aboutsummaryrefslogtreecommitdiff
path: root/helix-term/src/ui/markdown.rs
blob: 41021fde0fca2403c98edb0184f10011844f2410 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
use crate::compositor::{Component, Context};
use tui::{
    buffer::Buffer as Surface,
    text::{Span, Spans, Text},
};

use std::sync::Arc;

use pulldown_cmark::{CodeBlockKind, Event, HeadingLevel, Options, Parser, Tag};

use helix_core::{
    syntax::{self, HighlightEvent, Syntax},
    Rope,
};
use helix_view::{
    graphics::{Margin, Rect, Style},
    Theme,
};

fn styled_multiline_text<'a>(text: String, style: Style) -> Text<'a> {
    let spans: Vec<_> = text
        .lines()
        .map(|line| Span::styled(line.to_string(), style))
        .map(Spans::from)
        .collect();
    Text::from(spans)
}

pub fn highlighted_code_block<'a>(
    text: String,
    language: &str,
    theme: Option<&Theme>,
    config_loader: Arc<syntax::Loader>,
) -> Text<'a> {
    let mut spans = Vec::new();
    let mut lines = Vec::new();

    let get_theme = |key: &str| -> Style { theme.map(|t| t.get(key)).unwrap_or_default() };
    let text_style = get_theme(Markdown::TEXT_STYLE);
    let code_style = get_theme(Markdown::BLOCK_STYLE);

    let theme = match theme {
        Some(t) => t,
        None => return styled_multiline_text(text, code_style),
    };

    let rope = Rope::from(text.as_ref());
    let syntax = config_loader
        .language_configuration_for_injection_string(language)
        .and_then(|config| config.highlight_config(theme.scopes()))
        .map(|config| Syntax::new(&rope, config, Arc::clone(&config_loader)));

    let syntax = match syntax {
        Some(s) => s,
        None => return styled_multiline_text(text, code_style),
    };

    let mut highlights = Vec::new();

    for event in syntax.highlight_iter(rope.slice(..), None, None) {
        match event.unwrap() {
            HighlightEvent::HighlightStart(span) => {
                highlights.push(span);
            }
            HighlightEvent::HighlightEnd => {
                highlights.pop();
            }
            HighlightEvent::Source { start, end } => {
                let style = match highlights.first() {
                    Some(span) => theme.get(&theme.scopes()[span.0]),
                    None => text_style,
                };

                let mut slice = &text[start..end];
                // TODO: do we need to handle all unicode line endings
                // here, or is just '\n' okay?
                while let Some(end) = slice.find('\n') {
                    // emit span up to newline
                    let text = &slice[..end];
                    let text = text.replace('\t', "    "); // replace tabs
                    let span = Span::styled(text, style);
                    spans.push(span);

                    // truncate slice to after newline
                    slice = &slice[end + 1..];

                    // make a new line
                    let spans = std::mem::take(&mut spans);
                    lines.push(Spans::from(spans));
                }

                // if there's anything left, emit it too
                if !slice.is_empty() {
                    let span = Span::styled(slice.replace('\t', "    "), style);
                    spans.push(span);
                }
            }
        }
    }

    if !spans.is_empty() {
        let spans = std::mem::take(&mut spans);
        lines.push(Spans::from(spans));
    }

    Text::from(lines)
}

pub struct Markdown {
    contents: String,

    config_loader: Arc<syntax::Loader>,
}

// TODO: pre-render and self reference via Pin
// better yet, just use Tendril + subtendril for references

impl Markdown {
    const TEXT_STYLE: &'static str = "ui.text";
    const BLOCK_STYLE: &'static str = "markup.raw.inline";
    const HEADING_STYLES: [&'static str; 6] = [
        "markup.heading.1",
        "markup.heading.2",
        "markup.heading.3",
        "markup.heading.4",
        "markup.heading.5",
        "markup.heading.6",
    ];

    pub fn new(contents: String, config_loader: Arc<syntax::Loader>) -> Self {
        Self {
            contents,
            config_loader,
        }
    }

