feat: configuration mechanism

Cargo.lock

@@ -21,6 +21,8 @@ dependencies = [
  "futures",
  "num_cpus",
  "rand",
+ "serde",
+ "serde_json",
  "walkdir",
 ]
 
@@ -254,6 +256,12 @@ dependencies = [
  "hashbrown 0.12.3",
 ]
 
+[[package]]
+name = "itoa"
+version = "1.0.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "540654e97a3f4470a492cd30ff187bc95d89557a903a2bbf112e2fae98104ef2"
+
 [[package]]
 name = "libc"
 version = "0.2.161"
@@ -437,6 +445,12 @@ version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
 
+[[package]]
+name = "ryu"
+version = "1.0.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"
+
 [[package]]
 name = "same-file"
 version = "1.0.6"
@@ -466,6 +480,18 @@ dependencies = [
  "syn 2.0.87",
 ]
 
+[[package]]
+name = "serde_json"
+version = "1.0.133"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c7fceb2473b9166b2294ef05efcb65a3db80803f0b03ef86a5fc88a2b85ee377"
+dependencies = [
+ "itoa",
+ "memchr",
+ "ryu",
+ "serde",
+]
+
 [[package]]
 name = "shlex"
 version = "1.3.0"

README.md

@@ -239,6 +239,8 @@ Our public API consists of:
   exit codes,
   and stdout.
 
+With the exception of those explicitly marked as "experimental".
+
 ## Changelog
 
 Please read: [CHANGELOG](./CHANGELOG.md).

src/alejandra/Cargo.toml

@@ -1,6 +1,7 @@
 [dependencies]
-rnix = "0.10.2"
-rowan = "0.12.6" # follows rnix
+rnix = { version = "0.10.2", default-features = false, features = [] }
+# rowan follows rnix
+rowan = { version = "0.12.6", default-features = false, features = [] }
 
 [target.aarch64-unknown-linux-musl.dependencies.mimalloc]
 default-features = false

src/alejandra/src/builder.rs

@@ -1,3 +1,5 @@
+use crate::config::Config;
+
 #[derive(PartialEq)]
 pub(crate) enum Step {
     Comment(String),
@@ -13,6 +15,7 @@ pub(crate) enum Step {
 
 #[derive(Clone)]
 pub(crate) struct BuildCtx {
+    pub _config:            Config,
     pub force_wide:         bool,
     pub force_wide_success: bool,
     pub indentation:        usize,

src/alejandra/src/config.rs

@@ -0,0 +1,11 @@
+/// Configuration used by the formatter
+#[derive(Clone)]
+pub struct Config {}
+
+use std::default::Default;
+
+impl Default for Config {
+    fn default() -> Self {
+        Self {}
+    }
+}

src/alejandra/src/format.rs

@@ -1,7 +1,9 @@
+use crate::config::Config;
+
 /// Possibles results after formatting.
 #[derive(Clone)]
 pub enum Status {
-    /// An error ocurred, and its reason.
+    /// An error occurred, and its reason.
     Error(String),
     /// Formatting was successful,
     /// the file changed or not according to the boolean.
@@ -14,9 +16,13 @@ impl From<std::io::Error> for Status {
     }
 }
 
-/// Formats the content of `before` in-memory,
-/// and assume `path` in the displayed error messages
-pub fn in_memory(path: String, before: String) -> (Status, String) {
+/// Formats the content of `before` in-memory
+/// assuming the contents come from `path` when displaying error messages
+pub fn in_memory(
+    path: String,
+    before: String,
+    config: Config,
+) -> (Status, String) {
     let tokens = rnix::tokenizer::Tokenizer::new(&before);
     let ast = rnix::parser::parse(tokens);
 
@@ -26,6 +32,7 @@ pub fn in_memory(path: String, before: String) -> (Status, String) {
     }
 
     let mut build_ctx = crate::builder::BuildCtx {
+        _config: config,
         force_wide: false,
         force_wide_success: true,
         indentation: 0,
@@ -47,12 +54,13 @@ pub fn in_memory(path: String, before: String) -> (Status, String) {
 
