codespan_reporting/term/
renderer.rs

Help
1use std::io::{self, Write};
2use std::ops::Range;
3use termcolor::{ColorSpec, WriteColor};
4
5use crate::diagnostic::{LabelStyle, Severity};
6use crate::files::{Error, Location};
7use crate::term::{Chars, Config, Styles};
8
9/// The 'location focus' of a source code snippet.
10pub struct Locus {
11    /// The user-facing name of the file.
12    pub name: String,
13    /// The location.
14    pub location: Location,
15}
16
17/// Single-line label, with an optional message.
18///
19/// ```text
20/// ^^^^^^^^^ blah blah
21/// ```
22pub type SingleLabel<'diagnostic> = (LabelStyle, Range<usize>, &'diagnostic str);
23
24/// A multi-line label to render.
25///
26/// Locations are relative to the start of where the source code is rendered.
27pub enum MultiLabel<'diagnostic> {
28    /// Multi-line label top.
29    /// The contained value indicates where the label starts.
30    ///
31    /// ```text
32    /// ╭────────────^
33    /// ```
34    ///
35    /// Can also be rendered at the beginning of the line
36    /// if there is only whitespace before the label starts.
37    ///
38    /// /// ```text
39    /// ╭
40    /// ```
41    Top(usize),
42    /// Left vertical labels for multi-line labels.
43    ///
44    /// ```text
45    /// │
46    /// ```
47    Left,
48    /// Multi-line label bottom, with an optional message.
49    /// The first value indicates where the label ends.
50    ///
51    /// ```text
52    /// ╰────────────^ blah blah
53    /// ```
54    Bottom(usize, &'diagnostic str),
55}
56
57#[derive(Copy, Clone)]
58enum VerticalBound {
59    Top,
60    Bottom,
61}
62
63type Underline = (LabelStyle, VerticalBound);
64
65/// A renderer of display list entries.
66///
67/// The following diagram gives an overview of each of the parts of the renderer's output:
68///
69/// ```text
70///                     ┌ outer gutter
71///                     │ ┌ left border
72///                     │ │ ┌ inner gutter
73///                     │ │ │   ┌─────────────────────────── source ─────────────────────────────┐
74///                     │ │ │   │                                                                │
75///                  ┌────────────────────────────────────────────────────────────────────────────
76///        header ── │ error[0001]: oh noes, a cupcake has occurred!
77/// snippet start ── │    ┌─ test:9:0
78/// snippet empty ── │    │
79///  snippet line ── │  9 │   ╭ Cupcake ipsum dolor. Sit amet marshmallow topping cheesecake
80///  snippet line ── │ 10 │   │ muffin. Halvah croissant candy canes bonbon candy. Apple pie jelly
81///                  │    │ ╭─│─────────^
82/// snippet break ── │    · │ │
83///  snippet line ── │ 33 │ │ │ Muffin danish chocolate soufflé pastry icing bonbon oat cake.
84///  snippet line ── │ 34 │ │ │ Powder cake jujubes oat cake. Lemon drops tootsie roll marshmallow
85///                  │    │ │ ╰─────────────────────────────^ blah blah
86/// snippet break ── │    · │
87///  snippet line ── │ 38 │ │   Brownie lemon drops chocolate jelly-o candy canes. Danish marzipan
88///  snippet line ── │ 39 │ │   jujubes soufflé carrot cake marshmallow tiramisu caramels candy canes.
89///                  │    │ │           ^^^^^^^^^^^^^^^^^^^ -------------------- blah blah
90///                  │    │ │           │
91///                  │    │ │           blah blah
92///                  │    │ │           note: this is a note
93///  snippet line ── │ 40 │ │   Fruitcake jelly-o danish toffee. Tootsie roll pastry cheesecake
94///  snippet line ── │ 41 │ │   soufflé marzipan. Chocolate bar oat cake jujubes lollipop pastry
95///  snippet line ── │ 42 │ │   cupcake. Candy canes cupcake toffee gingerbread candy canes muffin
96///                  │    │ │                                ^^^^^^^^^^^^^^^^^^ blah blah
97///                  │    │ ╰──────────^ blah blah
98/// snippet break ── │    ·
99///  snippet line ── │ 82 │     gingerbread toffee chupa chups chupa chups jelly-o cotton candy.
