main: Write YAML to standard output

Create an adapter from `std::fmt::Write` to `std::io::Write` based on
the following idea in the standard library:

https://github.com/rust-lang/rust/blob/master/library/std/src/io/mod.rs#L1634-L1652

Since `yaml_rust::YamlEmitter::new()` requires a `std::fmt::Write`,
adapt standard output so the emitter can write to it.

1 files changed, 18 insertions, 0 deletions

diff --git a/src/yaml/write.rs b/src/yaml/write.rs
new file mode 100644
index 0000000..a1e52a5
--- /dev/null
+++ b/src/yaml/write.rs
@@ -0,0 +1,18 @@
+pub struct IoAdapter<'a, T: std::io::Write> {
+    inner: &'a mut T,
+}
+
+impl<'a, T: std::io::Write> IoAdapter<'a, T> {
+    pub fn new(writer: &'a mut T) -> Self {
+        IoAdapter { inner: writer }
+    }
+}
+
+impl<T: std::io::Write> std::fmt::Write for IoAdapter<'_, T> {
+    fn write_str(&mut self, s: &str) -> std::fmt::Result {
+        match self.inner.write_all(s.as_bytes()) {
+            Ok(()) => Ok(()),
+            Err(_) => Err(std::fmt::Error),
+        }
+    }
+}