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243
src/easy_mark/easy_mark_highlighter.rs
Normal file
243
src/easy_mark/easy_mark_highlighter.rs
Normal file
@ -0,0 +1,243 @@
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use egui::text::{CCursorRange, LayoutJob};
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use crate::easy_mark::easy_mark_parser;
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/// Highlight easymark, memoizing previous output to save CPU.
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///
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/// In practice, the highlighter is fast enough not to need any caching.
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#[derive(Default)]
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pub struct MemoizedHighlighter {
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style: egui::Style,
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code: String,
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output: LayoutJob,
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}
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impl MemoizedHighlighter {
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pub fn highlight(
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&mut self,
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egui_style: &egui::Style,
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code: &str,
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cursor: Option<CCursorRange>,
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) -> LayoutJob {
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if (&self.style, self.code.as_str()) != (egui_style, code) {
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self.style = egui_style.clone();
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code.clone_into(&mut self.code);
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self.output = highlight_easymark(egui_style, code, cursor);
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}
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self.output.clone()
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}
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}
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pub fn highlight_easymark(
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egui_style: &egui::Style,
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mut text: &str,
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// TODO: hide special characters where cursor isn't
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_cursor: Option<CCursorRange>,
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) -> LayoutJob {
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let mut job = LayoutJob::default();
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let mut style = easy_mark_parser::Style::default();
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let mut start_of_line = true;
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const CODE_INDENT: f32 = 10.0;
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while !text.is_empty() {
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if start_of_line && text.starts_with("```") {
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let astyle = format_from_style(
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egui_style,
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&easy_mark_parser::Style {
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code: true,
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..Default::default()
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},
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);
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// Render the initial backticks as spaces
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text = &text[3..];
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job.append(" ", CODE_INDENT, astyle.clone());
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match text.find("\n```") {
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Some(n) => {
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for line in text[..n + 1].lines() {
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job.append(line, CODE_INDENT, astyle.clone());
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job.append("\n", 0.0, astyle.clone());
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}
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// Render the final backticks as spaces
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job.append(" ", CODE_INDENT, astyle);
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text = &text[n + 4..];
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}
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None => {
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job.append(text, 0.0, astyle.clone());
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text = "";
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}
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};
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style = Default::default();
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continue;
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}
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if text.starts_with('`') {
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style.code = true;
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let end = text[1..]
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.find(&['`', '\n'][..])
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.map_or_else(|| text.len(), |i| i + 2);
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job.append(&text[..end], 0.0, format_from_style(egui_style, &style));
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text = &text[end..];
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style.code = false;
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continue;
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}
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let skip;
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// zero-width space
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let _zws = "\u{200b}";
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let mut apply_basic_style =
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|text: &mut &str,
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style: &mut easy_mark_parser::Style,
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access: fn(&mut easy_mark_parser::Style) -> &mut bool| {
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let skip = if *access(style) {
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// Include the character that is ending this style:
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job.append(&text[..1], 0.0, format_from_style(egui_style, style));
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*text = &text[1..];
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0
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} else {
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1
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};
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*access(style) ^= true;
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skip
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};
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if text.starts_with('*') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.strong);
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} else if text.starts_with('/') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.italics);
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} else if text.starts_with('_') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.underline);
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} else if text.starts_with('$') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.small);
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} else if text.starts_with('~') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.strikethrough);
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} else if text.starts_with('^') {
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skip = apply_basic_style(&mut text, &mut style, |style| &mut style.raised);
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} else if text.starts_with('\\') && text.len() >= 2 {
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skip = 2;
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} else if start_of_line && text.starts_with(' ') {
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// we don't preview indentation, because it is confusing
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skip = 1;
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} else if start_of_line && text.starts_with("###### ") {
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style.heading = true;
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skip = 7;
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} else if start_of_line && text.starts_with("##### ") {
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style.heading = true;
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skip = 6;
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} else if start_of_line && text.starts_with("#### ") {
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style.heading = true;
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skip = 5;
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} else if start_of_line && text.starts_with("### ") {
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style.heading = true;
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skip = 4;
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} else if start_of_line && text.starts_with("## ") {
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style.heading = true;
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skip = 3;
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} else if start_of_line && text.starts_with("# ") {
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style.heading = true;
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skip = 2;
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} else if start_of_line && text.starts_with("> ") {
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style.quoted = true;
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skip = 2;
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// we don't preview indentation, because it is confusing
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} else if start_of_line && text.trim_start().starts_with("- ") {
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job.append("• ", 0.0, format_from_style(egui_style, &style));
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text = &text[2..];
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skip = 0;
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// we don't preview indentation, because it is confusing
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} else {
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skip = 0;
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}
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// Note: we don't preview underline, strikethrough and italics because it confuses things.
