$as$u20$foo..Bar$LT$Test$GT$$GT$3barE",
+ "<Test + 'static as foo::Bar<Test>>::bar");
+ }
+
+ #[test]
+ fn demangle_without_hash() {
+ let s = "_ZN3foo17h05af221e174051e9E";
+ t!(s, "foo::h05af221e174051e9");
+ t_nohash!(s, "foo");
+ }
+
+ #[test]
+ fn demangle_without_hash_edgecases() {
+ // One element, no hash.
+ t_nohash!("_ZN3fooE", "foo");
+ // Two elements, no hash.
+ t_nohash!("_ZN3foo3barE", "foo::bar");
+ // Longer-than-normal hash.
+ t_nohash!("_ZN3foo20h05af221e174051e9abcE", "foo");
+ // Shorter-than-normal hash.
+ t_nohash!("_ZN3foo5h05afE", "foo");
+ // Valid hash, but not at the end.
+ t_nohash!("_ZN17h05af221e174051e93fooE", "h05af221e174051e9::foo");
+ // Not a valid hash, missing the 'h'.
+ t_nohash!("_ZN3foo16ffaf221e174051e9E", "foo::ffaf221e174051e9");
+ // Not a valid hash, has a non-hex-digit.
+ t_nohash!("_ZN3foo17hg5af221e174051e9E", "foo::hg5af221e174051e9");
+ }
+
+ #[test]
+ fn demangle_thinlto() {
+ // One element, no hash.
+ t!("_ZN3fooE.llvm.9D1C9369", "foo");
+ t!("_ZN3fooE.llvm.9D1C9369@@16", "foo");
+ t_nohash!("_ZN9backtrace3foo17hbb467fcdaea5d79bE.llvm.A5310EB9", "backtrace::foo");
+ }
+
+ #[test]
+ fn demangle_llvm_ir_branch_labels() {
+ t!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut::haf9727c2edfbc47b.exit.i.i");
+ t_nohash!("_ZN4core5slice77_$LT$impl$u20$core..ops..index..IndexMut$LT$I$GT$$u20$for$u20$$u5b$T$u5d$$GT$9index_mut17haf9727c2edfbc47bE.exit.i.i", "core::slice::<impl core::ops::index::IndexMut<I> for [T]>::index_mut.exit.i.i");
+ }
+
+ #[test]
+ fn demangle_ignores_suffix_that_doesnt_look_like_a_symbol() {
+ t_err!("_ZN3fooE.llvm moocow");
+ }
+
+ #[test]
+ fn dont_panic() {
+ ::demangle("_ZN2222222222222222222222EE").to_string();
+ ::demangle("_ZN5*70527e27.ll34csaғE").to_string();
+ ::demangle("_ZN5*70527a54.ll34_$b.1E").to_string();
+ ::demangle("\
+ _ZN5~saäb4e\n\
+ 2734cOsbE\n\
+ 5usage20h)3\0\0\0\0\0\0\07e2734cOsbE\
+ ").to_string();
+ }
+
+ #[test]
+ fn invalid_no_chop() {
+ t_err!("_ZNfooE");
+ }
+
+ #[test]
+ fn handle_assoc_types() {
+ t!("_ZN151_$LT$alloc..boxed..Box$LT$alloc..boxed..FnBox$LT$A$C$$u20$Output$u3d$R$GT$$u20$$u2b$$u20$$u27$a$GT$$u20$as$u20$core..ops..function..FnOnce$LT$A$GT$$GT$9call_once17h69e8f44b3723e1caE", "<alloc::boxed::Box<alloc::boxed::FnBox<A, Output=R> + 'a> as core::ops::function::FnOnce<A>>::call_once::h69e8f44b3723e1ca");
+ }
+
+ #[test]
+ fn handle_bang() {
+ t!(
+ "_ZN88_$LT$core..result..Result$LT$$u21$$C$$u20$E$GT$$u20$as$u20$std..process..Termination$GT$6report17hfc41d0da4a40b3e8E",
+ "<core::result::Result<!, E> as std::process::Termination>::report::hfc41d0da4a40b3e8"
+ );
+ }
+}
diff --git a/src/lib.rs b/src/lib.rs
index 12d3ffc..41bc796 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -30,25 +30,25 @@
#[macro_use]
extern crate std;
+mod legacy;
+mod v0;
+
use core::fmt;
/// Representation of a demangled symbol name.
pub struct Demangle<'a> {
+ style: Option<DemangleStyle<'a>>,
original: &'a str,
- inner: &'a str,
suffix: &'a str,
- valid: bool,
- /// The number of ::-separated elements in the original name.
- elements: usize,
+}
+
+enum DemangleStyle<'a> {
+ Legacy(legacy::Demangle<'a>),
+ V0(v0::Demangle<'a>),
}
/// De-mangles a Rust symbol into a more readable version
///
-/// All Rust symbols by default are mangled as they contain characters that
-/// cannot be represented in all object files. The mangling mechanism is similar
-/// to C++'s, but Rust has a few specifics to handle items like lifetimes in
-/// symbols.
-///
/// This function will take a **mangled** symbol and return a value. When printed,
/// the de-mangled version will be written. If the symbol does not look like
/// a mangled symbol, the original value will be written instead.
@@ -62,24 +62,6 @@
/// assert_eq!(demangle("_ZN3foo3barE").to_string(), "foo::bar");
/// assert_eq!(demangle("foo").to_string(), "foo");
/// ```
-
-// All Rust symbols are in theory lists of "::"-separated identifiers. Some
-// assemblers, however, can't handle these characters in symbol names. To get
-// around this, we use C++-style mangling. The mangling method is:
-//
-// 1. Prefix the symbol with "_ZN"
-// 2. For each element of the path, emit the length plus the element
-// 3. End the path with "E"
-//
-// For example, "_ZN4testE" => "test" and "_ZN3foo3barE" => "foo::bar".
