auto merge of #12098 : kballard/rust/from_utf8_lossy_tweak, r=huonw

MaybeOwned allows from_utf8_lossy to avoid allocation if there are no
invalid bytes in the input.

Before:
```
test str::bench::from_utf8_lossy_100_ascii                      ... bench:       183 ns/iter (+/- 5)
test str::bench::from_utf8_lossy_100_invalid                    ... bench:       341 ns/iter (+/- 15)
test str::bench::from_utf8_lossy_100_multibyte                  ... bench:       227 ns/iter (+/- 13)
test str::bench::from_utf8_lossy_invalid                        ... bench:       102 ns/iter (+/- 4)
test str::bench::is_utf8_100_ascii                              ... bench:         2 ns/iter (+/- 0)
test str::bench::is_utf8_100_multibyte                          ... bench:         2 ns/iter (+/- 0)
```

Now:
```
test str::bench::from_utf8_lossy_100_ascii                      ... bench:        96 ns/iter (+/- 4)
test str::bench::from_utf8_lossy_100_invalid                    ... bench:       318 ns/iter (+/- 10)
test str::bench::from_utf8_lossy_100_multibyte                  ... bench:       105 ns/iter (+/- 2)
test str::bench::from_utf8_lossy_invalid                        ... bench:       105 ns/iter (+/- 2)
test str::bench::is_utf8_100_ascii                              ... bench:         2 ns/iter (+/- 0)
test str::bench::is_utf8_100_multibyte                          ... bench:         2 ns/iter (+/- 0)
```

Author: bors

src/compiletest/runtest.rs

@@ -442,9 +442,7 @@ fn check_error_patterns(props: &TestProps,
                         testfile: &Path,
                         ProcRes: &ProcRes) {
     if props.error_patterns.is_empty() {
-        testfile.display().with_str(|s| {
-            fatal(~"no error pattern specified in " + s);
-        })
+        fatal(~"no error pattern specified in " + testfile.display().as_maybe_owned().as_slice());
     }
 
     if ProcRes.status.success() {

src/etc/vim/syntax/rust.vim

@@ -87,8 +87,7 @@ syn keyword rustTrait Primitive Int Float ToStrRadix ToPrimitive FromPrimitive
 syn keyword rustTrait GenericPath Path PosixPath WindowsPath
 syn keyword rustTrait RawPtr
 syn keyword rustTrait Buffer Writer Reader Seek
-syn keyword rustTrait SendStr SendStrOwned SendStrStatic IntoSendStr
-syn keyword rustTrait Str StrVector StrSlice OwnedStr
+syn keyword rustTrait Str StrVector StrSlice OwnedStr IntoMaybeOwned
 syn keyword rustTrait IterBytes
 syn keyword rustTrait ToStr IntoStr
 syn keyword rustTrait CloneableTuple ImmutableTuple

src/libextra/test.rs

@@ -893,8 +893,8 @@ pub fn run_test(force_ignore: bool,
         spawn(proc() {
             let mut task = task::task();
             task.name(match desc.name {
-                DynTestName(ref name) => SendStrOwned(name.clone()),
-                StaticTestName(name) => SendStrStatic(name),
+                DynTestName(ref name) => name.to_owned().into_maybe_owned(),
+                StaticTestName(name) => name.into_maybe_owned()
             });
             let result_future = task.future_result();
             task.spawn(testfn);

src/libgreen/lib.rs

@@ -257,7 +257,7 @@ pub fn run(main: proc()) -> int {
     let (port, chan) = Chan::new();
     let mut opts = TaskOpts::new();
     opts.notify_chan = Some(chan);
-    opts.name = Some(SendStrStatic("<main>"));
+    opts.name = Some("<main>".into_maybe_owned());
     pool.spawn(opts, main);
 
     // Wait for the main task to return, and set the process error code

src/libgreen/task.rs

@@ -510,7 +510,7 @@ mod tests {
     #[test]
     fn smoke_opts() {
         let mut opts = TaskOpts::new();
-        opts.name = Some(SendStrStatic("test"));
+        opts.name = Some("test".into_maybe_owned());
         opts.stack_size = Some(20 * 4096);
         let (p, c) = Chan::new();
         opts.notify_chan = Some(c);

src/libnative/task.rs

@@ -294,7 +294,7 @@ mod tests {
     #[test]
     fn smoke_opts() {
         let mut opts = TaskOpts::new();
-        opts.name = Some(SendStrStatic("test"));
+        opts.name = Some("test".into_maybe_owned());
         opts.stack_size = Some(20 * 4096);
         let (p, c) = Chan::new();
         opts.notify_chan = Some(c);

src/librustdoc/html/render.rs

@@ -436,7 +436,7 @@ impl<'a> SourceCollector<'a> {
         cur.push(p.filename().expect("source has no filename") + bytes!(".html"));
         let mut w = BufferedWriter::new(if_ok!(File::create(&cur)));
 
-        let title = cur.filename_display().with_str(|s| format!("{} -- source", s));
+        let title = format!("{} -- source", cur.filename_display());
         let page = layout::Page {
             title: title,
             ty: "source",

src/libstd/lib.rs

@@ -117,7 +117,6 @@ pub mod vec_ng;
 pub mod str;
 
 pub mod ascii;
-pub mod send_str;
 
 pub mod ptr;
 pub mod owned;

src/libstd/path/mod.rs

@@ -70,7 +70,7 @@ use fmt;
 use iter::Iterator;
 use option::{Option, None, Some};
 use str;
-use str::{OwnedStr, Str, StrSlice};
+use str::{MaybeOwned, OwnedStr, Str, StrSlice, from_utf8_lossy};
 use to_str::ToStr;
 use vec;
 use vec::{CloneableVector, OwnedCloneableVector, OwnedVector, Vector};
@@ -495,7 +495,7 @@ pub struct Display<'a, P> {
 
 impl<'a, P: GenericPath> fmt::Show for Display<'a, P> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        self.with_str(|s| f.pad(s))
+        self.as_maybe_owned().as_slice().fmt(f)
     }
 }
 