100///                  │    │                 ^^^^^^                         ------- blah blah
101/// snippet empty ── │    │
102///  snippet note ── │    = blah blah
103///  snippet note ── │    = blah blah blah
104///                  │      blah blah
105///  snippet note ── │    = blah blah blah
106///                  │      blah blah
107///         empty ── │
108/// ```
109///
110/// Filler text from http://www.cupcakeipsum.com
111pub struct Renderer<'writer, 'config> {
112    writer: &'writer mut dyn WriteColor,
113    config: &'config Config,
114}
115
116impl<'writer, 'config> Renderer<'writer, 'config> {
117    /// Construct a renderer from the given writer and config.
118    pub fn new(
119        writer: &'writer mut dyn WriteColor,
120        config: &'config Config,
121    ) -> Renderer<'writer, 'config> {
122        Renderer { writer, config }
123    }
124
125    fn chars(&self) -> &'config Chars {
126        &self.config.chars
127    }
128
129    fn styles(&self) -> &'config Styles {
130        &self.config.styles
131    }
132
133    /// Diagnostic header, with severity, code, and message.
134    ///
135    /// ```text
136    /// error[E0001]: unexpected type in `+` application
137    /// ```
138    pub fn render_header(
139        &mut self,
140        locus: Option<&Locus>,
141        severity: Severity,
142        code: Option<&str>,
143        message: &str,
144    ) -> Result<(), Error> {
145        // Write locus
146        //
147        // ```text
148        // test:2:9:
149        // ```
150        if let Some(locus) = locus {
151            self.snippet_locus(locus)?;
152            write!(self, ": ")?;
153        }
154
155        // Write severity name
156        //
157        // ```text
158        // error
159        // ```
160        self.set_color(self.styles().header(severity))?;
161        match severity {
162            Severity::Bug => write!(self, "bug")?,
163            Severity::Error => write!(self, "error")?,
164            Severity::Warning => write!(self, "warning")?,
165            Severity::Help => write!(self, "help")?,
166            Severity::Note => write!(self, "note")?,
167        }
168
169        // Write error code
170        //
171        // ```text
172        // [E0001]
173        // ```
174        if let Some(code) = &code.filter(|code| !code.is_empty()) {
175            write!(self, "[{}]", code)?;
176        }
177
178        // Write diagnostic message
179        //
180        // ```text
181        // : unexpected type in `+` application
182        // ```
183        self.set_color(&self.styles().header_message)?;
184        write!(self, ": {}", message)?;
185        self.reset()?;
186
187        writeln!(self)?;
188
189        Ok(())
190    }
191
192    /// Empty line.
193    pub fn render_empty(&mut self) -> Result<(), Error> {
194        writeln!(self)?;
195        Ok(())
196    }
197
198    /// Top left border and locus.
199    ///
200    /// ```text
201    /// ┌─ test:2:9
202    /// ```
203    pub fn render_snippet_start(
204        &mut self,
205        outer_padding: usize,
206        locus: &Locus,
207    ) -> Result<(), Error> {
208        self.outer_gutter(outer_padding)?;
209
210        self.set_color(&self.styles().source_border)?;
211        write!(self, "{}", self.chars().snippet_start)?;
212        self.reset()?;
213
214        write!(self, " ")?;
215        self.snippet_locus(&locus)?;
216
217        writeln!(self)?;
218
219        Ok(())
220    }
221
222    /// A line of source code.
223    ///
224    /// ```text
225    /// 10 │   │ muffin. Halvah croissant candy canes bonbon candy. Apple pie jelly
226    ///    │ ╭─│─────────^
227    /// ```
228    pub fn render_snippet_source(
229        &mut self,
230        outer_padding: usize,
231        line_number: usize,
232        source: &str,
233        severity: Severity,
234        single_labels: &[SingleLabel<'_>],
235        num_multi_labels: usize,
236        multi_labels: &[(usize, LabelStyle, MultiLabel<'_>)],
237    ) -> Result<(), Error> {
238        // Trim trailing newlines, linefeeds, and null chars from source, if they exist.