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// Swallow everything up to the next special character:
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let line_end = text[skip..]
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.find('\n')
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.map_or_else(|| text.len(), |i| (skip + i + 1));
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let end = text[skip..]
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.find(&['*', '`', '~', '_', '/', '$', '^', '\\', '<', '['][..])
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.map_or_else(|| text.len(), |i| (skip + i).max(1));
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if line_end <= end {
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job.append(
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&text[..line_end],
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0.0,
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format_from_style(egui_style, &style),
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);
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text = &text[line_end..];
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start_of_line = true;
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style = Default::default();
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} else {
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job.append(&text[..end], 0.0, format_from_style(egui_style, &style));
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text = &text[end..];
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start_of_line = false;
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}
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}
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job
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}
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fn format_from_style(
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egui_style: &egui::Style,
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emark_style: &easy_mark_parser::Style,
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) -> egui::text::TextFormat {
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use egui::{Align, Color32, Stroke, TextStyle};
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let color = if emark_style.strong || emark_style.heading {
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egui_style.visuals.strong_text_color()
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} else if emark_style.quoted {
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egui_style.visuals.weak_text_color()
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} else {
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egui_style.visuals.text_color()
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};
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let text_style = if emark_style.heading {
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TextStyle::Heading
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} else if emark_style.code {
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TextStyle::Monospace
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} else if emark_style.small | emark_style.raised {
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TextStyle::Small
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} else {
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TextStyle::Body
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};
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let background = if emark_style.code {
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egui_style.visuals.code_bg_color
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} else {
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Color32::TRANSPARENT
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};
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let underline = if emark_style.underline {
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Stroke::new(1.0, color)
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} else {
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Stroke::NONE
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};
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let strikethrough = if emark_style.strikethrough {
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Stroke::new(1.0, color)
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} else {
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Stroke::NONE
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};
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let valign = if emark_style.raised {
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Align::TOP
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} else {
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Align::BOTTOM
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};
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egui::text::TextFormat {
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font_id: text_style.resolve(egui_style),
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color,
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background,
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italics: emark_style.italics,
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underline,
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strikethrough,
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valign,
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..Default::default()
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}
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}
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346
src/easy_mark/easy_mark_parser.rs
Normal file
346
src/easy_mark/easy_mark_parser.rs
Normal file
@ -0,0 +1,346 @@
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//! A parser for `EasyMark`: a very simple markup language.
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//!
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//! WARNING: `EasyMark` is subject to change.
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//
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//! # `EasyMark` design goals:
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//! 1. easy to parse
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//! 2. easy to learn
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//! 3. similar to markdown
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#[derive(Copy, Clone, Debug, Eq, PartialEq)]
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pub enum Item<'a> {
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/// `\n`
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// TODO(emilk): add Style here so empty heading still uses up the right amount of space.
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Newline,
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/// Text
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Text(Style, &'a str),
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/// title, url
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Hyperlink(Style, &'a str, &'a str),
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/// leading space before e.g. a [`Self::BulletPoint`].
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Indentation(usize),
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/// >
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QuoteIndent,
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/// - a point well made.
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BulletPoint,
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/// 1. numbered list. The string is the number(s).
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NumberedPoint(&'a str),
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/// ---
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Separator,
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/// language, code
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CodeBlock(&'a str, &'a str),
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}
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#[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
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pub struct Style {
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/// # heading (large text)
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pub heading: bool,
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/// > quoted (slightly dimmer color or other font style)
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pub quoted: bool,
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/// `code` (monospace, some other color)
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pub code: bool,
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/// self.strong* (emphasized, e.g. bold)
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pub strong: bool,
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/// _underline_
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pub underline: bool,
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/// ~strikethrough~
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pub strikethrough: bool,
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/// /italics/
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pub italics: bool,
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/// $small$
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pub small: bool,
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/// ^raised^
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pub raised: bool,
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}
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/// Parser for the `EasyMark` markup language.
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pub struct Parser<'a> {
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/// The remainder of the input text
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s: &'a str,
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/// Are we at the start of a line?
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start_of_line: bool,
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/// Current self.style. Reset after a newline.
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style: Style,
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}
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impl<'a> Parser<'a> {
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pub fn new(s: &'a str) -> Self {
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Self {
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s,
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start_of_line: true,
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style: Style::default(),
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}
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}
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/// `1. `, `42. ` etc.