-//
-// We're the ones printing our backtraces, so we can't rely on anything else to
-// demangle our symbols. It's *much* nicer to look at demangled symbols, so
-// this function is implemented to give us nice pretty output.
-//
-// Note that this demangler isn't quite as fancy as it could be. We have lots
-// of other information in our symbols like hashes, version, type information,
-// etc. Additionally, this doesn't handle glue symbols at all.
pub fn demangle(mut s: &str) -> Demangle {
// During ThinLTO LLVM may import and rename internal symbols, so strip out
// those endings first as they're one of the last manglings applied to symbol
@@ -111,67 +93,17 @@
}
}
- // First validate the symbol. If it doesn't look like anything we're
- // expecting, we just print it literally. Note that we must handle non-Rust
- // symbols because we could have any function in the backtrace.
- let mut valid = true;
- let mut inner = s;
- if s.len() > 4 && s.starts_with("_ZN") && s.ends_with('E') {
- inner = &s[3..s.len() - 1];
- } else if s.len() > 3 && s.starts_with("ZN") && s.ends_with('E') {
- // On Windows, dbghelp strips leading underscores, so we accept "ZN...E"
- // form too.
- inner = &s[2..s.len() - 1];
- } else if s.len() > 5 && s.starts_with("__ZN") && s.ends_with('E') {
- // On OSX, symbols are prefixed with an extra _
- inner = &s[4..s.len() - 1];
- } else {
- valid = false;
- }
-
- // only work with ascii text
- if inner.bytes().any(|c| c & 0x80 != 0) {
- valid = false;
- }
-
- let mut elements = 0;
- if valid {
- let mut chars = inner.chars().peekable();
- while valid {
- let mut i = 0usize;
- while let Some(&c) = chars.peek() {
- if !c.is_digit(10) {
- break
- }
- chars.next();
- let next = i.checked_mul(10)
- .and_then(|i| i.checked_add(c as usize - '0' as usize));
- i = match next {
- Some(i) => i,
- None => {
- valid = false;
- break
- }
- };
- }
-
- if i == 0 {
- valid = chars.next().is_none();
- break;
- } else if chars.by_ref().take(i).count() != i {
- valid = false;
- } else {
- elements += 1;
- }
- }
- }
-
+ let style = match legacy::demangle(s) {
+ Ok(d) => Some(DemangleStyle::Legacy(d)),
+ Err(()) => match v0::demangle(s) {
+ Ok(d) => Some(DemangleStyle::V0(d)),
+ Err(v0::Invalid) => None,
+ },
+ };
Demangle {
- inner: inner,
- suffix: suffix,
- valid: valid,
- elements: elements,
+ style: style,
original: s,
+ suffix: suffix,
}
}
@@ -197,7 +129,7 @@
/// ```
pub fn try_demangle(s: &str) -> Result<Demangle, TryDemangleError> {
let sym = demangle(s);
- if sym.valid {
+ if sym.style.is_some() {
Ok(sym)
} else {
Err(TryDemangleError { _priv: () })
@@ -211,11 +143,6 @@
}
}
-// Rust hashes are hex digits with an `h` prepended.
-fn is_rust_hash(s: &str) -> bool {
- s.starts_with('h') && s[1..].chars().all(|c| c.is_digit(16))
-}
-
fn is_symbol_like(s: &str) -> bool {
s.chars().all(|c| {
// Once `char::is_ascii_punctuation` and `char::is_ascii_alphanumeric`
@@ -247,95 +174,16 @@
impl<'a> fmt::Display for Demangle<'a> {
fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
- // Alright, let's do this.
- if !self.valid {
- return f.write_str(self.original);
- }
-
- let mut inner = self.inner;
- for element in 0..self.elements {
- let mut rest = inner;
- while rest.chars().next().unwrap().is_digit(10) {
- rest = &rest[1..];
+ match self.style {
+ None => try!(f.write_str(self.original)),
+ Some(DemangleStyle::Legacy(ref d)) => {
+ try!(fmt::Display::fmt(d, f))
}
- let i: usize = inner[..(inner.len() - rest.len())].parse().unwrap();
- inner = &rest[i..];
- rest = &rest[..i];
- // Skip printing the hash if alternate formatting
- // was requested.
- if f.alternate() && element+1 == self.elements && is_rust_hash(&rest) {
- break;
- }
- if element != 0 {
- try!(f.write_str("::"));
- }
- if rest.starts_with("_$") {
- rest = &rest[1..];
- }
- while !rest.is_empty() {
- if rest.starts_with('.') {
- if let Some('.') = rest[1..].chars().next() {
- try!(f.write_str("::"));
- rest = &rest[2..];
- } else {
- try!(f.write_str("."));
- rest = &rest[1..];
- }
- } else if rest.starts_with('$') {
- macro_rules! demangle {
- ($($pat:expr => $demangled:expr,)*) => ({
- $(if rest.starts_with($pat) {
- try!(f.write_str($demangled));
- rest = &rest[$pat.len()..];
- } else)*
- {
- try!(f.write_str(rest));
- break;
- }
-
- })
- }
-
- // see src/librustc/back/link.rs for these mappings
- demangle! {
- "$SP$" => "@",
- "$BP$" => "*",
- "$RF$" => "&",
- "$LT$" => "<",
- "$GT$" => ">",
- "$LP$" => "(",
- "$RP$" => ")",
- "$C$" => ",",
-
- // in theory we can demangle any Unicode code point, but
- // for simplicity we just catch the common ones.