 /// Formats the file at `path`,
 /// optionally overriding it's contents if `in_place` is true.
-pub fn in_fs(path: String, in_place: bool) -> Status {
+pub fn in_fs(path: String, config: Config, in_place: bool) -> Status {
     use std::io::Write;
 
     match std::fs::read_to_string(&path) {
         Ok(before) => {
-            let (status, data) = crate::format::in_memory(path.clone(), before);
+            let (status, data) =
+                crate::format::in_memory(path.clone(), before, config);
 
             match status {
                 Status::Changed(changed) => {

src/alejandra/src/lib.rs

@@ -50,6 +50,8 @@ static GLOBAL: mimalloc::MiMalloc = mimalloc::MiMalloc;
 pub(crate) mod builder;
 pub(crate) mod children;
 pub(crate) mod children2;
+/// Configuration options for the formatter
+pub mod config;
 /// Functions for formatting Nix code.
 pub mod format;
 pub(crate) mod parsers;

src/alejandra/tests/fmt.rs

@@ -1,37 +1,50 @@
+use std::collections::HashMap;
+use std::collections::HashSet;
 use std::io::Write;
 
+use alejandra::config::Config;
 use pretty_assertions::assert_eq;
 
 #[test]
 fn cases() {
     let should_update = std::env::var("UPDATE").is_ok();
 
-    let cases: std::collections::HashSet<String> =
-        std::fs::read_dir("tests/cases")
-            .unwrap()
-            .map(|entry| entry.unwrap().file_name().into_string().unwrap())
-            .collect();
+    let cases: HashSet<String> = std::fs::read_dir("tests/cases")
+        .unwrap()
+        .map(|entry| entry.unwrap().file_name().into_string().unwrap())
+        .collect();
+
+    let configs = HashMap::from([("", Config::default())]);
 
     for case in cases {
         let path_in = format!("tests/cases/{}/in.nix", case);
-        let path_out = format!("tests/cases/{}/out.nix", case);
         let content_in = std::fs::read_to_string(path_in.clone()).unwrap();
-        let content_got =
-            alejandra::format::in_memory(path_in, content_in.clone()).1;
 
-        if should_update {
-            std::fs::File::create(&path_out)
-                .unwrap()
-                .write_all(content_got.as_bytes())
-                .unwrap();
+        for (config_name, config) in &configs {
+            let path_out =
+                format!("tests/cases/{}/out{}.nix", case, config_name);
+            let content_got = alejandra::format::in_memory(
+                path_in.clone(),
+                content_in.clone(),
+                config.clone(),
+            )
+            .1;
+
+            if should_update {
+                std::fs::File::create(&path_out)
+                    .unwrap()
+                    .write_all(content_got.as_bytes())
+                    .unwrap();
+            }
+
+            let content_out =
+                std::fs::read_to_string(path_out.clone()).unwrap();
+
+            assert_eq!(
+                content_out, content_got,
+                "Test case `{case}` failed; see \
+                 `src/alejandra/tests/cases/{case}/`"
+            );
         }
-
-        let content_out = std::fs::read_to_string(path_out.clone()).unwrap();
-
-        assert_eq!(
-            content_out, content_got,
-            "Test case `{case}` failed; see \
-             `src/alejandra/tests/cases/{case}/`"
-        );
     }
 }

src/alejandra_cli/Cargo.toml

@@ -19,6 +19,8 @@ rand = { version = "*", default-features = false, features = [
   "alloc",
   "getrandom",
 ] }
+serde = { version = "*", default-features = false, features = ["derive"] }
+serde_json = { version = "*", default-features = false, features = ["std"] }
 walkdir = { version = "*", default-features = false, features = [] }
 
 [package]

src/alejandra_cli/src/cli.rs

@@ -1,13 +1,16 @@
+use std::fs::read_to_string;
 use std::io::Read;
 
+use alejandra::config::Config;
+use clap::value_parser;
 use clap::ArgAction;
 use clap::Parser;
-use clap::value_parser;
 use futures::future::RemoteHandle;
 use futures::stream::FuturesUnordered;
 use futures::task::SpawnExt;
 
 use crate::ads::random_ad;
+use crate::config_options::ConfigOptions;
 use crate::verbosity::Verbosity;
 
 /// The Uncompromising Nix Code Formatter.
@@ -38,6 +41,10 @@ struct CLIArgs {
     #[clap(long, short)]
     check: bool,
 
