Implement LogBuffer::uninitialized().

Author: whitequark

.travis.yml

@@ -1,13 +1,13 @@
 sudo: required
 language: rust
 rust:
-  - stable
+  - nightly
 env:
   - secure: "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"
 after_script:
   - |
     if [ "${TRAVIS_BRANCH}" = "master" -a -n "${GH_TOKEN}" ]; then
-      cargo doc
+      cargo doc --features=const_fn
       git clone https://github.com/davisp/ghp-import
       ./ghp-import/ghp_import.py -n target/doc
       git push -fq https://${GH_TOKEN}@github.com/${TRAVIS_REPO_SLUG}.git gh-pages

Cargo.toml

@@ -8,3 +8,6 @@ repository = "https://github.com/whitequark/rust-log_buffer"
 homepage = "https://github.com/whitequark/rust-log_buffer"
 documentation = "https://whitequark.github.io/rust-log_buffer/log_buffer"
 description = "A zero-allocation ring buffer for storing text logs"
+
+[features]
+const_fn = []

src/lib.rs

@@ -40,6 +40,7 @@
 //! ```
 
 #![no_std]
+#![cfg_attr(feature = "const_fn", feature(const_fn))]
 
 /// A ring buffer that stores UTF-8 text.
 ///
@@ -52,7 +53,7 @@ pub struct LogBuffer<T: AsMut<[u8]>> {
 }
 
 impl<T: AsMut<[u8]>> LogBuffer<T> {
-    /// Creates a new ring buffer, backed by the slice `storage`.
+    /// Creates a new ring buffer, backed by `storage`.
     ///
     /// The buffer is cleared after creation.
     pub fn new(storage: T) -> LogBuffer<T> {
@@ -61,6 +62,16 @@ impl<T: AsMut<[u8]>> LogBuffer<T> {
         buffer
     }
 
+    /// Creates a new ring buffer, backed by `storage`.
+    ///
+    /// The buffer is *not* cleared after creation, and contains whatever is in `storage`.
+    /// The `clear()` method should be called before use.
+    /// However, this function can be used in a static initializer.
+    #[cfg(feature = "const_fn")]
+    pub const fn uninitialized(storage: T) -> LogBuffer<T> {
+        LogBuffer { buffer: storage, position: 0 }
+    }
+
     /// Clears the buffer.
     ///
     /// Only the text written after clearing will be read out by a future extraction.