239        // FIXME: Use the number of trimmed placeholders when rendering single line carets
240        let source = source.trim_end_matches(['\n', '\r', '\0'].as_ref());
241
242        // Write source line
243        //
244        // ```text
245        // 10 │   │ muffin. Halvah croissant candy canes bonbon candy. Apple pie jelly
246        // ```
247        {
248            // Write outer gutter (with line number) and border
249            self.outer_gutter_number(line_number, outer_padding)?;
250            self.border_left()?;
251
252            // Write inner gutter (with multi-line continuations on the left if necessary)
253            let mut multi_labels_iter = multi_labels.iter().peekable();
254            for label_column in 0..num_multi_labels {
255                match multi_labels_iter.peek() {
256                    Some((label_index, label_style, label)) if *label_index == label_column => {
257                        match label {
258                            MultiLabel::Top(start)
259                                if *start <= source.len() - source.trim_start().len() =>
260                            {
261                                self.label_multi_top_left(severity, *label_style)?;
262                            }
263                            MultiLabel::Top(..) => self.inner_gutter_space()?,
264                            MultiLabel::Left | MultiLabel::Bottom(..) => {
265                                self.label_multi_left(severity, *label_style, None)?;
266                            }
267                        }
268                        multi_labels_iter.next();
269                    }
270                    Some((_, _, _)) | None => self.inner_gutter_space()?,
271                }
272            }
273
274            // Write source text
275            write!(self, " ")?;
276            let mut in_primary = false;
277            for (metrics, ch) in self.char_metrics(source.char_indices()) {
278                let column_range = metrics.byte_index..(metrics.byte_index + ch.len_utf8());
279
280                // Check if we are overlapping a primary label
281                let is_primary = single_labels.iter().any(|(ls, range, _)| {
282                    *ls == LabelStyle::Primary && is_overlapping(range, &column_range)
283                }) || multi_labels.iter().any(|(_, ls, label)| {
284                    *ls == LabelStyle::Primary
285                        && match label {
286                            MultiLabel::Top(start) => column_range.start >= *start,
287                            MultiLabel::Left => true,
288                            MultiLabel::Bottom(start, _) => column_range.end <= *start,
289                        }
290                });
291
292                // Set the source color if we are in a primary label
293                if is_primary && !in_primary {
294                    self.set_color(self.styles().label(severity, LabelStyle::Primary))?;
295                    in_primary = true;
296                } else if !is_primary && in_primary {
297                    self.reset()?;
298                    in_primary = false;
299                }
300
301                match ch {
302                    '\t' => (0..metrics.unicode_width).try_for_each(|_| write!(self, " "))?,
303                    _ => write!(self, "{}", ch)?,
304                }
305            }
306            if in_primary {
307                self.reset()?;
308            }
309            writeln!(self)?;
310        }
311
312        // Write single labels underneath source
313        //
314        // ```text
315        //   │     - ---- ^^^ second mutable borrow occurs here
316        //   │     │ │
317        //   │     │ first mutable borrow occurs here
318        //   │     first borrow later used by call
319        //   │     help: some help here
320        // ```
321        if !single_labels.is_empty() {
322            // Our plan is as follows:
323            //
324            // 1. Do an initial scan to find:
325            //    - The number of non-empty messages.
326            //    - The right-most start and end positions of labels.
327            //    - A candidate for a trailing label (where the label's message
328            //      is printed to the left of the caret).
329            // 2. Check if the trailing label candidate overlaps another label -
330            //    if so we print it underneath the carets with the other labels.
331            // 3. Print a line of carets, and (possibly) the trailing message
332            //    to the left.
333            // 4. Print vertical lines pointing to the carets, and the messages
334            //    for those carets.
335            //
336            // We try our best avoid introducing new dynamic allocations,
337            // instead preferring to iterate over the labels multiple times. It
338            // is unclear what the performance tradeoffs are however, so further
339            // investigation may be required.
340
341            // The number of non-empty messages to print.
342            let mut num_messages = 0;
343            // The right-most start position, eg:
344            //
345            // ```text
346            // -^^^^---- ^^^^^^^
347            //           │
348            //           right-most start position
349            // ```
350            let mut max_label_start = 0;
351            // The right-most end position, eg:
352            //
353            // ```text
354            // -^^^^---- ^^^^^^^
355            //                 │
356            //                 right-most end position
357            // ```
358            let mut max_label_end = 0;
359            // A trailing message, eg:
360            //
361            // ```text
362            // ^^^ second mutable borrow occurs here
363            // ```
364            let mut trailing_label = None;
365
366            for (label_index, label) in single_labels.iter().enumerate() {
367                let (_, range, message) = label;
368                if !message.is_empty() {
369                    num_messages += 1;
370                }
371                max_label_start = std::cmp::max(max_label_start, range.start);
372                max_label_end = std::cmp::max(max_label_end, range.end);
373                // This is a candidate for the trailing label, so let's record it.