- "$u7e$" => "~",
- "$u20$" => " ",
- "$u27$" => "'",
- "$u3d$" => "=",
- "$u5b$" => "[",
- "$u5d$" => "]",
- "$u7b$" => "{",
- "$u7d$" => "}",
- "$u3b$" => ";",
- "$u2b$" => "+",
- "$u21$" => "!",
- "$u22$" => "\"",
- }
- } else {
- let idx = match rest.char_indices().find(|&(_, c)| c == '$' || c == '.') {
- None => rest.len(),
- Some((i, _)) => i,
- };
- try!(f.write_str(&rest[..idx]));
- rest = &rest[idx..];
- }
+ Some(DemangleStyle::V0(ref d)) => {
+ try!(fmt::Display::fmt(d, f))
}
}
-
- try!(f.write_str(self.suffix));
-
- Ok(())
+ f.write_str(self.suffix)
}
}
diff --git a/src/v0.rs b/src/v0.rs
new file mode 100644
index 0000000..e976d89
--- /dev/null
+++ b/src/v0.rs
@@ -0,0 +1,1071 @@
+use core::char;
+use core::fmt;
+use core::fmt::Display;
+
+/// Representation of a demangled symbol name.
+pub struct Demangle<'a> {
+ inner: &'a str,
+}
+
+/// De-mangles a Rust symbol into a more readable version
+///
+/// This function will take a **mangled** symbol and return a value. When printed,
+/// the de-mangled version will be written. If the symbol does not look like
+/// a mangled symbol, the original value will be written instead.
+pub fn demangle(s: &str) -> Result<Demangle, Invalid> {
+ // First validate the symbol. If it doesn't look like anything we're
+ // expecting, we just print it literally. Note that we must handle non-Rust
+ // symbols because we could have any function in the backtrace.
+ let inner;
+ if s.len() > 2 && s.starts_with("_R") {
+ inner = &s[2..];
+ } else if s.len() > 1 && s.starts_with("R") {
+ // On Windows, dbghelp strips leading underscores, so we accept "R..."
+ // form too.
+ inner = &s[1..];
+ } else if s.len() > 3 && s.starts_with("__R") {
+ // On OSX, symbols are prefixed with an extra _
+ inner = &s[3..];
+ } else {
+ return Err(Invalid);
+ }
+
+ // Paths always start with uppercase characters.
+ match inner.as_bytes()[0] {
+ b'A'...b'Z' => {}
+ _ => return Err(Invalid),
+ }
+
+ // only work with ascii text
+ if inner.bytes().any(|c| c & 0x80 != 0) {
+ return Err(Invalid);
+ }
+
+ // Verify that the symbol is indeed a valid path.
+ let mut parser = Parser {
+ sym: inner,
+ next: 0,
+ };
+ try!(parser.skip_path());
+ if parser.next < parser.sym.len() {
+ // Instantiating crate.
+ try!(parser.skip_path());
+ }
+ if parser.next != parser.sym.len() {
+ return Err(Invalid);
+ }
+
+ Ok(Demangle {
+ inner: inner,
+ })
+}
+
+impl<'s> Display for Demangle<'s> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ let mut printer = Printer {
+ parser: Ok(Parser {
+ sym: self.inner,
+ next: 0,
+ }),
+ out: f,
+ bound_lifetime_depth: 0,
+ };
+ printer.print_path(true)
+ }
+}
+
+#[derive(PartialEq, Eq)]
+pub struct Invalid;
+
+struct Ident<'s> {
+ /// ASCII part of the identifier.
+ ascii: &'s str,
+ /// Punycode insertion codes for Unicode codepoints, if any.
+ punycode: &'s str,
+}
+
+const SMALL_PUNYCODE_LEN: usize = 128;
+
+impl<'s> Ident<'s> {
+ /// Attempt to decode punycode on the stack (allocation-free),
+ /// and pass the char slice to the closure, if successful.
+ /// This supports up to `SMALL_PUNYCODE_LEN` characters.
+ fn try_small_punycode_decode<F: FnOnce(&[char]) -> R, R>(
+ &self,
+ f: F,
+ ) -> Option<R> {
+ let mut out = ['\0'; SMALL_PUNYCODE_LEN];
+ let mut out_len = 0;
+ let r = self.punycode_decode(|i, c| {
+ // Check there's space left for another character.
+ try!(out.get(out_len).ok_or(()));
+
+ // Move the characters after the insert position.
+ let mut j = out_len;
+ out_len += 1;
+
+ while j > i {
+ out[j] = out[j - 1];
+ j -= 1;
+ }
+
+ // Insert the new character.
+ out[i] = c;
+
+ Ok(())
+ });
+ if r.is_ok() {
+ Some(f(&out[..out_len]))
+ } else {
+ None
+ }
+ }
+
+ /// Decode punycode as insertion positions and characters
+ /// and pass them to the closure, which can return `Err(())`
+ /// to stop the decoding process.
+ fn punycode_decode<F: FnMut(usize, char) -> Result<(), ()>>(
+ &self,
+ mut insert: F,
+ ) -> Result<(), ()> {
+ let mut punycode_bytes = self.punycode.bytes().peekable();
+ if punycode_bytes.peek().is_none() {
+ return Err(());
+ }
+
+ let mut len = 0;
+
+ // Populate initial output from ASCII fragment.
+ for c in self.ascii.chars() {
+ try!(insert(len, c));
+ len += 1;
+ }
+
+ // Punycode parameters and initial state.
+ let base = 36;
+ let t_min = 1;
+ let t_max = 26;
+ let skew = 38;
+ let mut damp = 700;
+ let mut bias = 72;
+ let mut i: usize = 0;
+ let mut n: usize = 0x80;
+
+ loop {
+ // Read one delta value.