+    /// [Experimental] Path to a config file.
+    #[clap(long)]
+    experimental_config: Option<String>,
+
     /// Number of formatting threads to spawn. Defaults to the number of
     /// physical CPUs.
     #[clap(long, short, value_parser = value_parser!(u8).range(1..))]
@@ -55,7 +62,7 @@ struct FormattedPath {
     pub status: alejandra::format::Status,
 }
 
-fn format_stdin(verbosity: Verbosity) -> FormattedPath {
+fn format_stdin(config: Config, verbosity: Verbosity) -> FormattedPath {
     let mut before = String::new();
     let path = "<anonymous file on stdin>".to_string();
 
@@ -70,7 +77,7 @@ fn format_stdin(verbosity: Verbosity) -> FormattedPath {
         .expect("Unable to read stdin.");
 
     let (status, data) =
-        alejandra::format::in_memory(path.clone(), before.clone());
+        alejandra::format::in_memory(path.clone(), before.clone(), config);
 
     print!("{data}");
 
@@ -79,9 +86,10 @@ fn format_stdin(verbosity: Verbosity) -> FormattedPath {
 
 fn format_paths(
     paths: Vec<String>,
+    config: Config,
     in_place: bool,
-    verbosity: Verbosity,
     threads: usize,
+    verbosity: Verbosity,
 ) -> Vec<FormattedPath> {
     let paths_len = paths.len();
 
@@ -102,8 +110,11 @@ fn format_paths(
     let futures: FuturesUnordered<RemoteHandle<FormattedPath>> = paths
         .into_iter()
         .map(|path| {
+            let config = config.clone();
+
             pool.spawn_with_handle(async move {
-                let status = alejandra::format::in_fs(path.clone(), in_place);
+                let status =
+                    alejandra::format::in_fs(path.clone(), config, in_place);
 
                 if let alejandra::format::Status::Changed(changed) = status {
                     if changed && verbosity.allows_info() {
@@ -127,7 +138,7 @@ fn format_paths(
     futures::executor::block_on_stream(futures).collect()
 }
 
-pub fn main() -> std::io::Result<()> {
+pub fn main() -> ! {
     let args = CLIArgs::parse();
 
     let in_place = !args.check;
@@ -144,14 +155,18 @@ pub fn main() -> std::io::Result<()> {
         _ => Verbosity::NoErrors,
     };
 
+    let config = resolve_config(args.experimental_config.as_deref(), verbosity);
+
     let formatted_paths = match &include[..] {
         &[] | &["-"] => {
-            vec![crate::cli::format_stdin(verbosity)]
+            vec![crate::cli::format_stdin(config, verbosity)]
         }
         include => {
             let paths = crate::find::nix_files(include, &args.exclude);
 
-            crate::cli::format_paths(paths, in_place, verbosity, threads)
+            crate::cli::format_paths(
+                paths, config, in_place, threads, verbosity,
+            )
         }
     };
 
@@ -224,3 +239,30 @@ pub fn main() -> std::io::Result<()> {
 
     std::process::exit(0);
 }
+
+fn resolve_config(path: Option<&str>, verbosity: Verbosity) -> Config {
+    if let Some(path) = path {
+        if verbosity.allows_info() {
+            eprintln!("Using config from: {}", path);
+        }
+
+        let contents = read_to_string(path).unwrap_or_else(|error| {
+            if verbosity.allows_errors() {
+                eprintln!("Unable to read config: {}", error);
+            }
+            std::process::exit(1);
+        });
+
+        let config_file = serde_json::from_str::<ConfigOptions>(&contents)
+            .unwrap_or_else(|error| {
+                if verbosity.allows_errors() {
+                    eprintln!("Errors found in config: {}", error);
+                }
+                std::process::exit(1);
+            });
+
+        config_file.into()
+    } else {
+        Config::default()
+    }
+}

src/alejandra_cli/src/config_options.rs

@@ -0,0 +1,13 @@
+use alejandra::config::Config;
+use serde::Deserialize;
+
+#[derive(Deserialize)]
+pub(crate) struct ConfigOptions {}
+
+impl From<ConfigOptions> for Config {
+    fn from(_config_options: ConfigOptions) -> Config {
+        let config = Config::default();
+
+        config
+    }
+}

src/alejandra_cli/src/lib.rs

@@ -1,4 +1,5 @@
 mod ads;
 pub mod cli;
+mod config_options;
 mod find;
 mod verbosity;