374                if range.end == max_label_end {
375                    if message.is_empty() {
376                        trailing_label = None;
377                    } else {
378                        trailing_label = Some((label_index, label));
379                    }
380                }
381            }
382            if let Some((trailing_label_index, (_, trailing_range, _))) = trailing_label {
383                // Check to see if the trailing label candidate overlaps any of
384                // the other labels on the current line.
385                if single_labels
386                    .iter()
387                    .enumerate()
388                    .filter(|(label_index, _)| *label_index != trailing_label_index)
389                    .any(|(_, (_, range, _))| is_overlapping(trailing_range, range))
390                {
391                    // If it does, we'll instead want to render it below the
392                    // carets along with the other hanging labels.
393                    trailing_label = None;
394                }
395            }
396
397            // Write a line of carets
398            //
399            // ```text
400            //   │ ^^^^^^  -------^^^^^^^^^-------^^^^^----- ^^^^ trailing label message
401            // ```
402            self.outer_gutter(outer_padding)?;
403            self.border_left()?;
404            self.inner_gutter(severity, num_multi_labels, multi_labels)?;
405            write!(self, " ")?;
406
407            let mut previous_label_style = None;
408            let placeholder_metrics = Metrics {
409                byte_index: source.len(),
410                unicode_width: 1,
411            };
412            for (metrics, ch) in self
413                .char_metrics(source.char_indices())
414                // Add a placeholder source column at the end to allow for
415                // printing carets at the end of lines, eg:
416                //
417                // ```text
418                // 1 │ Hello world!
419                //   │             ^
420                // ```
421                .chain(std::iter::once((placeholder_metrics, '\0')))
422            {
423                // Find the current label style at this column
424                let column_range = metrics.byte_index..(metrics.byte_index + ch.len_utf8());
425                let current_label_style = single_labels
426                    .iter()
427                    .filter(|(_, range, _)| is_overlapping(range, &column_range))
428                    .map(|(label_style, _, _)| *label_style)
429                    .max_by_key(label_priority_key);
430
431                // Update writer style if necessary
432                if previous_label_style != current_label_style {
433                    match current_label_style {
434                        None => self.reset()?,
435                        Some(label_style) => {
436                            self.set_color(self.styles().label(severity, label_style))?;
437                        }
438                    }
439                }
440
441                let caret_ch = match current_label_style {
442                    Some(LabelStyle::Primary) => Some(self.chars().single_primary_caret),
443                    Some(LabelStyle::Secondary) => Some(self.chars().single_secondary_caret),
444                    // Only print padding if we are before the end of the last single line caret
445                    None if metrics.byte_index < max_label_end => Some(' '),
446                    None => None,
447                };
448                if let Some(caret_ch) = caret_ch {
449                    // FIXME: improve rendering of carets between character boundaries
450                    (0..metrics.unicode_width).try_for_each(|_| write!(self, "{}", caret_ch))?;
451                }
452
453                previous_label_style = current_label_style;
454            }
455            // Reset style if it was previously set
456            if previous_label_style.is_some() {
457                self.reset()?;
458            }
459            // Write first trailing label message
460            if let Some((_, (label_style, _, message))) = trailing_label {
461                write!(self, " ")?;
462                self.set_color(self.styles().label(severity, *label_style))?;
463                write!(self, "{}", message)?;
464                self.reset()?;
465            }
466            writeln!(self)?;
467
468            // Write hanging labels pointing to carets
469            //
470            // ```text
471            //   │     │ │
472            //   │     │ first mutable borrow occurs here
473            //   │     first borrow later used by call
474            //   │     help: some help here
475            // ```
476            if num_messages > trailing_label.iter().count() {
477                // Write first set of vertical lines before hanging labels
478                //
479                // ```text
480                //   │     │ │
481                // ```
482                self.outer_gutter(outer_padding)?;
483                self.border_left()?;
484                self.inner_gutter(severity, num_multi_labels, multi_labels)?;
485                write!(self, " ")?;
486                self.caret_pointers(
487                    severity,
488                    max_label_start,
489                    single_labels,
490                    trailing_label,
491                    source.char_indices(),
492                )?;
493                writeln!(self)?;
494
