Merge crate collections into alloc

src/liballoc/macros.rs

@@ -8,6 +8,89 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+/// Creates a `Vec` containing the arguments.
+///
+/// `vec!` allows `Vec`s to be defined with the same syntax as array expressions.
+/// There are two forms of this macro:
+///
+/// - Create a `Vec` containing a given list of elements:
+///
+/// ```
+/// let v = vec![1, 2, 3];
+/// assert_eq!(v[0], 1);
+/// assert_eq!(v[1], 2);
+/// assert_eq!(v[2], 3);
+/// ```
+///
+/// - Create a `Vec` from a given element and size:
+///
+/// ```
+/// let v = vec![1; 3];
+/// assert_eq!(v, [1, 1, 1]);
+/// ```
+///
+/// Note that unlike array expressions this syntax supports all elements
+/// which implement `Clone` and the number of elements doesn't have to be
+/// a constant.
+///
+/// This will use `clone()` to duplicate an expression, so one should be careful
+/// using this with types having a nonstandard `Clone` implementation. For
+/// example, `vec![Rc::new(1); 5]` will create a vector of five references
+/// to the same boxed integer value, not five references pointing to independently
+/// boxed integers.
+#[cfg(not(test))]
+#[macro_export]
+#[stable(feature = "rust1", since = "1.0.0")]
+#[allow_internal_unstable]
+macro_rules! vec {
+    ($elem:expr; $n:expr) => (
+        $crate::vec::from_elem($elem, $n)
+    );
+    ($($x:expr),*) => (
+        <[_]>::into_vec(box [$($x),*])
+    );
+    ($($x:expr,)*) => (vec![$($x),*])
+}
+
+// HACK(japaric): with cfg(test) the inherent `[T]::into_vec` method, which is
+// required for this macro definition, is not available. Instead use the
+// `slice::into_vec`  function which is only available with cfg(test)
+// NB see the slice::hack module in slice.rs for more information
+#[cfg(test)]
+macro_rules! vec {
+    ($elem:expr; $n:expr) => (
+        $crate::vec::from_elem($elem, $n)
+    );
+    ($($x:expr),*) => (
+        $crate::slice::into_vec(box [$($x),*])
+    );
+    ($($x:expr,)*) => (vec![$($x),*])
+}
+
+/// Use the syntax described in `std::fmt` to create a value of type `String`.
+/// See [`std::fmt`][fmt] for more information.
+///
+/// [fmt]: ../std/fmt/index.html
+///
+/// # Panics
+///
+/// `format!` panics if a formatting trait implementation returns an error.
+/// This indicates an incorrect implementation
+/// since `fmt::Write for String` never returns an error itself.
+///
+/// # Examples
+///
+/// ```
+/// format!("test");
+/// format!("hello {}", "world!");
+/// format!("x = {}, y = {y}", 10, y = 30);
+/// ```
+#[macro_export]
+#[stable(feature = "rust1", since = "1.0.0")]
+macro_rules! format {
+    ($($arg:tt)*) => ($crate::fmt::format(format_args!($($arg)*)))
+}
+
 // Private macro to get the offset of a struct field in bytes from the address of the struct.
 macro_rules! offset_of {
     ($container:path, $field:ident) => {{