+ let mut delta: usize = 0;
+ let mut w = 1;
+ let mut k: usize = 0;
+ loop {
+ use core::cmp::{min, max};
+
+ k += base;
+ let t = min(max(k.saturating_sub(bias), t_min), t_max);
+
+ let d = match punycode_bytes.next() {
+ Some(d @ b'a'...b'z') => d - b'a',
+ Some(d @ b'A'...b'J') => 26 + (d - b'A'),
+ _ => return Err(()),
+ };
+ let d = d as usize;
+ delta = try!(delta.checked_add(
+ try!(d.checked_mul(w).ok_or(()))
+ ).ok_or(()));
+ if d < t {
+ break;
+ }
+ w = try!(w.checked_mul(base - t).ok_or(()));
+ }
+
+ // Compute the new insert position and character.
+ len += 1;
+ i = try!(i.checked_add(delta).ok_or(()));
+ n = try!(n.checked_add(i / len).ok_or(()));
+ i %= len;
+
+ let n_u32 = n as u32;
+ let c = if n_u32 as usize == n {
+ try!(char::from_u32(n_u32).ok_or(()))
+ } else {
+ return Err(());
+ };
+
+ // Insert the new character and increment the insert position.
+ try!(insert(i, c));
+ i += 1;
+
+ // If there are no more deltas, decoding is complete.
+ if punycode_bytes.peek().is_none() {
+ return Ok(());
+ }
+
+ // Perform bias adaptation.
+ delta /= damp;
+ damp = 2;
+
+ delta += delta / len;
+ let mut k = 0;
+ while delta > ((base - t_min) * t_max) / 2 {
+ delta /= base - t_min;
+ k += base;
+ }
+ bias = k + ((base - t_min + 1) * delta) / (delta + skew);
+ }
+ }
+}
+
+impl<'s> Display for Ident<'s> {
+ fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+ self.try_small_punycode_decode(|chars| {
+ for &c in chars {
+ try!(c.fmt(f));
+ }
+ Ok(())
+ }).unwrap_or_else(|| {
+ if !self.punycode.is_empty() {
+ try!(f.write_str("punycode{"));
+
+ // Reconstruct a standard Punycode encoding,
+ // by using `-` as the separator and replacing
+ // [A-J] with [0-9] (in the base36 codes).
+ if !self.ascii.is_empty() {
+ try!(f.write_str(self.ascii));
+ try!(f.write_str("-"));
+ }
+ for mut b in self.punycode.bytes() {
+ if let b'A'...b'J' = b {
+ b = b - b'A' + b'0';
+ }
+ try!((b as char).fmt(f));
+ }
+
+ f.write_str("}")
+ } else {
+ f.write_str(self.ascii)
+ }
+ })
+ }
+}
+
+fn basic_type(tag: u8) -> Option<&'static str> {
+ Some(match tag {
+ b'b' => "bool",
+ b'c' => "char",
+ b'e' => "str",
+ b'u' => "()",
+ b'a' => "i8",
+ b's' => "i16",
+ b'l' => "i32",
+ b'x' => "i64",
+ b'n' => "i128",
+ b'i' => "isize",
+ b'h' => "u8",
+ b't' => "u16",
+ b'm' => "u32",
+ b'y' => "u64",
+ b'o' => "u128",
+ b'j' => "usize",
+ b'f' => "f32",
+ b'd' => "f64",
+ b'z' => "!",
+ b'p' => "_",
+ b'v' => "...",
+
+ _ => return None,
+ })
+}
+
+struct Parser<'s> {
+ sym: &'s str,
+ next: usize,
+}
+
+impl<'s> Parser<'s> {
+ fn peek(&self) -> Option<u8> {
+ self.sym.as_bytes().get(self.next).cloned()
+ }
+
+ fn eat(&mut self, b: u8) -> bool {
+ if self.peek() == Some(b) {
+ self.next += 1;
+ true
+ } else {
+ false
+ }
+ }
+
+ fn next(&mut self) -> Result<u8, Invalid> {
+ let b = try!(self.peek().ok_or(Invalid));
+ self.next += 1;
+ Ok(b)
+ }
+
+ fn hex_nibbles(&mut self) -> Result<&'s str, Invalid> {
+ let start = self.next;
+ loop {
+ match try!(self.next()) {
+ b'0'...b'9' | b'a'...b'f' => {}
+ b'_' => break,
+ _ => return Err(Invalid),
+ }
+ }
+ Ok(&self.sym[start..self.next - 1])
+ }
+
+ fn digit_10(&mut self) -> Result<u8, Invalid> {
+ let d = match self.peek() {
+ Some(d @ b'0'...b'9') => d - b'0',
+ _ => return Err(Invalid),
+ };
+ self.next += 1;
+ Ok(d)
+ }
+
+ fn digit_62(&mut self) -> Result<u8, Invalid> {
+ let d = match self.peek() {
+ Some(d @ b'0'...b'9') => d - b'0',
+ Some(d @ b'a'...b'z') => 10 + (d - b'a'),
+ Some(d @ b'A'...b'Z') => 10 + 26 + (d - b'A'),
+ _ => return Err(Invalid),
+ };
+ self.next += 1;
+ Ok(d)
+ }
+
+ fn integer_62(&mut self) -> Result<u64, Invalid> {
+ if self.eat(b'_') {
+ return Ok(0);
+ }
+
+ let mut x: u64 = 0;
+ while !self.eat(b'_') {
+ let d = try!(self.digit_62()) as u64;
+ x = try!(x.checked_mul(62).ok_or(Invalid));
+ x = try!(x.checked_add(d).ok_or(Invalid));
+ }
+ x.checked_add(1).ok_or(Invalid)
+ }
+
+ fn opt_integer_62(&mut self, tag: u8) -> Result<u64, Invalid> {
+ if !self.eat(tag) {
+ return Ok(0);
+ }
+ try!(self.integer_62()).checked_add(1).ok_or(Invalid)
+ }
+
+ fn disambiguator(&mut self) -> Result<u64, Invalid> {
+ self.opt_integer_62(b's')
+ }
+
+ fn namespace(&mut self) -> Result<Option<char>, Invalid> {
+ match try!(self.next()) {
+ // Special namespaces, like closures and shims.
