vcf/writer: Add builder

noodles-vcf/CHANGELOG.md

@@ -2,6 +2,10 @@
 
 ## Unreleased
 
+### Added
+
+  * vcf/writer: Add builder (`vcf::writer::Builder`).
+
 ### Fixed
 
   * vcf/record/genotypes/keys/key: Hash inner key.

noodles-vcf/src/lib.rs

@@ -29,7 +29,7 @@ pub mod reader;
 pub mod record;
 mod variant_reader;
 mod variant_writer;
-mod writer;
+pub mod writer;
 
 pub use self::{
     header::Header, indexed_reader::IndexedReader, reader::Reader, record::Record,

noodles-vcf/src/writer.rs

@@ -1,7 +1,11 @@
+//! VCF writer.
+
+mod builder;
 mod record;
 
 use std::io::{self, Write};
 
+pub use self::builder::Builder;
 use self::record::write_record;
 use super::{Header, Record, VariantWriter};
 

noodles-vcf/src/writer/builder.rs

@@ -0,0 +1,40 @@
+use std::{
+    fs::File,
+    io::{self, BufWriter, Write},
+    path::Path,
+};
+
+use noodles_bgzf as bgzf;
+
+use super::Writer;
+
+/// A BAM writer builder.
+#[derive(Debug, Default)]
+pub struct Builder;
+
+impl Builder {
+    /// Builds a VCF writer from a path.
+    ///
+    /// # Examples
+    ///
+    /// ```no_run
+    /// use noodles_vcf as vcf;
+    /// let writer = vcf::writer::Builder.build_from_path("out.vcf")?;
+    /// # Ok::<_, std::io::Error>(())
+    /// ```
+    pub fn build_from_path<P>(self, dst: P) -> io::Result<Writer<Box<dyn Write>>>
+    where
+        P: AsRef<Path>,
+    {
+        let dst = dst.as_ref();
+
+        let file = File::create(dst)?;
+
+        let writer: Box<dyn Write> = match dst.extension().and_then(|ext| ext.to_str()) {
+            Some("gz" | "bgz") => Box::new(bgzf::Writer::new(file)),
+            _ => Box::new(BufWriter::new(file)),
+        };
+
+        Ok(Writer::new(writer))
+    }
+}