    fn parse(&self, theme: Option<&Theme>) -> tui::text::Text<'_> {
        // // also 2021-03-04T16:33:58.553 helix_lsp::transport [INFO] <- {"contents":{"kind":"markdown","value":"\n```rust\ncore::num\n```\n\n```rust\npub const fn saturating_sub(self, rhs:Self) ->Self\n```\n\n---\n\n```rust\n```"},"range":{"end":{"character":61,"line":101},"start":{"character":47,"line":101}}}
        // let text = "\n```rust\ncore::iter::traits::iterator::Iterator\n```\n\n```rust\nfn collect<B: FromIterator<Self::Item>>(self) -> B\nwhere\n        Self: Sized,\n```\n\n---\n\nTransforms an iterator into a collection.\n\n`collect()` can take anything iterable, and turn it into a relevant\ncollection. This is one of the more powerful methods in the standard\nlibrary, used in a variety of contexts.\n\nThe most basic pattern in which `collect()` is used is to turn one\ncollection into another. You take a collection, call [`iter`](https://doc.rust-lang.org/nightly/core/iter/traits/iterator/trait.Iterator.html) on it,\ndo a bunch of transformations, and then `collect()` at the end.\n\n`collect()` can also create instances of types that are not typical\ncollections. For example, a [`String`](https://doc.rust-lang.org/nightly/core/iter/std/string/struct.String.html) can be built from [`char`](type@char)s,\nand an iterator of [`Result<T, E>`](https://doc.rust-lang.org/nightly/core/result/enum.Result.html) items can be collected\ninto `Result<Collection<T>, E>`. See the examples below for more.\n\nBecause `collect()` is so general, it can cause problems with type\ninference. As such, `collect()` is one of the few times you'll see\nthe syntax affectionately known as the 'turbofish': `::<>`. This\nhelps the inference algorithm understand specifically which collection\nyou're trying to collect into.\n\n# Examples\n\nBasic usage:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled: Vec<i32> = a.iter()\n                         .map(|&x| x * 2)\n                         .collect();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nNote that we needed the `: Vec<i32>` on the left-hand side. This is because\nwe could collect into, for example, a [`VecDeque<T>`](https://doc.rust-lang.org/nightly/core/iter/std/collections/struct.VecDeque.html) instead:\n\n```rust\nuse std::collections::VecDeque;\n\nlet a = [1, 2, 3];\n\nlet doubled: VecDeque<i32> = a.iter().map(|&x| x * 2).collect();\n\nassert_eq!(2, doubled[0]);\nassert_eq!(4, doubled[1]);\nassert_eq!(6, doubled[2]);\n```\n\nUsing the 'turbofish' instead of annotating `doubled`:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled = a.iter().map(|x| x * 2).collect::<Vec<i32>>();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nBecause `collect()` only cares about what you're collecting into, you can\nstill use a partial type hint, `_`, with the turbofish:\n\n```rust\nlet a = [1, 2, 3];\n\nlet doubled = a.iter().map(|x| x * 2).collect::<Vec<_>>();\n\nassert_eq!(vec![2, 4, 6], doubled);\n```\n\nUsing `collect()` to make a [`String`](https://doc.rust-lang.org/nightly/core/iter/std/string/struct.String.html):\n\n```rust\nlet chars = ['g', 'd', 'k', 'k', 'n'];\n\nlet hello: String = chars.iter()\n    .map(|&x| x as u8)\n    .map(|x| (x + 1) as char)\n    .collect();\n\nassert_eq!(\"hello\", hello);\n```\n\nIf you have a list of [`Result<T, E>`](https://doc.rust-lang.org/nightly/core/result/enum.Result.html)s, you can use `collect()` to\nsee if any of them failed:\n\n```rust\nlet results = [Ok(1), Err(\"nope\"), Ok(3), Err(\"bad\")];\n\nlet result: Result<Vec<_>, &str> = results.iter().cloned().collect();\n\n// gives us the first error\nassert_eq!(Err(\"nope\"), result);\n\nlet results = [Ok(1), Ok(3)];\n\nlet result: Result<Vec<_>, &str> = results.iter().cloned().collect();\n\n// gives us the list of answers\nassert_eq!(Ok(vec![1, 3]), result);\n```";

        let mut options = Options::empty();
        options.insert(Options::ENABLE_STRIKETHROUGH);
        let parser = Parser::new_ext(&self.contents, options);