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fn numbered_list(&mut self) -> Option<Item<'a>> {
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let n_digits = self.s.chars().take_while(|c| c.is_ascii_digit()).count();
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if n_digits > 0 && self.s.chars().skip(n_digits).take(2).eq(". ".chars()) {
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let number = &self.s[..n_digits];
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self.s = &self.s[(n_digits + 2)..];
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self.start_of_line = false;
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return Some(Item::NumberedPoint(number));
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}
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None
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}
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// ```{language}\n{code}```
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fn code_block(&mut self) -> Option<Item<'a>> {
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if let Some(language_start) = self.s.strip_prefix("```") {
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if let Some(newline) = language_start.find('\n') {
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let language = &language_start[..newline];
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let code_start = &language_start[newline + 1..];
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if let Some(end) = code_start.find("\n```") {
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let code = &code_start[..end].trim();
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self.s = &code_start[end + 4..];
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self.start_of_line = false;
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return Some(Item::CodeBlock(language, code));
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} else {
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self.s = "";
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return Some(Item::CodeBlock(language, code_start));
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}
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}
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}
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None
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}
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// `code`
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fn inline_code(&mut self) -> Option<Item<'a>> {
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if let Some(rest) = self.s.strip_prefix('`') {
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self.s = rest;
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self.start_of_line = false;
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self.style.code = true;
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let rest_of_line = &self.s[..self.s.find('\n').unwrap_or(self.s.len())];
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if let Some(end) = rest_of_line.find('`') {
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let item = Item::Text(self.style, &self.s[..end]);
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self.s = &self.s[end + 1..];
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self.style.code = false;
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return Some(item);
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} else {
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let end = rest_of_line.len();
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let item = Item::Text(self.style, rest_of_line);
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self.s = &self.s[end..];
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self.style.code = false;
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return Some(item);
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}
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}
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None
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}
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/// `<url>` or `[link](url)`
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fn url(&mut self) -> Option<Item<'a>> {
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if self.s.starts_with('<') {
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let this_line = &self.s[..self.s.find('\n').unwrap_or(self.s.len())];
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if let Some(url_end) = this_line.find('>') {
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let url = &self.s[1..url_end];
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self.s = &self.s[url_end + 1..];
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self.start_of_line = false;
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return Some(Item::Hyperlink(self.style, url, url));
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}
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}
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// [text](url)
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if self.s.starts_with('[') {
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let this_line = &self.s[..self.s.find('\n').unwrap_or(self.s.len())];
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if let Some(bracket_end) = this_line.find(']') {
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let text = &this_line[1..bracket_end];
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if this_line[bracket_end + 1..].starts_with('(') {
|
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if let Some(parens_end) = this_line[bracket_end + 2..].find(')') {
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let parens_end = bracket_end + 2 + parens_end;
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||||
let url = &self.s[bracket_end + 2..parens_end];
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self.s = &self.s[parens_end + 1..];
|
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self.start_of_line = false;
|
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return Some(Item::Hyperlink(self.style, text, url));
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
None
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a> Iterator for Parser<'a> {
|
||||
type Item = Item<'a>;
|
||||
|
||||
fn next(&mut self) -> Option<Self::Item> {
|
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loop {
|
||||
if self.s.is_empty() {
|
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return None;
|
||||
}
|
||||
|
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// \n
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if self.s.starts_with('\n') {
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self.s = &self.s[1..];
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self.start_of_line = true;
|
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self.style = Style::default();
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return Some(Item::Newline);
|
||||
}
|
||||
|
||||
// Ignore line break (continue on the same line)
|
||||
if self.s.starts_with("\\\n") && self.s.len() >= 2 {
|
||||
self.s = &self.s[2..];
|
||||
self.start_of_line = false;
|
||||
continue;
|
||||
}
|
||||
|
||||
// \ escape (to show e.g. a backtick)
|
||||
if self.s.starts_with('\\') && self.s.len() >= 2 {
|
||||
let text = &self.s[1..2];
|
||||
self.s = &self.s[2..];
|
||||
self.start_of_line = false;
|
||||
return Some(Item::Text(self.style, text));
|
||||
}
|
||||
|
||||
if self.start_of_line {
|
||||
// leading space (indentation)
|
||||
if self.s.starts_with(' ') {
|
||||
let length = self.s.find(|c| c != ' ').unwrap_or(self.s.len());
|
||||
self.s = &self.s[length..];
|
||||
self.start_of_line = true; // indentation doesn't count
|
||||
return Some(Item::Indentation(length));
|
||||
}
|
||||
|
||||
// # Heading
|
||||
if let Some(after) = self.s.strip_prefix("# ") {
|
||||
self.s = after;
|
||||
self.start_of_line = false;
|
||||
self.style.heading = true;
|
||||
continue;
|
||||
}
|
||||
|
||||
// > quote
|
||||
if let Some(after) = self.s.strip_prefix("> ") {
|
||||
self.s = after;
|
||||
self.start_of_line = true; // quote indentation doesn't count
|
||||
self.style.quoted = true;
|
||||
return Some(Item::QuoteIndent);
|
||||
}
|
||||
|
||||
// - bullet point
|
||||
if self.s.starts_with("- ") {
|
||||
self.s = &self.s[2..];
|
||||
self.start_of_line = false;
|
||||
return Some(Item::BulletPoint);
|
||||
}
|
||||
|
||||
// `1. `, `42. ` etc.
