417 lines
13 KiB
Rust
417 lines
13 KiB
Rust
//! Parse and display Markdown.
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//!
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//! You can enable the `highlighter` feature for syntax highligting
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//! in code blocks.
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//!
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//! Only the variants of [`Item`] are currently supported.
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use crate::core::font::{self, Font};
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use crate::core::padding;
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use crate::core::theme::{self, Theme};
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use crate::core::{self, Element, Length, Pixels};
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use crate::{column, container, rich_text, row, scrollable, span, text};
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pub use pulldown_cmark::HeadingLevel;
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pub use url::Url;
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/// A Markdown item.
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#[derive(Debug, Clone)]
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pub enum Item {
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/// A heading.
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Heading(pulldown_cmark::HeadingLevel, Vec<text::Span<'static, Url>>),
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/// A paragraph.
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Paragraph(Vec<text::Span<'static, Url>>),
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/// A code block.
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///
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/// You can enable the `highlighter` feature for syntax highligting.
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CodeBlock(Vec<text::Span<'static, Url>>),
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/// A list.
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List {
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/// The first number of the list, if it is ordered.
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start: Option<u64>,
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/// The items of the list.
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items: Vec<Vec<Item>>,
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},
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}
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/// Parse the given Markdown content.
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pub fn parse(
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markdown: &str,
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palette: theme::Palette,
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) -> impl Iterator<Item = Item> + '_ {
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struct List {
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start: Option<u64>,
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items: Vec<Vec<Item>>,
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}
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let mut spans = Vec::new();
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let mut strong = false;
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let mut emphasis = false;
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let mut metadata = false;
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let mut table = false;
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let mut link = None;
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let mut lists = Vec::new();
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#[cfg(feature = "highlighter")]
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let mut highlighter = None;
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let parser = pulldown_cmark::Parser::new_ext(
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markdown,
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pulldown_cmark::Options::ENABLE_YAML_STYLE_METADATA_BLOCKS
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| pulldown_cmark::Options::ENABLE_PLUSES_DELIMITED_METADATA_BLOCKS
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| pulldown_cmark::Options::ENABLE_TABLES,
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);
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let produce = |lists: &mut Vec<List>, item| {
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if lists.is_empty() {
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Some(item)
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} else {
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lists
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.last_mut()
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.expect("list context")
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.items
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.last_mut()
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.expect("item context")
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.push(item);
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None
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}
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};
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// We want to keep the `spans` capacity
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#[allow(clippy::drain_collect)]
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parser.filter_map(move |event| match event {
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pulldown_cmark::Event::Start(tag) => match tag {
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pulldown_cmark::Tag::Strong if !metadata && !table => {
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strong = true;
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None
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}
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pulldown_cmark::Tag::Emphasis if !metadata && !table => {
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emphasis = true;
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None
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}
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pulldown_cmark::Tag::Link { dest_url, .. }
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if !metadata && !table =>
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{
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match Url::parse(&dest_url) {
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Ok(url)
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if url.scheme() == "http"
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|| url.scheme() == "https" =>
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{
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link = Some(url);
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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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pulldown_cmark::Tag::List(first_item) if !metadata && !table => {
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lists.push(List {
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start: first_item,
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items: Vec::new(),
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});
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None
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}
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pulldown_cmark::Tag::Item => {
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lists
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.last_mut()
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.expect("list context")
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.items
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.push(Vec::new());
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None
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}
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pulldown_cmark::Tag::CodeBlock(
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pulldown_cmark::CodeBlockKind::Fenced(_language),
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) if !metadata && !table => {
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#[cfg(feature = "highlighter")]
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{
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use iced_highlighter::{self, Highlighter};
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use text::Highlighter as _;
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highlighter =
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Some(Highlighter::new(&iced_highlighter::Settings {
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theme: iced_highlighter::Theme::Base16Ocean,
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token: _language.to_string(),
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}));
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}
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None
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}
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pulldown_cmark::Tag::MetadataBlock(_) => {
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metadata = true;
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None
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}
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pulldown_cmark::Tag::Table(_) => {
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table = true;
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None
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}
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_ => None,
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},
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pulldown_cmark::Event::End(tag) => match tag {
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pulldown_cmark::TagEnd::Heading(level) if !metadata && !table => {
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produce(
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&mut lists,
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Item::Heading(level, spans.drain(..).collect()),
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)
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}
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pulldown_cmark::TagEnd::Emphasis if !metadata && !table => {
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emphasis = false;
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None
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}
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pulldown_cmark::TagEnd::Strong if !metadata && !table => {
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strong = false;
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None
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}
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pulldown_cmark::TagEnd::Link if !metadata && !table => {
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link = None;
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None
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}
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pulldown_cmark::TagEnd::Paragraph if !metadata && !table => {
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produce(&mut lists, Item::Paragraph(spans.drain(..).collect()))
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}
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pulldown_cmark::TagEnd::Item if !metadata && !table => {
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if spans.is_empty() {
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None
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} else {
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produce(
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&mut lists,
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Item::Paragraph(spans.drain(..).collect()),
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)
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}
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}
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pulldown_cmark::TagEnd::List(_) if !metadata && !table => {
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let list = lists.pop().expect("list context");
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produce(
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&mut lists,
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Item::List {
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start: list.start,
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items: list.items,
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},
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)
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}
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pulldown_cmark::TagEnd::CodeBlock if !metadata && !table => {
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#[cfg(feature = "highlighter")]
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{
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highlighter = None;
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}
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produce(&mut lists, Item::CodeBlock(spans.drain(..).collect()))
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}
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pulldown_cmark::TagEnd::MetadataBlock(_) => {
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metadata = false;
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None
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}
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pulldown_cmark::TagEnd::Table => {
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table = false;
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None
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}
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_ => None,
