Auto merge of #58051 - SimonSapin:str_escape, r=alexcrichton

Stabilize str::escape_* methods with new return types…

… that implement `Display` and `Iterator<Item=char>`, as proposed in FCP: #27791 (comment)

Author: bors

src/liballoc/lib.rs

@@ -68,7 +68,6 @@
 #![warn(intra_doc_link_resolution_failure)]
 #![warn(missing_debug_implementations)]
 
-#![cfg_attr(not(test), feature(fn_traits))]
 #![cfg_attr(not(test), feature(generator_trait))]
 #![cfg_attr(test, feature(test))]
 
@@ -86,6 +85,7 @@
 #![feature(dropck_eyepatch)]
 #![feature(exact_size_is_empty)]
 #![feature(fmt_internals)]
+#![feature(fn_traits)]
 #![feature(fundamental)]
 #![feature(futures_api)]
 #![feature(lang_items)]
@@ -100,6 +100,7 @@
 #![feature(receiver_trait)]
 #![feature(specialization)]
 #![feature(staged_api)]
+#![feature(std_internals)]
 #![feature(str_internals)]
 #![feature(trusted_len)]
 #![feature(try_reserve)]

src/liballoc/str.rs

@@ -29,8 +29,6 @@
 #![allow(unused_imports)]
 
 use core::borrow::Borrow;
-use core::fmt;
-use core::str as core_str;
 use core::str::pattern::{Pattern, Searcher, ReverseSearcher, DoubleEndedSearcher};
 use core::mem;
 use core::ptr;
@@ -443,45 +441,6 @@ impl str {
         return s;
     }
 
-    /// Escapes each char in `s` with [`char::escape_debug`].
-    ///
-    /// Note: only extended grapheme codepoints that begin the string will be
-    /// escaped.
-    ///
-    /// [`char::escape_debug`]: primitive.char.html#method.escape_debug
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
-    pub fn escape_debug(&self) -> String {
-        let mut string = String::with_capacity(self.len());
-        let mut chars = self.chars();
-        if let Some(first) = chars.next() {
-            string.extend(first.escape_debug_ext(true))
-        }
-        string.extend(chars.flat_map(|c| c.escape_debug_ext(false)));
-        string
-    }
-
-    /// Escapes each char in `s` with [`char::escape_default`].
-    ///
-    /// [`char::escape_default`]: primitive.char.html#method.escape_default
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
-    pub fn escape_default(&self) -> String {
-        self.chars().flat_map(|c| c.escape_default()).collect()
-    }
-
-    /// Escapes each char in `s` with [`char::escape_unicode`].
-    ///
-    /// [`char::escape_unicode`]: primitive.char.html#method.escape_unicode
-    #[unstable(feature = "str_escape",
-               reason = "return type may change to be an iterator",
-               issue = "27791")]
-    pub fn escape_unicode(&self) -> String {
-        self.chars().flat_map(|c| c.escape_unicode()).collect()
-    }
-
     /// Converts a [`Box<str>`] into a [`String`] without copying or allocating.
     ///
     /// [`String`]: string/struct.String.html
@@ -612,3 +571,4 @@ impl str {
 pub unsafe fn from_boxed_utf8_unchecked(v: Box<[u8]>) -> Box<str> {
     Box::from_raw(Box::into_raw(v) as *mut str)
 }
+

src/liballoc/tests/lib.rs

@@ -5,7 +5,6 @@
 #![feature(pattern)]
 #![feature(repeat_generic_slice)]
 #![feature(slice_sort_by_cached_key)]
-#![feature(str_escape)]
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
 #![feature(vecdeque_rotate)]

src/liballoc/tests/str.rs

@@ -990,15 +990,15 @@ fn test_split_at_boundscheck() {
 
 #[test]
 fn test_escape_unicode() {
-    assert_eq!("abc".escape_unicode(), "\\u{61}\\u{62}\\u{63}");
-    assert_eq!("a c".escape_unicode(), "\\u{61}\\u{20}\\u{63}");
-    assert_eq!("\r\n\t".escape_unicode(), "\\u{d}\\u{a}\\u{9}");
-    assert_eq!("'\"\\".escape_unicode(), "\\u{27}\\u{22}\\u{5c}");
-    assert_eq!("\x00\x01\u{fe}\u{ff}".escape_unicode(), "\\u{0}\\u{1}\\u{fe}\\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_unicode(), "\\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_unicode(), "\\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{fb00}".escape_unicode(), "\\u{61}\\u{62}\\u{fb00}");
-    assert_eq!("\u{1d4ea}\r".escape_unicode(), "\\u{1d4ea}\\u{d}");
+    assert_eq!("abc".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{63}");
+    assert_eq!("a c".escape_unicode().to_string(), "\\u{61}\\u{20}\\u{63}");
+    assert_eq!("\r\n\t".escape_unicode().to_string(), "\\u{d}\\u{a}\\u{9}");
+    assert_eq!("'\"\\".escape_unicode().to_string(), "\\u{27}\\u{22}\\u{5c}");
+    assert_eq!("\x00\x01\u{fe}\u{ff}".escape_unicode().to_string(), "\\u{0}\\u{1}\\u{fe}\\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_unicode().to_string(), "\\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_unicode().to_string(), "\\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{fb00}".escape_unicode().to_string(), "\\u{61}\\u{62}\\u{fb00}");
+    assert_eq!("\u{1d4ea}\r".escape_unicode().to_string(), "\\u{1d4ea}\\u{d}");
 }
 
