add scaffolding for implementing Unix tool mockups

Sponsored-by: author

3 files changed, 247 insertions, 1 deletions

diff --git a/Cargo.lock b/Cargo.lock
new file mode 100644
index 0000000..c826b51
--- /dev/null
+++ b/Cargo.lock
@@ -0,0 +1,208 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
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+checksum = "d9b39be18770d11421cdb1b9947a45dd3f37e93092cbf377614828a319d5fee8"
+dependencies = [
+ "hermit-abi",
+ "libc",
+ "winapi",
+]
+
+[[package]]
+name = "bitflags"
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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+dependencies = [
+ "atty",
+ "bitflags",
+ "clap_derive",
+ "clap_lex",
+ "once_cell",
+ "strsim",
+ "termcolor",
+]
+
+[[package]]
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+ "heck",
+ "proc-macro-error",
+ "proc-macro2",
+ "quote",
+ "syn",
+]
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+ "libc",
+]
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+ "proc-macro2",
+ "quote",
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+]
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+ "unicode-ident",
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+dependencies = [
+ "winapi-i686-pc-windows-gnu",
+ "winapi-x86_64-pc-windows-gnu",
+]
+
+[[package]]
+name = "winapi-i686-pc-windows-gnu"
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+dependencies = [
+ "winapi",
+]
+
+[[package]]
+name = "winapi-x86_64-pc-windows-gnu"
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diff --git a/Cargo.toml b/Cargo.toml
index 36b0da8..0ef4c77 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -6,3 +6,4 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+clap = { version = "4.0.15", features = ["derive"] }
diff --git a/src/main.rs b/src/main.rs
index e7a11a9..13c9d34 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,3 +1,40 @@
+use clap::{Parser, Subcommand};
+
 fn main() {
-    println!("Hello, world!");
+    let args = Args::parse();
+    match args.command {
+        Command::Echo(x) => x.run(),
+    }
+}
+
+#[derive(Parser)]
+struct Args {
+    #[clap(subcommand)]
+    command: Command,
+}
+
+#[derive(Subcommand)]
+enum Command {
+    Echo(Echo),
+}
+
+/// Write the words given on the command line to stdout, then a
+/// newline.
+#[derive(Parser)]
+struct Echo {
+    /// Words to write out, if any.
+    words: Vec<String>,
+}
+
+impl Echo {
+    fn run(&self) {
+        let mut words = self.words.iter();
+        if let Some(word) = words.next() {
+            print!("{}", word);
+        }
+        for word in words {
+            print!(" {}", word);
+        }
+        println!();
+    }
 }