Adding flag and logic for different output format (#185)

src/lib.rs

@@ -10,6 +10,7 @@ pub mod fs;
 pub mod linter;
 pub mod logging;
 pub mod message;
+pub mod printer;
 mod pyproject;
 mod python;
 pub mod settings;

src/logging.rs

@@ -3,15 +3,16 @@ use fern;
 
 #[macro_export]
 macro_rules! tell_user {
-    ($($arg:tt)*) => {
+    ($writer:expr,$($arg:tt)*) => {
-        println!(
+        writeln!(
+            $writer,
             "[{}] {}",
             chrono::Local::now()
                 .format("%H:%M:%S %p")
                 .to_string()
                 .dimmed(),
             format_args!($($arg)*)
-        )
+        )?
     }
 }
 

src/main.rs

@@ -1,3 +1,4 @@
+use std::io::{stdout, BufWriter, Write};
 use std::path::PathBuf;
 use std::process::ExitCode;
 use std::sync::mpsc::channel;
@@ -18,6 +19,7 @@ use ::ruff::fs::iter_python_files;
 use ::ruff::linter::lint_path;
 use ::ruff::logging::set_up_logging;
 use ::ruff::message::Message;
+use ::ruff::printer::{Printer, SerializationFormat};
 use ::ruff::settings::Settings;
 use ::ruff::tell_user;
 
@@ -57,6 +59,9 @@ struct Cli {
     /// List of file and/or directory patterns to exclude from checks.
     #[clap(long, multiple = true)]
     exclude: Vec<Pattern>,
+    /// Output formatting of linting messages
+    #[clap(long, arg_enum, default_value_t=SerializationFormat::Text)]
+    format: SerializationFormat,
 }
 
 #[cfg(feature = "update-informer")]
@@ -130,60 +135,14 @@ fn run_once(
     Ok(messages)
 }
 
-fn report_once(messages: &[Message]) -> Result<()> {
-    let (fixed, outstanding): (Vec<&Message>, Vec<&Message>) =
-        messages.iter().partition(|message| message.fixed);
-    let num_fixable = outstanding
-        .iter()
-        .filter(|message| message.kind.fixable())
-        .count();
-
-    if !outstanding.is_empty() {
-        for message in &outstanding {
-            println!("{}", message);
-        }
-        println!();
-    }
-
-    if !fixed.is_empty() {
-        println!(
-            "Found {} error(s) ({} fixed).",
-            outstanding.len(),
-            fixed.len()
-        );
-    } else {
-        println!("Found {} error(s).", outstanding.len());
-    }
-
-    if num_fixable > 0 {
-        println!("{num_fixable} potentially fixable with the --fix option.");
-    }
-
-    Ok(())
-}
-
-fn report_continuously(messages: &[Message]) -> Result<()> {
-    tell_user!(
-        "Found {} error(s). Watching for file changes.",
-        messages.len(),
-    );
-
-    if !messages.is_empty() {
-        println!();
-        for message in messages {
-            println!("{}", message);
-        }
-    }
-
-    Ok(())
-}
-
 fn inner_main() -> Result<ExitCode> {
     let cli = Cli::parse();
 
     set_up_logging(cli.verbose)?;
 
     let mut settings = Settings::from_paths(&cli.files);
+    let mut printer = Printer::new(BufWriter::new(stdout()), cli.format);
+
     if !cli.select.is_empty() {
         settings.select(cli.select);
     }
@@ -201,11 +160,11 @@ fn inner_main() -> Result<ExitCode> {
 
         // Perform an initial run instantly.
         clearscreen::clear()?;
-        tell_user!("Starting linter in watch mode...\n");
+        tell_user!(printer.writer, "Starting linter in watch mode...\n");
 
         let messages = run_once(&cli.files, &settings, !cli.no_cache, false)?;
         if !cli.quiet {
-            report_continuously(&messages)?;
+            printer.write_continuously(&messages)?;
         }
 
         // Configure the file watcher.
@@ -221,11 +180,11 @@ fn inner_main() -> Result<ExitCode> {
                     if let Some(path) = e.path {
                         if path.to_string_lossy().ends_with(".py") {
                             clearscreen::clear()?;
-                            tell_user!("File change detected...\n");
+                            tell_user!(printer.writer, "File change detected...\n");
 
                             let messages = run_once(&cli.files, &settings, !cli.no_cache, false)?;
                             if !cli.quiet {
-                                report_continuously(&messages)?;
+                                printer.write_continuously(&messages)?;
                             }
                         }
                     }
@@ -236,7 +195,7 @@ fn inner_main() -> Result<ExitCode> {
     } else {
         let messages = run_once(&cli.files, &settings, !cli.no_cache, cli.fix)?;
         if !cli.quiet {
-            report_once(&messages)?;
+            printer.write_once(&messages)?;
         }
 
         #[cfg(feature = "update-informer")]

src/printer.rs

@@ -0,0 +1,82 @@
+use colored::Colorize;
+use std::io::Write;
+
+use anyhow::Result;
+use clap::ValueEnum;
+
+use crate::message::Message;
+use crate::tell_user;
+
+#[derive(Clone, ValueEnum, PartialEq, Eq, Debug)]
+pub enum SerializationFormat {
+    Text,
+    Json,
+}
+
+pub struct Printer<W> {
+    pub writer: W,
+    format: SerializationFormat,
+}
+
+impl<W: Write> Printer<W> {
+    pub fn new(writer: W, format: SerializationFormat) -> Self {
+        Self { writer, format }
+    }
+
+    pub fn write_once(&mut self, messages: &[Message]) -> Result<()> {
+        let (fixed, outstanding): (Vec<&Message>, Vec<&Message>) =
+            messages.iter().partition(|message| message.fixed);
+        let num_fixable = outstanding
+            .iter()
+            .filter(|message| message.kind.fixable())
+            .count();
+
+        match self.format {
+            SerializationFormat::Json => {
+                writeln!(self.writer, "{}", serde_json::to_string_pretty(&messages)?)?
+            }
+            SerializationFormat::Text => {
+                if !fixed.is_empty() {
+                    writeln!(
+                        self.writer,
+                        "Found {} error(s) ({} fixed).",
+                        outstanding.len(),
+                        fixed.len()
+                    )?
+                } else {
+                    writeln!(self.writer, "Found {} error(s).", outstanding.len())?
+                }
+
+                for message in outstanding {
+                    writeln!(self.writer, "{}", message)?
+                }
+
+                if num_fixable > 0 {
+                    writeln!(
+                        self.writer,
+                        "{num_fixable} potentially fixable with the --fix option."
+                    )?
+                }
+            }
+        }
+
+        Ok(())
+    }
+
+    pub fn write_continuously(&mut self, messages: &[Message]) -> Result<()> {
+        tell_user!(
+            self.writer,
+            "Found {} error(s). Watching for file changes.",
+            messages.len(),
+        );
+
+        if !messages.is_empty() {
+            writeln!(self.writer, "\n")?;
+            for message in messages {
+                writeln!(self.writer, "{}", message)?
+            }
+        }
+
+        Ok(())
+    }
+}