 #[test]
@@ -1009,31 +1009,32 @@ fn test_escape_debug() {
     // they are escaped. However, when the character is unescaped (e.g., for
     // printable characters), only a single backslash appears (as the character
     // itself appears in the debug string).
-    assert_eq!("abc".escape_debug(), "abc");
-    assert_eq!("a c".escape_debug(), "a c");
-    assert_eq!("éèê".escape_debug(), "éèê");
-    assert_eq!("\r\n\t".escape_debug(), "\\r\\n\\t");
-    assert_eq!("'\"\\".escape_debug(), "\\'\\\"\\\\");
-    assert_eq!("\u{7f}\u{ff}".escape_debug(), "\\u{7f}\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_debug(), "\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_debug(), "\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{200b}".escape_debug(), "ab\\u{200b}");
-    assert_eq!("\u{10d4ea}\r".escape_debug(), "\\u{10d4ea}\\r");
-    assert_eq!("\u{301}a\u{301}bé\u{e000}".escape_debug(), "\\u{301}a\u{301}bé\\u{e000}");
+    assert_eq!("abc".escape_debug().to_string(), "abc");
+    assert_eq!("a c".escape_debug().to_string(), "a c");
+    assert_eq!("éèê".escape_debug().to_string(), "éèê");
+    assert_eq!("\r\n\t".escape_debug().to_string(), "\\r\\n\\t");
+    assert_eq!("'\"\\".escape_debug().to_string(), "\\'\\\"\\\\");
+    assert_eq!("\u{7f}\u{ff}".escape_debug().to_string(), "\\u{7f}\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_debug().to_string(), "\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_debug().to_string(), "\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{200b}".escape_debug().to_string(), "ab\\u{200b}");
+    assert_eq!("\u{10d4ea}\r".escape_debug().to_string(), "\\u{10d4ea}\\r");
+    assert_eq!("\u{301}a\u{301}bé\u{e000}".escape_debug().to_string(),
+               "\\u{301}a\u{301}bé\\u{e000}");
 }
 
 #[test]
 fn test_escape_default() {
-    assert_eq!("abc".escape_default(), "abc");
-    assert_eq!("a c".escape_default(), "a c");
-    assert_eq!("éèê".escape_default(), "\\u{e9}\\u{e8}\\u{ea}");
-    assert_eq!("\r\n\t".escape_default(), "\\r\\n\\t");
-    assert_eq!("'\"\\".escape_default(), "\\'\\\"\\\\");
-    assert_eq!("\u{7f}\u{ff}".escape_default(), "\\u{7f}\\u{ff}");
-    assert_eq!("\u{100}\u{ffff}".escape_default(), "\\u{100}\\u{ffff}");
-    assert_eq!("\u{10000}\u{10ffff}".escape_default(), "\\u{10000}\\u{10ffff}");
-    assert_eq!("ab\u{200b}".escape_default(), "ab\\u{200b}");
-    assert_eq!("\u{10d4ea}\r".escape_default(), "\\u{10d4ea}\\r");
+    assert_eq!("abc".escape_default().to_string(), "abc");
+    assert_eq!("a c".escape_default().to_string(), "a c");
+    assert_eq!("éèê".escape_default().to_string(), "\\u{e9}\\u{e8}\\u{ea}");
+    assert_eq!("\r\n\t".escape_default().to_string(), "\\r\\n\\t");
+    assert_eq!("'\"\\".escape_default().to_string(), "\\'\\\"\\\\");
+    assert_eq!("\u{7f}\u{ff}".escape_default().to_string(), "\\u{7f}\\u{ff}");
+    assert_eq!("\u{100}\u{ffff}".escape_default().to_string(), "\\u{100}\\u{ffff}");
+    assert_eq!("\u{10000}\u{10ffff}".escape_default().to_string(), "\\u{10000}\\u{10ffff}");
+    assert_eq!("ab\u{200b}".escape_default().to_string(), "ab\\u{200b}");
+    assert_eq!("\u{10d4ea}\r".escape_default().to_string(), "\\u{10d4ea}\\r");
 }
 