+ ns @ b'A'...b'Z' => Ok(Some(ns as char)),
+
+ // Implementation-specific/unspecified namespaces.
+ b'a'...b'z' => Ok(None),
+
+ _ => Err(Invalid),
+ }
+ }
+
+ fn backref(&mut self) -> Result<Parser<'s>, Invalid> {
+ let s_start = self.next - 1;
+ let i = try!(self.integer_62());
+ if i >= s_start as u64 {
+ return Err(Invalid);
+ }
+ Ok(Parser {
+ sym: self.sym,
+ next: i as usize,
+ })
+ }
+
+ fn ident(&mut self) -> Result<Ident<'s>, Invalid> {
+ let is_punycode = self.eat(b'u');
+ let mut len = try!(self.digit_10()) as usize;
+ if len != 0 {
+ loop {
+ match self.digit_10() {
+ Ok(d) => {
+ len = try!(len.checked_mul(10).ok_or(Invalid));
+ len = try!(len.checked_add(d as usize).ok_or(Invalid));
+ }
+ Err(Invalid) => break,
+ }
+ }
+ }
+
+ let start = self.next;
+ self.next = try!(self.next.checked_add(len).ok_or(Invalid));
+ if self.next > self.sym.len() {
+ return Err(Invalid);
+ }
+
+ let ident = &self.sym[start..self.next];
+
+ if is_punycode {
+ let ident = match ident.bytes().rposition(|b| b == b'_') {
+ Some(i) => Ident {
+ ascii: &ident[..i],
+ punycode: &ident[i + 1..],
+ },
+ None => Ident {
+ ascii: "",
+ punycode: ident,
+ },
+ };
+ if ident.punycode.is_empty() {
+ return Err(Invalid);
+ }
+ Ok(ident)
+ } else {
+ Ok(Ident {
+ ascii: ident,
+ punycode: "",
+ })
+ }
+ }
+
+ fn skip_path(&mut self) -> Result<(), Invalid> {
+ match try!(self.next()) {
+ b'C' => {
+ try!(self.disambiguator());
+ try!(self.ident());
+ }
+ b'N' => {
+ try!(self.namespace());
+ try!(self.skip_path());
+ try!(self.disambiguator());
+ try!(self.ident());
+ }
+ b'M' => {
+ try!(self.disambiguator());
+ try!(self.skip_path());
+ try!(self.skip_type());
+ }
+ b'X' => {
+ try!(self.disambiguator());
+ try!(self.skip_path());
+ try!(self.skip_type());
+ try!(self.skip_path());
+ }
+ b'Y' => {
+ try!(self.skip_type());
+ try!(self.skip_path());
+ }
+ b'I' => {
+ try!(self.skip_path());
+ while !self.eat(b'E') {
+ try!(self.skip_generic_arg());
+ }
+ }
+ b'B' => {
+ try!(self.backref());
+ }
+ _ => return Err(Invalid),
+ }
+ Ok(())
+ }
+
+ fn skip_generic_arg(&mut self) -> Result<(), Invalid> {
+ if self.eat(b'L') {
+ try!(self.integer_62());
+ Ok(())
+ } else if self.eat(b'K') {
+ self.skip_const()
+ } else {
+ self.skip_type()
+ }
+ }
+
+ fn skip_type(&mut self) -> Result<(), Invalid> {
+ match try!(self.next()) {
+ tag if basic_type(tag).is_some() => {}
+
+ b'R' | b'Q' => {
+ if self.eat(b'L') {
+ try!(self.integer_62());
+ }
+ try!(self.skip_type());
+ }
+ b'P' | b'O' | b'S' => try!(self.skip_type()),
+ b'A' => {
+ try!(self.skip_type());
+ try!(self.skip_const());
+ }
+ b'T' => while !self.eat(b'E') {
+ try!(self.skip_type());
+ },
+ b'F' => {
+ let _binder = try!(self.opt_integer_62(b'G'));
+ let _is_unsafe = self.eat(b'U');
+ if self.eat(b'K') {
+ let c_abi = self.eat(b'C');
+ if !c_abi {
+ let abi = try!(self.ident());
+ if abi.ascii.is_empty() || !abi.punycode.is_empty() {
+ return Err(Invalid);
+ }
+ }
+ }
+ while !self.eat(b'E') {
+ try!(self.skip_type());
+ }
+ try!(self.skip_type());
+ }
+ b'D' => {
+ let _binder = try!(self.opt_integer_62(b'G'));
+ while !self.eat(b'E') {
+ try!(self.skip_path());
+ while self.eat(b'p') {
+ try!(self.ident());
+ try!(self.skip_type());
+ }
+ }
+ if !self.eat(b'L') {
+ return Err(Invalid);
+ }
+ try!(self.integer_62());
+ }
+ b'B' => {
+ try!(self.backref());
+ }
+ _ => {
+ // Go back to the tag, so `skip_path` also sees it.
+ self.next -= 1;
+ try!(self.skip_path());
+ }
+ }
+ Ok(())
+ }
+
+ fn skip_const(&mut self) -> Result<(), Invalid> {
+ if self.eat(b'B') {
+ try!(self.backref());
+ return Ok(());
+ }
+
+ match try!(self.next()) {
+ // Unsigned integer types.