        // TODO: if possible, render links as terminal hyperlinks: https://gist.github.com/egmontkob/eb114294efbcd5adb1944c9f3cb5feda
        let mut tags = Vec::new();
        let mut spans = Vec::new();
        let mut lines = Vec::new();

        let get_theme = |key: &str| -> Style { theme.map(|t| t.get(key)).unwrap_or_default() };
        let text_style = get_theme(Self::TEXT_STYLE);
        let code_style = get_theme(Self::BLOCK_STYLE);
        let heading_styles: Vec<Style> = Self::HEADING_STYLES
            .iter()
            .map(|key| get_theme(key))
            .collect();

        let mut list_stack = Vec::new();

        for event in parser {
            match event {
                Event::Start(Tag::List(list)) => list_stack.push(list),
                Event::End(Tag::List(_)) => {
                    list_stack.pop();
                }
                Event::Start(Tag::Item) => {
                    tags.push(Tag::Item);
                    spans.push(Span::from("- "));
                }
                Event::Start(tag) => {
                    tags.push(tag);
                }
                Event::End(tag) => {
                    tags.pop();
                    match tag {
                        Tag::Heading(_, _, _)
                        | Tag::Paragraph
                        | Tag::CodeBlock(CodeBlockKind::Fenced(_))
                        | Tag::Item => {
                            // whenever code block or paragraph closes, new line
                            let spans = std::mem::take(&mut spans);
                            if !spans.is_empty() {
                                lines.push(Spans::from(spans));
                            }
                            lines.push(Spans::default());
                        }
                        _ => (),
                    }
                }
                Event::Text(text) => {
                    // TODO: temp workaround
                    if let Some(Tag::CodeBlock(CodeBlockKind::Fenced(language))) = tags.last() {
                        let tui_text = highlighted_code_block(
                            text.to_string(),
                            language,
                            theme,
                            Arc::clone(&self.config_loader),
                        );
                        lines.extend(tui_text.lines.into_iter());
                    } else {
                        let style = if let Some(Tag::Heading(level, ..)) = tags.last() {
                            match level {
                                HeadingLevel::H1 => heading_styles[0],
                                HeadingLevel::H2 => heading_styles[1],
                                HeadingLevel::H3 => heading_styles[2],
                                HeadingLevel::H4 => heading_styles[3],
                                HeadingLevel::H5 => heading_styles[4],
                                HeadingLevel::H6 => heading_styles[5],
                            }
                        } else {
                            text_style
                        };
                        spans.push(Span::styled(text, style));
                    }
                }
                Event::Code(text) | Event::Html(text) => {
                    spans.push(Span::styled(text, code_style));
                }
                Event::SoftBreak | Event::HardBreak => {
                    // let spans = std::mem::replace(&mut spans, Vec::new());
                    // lines.push(Spans::from(spans));
                    spans.push(Span::raw(" "));
                }
                Event::Rule => {
                    lines.push(Spans::from(Span::styled("---", code_style)));
                    lines.push(Spans::default());
                }
                // TaskListMarker(bool) true if checked
                _ => {
                    log::warn!("unhandled markdown event {:?}", event);
                }
            }
            // build up a vec of Paragraph tui widgets
        }

        if !spans.is_empty() {
            lines.push(Spans::from(spans));
        }

        // if last line is empty, remove it
        if let Some(line) = lines.last() {
            if line.0.is_empty() {
                lines.pop();
            }
        }

        Text::from(lines)
    }
}

impl Component for Markdown {
    fn render(&mut self, area: Rect, surface: &mut Surface, cx: &mut Context) {
        use tui::widgets::{Paragraph, Widget, Wrap};

        let text = self.parse(Some(&cx.editor.theme));

        let par = Paragraph::new(text)
            .wrap(Wrap { trim: false })
            .scroll((cx.scroll.unwrap_or_default() as u16, 0));

        let margin = Margin {
            vertical: 1,
            horizontal: 1,
        };
        par.render(area.inner(&margin), surface);
    }

    fn required_size(&mut self, viewport: (u16, u16)) -> Option<(u16, u16)> {
        let padding = 2;
        if padding >= viewport.1 || padding >= viewport.0 {
            return None;
        }
        let contents = self.parse(None);

        // TODO: account for tab width
        let max_text_width = (viewport.0 - padding).min(120);
        let (width, height) = crate::ui::text::required_size(&contents, max_text_width);

        Some((width + padding, height + padding))
    }
}