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},
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pulldown_cmark::Event::Text(text) if !metadata && !table => {
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#[cfg(feature = "highlighter")]
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if let Some(highlighter) = &mut highlighter {
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use text::Highlighter as _;
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for (range, highlight) in
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highlighter.highlight_line(text.as_ref())
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{
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let span = span(text[range].to_owned())
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.color_maybe(highlight.color())
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.font_maybe(highlight.font());
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spans.push(span);
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}
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return None;
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}
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let span = span(text.into_string());
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let span = if strong || emphasis {
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span.font(Font {
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weight: if strong {
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font::Weight::Bold
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} else {
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font::Weight::Normal
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},
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style: if emphasis {
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font::Style::Italic
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} else {
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font::Style::Normal
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},
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..Font::default()
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})
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} else {
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span
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};
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let span = if let Some(link) = link.as_ref() {
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span.color(palette.primary).link(link.clone())
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} else {
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span
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};
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spans.push(span);
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None
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}
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pulldown_cmark::Event::Code(code) if !metadata && !table => {
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let span = span(code.into_string()).font(Font::MONOSPACE);
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let span = if let Some(link) = link.as_ref() {
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span.color(palette.primary).link(link.clone())
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} else {
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span
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};
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spans.push(span);
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None
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}
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pulldown_cmark::Event::SoftBreak if !metadata && !table => {
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spans.push(span(" "));
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None
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}
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pulldown_cmark::Event::HardBreak if !metadata && !table => {
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spans.push(span("\n"));
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None
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}
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_ => None,
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})
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}
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/// Configuration controlling Markdown rendering in [`view`].
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#[derive(Debug, Clone, Copy)]
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pub struct Settings {
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/// The base text size.
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pub text_size: Pixels,
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/// The text size of level 1 heading.
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pub h1_size: Pixels,
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/// The text size of level 2 heading.
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pub h2_size: Pixels,
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/// The text size of level 3 heading.
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pub h3_size: Pixels,
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/// The text size of level 4 heading.
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pub h4_size: Pixels,
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/// The text size of level 5 heading.
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pub h5_size: Pixels,
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/// The text size of level 6 heading.
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pub h6_size: Pixels,
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/// The text size used in code blocks.
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pub code_size: Pixels,
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}
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impl Settings {
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/// Creates new [`Settings`] with the given base text size in [`Pixels`].
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///
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/// Heading levels will be adjusted automatically. Specifically,
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/// the first level will be twice the base size, and then every level
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/// after that will be 25% smaller.
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pub fn with_text_size(text_size: impl Into<Pixels>) -> Self {
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let text_size = text_size.into();
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Self {
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text_size,
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h1_size: text_size * 2.0,
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h2_size: text_size * 1.75,
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h3_size: text_size * 1.5,
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h4_size: text_size * 1.25,
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h5_size: text_size,
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h6_size: text_size,
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code_size: text_size * 0.75,
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}
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}
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}
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impl Default for Settings {
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fn default() -> Self {
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Self::with_text_size(16)
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}
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}
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/// Display a bunch of Markdown items.
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///
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/// You can obtain the items with [`parse`].
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pub fn view<'a, Renderer>(
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items: impl IntoIterator<Item = &'a Item>,
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settings: Settings,
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) -> Element<'a, Url, Theme, Renderer>
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where
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Renderer: core::text::Renderer<Font = Font> + 'a,
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{
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let Settings {
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text_size,
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h1_size,
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h2_size,
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h3_size,
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h4_size,
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h5_size,
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h6_size,
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code_size,
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} = settings;
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let spacing = text_size * 0.625;
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let blocks = items.into_iter().enumerate().map(|(i, item)| match item {
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Item::Heading(level, heading) => {
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container(rich_text(heading).size(match level {
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pulldown_cmark::HeadingLevel::H1 => h1_size,
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pulldown_cmark::HeadingLevel::H2 => h2_size,
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pulldown_cmark::HeadingLevel::H3 => h3_size,
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pulldown_cmark::HeadingLevel::H4 => h4_size,
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pulldown_cmark::HeadingLevel::H5 => h5_size,
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pulldown_cmark::HeadingLevel::H6 => h6_size,
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}))
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.padding(padding::top(if i > 0 {
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text_size / 2.0
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} else {
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Pixels::ZERO
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}))
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.into()
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}
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Item::Paragraph(paragraph) => {
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rich_text(paragraph).size(text_size).into()
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}
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Item::List { start: None, items } => {
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column(items.iter().map(|items| {
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row![text("•").size(text_size), view(items, settings)]
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.spacing(spacing)
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.into()
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}))
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.spacing(spacing)
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.into()
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}
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Item::List {
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start: Some(start),
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items,
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} => column(items.iter().enumerate().map(|(i, items)| {
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row![
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text!("{}.", i as u64 + *start).size(text_size),
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view(items, settings)
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]
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.spacing(spacing)
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.into()
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}))
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.spacing(spacing)
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.into(),
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Item::CodeBlock(code) => container(
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scrollable(
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container(
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rich_text(code).font(Font::MONOSPACE).size(code_size),
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)
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.padding(spacing.0 / 2.0),
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)
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.direction(scrollable::Direction::Horizontal(
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scrollable::Scrollbar::default()
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.width(spacing.0 / 2.0)
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.scroller_width(spacing.0 / 2.0),
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)),
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)
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.width(Length::Fill)
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.padding(spacing.0 / 2.0)
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.style(container::rounded_box)
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.into(),
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});
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Element::new(column(blocks).width(Length::Fill).spacing(text_size))
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}
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