495                // Write hanging labels pointing to carets
496                //
497                // ```text
498                //   │     │ first mutable borrow occurs here
499                //   │     first borrow later used by call
500                //   │     help: some help here
501                // ```
502                for (label_style, range, message) in
503                    hanging_labels(single_labels, trailing_label).rev()
504                {
505                    self.outer_gutter(outer_padding)?;
506                    self.border_left()?;
507                    self.inner_gutter(severity, num_multi_labels, multi_labels)?;
508                    write!(self, " ")?;
509                    self.caret_pointers(
510                        severity,
511                        max_label_start,
512                        single_labels,
513                        trailing_label,
514                        source
515                            .char_indices()
516                            .take_while(|(byte_index, _)| *byte_index < range.start),
517                    )?;
518                    self.set_color(self.styles().label(severity, *label_style))?;
519                    write!(self, "{}", message)?;
520                    self.reset()?;
521                    writeln!(self)?;
522                }
523            }
524        }
525
526        // Write top or bottom label carets underneath source
527        //
528        // ```text
529        //     │ ╰───│──────────────────^ woops
530        //     │   ╭─│─────────^
531        // ```
532        for (multi_label_index, (_, label_style, label)) in multi_labels.iter().enumerate() {
533            let (label_style, range, bottom_message) = match label {
534                MultiLabel::Left => continue, // no label caret needed
535                // no label caret needed if this can be started in front of the line
536                MultiLabel::Top(start) if *start <= source.len() - source.trim_start().len() => {
537                    continue
538                }
539                MultiLabel::Top(range) => (*label_style, range, None),
540                MultiLabel::Bottom(range, message) => (*label_style, range, Some(message)),
541            };
542
543            self.outer_gutter(outer_padding)?;
544            self.border_left()?;
545
546            // Write inner gutter.
547            //
548            // ```text
549            //  │ ╭─│───│
550            // ```
551            let mut underline = None;
552            let mut multi_labels_iter = multi_labels.iter().enumerate().peekable();
553            for label_column in 0..num_multi_labels {
554                match multi_labels_iter.peek() {
555                    Some((i, (label_index, ls, label))) if *label_index == label_column => {
556                        match label {
557                            MultiLabel::Left => {
558                                self.label_multi_left(severity, *ls, underline.map(|(s, _)| s))?;
559                            }
560                            MultiLabel::Top(..) if multi_label_index > *i => {
561                                self.label_multi_left(severity, *ls, underline.map(|(s, _)| s))?;
562                            }
563                            MultiLabel::Bottom(..) if multi_label_index < *i => {
564                                self.label_multi_left(severity, *ls, underline.map(|(s, _)| s))?;
565                            }
566                            MultiLabel::Top(..) if multi_label_index == *i => {
567                                underline = Some((*ls, VerticalBound::Top));
568                                self.label_multi_top_left(severity, label_style)?
569                            }
570                            MultiLabel::Bottom(..) if multi_label_index == *i => {
571                                underline = Some((*ls, VerticalBound::Bottom));
572                                self.label_multi_bottom_left(severity, label_style)?;
573                            }
574                            MultiLabel::Top(..) | MultiLabel::Bottom(..) => {
575                                self.inner_gutter_column(severity, underline)?;
576                            }
577                        }
578                        multi_labels_iter.next();
579                    }
580                    Some((_, _)) | None => self.inner_gutter_column(severity, underline)?,
581                }
582            }
583
584            // Finish the top or bottom caret
585            match bottom_message {
586                None => self.label_multi_top_caret(severity, label_style, source, *range)?,
587                Some(message) => {
588                    self.label_multi_bottom_caret(severity, label_style, source, *range, message)?
589                }
590            }
591        }
592
593        Ok(())
594    }
595
596    /// An empty source line, for providing additional whitespace to source snippets.
597    ///
598    /// ```text
599    /// │ │ │
600    /// ```
601    pub fn render_snippet_empty(
602        &mut self,
603        outer_padding: usize,
604        severity: Severity,
605        num_multi_labels: usize,
606        multi_labels: &[(usize, LabelStyle, MultiLabel<'_>)],
607    ) -> Result<(), Error> {
608        self.outer_gutter(outer_padding)?;
609        self.border_left()?;
610        self.inner_gutter(severity, num_multi_labels, multi_labels)?;
611        writeln!(self)?;
612        Ok(())
613    }
614
615    /// A broken source line, for labeling skipped sections of source.
