feat: Make multiline label collapsing configurable per label

Author: TurtleArmyMc

src/lib.rs

@@ -120,13 +120,25 @@ impl<Id: fmt::Debug + Hash + PartialEq + Eq + ToOwned> Span for (Id, RangeInclus
     }
 }
 
+/// A type that describes when a multiline label should hide its contents with ellipses
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum LabelCollapseLines {
+    /// Hides the contents of the label with ellipses if it is over the line limit
+    MaxLines(usize),
+    /// Always hides contents of multiline labels with ellipses
+    Always,
+    /// Always show the entire label contents (never use ellipses)
+    Never,
+}
+
 /// A type that represents the way a label should be displayed.
 #[derive(Clone, Debug, Hash, PartialEq, Eq)]
 struct LabelDisplay {
     msg: Option<String>,
     color: Option<Color>,
     order: i32,
     priority: i32,
+    collapse_when: LabelCollapseLines,
 }
 
 /// A type that represents a labelled section of source code.
@@ -153,6 +165,7 @@ impl<S: Span> Label<S> {
                 color: None,
                 order: 0,
                 priority: 0,
+                collapse_when: LabelCollapseLines::Always,
             },
         }
     }
@@ -197,6 +210,14 @@ impl<S: Span> Label<S> {
         self.display_info.priority = priority;
         self
     }
+
+    /// Specify when the label should hide multiline contents with ellipses
+    ///
+    /// If unspecified, defaults to always collapsing multiline labels with `LabelCollapseLines::Always`
+    pub fn with_collapse_lines_when(mut self, collapse_when: LabelCollapseLines) -> Self {
+        self.display_info.collapse_when = collapse_when;
+        self
+    }
 }
 
 /// A type representing a diagnostic that is ready to be written to output.

src/write.rs

@@ -1,7 +1,7 @@
 use std::io;
 use std::ops::Range;
 
-use crate::{Config, IndexType, LabelDisplay};
+use crate::{Config, IndexType, LabelCollapseLines, LabelDisplay};
 
 use super::draw::{self, StreamAwareFmt, StreamType, WrappedWriter};
 use super::{Cache, CharSet, LabelAttach, Report, ReportStyle, Show, Span, Write};
@@ -626,7 +626,20 @@ impl<S: Span, K: ReportStyle> Report<S, K> {
                         .iter()
                         .any(|label| label.char_span.contains(&line.span().start()));
                     if !is_ellipsis && within_label {
-                        is_ellipsis = true;
+                        // Check to see if all the multiline labels containing this line use ellipses
+                        let should_collapse = multi_labels
+                            .iter()
+                            .filter(|label| label.char_span.contains(&line.span().start()))
+                            .all(|label| match label.display_info.collapse_when {
+                                LabelCollapseLines::Always => true,
+                                LabelCollapseLines::MaxLines(max_lines) => {
+                                    label.end_line - label.start_line >= max_lines
+                                }
+                                LabelCollapseLines::Never => false,
+                            });
+                        if should_collapse {
+                            is_ellipsis = true;
+                        }
                     } else {
                         if !self.config.compact && !is_ellipsis {
                             write_margin(&mut w, idx, false, is_ellipsis, false, None, &[], &None)?;
@@ -1000,7 +1013,8 @@ mod tests {
     use insta::assert_snapshot;
 
     use crate::{
-        Cache, CharSet, Config, IndexType, Label, Report, ReportKind, ReportStyle, Source, Span,
+        Cache, CharSet, Config, IndexType, Label, LabelCollapseLines, Report, ReportKind,
+        ReportStyle, Source, Span,
     };
 
     impl<S: Span, K: ReportStyle> Report<S, K> {
@@ -1405,6 +1419,60 @@ mod tests {
         "###);
     }
 
+    #[test]
+    fn multiline_label_show_3() {
+        let source = "pear\napple\n==\norange\nbanana";
+        let msg = remove_trailing(
+            Report::build(ReportKind::Error, 0..0)
+                .with_config(no_color_and_ascii())
+                .with_label(
+                    Label::new(5..20)
+                        .with_message("illegal comparison")
+                        .with_collapse_lines_when(LabelCollapseLines::MaxLines(3)),
+                )
+                .finish()
+                .write_to_string(Source::from(source)),
+        );
+        assert_snapshot!(msg, @r"
+        Error:
+           ,-[ <unknown>:1:1 ]
+           |
+         2 | ,-> apple
+         3 | |   ==
+         4 | |-> orange
+           | |
+           | `------------ illegal comparison
+        ---'
+        ");
+    }
+
+    #[test]
+    fn multiline_label_longer_than_max_span_line_count() {
+        let source = "pear\napple\n==\norange\nbanana";
+        let msg = remove_trailing(
+            Report::build(ReportKind::Error, 0..0)
+                .with_config(no_color_and_ascii())
+                .with_label(
+                    Label::new(5..source.len())
+                        .with_message("illegal comparison")
+                        .with_collapse_lines_when(LabelCollapseLines::MaxLines(3)),
+                )
+                .finish()
+                .write_to_string(Source::from(source)),
+        );
+        assert_snapshot!(msg, @r"
+        Error:
+           ,-[ <unknown>:1:1 ]
+           |
+         2 | ,-> apple
+           : :
+         5 | |-> banana
+           | |
+           | `----------- illegal comparison
+        ---'
+        ");
+    }
+
     #[test]
     fn multiline_context_label() {
         let source = "apple\nbanana\ncarrot\ndragonfruit\negg\nfruit\ngrapes";