Use trait to abstract emit modes (rust-lang#3616)

Author: Ruben Schmidmeister

src/checkstyle.rs

@@ -0,0 +1,50 @@
+pub(crate) use self::checkstyle::*;
+pub(crate) use self::diff::*;
+pub(crate) use self::files::*;
+pub(crate) use self::files_with_backup::*;
+pub(crate) use self::modified_lines::*;
+pub(crate) use self::stdout::*;
+use crate::FileName;
+use std::io::{self, Write};
+use std::path::Path;
+
+mod checkstyle;
+mod diff;
+mod files;
+mod files_with_backup;
+mod modified_lines;
+mod stdout;
+
+pub(crate) struct FormattedFile<'a> {
+    pub(crate) filename: &'a FileName,
+    pub(crate) original_text: &'a str,
+    pub(crate) formatted_text: &'a str,
+}
+
+#[derive(Debug, Default, Clone)]
+pub(crate) struct EmitterResult {
+    pub(crate) has_diff: bool,
+}
+
+pub(crate) trait Emitter {
+    fn emit_formatted_file(
+        &self,
+        output: &mut dyn Write,
+        formatted_file: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error>;
+
+    fn emit_header(&self, _output: &mut dyn Write) -> Result<(), io::Error> {
+        Ok(())
+    }
+
+    fn emit_footer(&self, _output: &mut dyn Write) -> Result<(), io::Error> {
+        Ok(())
+    }
+}
+
+fn ensure_real_path(filename: &FileName) -> &Path {
+    match *filename {
+        FileName::Real(ref path) => path,
+        _ => panic!("cannot format `{}` and emit to files", filename),
+    }
+}

src/emitter.rs

@@ -0,0 +1,64 @@
+use self::xml::XmlEscaped;
+use super::*;
+use crate::rustfmt_diff::{make_diff, DiffLine, Mismatch};
+use std::io::{self, Write};
+use std::path::Path;
+
+mod xml;
+
+#[derive(Debug, Default)]
+pub(crate) struct CheckstyleEmitter;
+
+impl Emitter for CheckstyleEmitter {
+    fn emit_header(&self, output: &mut dyn Write) -> Result<(), io::Error> {
+        writeln!(output, r#"<?xml version="1.0" encoding="utf-8"?>"#)?;
+        write!(output, r#"<checkstyle version="4.3">"#)?;
+        Ok(())
+    }
+
+    fn emit_footer(&self, output: &mut dyn Write) -> Result<(), io::Error> {
+        writeln!(output, "</checkstyle>")
+    }
+
+    fn emit_formatted_file(
+        &self,
+        output: &mut dyn Write,
+        FormattedFile {
+            filename,
+            original_text,
+            formatted_text,
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        const CONTEXT_SIZE: usize = 3;
+        let filename = ensure_real_path(filename);
+        let diff = make_diff(original_text, formatted_text, CONTEXT_SIZE);
+        output_checkstyle_file(output, filename, diff)?;
+        Ok(EmitterResult::default())
+    }
+}
+
+pub(crate) fn output_checkstyle_file<T>(
+    mut writer: T,
+    filename: &Path,
+    diff: Vec<Mismatch>,
+) -> Result<(), io::Error>
+where
+    T: Write,
+{
+    write!(writer, r#"<file name="{}">"#, filename.display())?;
+    for mismatch in diff {
+        for line in mismatch.lines {
+            // Do nothing with `DiffLine::Context` and `DiffLine::Resulting`.
+            if let DiffLine::Expected(message) = line {
+                write!(
+                    writer,
+                    r#"<error line="{}" severity="warning" message="Should be `{}`" />"#,
+                    mismatch.line_number,
+                    XmlEscaped(&message)
+                )?;
+            }
+        }
+    }
+    write!(writer, "</file>")?;
+    Ok(())
+}