616    ///
617    /// ```text
618    /// · │ │
619    /// ```
620    pub fn render_snippet_break(
621        &mut self,
622        outer_padding: usize,
623        severity: Severity,
624        num_multi_labels: usize,
625        multi_labels: &[(usize, LabelStyle, MultiLabel<'_>)],
626    ) -> Result<(), Error> {
627        self.outer_gutter(outer_padding)?;
628        self.border_left_break()?;
629        self.inner_gutter(severity, num_multi_labels, multi_labels)?;
630        writeln!(self)?;
631        Ok(())
632    }
633
634    /// Additional notes.
635    ///
636    /// ```text
637    /// = expected type `Int`
638    ///      found type `String`
639    /// ```
640    pub fn render_snippet_note(
641        &mut self,
642        outer_padding: usize,
643        message: &str,
644    ) -> Result<(), Error> {
645        for (note_line_index, line) in message.lines().enumerate() {
646            self.outer_gutter(outer_padding)?;
647            match note_line_index {
648                0 => {
649                    self.set_color(&self.styles().note_bullet)?;
650                    write!(self, "{}", self.chars().note_bullet)?;
651                    self.reset()?;
652                }
653                _ => write!(self, " ")?,
654            }
655            // Write line of message
656            writeln!(self, " {}", line)?;
657        }
658
659        Ok(())
660    }
661
662    /// Adds tab-stop aware unicode-width computations to an iterator over
663    /// character indices. Assumes that the character indices begin at the start
664    /// of the line.
665    fn char_metrics(
666        &self,
667        char_indices: impl Iterator<Item = (usize, char)>,
668    ) -> impl Iterator<Item = (Metrics, char)> {
669        use unicode_width::UnicodeWidthChar;
670
671        let tab_width = self.config.tab_width;
672        let mut unicode_column = 0;
673
674        char_indices.map(move |(byte_index, ch)| {
675            let metrics = Metrics {
676                byte_index,
677                unicode_width: match (ch, tab_width) {
678                    ('\t', 0) => 0, // Guard divide-by-zero
679                    ('\t', _) => tab_width - (unicode_column % tab_width),
680                    (ch, _) => ch.width().unwrap_or(0),
681                },
682            };
683            unicode_column += metrics.unicode_width;
684
685            (metrics, ch)
686        })
687    }
688
689    /// Location focus.
690    fn snippet_locus(&mut self, locus: &Locus) -> Result<(), Error> {
691        write!(
692            self,
693            "{name}:{line_number}:{column_number}",
694            name = locus.name,
695            line_number = locus.location.line_number,
696            column_number = locus.location.column_number,
697        )?;
698        Ok(())
699    }
700
701    /// The outer gutter of a source line.
702    fn outer_gutter(&mut self, outer_padding: usize) -> Result<(), Error> {
703        write!(self, "{space: >width$} ", space = "", width = outer_padding)?;
704        Ok(())
705    }
706
707    /// The outer gutter of a source line, with line number.
708    fn outer_gutter_number(
709        &mut self,
710        line_number: usize,
711        outer_padding: usize,
712    ) -> Result<(), Error> {
713        self.set_color(&self.styles().line_number)?;
714        write!(
715            self,
716            "{line_number: >width$}",
717            line_number = line_number,
718            width = outer_padding,
719        )?;
720        self.reset()?;
721        write!(self, " ")?;
722        Ok(())
723    }
724
725    /// The left-hand border of a source line.
726    fn border_left(&mut self) -> Result<(), Error> {
727        self.set_color(&self.styles().source_border)?;
728        write!(self, "{}", self.chars().source_border_left)?;
729        self.reset()?;
730        Ok(())
731    }
732
733    /// The broken left-hand border of a source line.
734    fn border_left_break(&mut self) -> Result<(), Error> {
735        self.set_color(&self.styles().source_border)?;
736        write!(self, "{}", self.chars().source_border_left_break)?;
737        self.reset()?;
738        Ok(())
739    }
740
741    /// Write vertical lines pointing to carets.
742    fn caret_pointers(
743        &mut self,
744        severity: Severity,
745        max_label_start: usize,
746        single_labels: &[SingleLabel<'_>],
747        trailing_label: Option<(usize, &SingleLabel<'_>)>,
748        char_indices: impl Iterator<Item = (usize, char)>,
749    ) -> Result<(), Error> {
750        for (metrics, ch) in self.char_metrics(char_indices) {
751            let column_range = metrics.byte_index..(metrics.byte_index + ch.len_utf8());
752            let label_style = hanging_labels(single_labels, trailing_label)
753                .filter(|(_, range, _)| column_range.contains(&range.start))
754                .map(|(label_style, _, _)| *label_style)
755                .max_by_key(label_priority_key);
756
757            let mut spaces = match label_style {
758                None => 0..metrics.unicode_width,
759                Some(label_style) => {
760                    self.set_color(self.styles().label(severity, label_style))?;
761                    write!(self, "{}", self.chars().pointer_left)?;
762                    self.reset()?;
763                    1..metrics.unicode_width
764                }
765            };
766            // Only print padding if we are before the end of the last single line caret
767            if metrics.byte_index <= max_label_start {
768                spaces.try_for_each(|_| write!(self, " "))?;
769            }
770        }
771
772        Ok(())
773    }
774
775    /// The left of a multi-line label.