+ b'h' | b't' | b'm' | b'y' | b'o' | b'j' => {}
+
+ _ => return Err(Invalid),
+ }
+
+ if self.eat(b'p') {
+ return Ok(());
+ }
+ try!(self.hex_nibbles());
+ Ok(())
+ }
+}
+
+struct Printer<'a, 'b: 'a, 's> {
+ parser: Result<Parser<'s>, Invalid>,
+ out: &'a mut fmt::Formatter<'b>,
+ bound_lifetime_depth: u32,
+}
+
+/// Mark the parser as errored, print `?` and return early.
+/// This allows callers to keep printing the approximate
+/// syntax of the path/type/const, despite having errors.
+/// E.g. `Vec<[(A, ?); ?]>` instead of `Vec<[(A, ?`.
+macro_rules! invalid {
+ ($printer:ident) => {{
+ $printer.parser = Err(Invalid);
+ return $printer.out.write_str("?");
+ }}
+}
+
+/// Call a parser method (if the parser hasn't errored yet),
+/// and mark the parser as errored if it returns `Err(Invalid)`.
+///
+/// If the parser errored, before or now, prints `?`, and
+/// returns early the current function (see `invalid!` above).
+macro_rules! parse {
+ ($printer:ident, $method:ident $(($($arg:expr),*))*) => {
+ match $printer.parser_mut().and_then(|p| p.$method($($($arg),*)*)) {
+ Ok(x) => x,
+ Err(Invalid) => invalid!($printer),
+ }
+ };
+}
+
+impl<'a, 'b, 's> Printer<'a, 'b, 's> {
+ fn parser_mut<'c>(&'c mut self) -> Result<&'c mut Parser<'s>, Invalid> {
+ self.parser.as_mut().map_err(|_| Invalid)
+ }
+
+ /// Eat the given character from the parser,
+ /// returning `false` if the parser errored.
+ fn eat(&mut self, b: u8) -> bool {
+ self.parser_mut().map(|p| p.eat(b)) == Ok(true)
+ }
+
+ /// Return a nested parser for a backref.
+ fn backref_printer<'c>(&'c mut self) -> Printer<'c, 'b, 's> {
+ Printer {
+ parser: self.parser_mut().and_then(|p| p.backref()),
+ out: self.out,
+ bound_lifetime_depth: self.bound_lifetime_depth,
+ }
+ }
+
+ /// Print the lifetime according to the previously decoded index.
+ /// An index of `0` always refers to `'_`, but starting with `1`,
+ /// indices refer to late-bound lifetimes introduced by a binder.
+ fn print_lifetime_from_index(&mut self, lt: u64) -> fmt::Result {
+ try!(self.out.write_str("'"));
+ if lt == 0 {
+ return self.out.write_str("_");
+ }
+ match (self.bound_lifetime_depth as u64).checked_sub(lt) {
+ Some(depth) => {
+ // Try to print lifetimes alphabetically first.
+ if depth < 26 {
+ let c = (b'a' + depth as u8) as char;
+ c.fmt(self.out)
+ } else {
+ // Use `'_123` after running out of letters.
+ try!(self.out.write_str("_"));
+ depth.fmt(self.out)
+ }
+ }
+ None => invalid!(self),
+ }
+ }
+
+ /// Optionally enter a binder ('G') for late-bound lifetimes,
+ /// printing e.g. `for<'a, 'b> ` before calling the closure,
+ /// and make those lifetimes visible to it (via depth level).
+ fn in_binder<F>(&mut self, f: F) -> fmt::Result
+ where F: FnOnce(&mut Self) -> fmt::Result,
+ {
+ let bound_lifetimes = parse!(self, opt_integer_62(b'G'));
+
+ if bound_lifetimes > 0 {
+ try!(self.out.write_str("for<"));
+ for i in 0..bound_lifetimes {
+ if i > 0 {
+ try!(self.out.write_str(", "));
+ }
+ self.bound_lifetime_depth += 1;
+ try!(self.print_lifetime_from_index(1));
+ }
+ try!(self.out.write_str("> "));
+ }
+
+ let r = f(self);
+
+ // Restore `bound_lifetime_depth` to the previous value.
+ self.bound_lifetime_depth -= bound_lifetimes as u32;
+
+ r
+ }
+
+ /// Print list elements using the given closure and separator,
+ /// until the end of the list ('E') is found, or the parser errors.
+ /// Returns the number of elements printed.
+ fn print_sep_list<F>(&mut self, f: F, sep: &str) -> Result<usize, fmt::Error>
+ where F: Fn(&mut Self) -> fmt::Result,
+ {
+ let mut i = 0;
+ while self.parser.is_ok() && !self.eat(b'E') {
+ if i > 0 {
+ try!(self.out.write_str(sep));
+ }
+ try!(f(self));
+ i += 1;
+ }
+ Ok(i)
+ }
+
+ fn print_path(&mut self, in_value: bool) -> fmt::Result {
+ let tag = parse!(self, next);
+ match tag {
+ b'C' => {
+ let dis = parse!(self, disambiguator);
+ let name = parse!(self, ident);
+
+ if name.punycode.is_empty() {
+ // Unescape `_[0-9_]`.
+ let mut name = name.ascii;
+ if name.starts_with("_") {
+ name = &name[1..];
+ }
+ try!(self.out.write_str(name));
+ } else {
+ try!(name.fmt(self.out));
+ }
+ if !self.out.alternate() {
+ try!(self.out.write_str("["));
+ try!(fmt::LowerHex::fmt(&dis, self.out));
+ try!(self.out.write_str("]"));
+ }
+ }
+ b'N' => {
+ let ns = parse!(self, namespace);
+
+ try!(self.print_path(in_value));
+
+ let dis = parse!(self, disambiguator);
+ let name = parse!(self, ident);
+
+ match ns {
+ // Special namespaces, like closures and shims.
