1 files changed, 47 insertions, 0 deletions
diff --git a/src/main.rs b/src/main.rs
new file mode 100644
index 0000000..044852b
--- /dev/null
+++ b/src/main.rs
@@ -0,0 +1,47 @@
+use std::io;
+use zsh_history as zh;
+
+fn print_usage(prog: &str) {
+    eprintln!("Usage:");
+    eprintln!("  {} merge <left> <right>            # two–way merge", prog);
+    eprintln!("  {} merge <left> <right> <ancestor> # three–way merge", prog);
+}
+
+fn main() -> Result<(), Box<dyn std::error::Error>> {
+    let args: Vec<String> = std::env::args().collect();
+    let prog = &args[0];
+
+    if args.len() < 4 || args.len() > 5 || args[1] != "merge" {
+        print_usage(prog);
+        return Ok(());
+    }
+
+    // Open files and create readers in one go.
+    let mut readers: Vec<_> = args[2..]
+        .iter()
+        .map(|name| {
+            std::fs::File::open(name)
+                .map_err(zh::Error::Io)
+                .map(zh::Reader::new)
+        })
+        .collect::<Result<_, _>>()?;
+
+    let mut out = io::stdout().lock();
+
+    let result = match readers.len() {
+        2 => {
+            let ancestor = zh::Reader::new(io::empty());
+            zh::merge(readers.remove(0), readers.remove(0), ancestor, &mut out)
+        }
+        3 => zh::merge(
+            readers.remove(0),
+            readers.remove(0),
+            readers.remove(0),
+            &mut out,
+        ),
+        _ => unreachable!(),
+    };
+
+    result?;
+    Ok(())
+}