feat: Add full label printing support

src/label.rs

@@ -11,6 +11,7 @@ pub(crate) struct LabelDisplay {
     pub color: Option<Color>,
     pub order: i32,
     pub priority: i32,
+    pub collapse_when: LabelCollapseLines,
 }
 
 /// A type that represents a labelled section of source code.
@@ -37,6 +38,7 @@ impl<S: Span> Label<S> {
                 color: None,
                 order: 0,
                 priority: 0,
+                collapse_when: LabelCollapseLines::Always,
             },
         }
     }
@@ -81,6 +83,14 @@ impl<S: Span> Label<S> {
         self.display_info.priority = priority;
         self
     }
+
+    /// Specify when the label should hide multiline spans
+    ///
+    /// 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
+    }
 }
 
 /// The attachment point of inline label arrows
@@ -93,6 +103,18 @@ pub enum LabelAttach {
     /// Arrows should attach to the end of the label span.
     End,
 }
+
+/// Whether a multiline label should hide its contents
+#[derive(Clone, Debug, Hash, PartialEq, Eq)]
+pub enum LabelCollapseLines {
+    /// Hides the contents of the label with if it's over the line limit
+    MaxLines(usize),
+    /// Always hides contents of multiline labels (only show first and last lines)
+    Always,
+    /// Always show the entire label contents (always show full span)
+    Never,
+}
+
 #[test]
 #[should_panic]
 #[allow(clippy::reversed_empty_ranges)]

src/report/tests.rs

@@ -10,7 +10,8 @@
 use insta::assert_snapshot;
 
 use crate::{
-    Cache, Config, FnCache, IndexType, Label, Report, ReportKind, ReportStyle, Source, Span,
+    Cache, Config, FnCache, IndexType, Label, LabelCollapseLines, Report, ReportKind, ReportStyle,
+    Source, Span,
 };
 
 impl<S: Span, K: ReportStyle> Report<S, K> {
@@ -498,6 +499,60 @@ fn multiple_multilines_same_span() {
     ");
 }
 
+#[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())
+            .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())
+            .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";

src/report/write.rs

@@ -4,7 +4,7 @@ use std::io;
 use std::ops::Range;
 
 use crate::source::Location;
-use crate::{Config, IndexType, LabelDisplay, Source};
+use crate::{Config, IndexType, LabelCollapseLines, LabelDisplay, Source};
 
 use super::draw::{self, StreamAwareFmt, StreamType, WrappedWriter};
 use super::{Cache, CharSet, LabelAttach, Report, ReportStyle, Rept, Show, Span, Write};
@@ -601,7 +601,20 @@ 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 should be hidden
+                        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)?;