Rename ruff crate to ruff_linter (#7529)

crates/ruff_linter/src/message/diff.rs

@@ -0,0 +1,200 @@
+use std::fmt::{Display, Formatter};
+use std::num::NonZeroUsize;
+
+use colored::{Color, ColoredString, Colorize, Styles};
+
+use ruff_text_size::{Ranged, TextRange, TextSize};
+use similar::{ChangeTag, TextDiff};
+
+use ruff_diagnostics::{Applicability, Fix};
+use ruff_source_file::{OneIndexed, SourceFile};
+
+use crate::message::Message;
+
+/// Renders a diff that shows the code fixes.
+///
+/// The implementation isn't fully fledged out and only used by tests. Before using in production, try
+/// * Improve layout
+/// * Replace tabs with spaces for a consistent experience across terminals
+/// * Replace zero-width whitespaces
+/// * Print a simpler diff if only a single line has changed
+/// * Compute the diff from the [`Edit`] because diff calculation is expensive.
+pub(super) struct Diff<'a> {
+    fix: &'a Fix,
+    source_code: &'a SourceFile,
+}
+
+impl<'a> Diff<'a> {
+    pub(crate) fn from_message(message: &'a Message) -> Option<Diff> {
+        message.fix.as_ref().map(|fix| Diff {
+            source_code: &message.file,
+            fix,
+        })
+    }
+}
+
+impl Display for Diff<'_> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> std::fmt::Result {
+        let mut output = String::with_capacity(self.source_code.source_text().len());
+        let mut last_end = TextSize::default();
+
+        for edit in self.fix.edits() {
+            output.push_str(
+                self.source_code
+                    .slice(TextRange::new(last_end, edit.start())),
+            );
+            output.push_str(edit.content().unwrap_or_default());
+            last_end = edit.end();
+        }
+
+        output.push_str(&self.source_code.source_text()[usize::from(last_end)..]);
+
+        let diff = TextDiff::from_lines(self.source_code.source_text(), &output);
+
+        let message = match self.fix.applicability() {
+            Applicability::Automatic => "Fix",
+            Applicability::Suggested => "Suggested fix",
+            Applicability::Manual => "Possible fix",
+            Applicability::Unspecified => "Suggested fix", /* For backwards compatibility, unspecified fixes are 'suggested' */
+        };
+        writeln!(f, "ℹ {}", message.blue())?;
+
+        let (largest_old, largest_new) = diff
+            .ops()
+            .last()
+            .map(|op| (op.old_range().start, op.new_range().start))
+            .unwrap_or_default();
+
+        let digit_with =
+            calculate_print_width(OneIndexed::from_zero_indexed(largest_new.max(largest_old)));
+
+        for (idx, group) in diff.grouped_ops(3).iter().enumerate() {
+            if idx > 0 {
+                writeln!(f, "{:-^1$}", "-", 80)?;
+            }
+            for op in group {
+                for change in diff.iter_inline_changes(op) {
+                    let sign = match change.tag() {
+                        ChangeTag::Delete => "-",
+                        ChangeTag::Insert => "+",
+                        ChangeTag::Equal => " ",
+                    };
+
+                    let line_style = LineStyle::from(change.tag());
+
+                    let old_index = change.old_index().map(OneIndexed::from_zero_indexed);
+                    let new_index = change.new_index().map(OneIndexed::from_zero_indexed);
+
+                    write!(
+                        f,
+                        "{} {} |{}",
+                        Line {
+                            index: old_index,
+                            width: digit_with
+                        },
+                        Line {
+                            index: new_index,
+                            width: digit_with
+                        },
+                        line_style.apply_to(sign).bold()
+                    )?;
+
+                    for (emphasized, value) in change.iter_strings_lossy() {
+                        if emphasized {
+                            write!(f, "{}", line_style.apply_to(&value).underline().on_black())?;
+                        } else {
+                            write!(f, "{}", line_style.apply_to(&value))?;
+                        }
+                    }
+                    if change.missing_newline() {
+                        writeln!(f)?;
+                    }
+                }
+            }
+        }
+
+        Ok(())
+    }
+}
+
+struct LineStyle {
+    fgcolor: Option<Color>,
+    style: Option<Styles>,
+}
+
+impl LineStyle {
+    fn apply_to(&self, input: &str) -> ColoredString {
+        let mut colored = ColoredString::from(input);
+        if let Some(color) = self.fgcolor {
+            colored = colored.color(color);
+        }
+
+        if let Some(style) = self.style {
+            match style {
+                Styles::Clear => colored.clear(),
+                Styles::Bold => colored.bold(),
+                Styles::Dimmed => colored.dimmed(),
+                Styles::Underline => colored.underline(),
+                Styles::Reversed => colored.reversed(),
+                Styles::Italic => colored.italic(),
+                Styles::Blink => colored.blink(),
+                Styles::Hidden => colored.hidden(),
+                Styles::Strikethrough => colored.strikethrough(),
+            }
+        } else {
+            colored
+        }
+    }
+}
+
+impl From<ChangeTag> for LineStyle {
+    fn from(value: ChangeTag) -> Self {
+        match value {
+            ChangeTag::Equal => LineStyle {
+                fgcolor: None,
+                style: Some(Styles::Dimmed),
+            },
+            ChangeTag::Delete => LineStyle {
+                fgcolor: Some(Color::Red),
+                style: None,
+            },
+            ChangeTag::Insert => LineStyle {
+                fgcolor: Some(Color::Green),
+                style: None,
+            },
+        }
+    }
+}
+
+struct Line {
+    index: Option<OneIndexed>,
+    width: NonZeroUsize,
+}
+
+impl Display for Line {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        match self.index {
+            None => {
+                for _ in 0..self.width.get() {
+                    f.write_str(" ")?;
+                }
+                Ok(())
+            }
+            Some(idx) => write!(f, "{:<width$}", idx, width = self.width.get()),
+        }
+    }
+}
+
+/// Calculate the length of the string representation of `value`
+pub(super) fn calculate_print_width(mut value: OneIndexed) -> NonZeroUsize {
+    const TEN: OneIndexed = OneIndexed::from_zero_indexed(9);
+
+    let mut width = OneIndexed::ONE;
+
+    while value >= TEN {
+        value = OneIndexed::new(value.get() / 10).unwrap_or(OneIndexed::MIN);
+        width = width.checked_add(1).unwrap();
+    }
+
+    width
+}