@@ -505,33 +505,25 @@ impl<'a, P: GenericPath> ToStr for Display<'a, P> {
     /// If the path is not UTF-8, invalid sequences with be replaced with the
     /// unicode replacement char. This involves allocation.
     fn to_str(&self) -> ~str {
-        if self.filename {
-            match self.path.filename() {
-                None => ~"",
-                Some(v) => str::from_utf8_lossy(v)
-            }
-        } else {
-            str::from_utf8_lossy(self.path.as_vec())
-        }
+        self.as_maybe_owned().into_owned()
     }
 }
 
 impl<'a, P: GenericPath> Display<'a, P> {
-    /// Provides the path as a string to a closure
+    /// Returns the path as a possibly-owned string.
     ///
     /// If the path is not UTF-8, invalid sequences will be replaced with the
     /// unicode replacement char. This involves allocation.
     #[inline]
-    pub fn with_str<T>(&self, f: |&str| -> T) -> T {
-        let opt = if self.filename { self.path.filename_str() }
-                  else { self.path.as_str() };
-        match opt {
-            Some(s) => f(s),
-            None => {
-                let s = self.to_str();
-                f(s.as_slice())
+    pub fn as_maybe_owned(&self) -> MaybeOwned<'a> {
+        from_utf8_lossy(if self.filename {
+            match self.path.filename() {
+                None => &[],
+                Some(v) => v
             }
-        }
+        } else {
+            self.path.as_vec()
+        })
     }
 }
 
@@ -591,6 +583,23 @@ impl BytesContainer for CString {
     }
 }
 
+impl<'a> BytesContainer for str::MaybeOwned<'a> {
+    #[inline]
+    fn container_as_bytes<'b>(&'b self) -> &'b [u8] {
+        self.as_slice().as_bytes()
+    }
+    #[inline]
+    fn container_into_owned_bytes(self) -> ~[u8] {
+        self.into_owned().into_bytes()
+    }
+    #[inline]
+    fn container_as_str<'b>(&'b self) -> Option<&'b str> {
+        Some(self.as_slice())
+    }
+    #[inline]
+    fn is_str(_: Option<str::MaybeOwned>) -> bool { true }
+}
+
 #[inline(always)]
 fn contains_nul(v: &[u8]) -> bool {
     v.iter().any(|&x| x == 0)

src/libstd/path/posix.rs

@@ -564,24 +564,16 @@ mod tests {
         macro_rules! t(
             ($path:expr, $exp:expr) => (
                 {
-                    let mut called = false;
                     let path = Path::new($path);
-                    path.display().with_str(|s| {
-                        assert_eq!(s, $exp);
-                        called = true;
-                    });
-                    assert!(called);
+                    let mo = path.display().as_maybe_owned();
+                    assert_eq!(mo.as_slice(), $exp);
                 }
             );
             ($path:expr, $exp:expr, filename) => (
                 {
-                    let mut called = false;
                     let path = Path::new($path);
-                    path.filename_display().with_str(|s| {
-                        assert_eq!(s, $exp);
-                        called = true;
-                    });
-                    assert!(called);
+                    let mo = path.filename_display().as_maybe_owned();
+                    assert_eq!(mo.as_slice(), $exp);
                 }
             )
         )

src/libstd/path/windows.rs

@@ -1278,20 +1278,12 @@ mod tests {
         let path = Path::new(b!("\\"));
         assert_eq!(path.filename_display().to_str(), ~"");
 
-        let mut called = false;
         let path = Path::new("foo");
-        path.display().with_str(|s| {
-            assert_eq!(s, "foo");
-            called = true;
-        });
-        assert!(called);
-        called = false;
+        let mo = path.display().as_maybe_owned();
+        assert_eq!(mo.as_slice(), "foo");
         let path = Path::new(b!("\\"));
-        path.filename_display().with_str(|s| {
-            assert_eq!(s, "");
-            called = true;
-        });
-        assert!(called);
+        let mo = path.filename_display().as_maybe_owned();
+        assert_eq!(mo.as_slice(), "");
     }
 
     #[test]

src/libstd/prelude.rs

@@ -63,8 +63,7 @@ pub use num::{Primitive, Int, Float, ToStrRadix, ToPrimitive, FromPrimitive};
 pub use path::{GenericPath, Path, PosixPath, WindowsPath};
 pub use ptr::RawPtr;
 pub use io::{Buffer, Writer, Reader, Seek};
-pub use send_str::{SendStr, SendStrOwned, SendStrStatic, IntoSendStr};
-pub use str::{Str, StrVector, StrSlice, OwnedStr};
+pub use str::{Str, StrVector, StrSlice, OwnedStr, IntoMaybeOwned};
 pub use to_bytes::IterBytes;
 pub use to_str::{ToStr, IntoStr};
 pub use tuple::{CloneableTuple, ImmutableTuple};

src/libstd/rt/task.rs

@@ -30,7 +30,7 @@ use rt::local::Local;
 use rt::local_heap::LocalHeap;
 use rt::rtio::LocalIo;
 use rt::unwind::Unwinder;
-use send_str::SendStr;
+use str::SendStr;
 use sync::arc::UnsafeArc;
 use sync::atomics::{AtomicUint, SeqCst};
 use task::{TaskResult, TaskOpts};