+ Some(ns) => {
+ try!(self.out.write_str("::{"));
+ match ns {
+ 'C' => try!(self.out.write_str("closure")),
+ 'S' => try!(self.out.write_str("shim")),
+ _ => try!(ns.fmt(self.out)),
+ }
+ if !name.ascii.is_empty() || !name.punycode.is_empty() {
+ try!(self.out.write_str(":"));
+ try!(name.fmt(self.out));
+ }
+ try!(self.out.write_str("#"));
+ try!(dis.fmt(self.out));
+ try!(self.out.write_str("}"));
+ }
+
+ // Implementation-specific/unspecified namespaces.
+ None => {
+ if !name.ascii.is_empty() || !name.punycode.is_empty() {
+ try!(self.out.write_str("::"));
+ try!(name.fmt(self.out));
+ }
+ }
+ }
+ }
+ b'M' | b'X' | b'Y' => {
+ if tag != b'Y' {
+ // Ignore the `impl`'s own path.
+ parse!(self, disambiguator);
+ parse!(self, skip_path);
+ }
+
+ try!(self.out.write_str("<"));
+ try!(self.print_type());
+ if tag != b'M' {
+ try!(self.out.write_str(" as "));
+ try!(self.print_path(false));
+ }
+ try!(self.out.write_str(">"));
+ }
+ b'I' => {
+ try!(self.print_path(in_value));
+ if in_value {
+ try!(self.out.write_str("::"));
+ }
+ try!(self.out.write_str("<"));
+ try!(self.print_sep_list(Self::print_generic_arg, ", "));
+ try!(self.out.write_str(">"));
+ }
+ b'B' => {
+ try!(self.backref_printer().print_path(in_value));
+ }
+ _ => invalid!(self),
+ }
+ Ok(())
+ }
+
+ fn print_generic_arg(&mut self) -> fmt::Result {
+ if self.eat(b'L') {
+ let lt = parse!(self, integer_62);
+ self.print_lifetime_from_index(lt)
+ } else if self.eat(b'K') {
+ self.print_const()
+ } else {
+ self.print_type()
+ }
+ }
+
+ fn print_type(&mut self) -> fmt::Result {
+ let tag = parse!(self, next);
+
+ match basic_type(tag) {
+ Some(ty) => return self.out.write_str(ty),
+ None => {}
+ }
+
+ match tag {
+ b'R' | b'Q' => {
+ try!(self.out.write_str("&"));
+ if self.eat(b'L') {
+ let lt = parse!(self, integer_62);
+ if lt != 0 {
+ try!(self.print_lifetime_from_index(lt));
+ try!(self.out.write_str(" "));
+ }
+ }
+ if tag != b'R' {
+ try!(self.out.write_str("mut "));
+ }
+ try!(self.print_type());
+ }
+
+ b'P' | b'O' => {
+ try!(self.out.write_str("*"));
+ if tag != b'P' {
+ try!(self.out.write_str("mut "));
+ } else {
+ try!(self.out.write_str("const "));
+ }
+ try!(self.print_type());
+ }
+
+ b'A' | b'S' => {
+ try!(self.out.write_str("["));
+ try!(self.print_type());
+ if tag == b'A' {
+ try!(self.out.write_str("; "));
+ try!(self.print_const());
+ }
+ try!(self.out.write_str("]"));
+ }
+ b'T' => {
+ try!(self.out.write_str("("));
+ let count = try!(self.print_sep_list(Self::print_type, ", "));
+ if count == 1 {
+ try!(self.out.write_str(","));
+ }
+ try!(self.out.write_str(")"));
+ }
+ b'F' => try!(self.in_binder(|this| {
+ let is_unsafe = this.eat(b'U');
+ let abi = if this.eat(b'K') {
+ if this.eat(b'C') {
+ Some("C")
+ } else {
+ let abi = parse!(this, ident);
+ if abi.ascii.is_empty() || !abi.punycode.is_empty() {
+ invalid!(this);
+ }
+ Some(abi.ascii)
+ }
+ } else {
+ None
+ };
+
+ if is_unsafe {
+ try!(this.out.write_str("unsafe "));
+ }
+
+ match abi {
+ Some(abi) => {
+ try!(this.out.write_str("extern \""));
+
+ // If the ABI had any `-`, they were replaced with `_`,
+ // so the parts between `_` have to be re-joined with `-`.
+ let mut parts = abi.split('_');
+ try!(this.out.write_str(parts.next().unwrap()));
+ for part in parts {
+ try!(this.out.write_str("-"));
+ try!(this.out.write_str(part));
+ }
+
+ try!(this.out.write_str("\" "));
+ }
+ None => {}
+ }
+
+ try!(this.out.write_str("fn("));
+ try!(this.print_sep_list(Self::print_type, ", "));
+ try!(this.out.write_str(")"));
+
+ if this.eat(b'u') {
+ // Skip printing the return type if it's 'u', i.e. `()`.
+ } else {
+ try!(this.out.write_str(" -> "));
+ try!(this.print_type());
+ }
+
+ Ok(())
+ })),
+ b'D' => {
+ try!(self.out.write_str("dyn "));
+ try!(self.in_binder(|this| {
+ try!(this.print_sep_list(Self::print_dyn_trait, " + "));
+ Ok(())
+ }));
+
+ if !self.eat(b'L') {
+ invalid!(self);
+ }
+ let lt = parse!(self, integer_62);
+ if lt != 0 {
+ try!(self.out.write_str(" + "));
+ try!(self.print_lifetime_from_index(lt));
+ }
+ }
+ b'B' => {
+ try!(self.backref_printer().print_type());
+ }
+ _ => {
+ // Go back to the tag, so `print_path` also sees it.
+ let _ = self.parser_mut().map(|p| p.next -= 1);
+ try!(self.print_path(false));
+ }
+ }
+ Ok(())
+ }
+
+ /// A trait in a trait object may have some "existential projections"
+ /// (i.e. associated type bindings) after it, which should be printed
+ /// in the `<...>` of the trait, e.g. `dyn Trait<T, U, Assoc=X>`.
