Add a safe interface

.travis.yml

@@ -4,6 +4,3 @@ rust:
   - nightly
   - beta
   - stable
-
-script:
-  - cargo test --features pretty

Cargo.toml

@@ -4,17 +4,8 @@ version = "0.0.0"
 authors = ["David Tolnay <dtolnay@gmail.com>"]
 publish = false
 
-[features]
-pretty = []
-
 [dependencies]
 no-panic = { version = "0.1", optional = true }
 
 [dev-dependencies]
 rand = "0.5"
-
-[package.metadata.docs.rs]
-features = ["pretty"]
-
-[package.metadata.playground]
-features = ["pretty"]

src/buffer/mod.rs

@@ -0,0 +1,40 @@
+use core::str;
+
+use pretty;
+
+pub struct Buffer {
+    bytes: [u8; 24],
+}
+
+impl Buffer {
+    pub fn write<F: Float>(&mut self, f: F) -> &str {
+        f.write_to_ryu_buffer(self)
+    }
+}
+
+pub trait Float: Sealed {
+    #[doc(hidden)]
+    fn write_to_ryu_buffer(self, buffer: &mut Buffer) -> &str;
+}
+
+impl Float for f32 {
+    fn write_to_ryu_buffer(self, buffer: &mut Buffer) -> &str {
+        unsafe {
+            let n = pretty::f2s_buffered_n(self, &mut buffer.bytes[0]);
+            str::from_utf8_unchecked(&buffer.bytes[..n])
+        }
+    }
+}
+
+impl Float for f64 {
+    fn write_to_ryu_buffer(self, buffer: &mut Buffer) -> &str {
+        unsafe {
+            let n = pretty::d2s_buffered_n(self, &mut buffer.bytes[0]);
+            str::from_utf8_unchecked(&buffer.bytes[..n])
+        }
+    }
+}
+
+pub trait Sealed {}
+impl Sealed for f32 {}
+impl Sealed for f64 {}

src/lib.rs

@@ -14,14 +14,14 @@
 #[cfg(feature = "no-panic")]
 extern crate no_panic;
 
+mod buffer;
 mod common;
 mod d2s;
 mod d2s_full_table;
 mod digit_table;
 mod f2s;
+mod pretty;
 
-#[cfg(feature = "pretty")]
-pub mod pretty;
-
+pub use buffer::{Buffer, Float};
 pub use d2s::d2s_buffered_n;
 pub use f2s::f2s_buffered_n;