feat(tabs): Add replace tabs with spaces option (#82)

Fixes: https://github.com/zkat/miette/issues/73

README.md

@@ -389,6 +389,7 @@ miette::set_hook(Box::new(|_| {
         .terminal_links(true)
         .unicode(false)
         .context_lines(3)
+        .tab_width(4)
         .build())
 }))
 

src/handler.rs

@@ -39,6 +39,7 @@ pub struct MietteHandlerOpts {
     pub(crate) unicode: Option<bool>,
     pub(crate) footer: Option<String>,
     pub(crate) context_lines: Option<usize>,
+    pub(crate) tab_width: Option<usize>,
 }
 
 impl MietteHandlerOpts {
@@ -119,6 +120,12 @@ impl MietteHandlerOpts {
         self
     }
 
+    /// Set the displayed tab width in spaces.
+    pub fn tab_width(mut self, width: usize) -> Self {
+        self.tab_width = Some(width);
+        self
+    }
+
     /// Builds a [MietteHandler] from this builder.
     pub fn build(self) -> MietteHandler {
         let graphical = self.is_graphical();
@@ -167,6 +174,9 @@ impl MietteHandlerOpts {
             if let Some(context_lines) = self.context_lines {
                 handler = handler.with_context_lines(context_lines);
             }
+            if let Some(w) = self.tab_width {
+                handler = handler.tab_width(w);
+            }
             MietteHandler {
                 inner: Box::new(handler),
             }

src/handlers/graphical.rs

@@ -25,6 +25,7 @@ pub struct GraphicalReportHandler {
     pub(crate) theme: GraphicalTheme,
     pub(crate) footer: Option<String>,
     pub(crate) context_lines: usize,
+    pub(crate) tab_width: Option<usize>,
 }
 
 impl GraphicalReportHandler {
@@ -37,6 +38,7 @@ impl GraphicalReportHandler {
             theme: GraphicalTheme::default(),
             footer: None,
             context_lines: 1,
+            tab_width: None,
         }
     }
 
@@ -48,9 +50,16 @@ impl GraphicalReportHandler {
             theme,
             footer: None,
             context_lines: 1,
+            tab_width: None,
         }
     }
 
+    /// Set the displayed tab width in spaces.
+    pub fn tab_width(mut self, width: usize) -> Self {
+        self.tab_width = Some(width);
+        self
+    }
+
     /// Whether to enable error code linkification using [Diagnostic::url].
     pub fn with_links(mut self, links: bool) -> Self {
         self.linkify_code = links;
@@ -376,7 +385,12 @@ impl GraphicalReportHandler {
             self.render_line_gutter(f, max_gutter, line, &labels)?;
 
             // And _now_ we can print out the line text itself!
-            writeln!(f, "{}", line.text)?;
+            if let Some(w) = self.tab_width {
+                let text = line.text.replace("\t", " ".repeat(w).as_str());
+                writeln!(f, "{}", text)?;
+            } else {
+                writeln!(f, "{}", line.text)?;
+            };
 
             // Next, we write all the highlights that apply to this particular line.
             let (single_line, multi_line): (Vec<_>, Vec<_>) = labels
@@ -545,10 +559,20 @@ impl GraphicalReportHandler {
     ) -> fmt::Result {
         let mut underlines = String::new();
         let mut highest = 0;
+
         let chars = &self.theme.characters;
         for hl in single_liners {
             let hl_len = std::cmp::max(1, hl.len());
-            let local_offset = hl.offset() - line.offset;
+
+            let local_offset = if let Some(w) = self.tab_width {
+                // Only count tabs that affect the position of the highlighted line and ignore tabs past the span.
+                let tab_count = &line.text[..hl.offset() - line.offset].matches('\t').count();
+                let tabs_as_spaces = tab_count * w - tab_count;
+                hl.offset() - line.offset + tabs_as_spaces
+            } else {
+                hl.offset() - line.offset
+            };
+
             let vbar_offset = local_offset + (hl_len / 2);
             let num_left = vbar_offset - local_offset;
             let num_right = local_offset + hl_len - vbar_offset - 1;
@@ -581,10 +605,15 @@ impl GraphicalReportHandler {
         let vbar_offsets: Vec<_> = single_liners
             .iter()
             .map(|hl| {
-                (
+                let local_offset = if let Some(w) = self.tab_width {
-                    hl,
+                    // Only count tabs that affect the position of the highlighted line and ignore tabs past the span.
-                    (hl.offset() - line.offset) + (std::cmp::max(1, hl.len()) / 2),
+                    let tab_count = &line.text[..hl.offset() - line.offset].matches('\t').count();
-                )
+                    let tabs_as_spaces = tab_count * w - tab_count;
+                    hl.offset() - line.offset + tabs_as_spaces
+                } else {
+                    hl.offset() - line.offset
+                };
+                (hl, local_offset + (std::cmp::max(1, hl.len()) / 2))
             })
             .collect();
         for hl in single_liners.iter().rev() {

tests/graphical.rs

@@ -19,6 +19,12 @@ fn fmt_report(diag: Report) -> String {
         NarratableReportHandler::new()
             .render_report(&mut out, diag.as_ref())
             .unwrap();
+    } else if let Ok(w) = std::env::var("REPLACE_TABS") {
+        GraphicalReportHandler::new_themed(GraphicalTheme::unicode_nocolor())
+            .with_width(80)
+            .tab_width(w.parse().expect("Invalid tab width."))
+            .render_report(&mut out, diag.as_ref())
+            .unwrap();
     } else {
         GraphicalReportHandler::new_themed(GraphicalTheme::unicode_nocolor())
             .with_width(80)
@@ -65,6 +71,84 @@ fn single_line_with_wide_char() -> Result<(), MietteError> {
     Ok(())
 }
 
