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Move easy_mark from egui deo egui_demo_lib

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This commit is contained in:
Emil Ernerfeldt
2021-04-24 00:34:58 +02:00
parent 641e9c2d26
commit 6b24dbc997
10 changed files with 17 additions and 15 deletions
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126
egui_demo_lib/src/easy_mark/easy_mark_editor.rs Normal file
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use egui::*;
#[cfg_attr(feature = "persistence", derive(serde::Deserialize, serde::Serialize))]
#[derive(PartialEq)]
pub struct EasyMarkEditor {
code: String,
}
impl Default for EasyMarkEditor {
fn default() -> Self {
Self {
code: DEFAULT_CODE.trim().to_owned(),
}
}
}
impl epi::App for EasyMarkEditor {
fn name(&self) -> &str {
"🖹 EasyMark editor"
}
fn update(&mut self, ctx: &egui::CtxRef, _frame: &mut epi::Frame<'_>) {
egui::CentralPanel::default().show(ctx, |ui| {
self.ui(ui);
});
}
}
impl EasyMarkEditor {
fn ui(&mut self, ui: &mut egui::Ui) {
ui.vertical_centered(|ui| {
egui::reset_button(ui, self);
ui.add(crate::__egui_github_link_file!());
});
ui.separator();
ui.columns(2, |columns| {
ScrollArea::auto_sized()
.id_source("source")
.show(&mut columns[0], |ui| {
ui.add(TextEdit::multiline(&mut self.code).text_style(TextStyle::Monospace));
// let cursor = TextEdit::cursor(response.id);
// TODO: cmd-i, cmd-b, etc for italics, bold, ....
});
ScrollArea::auto_sized()
.id_source("rendered")
.show(&mut columns[1], |ui| {
crate::easy_mark::easy_mark(ui, &self.code);
});
});
}
}
const DEFAULT_CODE: &str = r#"
# EasyMark
EasyMark is a markup language, designed for extreme simplicity.
```
WARNING: EasyMark is still an evolving specification,
and is also missing some features.
```
----------------
# At a glance
- inline text:
- normal, `code`, *strong*, ~strikethrough~, _underline_, /italics/, ^raised^, $small$
- `\` escapes the next character
- [hyperlink](https://github.com/emilk/egui)
- Embedded URL: <https://github.com/emilk/egui>
- `# ` header
- `---` separator (horizontal line)
- `> ` quote
- `- ` bullet list
- `1. ` numbered list
- \`\`\` code fence
- a^2^ + b^2^ = c^2^
- $Remember to read the small print$
# Design
> /"Why do what everyone else is doing, when everyone else is already doing it?"
> \- Emil
Goals:
1. easy to parse
2. easy to learn
3. similar to markdown
[The reference parser](https://github.com/emilk/egui/blob/master/egui/src/experimental/easy_mark_parser.rs) is \~250 lines of code, using only the Rust standard library. The parser uses no look-ahead or recursion.
There is never more than one way to accomplish the same thing, and each special character is only used for one thing. For instance `*` is used for *strong* and `-` is used for bullet lists. There is no alternative way to specify the *strong* style or getting a bullet list.
Similarity to markdown is kept when possible, but with much less ambiguity and some improvements (like _underlining_).
# Details
All style changes are single characters, so it is `*strong*`, NOT `**strong**`. Style is reset by a matching character, or at the end of the line.
Style change characters and escapes (`\`) work everywhere except for in inline code, code blocks and in URLs.
You can mix styles. For instance: /italics _underline_/ and *strong `code`*.
You can use styles on URLs: ~my webpage is at <http://www.example.com>~.
Newlines are preserved. If you want to continue text on the same line, just do so. Alternatively, escape the newline by ending the line with a backslash (`\`). \
Escaping the newline effectively ignores it.
The style characters are chosen to be similar to what they are representing:
`_` = _underline_
`~` = ~strikethrough~ (`-` is used for bullet points)
`/` = /italics/
`*` = *strong*
`$` = $small$
`^` = ^raised^
# TODO
- Sub-headers (`## h2`, `### h3` etc)
- Images
- we want to be able to optionally specify size (width and\/or height)
- centering of images is very desirable
- captioning (image with a text underneath it)
- `![caption=My image][width=200][center](url)` ?
- Nicer URL:s
- `<url>` and `[url](url)` do the same thing yet look completely different.
- let's keep similarity with images
- Tables
- Inspiration: <https://mycorrhiza.lesarbr.es/page/mycomarkup>
"#;

356
egui_demo_lib/src/easy_mark/easy_mark_parser.rs Normal file
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//! A parser for `EasyMark`: a very simple markup language.
//!
//! WARNING: `EasyMark` is subject to change.
//!
//! This module does not depend on anything else in egui
//! and should perhaps be its own crate.
//
//! # `EasyMark` design goals:
//! 1. easy to parse
//! 2. easy to learn
//! 3. similar to markdown
#[derive(Copy, Clone, Debug, Eq, PartialEq)]
pub enum Item<'a> {
/// `\n`
// TODO: add Style here so empty heading still uses up the right amount of space.
