Refactor the Nickel CLI

Cargo.toml

@@ -37,6 +37,7 @@ anyhow = "1.0"
 assert_cmd = "2.0.11"
 assert_matches = "1.5.0"
 clap = "4.3"
+clap_complete = "4.3.2"
 codespan = "0.11"
 codespan-lsp = "0.11"
 codespan-reporting = "0.11"
@@ -46,6 +47,7 @@ csv = "1"
 derive_more = "0.99"
 directories = "4.0.1"
 env_logger = "0.10"
+git-version = "0.3.5"
 indexmap = "1.9.3"
 indoc = "2"
 insta = "1.29.0"
@@ -85,7 +87,6 @@ toml = "0.7.2"
 typed-arena = "2.0.2"
 unicode-segmentation = "1.10.1"
 void = "1"
-git-version = "0.3.5"
 
 topiary = { version = "0.2.3", git = "https://github.com/tweag/topiary.git", rev = "refs/heads/main" }
 # This should be kept in sync with the revision in topiary

cli/Cargo.toml

@@ -12,7 +12,7 @@ readme.workspace = true
 
 [[bin]]
 name = "nickel"
-path = "bin/nickel.rs"
+path = "src/main.rs"
 bench = false
 
 [features]
@@ -33,6 +33,7 @@ tree-sitter-nickel = { workspace = true, optional = true }
 tempfile = { workspace = true, optional = true }
 
 git-version = { workspace = true }
+clap_complete = { workspace = true }
 
 [dev-dependencies]
 nickel-lang-utils.workspace = true

cli/src/cli.rs

@@ -0,0 +1,80 @@
+//! Command-line options and subcommands.
+use std::path::PathBuf;
+
+use git_version::git_version;
+
+use crate::{
+    completions::GenCompletionsCommand, eval::EvalCommand, export::ExportCommand,
+    pprint_ast::PprintAstCommand, query::QueryCommand, typecheck::TypecheckCommand,
+};
+
+#[cfg(feature = "repl")]
+use crate::repl::ReplCommand;
+
+#[cfg(feature = "doc")]
+use crate::doc::DocCommand;
+
+#[cfg(feature = "format")]
+use crate::format::FormatCommand;
+
+#[derive(clap::Parser, Debug)]
+/// The interpreter of the Nickel language.
+#[command(
+    author,
+    about,
+    long_about = None,
+    version = format!("{} {} (rev {})", env!("CARGO_BIN_NAME"), env!("CARGO_PKG_VERSION"), git_version!(fallback = env!("NICKEL_NIX_BUILD_REV")))
+)]
+pub struct Options {
+    #[command(flatten)]
+    pub global: GlobalOptions,
+
+    #[command(subcommand)]
+    pub command: Option<Command>,
+}
+
+#[derive(clap::Parser, Debug)]
+pub struct GlobalOptions {
+    #[cfg(debug_assertions)]
+    /// Skips the standard library import. For debugging only. This does not affect REPL
+    #[arg(long, global = true)]
+    pub nostdlib: bool,
+
+    /// Configure when to output messages in color
+    #[arg(long, global = true, value_enum, default_value_t)]
+    pub color: clap::ColorChoice,
+
+    /// Input file, omit to read from stdin
+    #[arg(long, short, global = true)]
+    pub file: Option<PathBuf>,
+}
+
+/// Available subcommands.
+#[derive(clap::Subcommand, Debug)]
+pub enum Command {
+    /// Evaluate a Nickel program and pretty-print the result.
+    #[command(hide = true)]
+    Eval(EvalCommand),
+
+    /// Converts the parsed representation (AST) back to Nickel source code and prints it. Used for
+    /// debugging purpose
+    PprintAst(PprintAstCommand),
+    /// Exports the result to a different format
+    Export(ExportCommand),
+    /// Prints the metadata attached to an attribute, given as a path
+    Query(QueryCommand),
+    /// Typechecks the program but do not run it
+    Typecheck(TypecheckCommand),
+    /// Starts a REPL session
+    #[cfg(feature = "repl")]
+    Repl(ReplCommand),
+    /// Generates the documentation files for the specified nickel file
+    #[cfg(feature = "doc")]
+    Doc(DocCommand),
+    /// Format Nickel files
+    #[cfg(feature = "format")]
+    Format(FormatCommand),
+
+    /// Generate shell completion files
+    GenCompletions(GenCompletionsCommand),
+}