+ /// To this end, this method will keep the `<...>` of an 'I' path
+ /// open, by omitting the `>`, and return `Ok(true)` in that case.
+ fn print_path_maybe_open_generics(&mut self) -> Result<bool, fmt::Error> {
+ if self.eat(b'B') {
+ self.backref_printer().print_path_maybe_open_generics()
+ } else if self.eat(b'I') {
+ try!(self.print_path(false));
+ try!(self.out.write_str("<"));
+ try!(self.print_sep_list(Self::print_generic_arg, ", "));
+ Ok(true)
+ } else {
+ try!(self.print_path(false));
+ Ok(false)
+ }
+ }
+
+ fn print_dyn_trait(&mut self) -> fmt::Result {
+ let mut open = try!(self.print_path_maybe_open_generics());
+
+ while self.eat(b'p') {
+ if !open {
+ try!(self.out.write_str("<"));
+ open = true;
+ } else {
+ try!(self.out.write_str(", "));
+ }
+
+ let name = parse!(self, ident);
+ try!(name.fmt(self.out));
+ try!(self.out.write_str(" = "));
+ try!(self.print_type());
+ }
+
+ if open {
+ try!(self.out.write_str(">"));
+ }
+
+ Ok(())
+ }
+
+ fn print_const(&mut self) -> fmt::Result {
+ if self.eat(b'B') {
+ return self.backref_printer().print_const();
+ }
+
+ let ty_tag = parse!(self, next);
+ let ty = match ty_tag {
+ // Unsigned integer types.
+ b'h' | b't' | b'm' | b'y' | b'o' | b'j' => {
+ basic_type(ty_tag).unwrap()
+ }
+
+ _ => invalid!(self),
+ };
+
+
+ if self.eat(b'p') {
+ try!(self.out.write_str("_"));
+ } else {
+ try!(self.print_const_uint());
+ }
+
+ if !self.out.alternate() {
+ try!(self.out.write_str(": "));
+ try!(self.out.write_str(ty));
+ }
+
+ Ok(())
+ }
+
+ fn print_const_uint(&mut self) -> fmt::Result {
+ let hex = parse!(self, hex_nibbles);
+
+ // Print anything that doesn't fit in `u64` verbatim.
+ if hex.len() > 16 {
+ try!(self.out.write_str("0x"));
+ return self.out.write_str(hex);
+ }
+
+ let mut v = 0;
+ for c in hex.chars() {
+ v = (v << 4) | (c.to_digit(16).unwrap() as u64);
+ }
+ v.fmt(self.out)
+ }
+}
+
+#[cfg(test)]
+mod tests {
+ macro_rules! t_nohash {
+ ($a:expr, $b:expr) => ({
+ assert_eq!(format!("{:#}", ::demangle($a)), $b);
+ })
+ }
+ macro_rules! t_nohash_type {
+ ($a:expr, $b:expr) => (
+ t_nohash!(concat!("_RMC0", $a), concat!("<", $b, ">"))
+ )
+ }
+
+ #[test]
+ fn demangle_utf8_idents() {
+ t_nohash!(
+ "_RNqCs4fqI2P2rA04_11utf8_identsu30___HhkackfeceaBcbdathfdhJhlqGy",
+ "utf8_idents::საჭმელად_გემრიელი_სადილი"
+ );
+ }
+
+ #[test]
+ fn demangle_closure() {
+ t_nohash!(
+ "_RNCNCNgCs6DXkGYLi8lr_2cc5spawn00B5_",
+ "cc::spawn::{closure#0}::{closure#0}"
+ );
+ t_nohash!(
+ "_RNCINkXs25_NgCsbmNqQUJIY6D_4core5sliceINyB9_4IterhENuNgNoBb_4iter8iterator8Iterator9rpositionNCNgNpB9_6memchr7memrchrs_0E0Bb_",
+ "<core::slice::Iter<u8> as core::iter::iterator::Iterator>::rposition::<core::slice::memchr::memrchr::{closure#1}>::{closure#0}"
+ );
+ }
+
+ #[test]
+ fn demangle_dyn_trait() {
+ t_nohash!(
+ "_RINbNbCskIICzLVDPPb_5alloc5alloc8box_freeDINbNiB4_5boxed5FnBoxuEp6OutputuEL_ECs1iopQbuBiw2_3std",
+ "alloc::alloc::box_free::<dyn alloc::boxed::FnBox<(), Output = ()>>"
+ );
+ }
+
+ #[test]
+ fn demangle_const_generics() {
+ // NOTE(eddyb) this was hand-written, before rustc had working
+ // const generics support (but the mangling format did include them).
+ t_nohash_type!(
+ "INtC8arrayvec8ArrayVechKj7b_E",
+ "arrayvec::ArrayVec<u8, 123>"
+ );
+ }
+
+ #[test]
+ fn demangle_exponential_explosion() {
+ // NOTE(eddyb) because of the prefix added by `t_nohash_type!` is
+ // 3 bytes long, `B2_` refers to the start of the type, not `B_`.
+ // 6 backrefs (`B8_E` through `B3_E`) result in 2^6 = 64 copies of `_`.
+ // Also, because the `p` (`_`) type is after all of the starts of the
+ // backrefs, it can be replaced with any other type, independently.
+ t_nohash_type!(
+ concat!("TTTTTT", "p", "B8_E", "B7_E", "B6_E", "B5_E", "B4_E", "B3_E"),
+ "((((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _)))), \
+ ((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _))))), \
+ (((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _)))), \
+ ((((_, _), (_, _)), ((_, _), (_, _))), (((_, _), (_, _)), ((_, _), (_, _))))))"
+ );
+ }
+}