Newline,
///
Text(Style, &'a str),
/// title, url
Hyperlink(Style, &'a str, &'a str),
/// leading space before e.g. a [`Self::BulletPoint`].
Indentation(usize),
/// >
QuoteIndent,
/// - a point well made.
BulletPoint,
/// 1. numbered list. The string is the number(s).
NumberedPoint(&'a str),
/// ---
Separator,
/// language, code
CodeBlock(&'a str, &'a str),
}
#[derive(Copy, Clone, Debug, Default, Eq, PartialEq)]
pub struct Style {
/// # heading (large text)
pub heading: bool,
/// > quoted (slightly dimmer color or other font style)
pub quoted: bool,
/// `code` (monospace, some other color)
pub code: bool,
/// self.strong* (emphasized, e.g. bold)
pub strong: bool,
/// _underline_
pub underline: bool,
/// -strikethrough-
pub strikethrough: bool,
/// /italics/
pub italics: bool,
/// $small$
pub small: bool,
/// ^raised^
pub raised: bool,
}
/// Parser for the `EasyMark` markup language.
///
/// See the module-level documentation for details.
///
/// # Example:
/// ```
/// # use egui_demo_lib::easy_mark::parser::Parser;
/// for item in Parser::new("Hello *world*!") {
/// }
///
/// ```
pub struct Parser<'a> {
/// The remainer of the input text
s: &'a str,
/// Are we at the start of a line?
start_of_line: bool,
/// Current self.style. Reset after a newline.
style: Style,
}
impl<'a> Parser<'a> {
pub fn new(s: &'a str) -> Self {
Self {
s,
start_of_line: true,
style: Style::default(),
}
}
/// `1. `, `42. ` etc.
fn numbered_list(&mut self) -> Option<Item<'a>> {
let bytes = self.s.as_bytes();
// 1. numbered bullet
if bytes.len() >= 3 && bytes[0].is_ascii_digit() && bytes[1] == b'.' && bytes[2] == b' ' {
let number = &self.s[0..1];
self.s = &self.s[3..];
self.start_of_line = false;
return Some(Item::NumberedPoint(number));
}
// 42. double-digit numbered bullet
if bytes.len() >= 4
&& bytes[0].is_ascii_digit()
&& bytes[1].is_ascii_digit()
&& bytes[2] == b'.'
&& bytes[3] == b' '
{
let number = &self.s[0..2];
self.s = &self.s[4..];
self.start_of_line = false;
return Some(Item::NumberedPoint(number));
}
// There is no triple-digit numbered bullet. Please don't make numbered lists that long.
None
}
// ```{language}\n{code}```
fn code_block(&mut self) -> Option<Item<'a>> {
if let Some(language_start) = self.s.strip_prefix("```") {
if let Some(newline) = language_start.find('\n') {
let language = &language_start[..newline];
let code_start = &language_start[newline + 1..];
if let Some(end) = code_start.find("\n```") {
let code = &code_start[..end].trim();
self.s = &code_start[end + 4..];
self.start_of_line = false;
return Some(Item::CodeBlock(language, code));
} else {
self.s = "";
return Some(Item::CodeBlock(language, code_start));
}
}
}
None
}
// `code`
fn inline_code(&mut self) -> Option<Item<'a>> {
if let Some(rest) = self.s.strip_prefix('`') {
self.s = rest;
self.start_of_line = false;
self.style.code = true;
let rest_of_line = &self.s[..self.s.find('\n').unwrap_or_else(|| self.s.len())];
if let Some(end) = rest_of_line.find('`') {
let item = Item::Text(self.style, &self.s[..end]);
self.s = &self.s[end + 1..];
self.style.code = false;
return Some(item);
} else {
let end = rest_of_line.len();
let item = Item::Text(self.style, rest_of_line);
self.s = &self.s[end..];
self.style.code = false;
return Some(item);
}
}
None
}
/// `<url>` or `[link](url)`
fn url(&mut self) -> Option<Item<'a>> {
if self.s.starts_with('<') {
let this_line = &self.s[..self.s.find('\n').unwrap_or_else(|| self.s.len())];
if let Some(url_end) = this_line.find('>') {
let url = &self.s[1..url_end];
self.s = &self.s[url_end + 1..];
self.start_of_line = false;
return Some(Item::Hyperlink(self.style, url, url));
}
}
// [text](url)
if self.s.starts_with('[') {
let this_line = &self.s[..self.s.find('\n').unwrap_or_else(|| self.s.len())];
if let Some(bracket_end) = this_line.find(']') {
let text = &this_line[1..bracket_end];
if this_line[bracket_end + 1..].starts_with('(') {
if let Some(parens_end) = this_line[bracket_end + 2..].find(')') {
let parens_end = bracket_end + 2 + parens_end;
let url = &self.s[bracket_end + 2..parens_end];
self.s = &self.s[parens_end + 1..];
self.start_of_line = false;
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> {
loop {
if self.s.is_empty() {
return None;
}
// \n
if self.s.starts_with('\n') {
self.s = &self.s[1..];
self.start_of_line = true;
self.style = Style::default();
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_else(|| 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(|special| special.max(1)) // make sure we swallow at least one character
.unwrap_or_else(|| self.s.len());
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"
),
]
);
}

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egui_demo_lib/src/easy_mark/easy_mark_viewer.rs Normal file
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use super::easy_mark_parser as easy_mark;
use egui::*;
/// Parse and display a VERY simple and small subset of Markdown.