776    ///
777    /// ```text
778    ///  │
779    /// ```
780    fn label_multi_left(
781        &mut self,
782        severity: Severity,
783        label_style: LabelStyle,
784        underline: Option<LabelStyle>,
785    ) -> Result<(), Error> {
786        match underline {
787            None => write!(self, " ")?,
788            // Continue an underline horizontally
789            Some(label_style) => {
790                self.set_color(self.styles().label(severity, label_style))?;
791                write!(self, "{}", self.chars().multi_top)?;
792                self.reset()?;
793            }
794        }
795        self.set_color(self.styles().label(severity, label_style))?;
796        write!(self, "{}", self.chars().multi_left)?;
797        self.reset()?;
798        Ok(())
799    }
800
801    /// The top-left of a multi-line label.
802    ///
803    /// ```text
804    ///  ╭
805    /// ```
806    fn label_multi_top_left(
807        &mut self,
808        severity: Severity,
809        label_style: LabelStyle,
810    ) -> Result<(), Error> {
811        write!(self, " ")?;
812        self.set_color(self.styles().label(severity, label_style))?;
813        write!(self, "{}", self.chars().multi_top_left)?;
814        self.reset()?;
815        Ok(())
816    }
817
818    /// The bottom left of a multi-line label.
819    ///
820    /// ```text
821    ///  ╰
822    /// ```
823    fn label_multi_bottom_left(
824        &mut self,
825        severity: Severity,
826        label_style: LabelStyle,
827    ) -> Result<(), Error> {
828        write!(self, " ")?;
829        self.set_color(self.styles().label(severity, label_style))?;
830        write!(self, "{}", self.chars().multi_bottom_left)?;
831        self.reset()?;
832        Ok(())
833    }
834
835    /// Multi-line label top.
836    ///
837    /// ```text
838    /// ─────────────^
839    /// ```
840    fn label_multi_top_caret(
841        &mut self,
842        severity: Severity,
843        label_style: LabelStyle,
844        source: &str,
845        start: usize,
846    ) -> Result<(), Error> {
847        self.set_color(self.styles().label(severity, label_style))?;
848
849        for (metrics, _) in self
850            .char_metrics(source.char_indices())
851            .take_while(|(metrics, _)| metrics.byte_index < start + 1)
852        {
853            // FIXME: improve rendering of carets between character boundaries
854            (0..metrics.unicode_width)
855                .try_for_each(|_| write!(self, "{}", self.chars().multi_top))?;
856        }
857
858        let caret_start = match label_style {
859            LabelStyle::Primary => self.config.chars.multi_primary_caret_start,
860            LabelStyle::Secondary => self.config.chars.multi_secondary_caret_start,
861        };
862        write!(self, "{}", caret_start)?;
863        self.reset()?;
864        writeln!(self)?;
865        Ok(())
866    }
867
868    /// Multi-line label bottom, with a message.
869    ///
870    /// ```text
871    /// ─────────────^ expected `Int` but found `String`
872    /// ```
873    fn label_multi_bottom_caret(
874        &mut self,
875        severity: Severity,
876        label_style: LabelStyle,
877        source: &str,
878        start: usize,
879        message: &str,
880    ) -> Result<(), Error> {
881        self.set_color(self.styles().label(severity, label_style))?;
882
883        for (metrics, _) in self
884            .char_metrics(source.char_indices())
885            .take_while(|(metrics, _)| metrics.byte_index < start)
886        {
887            // FIXME: improve rendering of carets between character boundaries
888            (0..metrics.unicode_width)
889                .try_for_each(|_| write!(self, "{}", self.chars().multi_bottom))?;
890        }
891
892        let caret_end = match label_style {
893            LabelStyle::Primary => self.config.chars.multi_primary_caret_start,
894            LabelStyle::Secondary => self.config.chars.multi_secondary_caret_start,
895        };
896        write!(self, "{}", caret_end)?;
897        if !message.is_empty() {
898            write!(self, " {}", message)?;
899        }
900        self.reset()?;
901        writeln!(self)?;
902        Ok(())
903    }
904
905    /// Writes an empty gutter space, or continues an underline horizontally.