+#[test]
+fn single_line_with_two_tabs() -> Result<(), MietteError> {
+    #[derive(Debug, Diagnostic, Error)]
+    #[error("oops!")]
+    #[diagnostic(code(oops::my::bad), help("try doing it better next time?"))]
+    struct MyBad {
+        #[source_code]
+        src: NamedSource,
+        #[label("this bit here")]
+        highlight: SourceSpan,
+    }
+
+    std::env::set_var("REPLACE_TABS", "4");
+
+    let src = "source\n\t\ttext\n    here".to_string();
+    let err = MyBad {
+        src: NamedSource::new("bad_file.rs", src),
+        highlight: (9, 4).into(),
+    };
+    let out = fmt_report(err.into());
+    println!("Error: {}", out);
+    let expected = r#"oops::my::bad
+
+  × oops!
+   ╭─[bad_file.rs:1:1]
+ 1 │ source
+ 2 │         text
+   ·         ──┬─
+   ·           ╰── this bit here
+ 3 │     here
+   ╰────
+  help: try doing it better next time?
+"#
+    .trim_start()
+    .to_string();
+    assert_eq!(expected, out);
+    Ok(())
+}
+
+#[test]
+fn single_line_with_tab_in_middle() -> Result<(), MietteError> {
+    #[derive(Debug, Diagnostic, Error)]
+    #[error("oops!")]
+    #[diagnostic(code(oops::my::bad), help("try doing it better next time?"))]
+    struct MyBad {
+        #[source_code]
+        src: NamedSource,
+        #[label("this bit here")]
+        highlight: SourceSpan,
+    }
+
+    std::env::set_var("REPLACE_TABS", "4");
+
+    let src = "source\ntext\ttext\n    here".to_string();
+    let err = MyBad {
+        src: NamedSource::new("bad_file.rs", src),
+        highlight: (12, 4).into(),
+    };
+    let out = fmt_report(err.into());
+    println!("Error: {}", out);
+    let expected = r#"oops::my::bad
+
+  × oops!
+   ╭─[bad_file.rs:1:1]
+ 1 │ source
+ 2 │ text    text
+   ·         ──┬─
+   ·           ╰── this bit here
+ 3 │     here
+   ╰────
+  help: try doing it better next time?
+"#
+    .trim_start()
+    .to_string();
+    assert_eq!(expected, out);
+    Ok(())
+}
+
 #[test]
 fn single_line_highlight() -> Result<(), MietteError> {
     #[derive(Debug, Diagnostic, Error)]
@@ -293,6 +377,53 @@ fn multiple_same_line_highlights() -> Result<(), MietteError> {
     Ok(())
 }
 
+#[test]
+fn multiple_same_line_highlights_with_tabs_in_middle() -> Result<(), MietteError> {
+    #[derive(Debug, Diagnostic, Error)]
+    #[error("oops!")]
+    #[diagnostic(code(oops::my::bad), help("try doing it better next time?"))]
+    struct MyBad {
+        #[source_code]
+        src: NamedSource,
+        #[label = "x"]
+        highlight1: SourceSpan,
+        #[label = "y"]
+        highlight2: SourceSpan,
+        #[label = "z"]
+        highlight3: SourceSpan,
+    }
+
+    std::env::set_var("REPLACE_TABS", "4");
+
+    let src = "source\n  text text text\ttext text\n    here".to_string();
+    let err = MyBad {
+        src: NamedSource::new("bad_file.rs", src),
+        highlight1: (9, 4).into(),
+        highlight2: (14, 4).into(),
+        highlight3: (24, 4).into(),
+    };
+    let out = fmt_report(err.into());
+    println!("Error: {}", out);
+    let expected = r#"oops::my::bad
+
+  × oops!
+   ╭─[bad_file.rs:1:1]
+ 1 │ source
+ 2 │   text text text    text text
+   ·   ──┬─ ──┬─         ──┬─
+   ·     │    │            ╰── z
+   ·     │    ╰── y
+   ·     ╰── x
+ 3 │     here
+   ╰────
+  help: try doing it better next time?
+"#
+    .trim_start()
+    .to_string();
+    assert_eq!(expected, out);
+    Ok(())
+}
+
 #[test]
 fn multiline_highlight_adjacent() -> Result<(), MietteError> {
     #[derive(Debug, Diagnostic, Error)]

tests/test_location.rs

@@ -30,7 +30,6 @@ impl miette::ReportHandler for LocationHandler {
     }
 
     fn track_caller(&mut self, location: &'static Location<'static>) {
-        dbg!(location);
         self.actual = Some(location.file());
     }
 }