pub fn easy_mark(ui: &mut Ui, easy_mark: &str) {
easy_mark_it(ui, easy_mark::Parser::new(easy_mark))
}
pub fn easy_mark_it<'em>(ui: &mut Ui, items: impl Iterator<Item = easy_mark::Item<'em>>) {
ui.horizontal_wrapped(|ui| {
ui.spacing_mut().item_spacing = Vec2::new(0.0, 0.0);
ui.set_row_height(ui.fonts()[TextStyle::Body].row_height());
for item in items {
item_ui(ui, item);
}
});
}
pub fn item_ui(ui: &mut Ui, item: easy_mark::Item<'_>) {
let row_height = ui.fonts()[TextStyle::Body].row_height();
let one_indent = row_height / 2.0;
match item {
easy_mark::Item::Newline => {
// ui.label("\n"); // too much spacing (paragraph spacing)
ui.allocate_exact_size(vec2(0.0, row_height), Sense::hover()); // make sure we take up some height
ui.end_row();
ui.set_row_height(row_height);
}
easy_mark::Item::Text(style, text) => {
ui.add(label_from_style(text, &style));
}
easy_mark::Item::Hyperlink(style, text, url) => {
let label = label_from_style(text, &style);
ui.add(Hyperlink::from_label_and_url(label, url));
}
easy_mark::Item::Separator => {
ui.add(Separator::default().horizontal());
}
easy_mark::Item::Indentation(indent) => {
let indent = indent as f32 * one_indent;
ui.allocate_exact_size(vec2(indent, row_height), Sense::hover());
}
easy_mark::Item::QuoteIndent => {
let rect = ui
.allocate_exact_size(vec2(2.0 * one_indent, row_height), Sense::hover())
.0;
let rect = rect.expand2(ui.style().spacing.item_spacing * 0.5);
ui.painter().line_segment(
[rect.center_top(), rect.center_bottom()],
(1.0, ui.visuals().weak_text_color()),
);
}
easy_mark::Item::BulletPoint => {
ui.allocate_exact_size(vec2(one_indent, row_height), Sense::hover());
bullet_point(ui, one_indent);
ui.allocate_exact_size(vec2(one_indent, row_height), Sense::hover());
}
easy_mark::Item::NumberedPoint(number) => {
let width = 3.0 * one_indent;
numbered_point(ui, width, number);
ui.allocate_exact_size(vec2(one_indent, row_height), Sense::hover());
}
easy_mark::Item::CodeBlock(_language, code) => {
let where_to_put_background = ui.painter().add(Shape::Noop);
let mut rect = ui.monospace(code).rect;
rect = rect.expand(1.0); // looks better
rect.max.x = ui.max_rect_finite().max.x;
let code_bg_color = ui.visuals().code_bg_color;
ui.painter().set(
where_to_put_background,
Shape::rect_filled(rect, 1.0, code_bg_color),
);
}
};
}
fn label_from_style(text: &str, style: &easy_mark::Style) -> Label {
let easy_mark::Style {
heading,
quoted,
code,
strong,
underline,
strikethrough,
italics,
small,
raised,
} = *style;
let small = small || raised; // Raised text is also smaller
let mut label = Label::new(text);
if heading && !small {
label = label.heading().strong();
}
if small && !heading {
label = label.small();
}
if code {
label = label.code();
}
if strong {
label = label.strong();
} else if quoted {
label = label.weak();
}
if underline {
label = label.underline();
}
if strikethrough {
label = label.strikethrough();
}
if italics {
label = label.italics();
}
if raised {
label = label.raised();
}
label
}
fn bullet_point(ui: &mut Ui, width: f32) -> Response {
let row_height = ui.fonts()[TextStyle::Body].row_height();
let (rect, response) = ui.allocate_exact_size(vec2(width, row_height), Sense::hover());
ui.painter().circle_filled(
rect.center(),
rect.height() / 8.0,
ui.visuals().strong_text_color(),
);
response
}
fn numbered_point(ui: &mut Ui, width: f32, number: &str) -> Response {
let row_height = ui.fonts()[TextStyle::Body].row_height();
let (rect, response) = ui.allocate_exact_size(vec2(width, row_height), Sense::hover());
let text = format!("{}.", number);
let text_color = ui.visuals().strong_text_color();
ui.painter().text(
rect.right_center(),
Align2::RIGHT_CENTER,
text,
TextStyle::Body,
text_color,
);
response
}

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egui_demo_lib/src/easy_mark/mod.rs Normal file
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//! Experimental markup language
mod easy_mark_editor;
pub mod easy_mark_parser;
mod easy_mark_viewer;
pub use easy_mark_editor::EasyMarkEditor;
pub use easy_mark_parser as parser;
pub use easy_mark_viewer::easy_mark;