906    fn inner_gutter_column(
907        &mut self,
908        severity: Severity,
909        underline: Option<Underline>,
910    ) -> Result<(), Error> {
911        match underline {
912            None => self.inner_gutter_space(),
913            Some((label_style, vertical_bound)) => {
914                self.set_color(self.styles().label(severity, label_style))?;
915                let ch = match vertical_bound {
916                    VerticalBound::Top => self.config.chars.multi_top,
917                    VerticalBound::Bottom => self.config.chars.multi_bottom,
918                };
919                write!(self, "{0}{0}", ch)?;
920                self.reset()?;
921                Ok(())
922            }
923        }
924    }
925
926    /// Writes an empty gutter space.
927    fn inner_gutter_space(&mut self) -> Result<(), Error> {
928        write!(self, "  ")?;
929        Ok(())
930    }
931
932    /// Writes an inner gutter, with the left lines if necessary.
933    fn inner_gutter(
934        &mut self,
935        severity: Severity,
936        num_multi_labels: usize,
937        multi_labels: &[(usize, LabelStyle, MultiLabel<'_>)],
938    ) -> Result<(), Error> {
939        let mut multi_labels_iter = multi_labels.iter().peekable();
940        for label_column in 0..num_multi_labels {
941            match multi_labels_iter.peek() {
942                Some((label_index, ls, label)) if *label_index == label_column => match label {
943                    MultiLabel::Left | MultiLabel::Bottom(..) => {
944                        self.label_multi_left(severity, *ls, None)?;
945                        multi_labels_iter.next();
946                    }
947                    MultiLabel::Top(..) => {
948                        self.inner_gutter_space()?;
949                        multi_labels_iter.next();
950                    }
951                },
952                Some((_, _, _)) | None => self.inner_gutter_space()?,
953            }
954        }
955
956        Ok(())
957    }
958}
959
960impl<'writer, 'config> Write for Renderer<'writer, 'config> {
961    fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
962        self.writer.write(buf)
963    }
964
965    fn flush(&mut self) -> io::Result<()> {
966        self.writer.flush()
967    }
968}
969
970impl<'writer, 'config> WriteColor for Renderer<'writer, 'config> {
971    fn supports_color(&self) -> bool {
972        self.writer.supports_color()
973    }
974
975    fn set_color(&mut self, spec: &ColorSpec) -> io::Result<()> {
976        self.writer.set_color(spec)
977    }
978
979    fn reset(&mut self) -> io::Result<()> {
980        self.writer.reset()
981    }
982
983    fn is_synchronous(&self) -> bool {
984        self.writer.is_synchronous()
985    }
986}
987
988struct Metrics {
989    byte_index: usize,
990    unicode_width: usize,
991}
992
993/// Check if two ranges overlap
994fn is_overlapping(range0: &Range<usize>, range1: &Range<usize>) -> bool {
995    let start = std::cmp::max(range0.start, range1.start);
996    let end = std::cmp::min(range0.end, range1.end);
997    start < end
998}
999
1000/// For prioritizing primary labels over secondary labels when rendering carets.
1001fn label_priority_key(label_style: &LabelStyle) -> u8 {
1002    match label_style {
1003        LabelStyle::Secondary => 0,
1004        LabelStyle::Primary => 1,
1005    }
1006}
1007
1008/// Return an iterator that yields the labels that require hanging messages
1009/// rendered underneath them.
1010fn hanging_labels<'labels, 'diagnostic>(
1011    single_labels: &'labels [SingleLabel<'diagnostic>],
1012    trailing_label: Option<(usize, &'labels SingleLabel<'diagnostic>)>,
1013) -> impl 'labels + DoubleEndedIterator<Item = &'labels SingleLabel<'diagnostic>> {
1014    single_labels
1015        .iter()
1016        .enumerate()
1017        .filter(|(_, (_, _, message))| !message.is_empty())
1018        .filter(move |(i, _)| trailing_label.map_or(true, |(j, _)| *i != j))
1019        .map(|(_, label)| label)
1020}
codespan_reporting/term/renderer.rs

codespan_reporting/term/
renderer.rs