 #[test]

src/libcore/char/methods.rs

@@ -189,10 +189,8 @@ impl char {
     /// An extended version of `escape_debug` that optionally permits escaping
     /// Extended Grapheme codepoints. This allows us to format characters like
     /// nonspacing marks better when they're at the start of a string.
-    #[doc(hidden)]
-    #[unstable(feature = "str_internals", issue = "0")]
     #[inline]
-    pub fn escape_debug_ext(self, escape_grapheme_extended: bool) -> EscapeDebug {
+    pub(crate) fn escape_debug_ext(self, escape_grapheme_extended: bool) -> EscapeDebug {
         let init_state = match self {
             '\t' => EscapeDefaultState::Backslash('t'),
             '\r' => EscapeDefaultState::Backslash('r'),

src/libcore/internal_macros.rs

@@ -75,3 +75,47 @@ macro_rules! forward_ref_op_assign {
         }
     }
 }
+
+/// Create a zero-size type similar to a closure type, but named.
+#[unstable(feature = "std_internals", issue = "0")]
+macro_rules! impl_fn_for_zst {
+    ($(
+        $( #[$attr: meta] )*
+        // FIXME: when libcore is in the 2018 edition, use `?` repetition in
+        // $( <$( $li : lifetime ),+> )?
+        struct $Name: ident impl$( <$( $lifetime : lifetime ),+> )* Fn =
+            |$( $arg: ident: $ArgTy: ty ),*| -> $ReturnTy: ty
+            $body: block;
+    )+) => {
+        $(
+            $( #[$attr] )*
+            struct $Name;
+
+            impl $( <$( $lifetime ),+> )* Fn<($( $ArgTy, )*)> for $Name {
+                #[inline]
+                extern "rust-call" fn call(&self, ($( $arg, )*): ($( $ArgTy, )*)) -> $ReturnTy {
+                    $body
+                }
+            }
+
+            impl $( <$( $lifetime ),+> )* FnMut<($( $ArgTy, )*)> for $Name {
+                #[inline]
+                extern "rust-call" fn call_mut(
+                    &mut self,
+                    ($( $arg, )*): ($( $ArgTy, )*)
+                ) -> $ReturnTy {
+                    Fn::call(&*self, ($( $arg, )*))
+                }
+            }
+
+            impl $( <$( $lifetime ),+> )* FnOnce<($( $ArgTy, )*)> for $Name {
+                type Output = $ReturnTy;
+
+                #[inline]
+                extern "rust-call" fn call_once(self, ($( $arg, )*): ($( $ArgTy, )*)) -> $ReturnTy {
+                    Fn::call(&self, ($( $arg, )*))
+                }
+            }
+        )+
+    }
+}

src/libcore/lib.rs

@@ -95,6 +95,7 @@
 #![feature(simd_ffi)]
 #![feature(specialization)]
 #![feature(staged_api)]
+#![feature(std_internals)]
 #![feature(stmt_expr_attributes)]
 #![feature(unboxed_closures)]
 #![feature(unsized_locals)]

src/libcore/str/mod.rs

@@ -277,7 +277,6 @@
 #![deny(rust_2018_idioms)]
 
 #![feature(nll)]
-#![feature(str_escape)]
 
 use LabelText::*;
 
@@ -538,7 +537,7 @@ impl<'a> LabelText<'a> {
             EscStr(s) => s,
             LabelStr(s) => {
                 if s.contains('\\') {
-                    (&*s).escape_default().into()
+                    (&*s).escape_default().to_string().into()
                 } else {
                     s
                 }

src/libgraphviz/lib.rs

@@ -634,7 +634,7 @@ impl LitKind {
 
         match *self {
             LitKind::Str(string, ast::StrStyle::Cooked) => {
-                let escaped = string.as_str().escape_default();
+                let escaped = string.as_str().escape_default().to_string();
                 Token::Literal(token::Lit::Str_(Symbol::intern(&escaped)), None)
             }
             LitKind::Str(string, ast::StrStyle::Raw(n)) => {

src/libsyntax/attr/mod.rs

@@ -15,7 +15,6 @@
 #![feature(rustc_attrs)]
 #![feature(rustc_diagnostic_macros)]
 #![feature(slice_sort_by_cached_key)]
-#![feature(str_escape)]
 #![feature(step_trait)]
 #![feature(try_trait)]
 #![feature(unicode_internals)]

src/libsyntax/lib.rs

@@ -606,7 +606,7 @@ pub trait PrintState<'a> {
         match lit.node {
             ast::LitKind::Str(st, style) => self.print_string(&st.as_str(), style),
             ast::LitKind::Err(st) => {
-                let st = st.as_str().escape_debug();
+                let st = st.as_str().escape_debug().to_string();
                 let mut res = String::with_capacity(st.len() + 2);
                 res.push('\'');
                 res.push_str(&st);

src/libsyntax/print/pprust.rs

@@ -10,7 +10,6 @@
 #![feature(proc_macro_span)]
 #![feature(decl_macro)]
 #![feature(nll)]
-#![feature(str_escape)]
 #![feature(rustc_diagnostic_macros)]
 
 #![recursion_limit="256"]

src/libsyntax_ext/lib.rs

@@ -2,9 +2,6 @@
 // pretty-expanded FIXME #23616
 
 #![allow(warnings)]
-#![feature(iter_empty)]
-#![feature(iter_once)]
-#![feature(str_escape)]
 
 use std::iter::{empty, once, repeat};