|
||||
if let Some(item) = self.numbered_list() {
|
||||
return Some(item);
|
||||
}
|
||||
|
||||
// --- separator
|
||||
if let Some(after) = self.s.strip_prefix("---") {
|
||||
self.s = after.trim_start_matches('-'); // remove extra dashes
|
||||
self.s = self.s.strip_prefix('\n').unwrap_or(self.s); // remove trailing newline
|
||||
self.start_of_line = false;
|
||||
return Some(Item::Separator);
|
||||
}
|
||||
|
||||
// ```{language}\n{code}```
|
||||
if let Some(item) = self.code_block() {
|
||||
return Some(item);
|
||||
}
|
||||
}
|
||||
|
||||
// `code`
|
||||
if let Some(item) = self.inline_code() {
|
||||
return Some(item);
|
||||
}
|
||||
|
||||
if let Some(rest) = self.s.strip_prefix('*') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.strong = !self.style.strong;
|
||||
continue;
|
||||
}
|
||||
if let Some(rest) = self.s.strip_prefix('_') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.underline = !self.style.underline;
|
||||
continue;
|
||||
}
|
||||
if let Some(rest) = self.s.strip_prefix('~') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.strikethrough = !self.style.strikethrough;
|
||||
continue;
|
||||
}
|
||||
if let Some(rest) = self.s.strip_prefix('/') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.italics = !self.style.italics;
|
||||
continue;
|
||||
}
|
||||
if let Some(rest) = self.s.strip_prefix('$') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.small = !self.style.small;
|
||||
continue;
|
||||
}
|
||||
if let Some(rest) = self.s.strip_prefix('^') {
|
||||
self.s = rest;
|
||||
self.start_of_line = false;
|
||||
self.style.raised = !self.style.raised;
|
||||
continue;
|
||||
}
|
||||
|
||||
// `<url>` or `[link](url)`
|
||||
if let Some(item) = self.url() {
|
||||
return Some(item);
|
||||
}
|
||||
|
||||
// Swallow everything up to the next special character:
|
||||
let end = self
|
||||
.s
|
||||
.find(&['*', '`', '~', '_', '/', '$', '^', '\\', '<', '[', '\n'][..])
|
||||
.map_or_else(|| self.s.len(), |special| special.max(1));
|
||||
|
||||
let item = Item::Text(self.style, &self.s[..end]);
|
||||
self.s = &self.s[end..];
|
||||
self.start_of_line = false;
|
||||
return Some(item);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn test_easy_mark_parser() {
|
||||
let items: Vec<_> = Parser::new("~strikethrough `code`~").collect();
|
||||
assert_eq!(
|
||||
items,
|
||||
vec![
|
||||
Item::Text(
|
||||
Style {
|
||||
strikethrough: true,
|
||||
..Default::default()
|
||||
},
|
||||
"strikethrough "
|
||||
),
|
||||
Item::Text(
|
||||
Style {
|
||||
code: true,
|
||||
strikethrough: true,
|
||||
..Default::default()
|
||||
},
|
||||
"code"
|
||||
),
|
||||
]
|
||||
);
|
||||
}
|
||||
7
src/easy_mark/mod.rs
Normal file
7
src/easy_mark/mod.rs
Normal file
@ -0,0 +1,7 @@
|
||||
//! Experimental markup language
|
||||
|
||||
mod easy_mark_highlighter;
|
||||
pub mod easy_mark_parser;
|
||||
|
||||
pub use easy_mark_highlighter::{MemoizedHighlighter, highlight_easymark};
|
||||
pub use easy_mark_parser as parser;
|
||||
Reference in New Issue
Block a user