src/emitter/checkstyle.rs

@@ -0,0 +1,52 @@
+use std::fmt::{self, Display};
+
+/// Convert special characters into XML entities.
+/// This is needed for checkstyle output.
+pub(super) struct XmlEscaped<'a>(pub(super) &'a str);
+
+impl<'a> Display for XmlEscaped<'a> {
+    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
+        for char in self.0.chars() {
+            match char {
+                '<' => write!(formatter, "&lt;"),
+                '>' => write!(formatter, "&gt;"),
+                '"' => write!(formatter, "&quot;"),
+                '\'' => write!(formatter, "&apos;"),
+                '&' => write!(formatter, "&amp;"),
+                _ => write!(formatter, "{}", char),
+            }?;
+        }
+
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn special_characters_are_escaped() {
+        assert_eq!(
+            "&lt;&gt;&quot;&apos;&amp;",
+            format!("{}", XmlEscaped(r#"<>"'&"#)),
+        );
+    }
+
+    #[test]
+    fn special_characters_are_escaped_in_string_with_other_characters() {
+        assert_eq!(
+            "The quick brown &quot;🦊&quot; jumps &lt;over&gt; the lazy 🐶",
+            format!(
+                "{}",
+                XmlEscaped(r#"The quick brown "🦊" jumps <over> the lazy 🐶"#)
+            ),
+        );
+    }
+
+    #[test]
+    fn other_characters_are_not_escaped() {
+        let string = "The quick brown 🦊 jumps over the lazy 🐶";
+        assert_eq!(string, format!("{}", XmlEscaped(string)));
+    }
+}

src/emitter/checkstyle/xml.rs

@@ -0,0 +1,35 @@
+use super::*;
+use crate::config::Config;
+use crate::rustfmt_diff::{make_diff, print_diff};
+
+pub(crate) struct DiffEmitter {
+    config: Config,
+}
+
+impl DiffEmitter {
+    pub(crate) fn new(config: Config) -> Self {
+        Self { config }
+    }
+}
+
+impl Emitter for DiffEmitter {
+    fn emit_formatted_file(
+        &self,
+        _output: &mut dyn Write,
+        FormattedFile {
+            filename,
+            original_text,
+            formatted_text,
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        const CONTEXT_SIZE: usize = 3;
+        let mismatch = make_diff(&original_text, formatted_text, CONTEXT_SIZE);
+        let has_diff = !mismatch.is_empty();
+        print_diff(
+            mismatch,
+            |line_num| format!("Diff in {} at line {}:", filename, line_num),
+            &self.config,
+        );
+        return Ok(EmitterResult { has_diff });
+    }
+}

src/emitter/diff.rs

@@ -0,0 +1,24 @@
+use super::*;
+use std::fs;
+
+#[derive(Debug, Default)]
+pub(crate) struct FilesEmitter;
+
+impl Emitter for FilesEmitter {
+    fn emit_formatted_file(
+        &self,
+        _output: &mut dyn Write,
+        FormattedFile {
+            filename,
+            original_text,
+            formatted_text,
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        // Write text directly over original file if there is a diff.
+        let filename = ensure_real_path(filename);
+        if original_text != formatted_text {
+            fs::write(filename, formatted_text)?;
+        }
+        Ok(EmitterResult::default())
+    }
+}

src/emitter/files.rs

@@ -0,0 +1,31 @@
+use super::*;
+use std::fs;
+
+#[derive(Debug, Default)]
+pub(crate) struct FilesWithBackupEmitter;
+
+impl Emitter for FilesWithBackupEmitter {
+    fn emit_formatted_file(
+        &self,
+        _output: &mut dyn Write,
+        FormattedFile {
+            filename,
+            original_text,
+            formatted_text,
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        let filename = ensure_real_path(filename);
+        if original_text != formatted_text {
+            // Do a little dance to make writing safer - write to a temp file
+            // rename the original to a .bk, then rename the temp file to the
+            // original.
+            let tmp_name = filename.with_extension("tmp");
+            let bk_name = filename.with_extension("bk");
+
+            fs::write(&tmp_name, formatted_text)?;
+            fs::rename(filename, bk_name)?;
+            fs::rename(tmp_name, filename)?;
+        }
+        Ok(EmitterResult::default())
+    }
+}

src/emitter/files_with_backup.rs

@@ -0,0 +1,24 @@
+use super::*;
+use crate::rustfmt_diff::{make_diff, ModifiedLines};
+use std::io::Write;
+
+#[derive(Debug, Default)]
+pub(crate) struct ModifiedLinesEmitter;
+
+impl Emitter for ModifiedLinesEmitter {
+    fn emit_formatted_file(
+        &self,
+        output: &mut dyn Write,
+        FormattedFile {
+            original_text,
+            formatted_text,
+            ..
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        const CONTEXT_SIZE: usize = 0;
+        let mismatch = make_diff(original_text, formatted_text, CONTEXT_SIZE);
+        let has_diff = !mismatch.is_empty();
+        write!(output, "{}", ModifiedLines::from(mismatch))?;
+        Ok(EmitterResult { has_diff })
+    }
+}