wip

src/easy_mark/easy_mark_highlighter.rs

@@ -1,6 +1,12 @@
 use egui::text::{CCursorRange, LayoutJob};
 
-use crate::easy_mark::easy_mark_parser;
+use crate::{
+    easy_mark::easy_mark_parser,
+    markdown::{
+        span::Span,
+        tokenizer::{Token, TokenKind, tokenize},
+    },
+};
 
 /// Highlight easymark, memoizing previous output to save CPU.
 ///
@@ -29,6 +35,131 @@ impl MemoizedHighlighter {
 }
 
 pub fn highlight_easymark(
+    egui_style: &egui::Style,
+    text: &str,
+
+    // TODO: hide special characters where cursor isn't
+    _cursor: Option<CCursorRange>,
+) -> LayoutJob {
+    let mut job = LayoutJob::default();
+    let mut style = easy_mark_parser::Style::default();
+
+    let mut prev = TokenKind::Newline;
+
+    let tokens: Vec<_> = tokenize(text).collect();
+    let mut tokens = &tokens[..];
+
+    const CODE_INDENT: f32 = 10.0;
+
+    while !tokens.is_empty() {
+        let token = tokens.first().unwrap();
+        tokens = &tokens[1..];
+
+        let start_of_line = prev == TokenKind::Newline;
+        prev = token.kind;
+
+        match token.kind {
+            TokenKind::CodeBlock if start_of_line => {
+                let astyle = format_from_style(
+                    egui_style,
+                    &easy_mark_parser::Style {
+                        code: true,
+                        ..Default::default()
+                    },
+                );
+
+                let span = collect_until(
+                    token,
+                    &mut tokens,
+                    series([TokenKind::Newline, TokenKind::CodeBlock]),
+                );
+
+                job.append(&*span, CODE_INDENT, astyle.clone());
+                style = Default::default();
+                continue;
+            }
+
+            TokenKind::Newline => style = easy_mark_parser::Style::default(),
+            TokenKind::Strong => style.strong ^= true,
+            TokenKind::Italic => style.italics ^= true,
+            TokenKind::Strikethrough => style.strikethrough ^= true,
+            TokenKind::Heading(_h) if start_of_line => style.heading = true,
+            TokenKind::Quote if start_of_line => style.quoted = true,
+
+            TokenKind::CodeBlock | TokenKind::Mono => {
+                style.code = true;
+                let span = collect_until(
+                    token,
+                    &mut tokens,
+                    any_of([TokenKind::Mono, TokenKind::CodeBlock, TokenKind::Newline]),
+                );
+                job.append(&*span, 0.0, format_from_style(egui_style, &style));
+                style.code = false;
+                continue;
+            }
+
+            TokenKind::Heading(..) | TokenKind::Quote | TokenKind::Text => {}
+        }
+
+        job.append(&token.span, 0.0, format_from_style(egui_style, &style));
+    }
+
+    job
+}
+
+fn series<'a, const N: usize>(of: [TokenKind; N]) -> impl FnMut(&[Token<'a>; N]) -> bool {
+    move |token| {
+        of.iter()
+            .zip(token)
+            .all(|(kind, token)| kind == &token.kind)
+    }
+}
+
+fn any_of<'a, const N: usize>(these: [TokenKind; N]) -> impl FnMut(&[Token<'a>; 1]) -> bool {
+    move |[token]| these.contains(&token.kind)
+}
+
+/// Collect all tokens up to and including `pattern`, and merge them into a signle span.
+///
+/// `N` determines how many specific and consecutive tokens we are looking for.
+/// i.e. if we were looking for a [TokenKind::Newline] followed by a [TokenKind::Quote], `N`
+/// would equal `2`.
+///
+/// `pattern` is a function that accepts an array of `N` tokens and returns `true` if they match,
+/// i.e. if we should stop collecting. [any_of] and [series] can help to construct this function.
+///
+/// The collected tokens will be split off the head of the slice referred to by `tokens`.
+///
+/// # Panic
+/// Panics if `tokens` does not contain only consecutive adjacent spans.
+fn collect_until<'a, const N: usize>(
+    token: &Token<'a>,
+    tokens: &mut &[Token<'a>],
+    pattern: impl FnMut(&[Token<'a>; N]) -> bool,
+) -> Span<'a>
+where
+    for<'b> &'b [Token<'a>; N]: TryFrom<&'b [Token<'a>]>,
+{
+    let mut windows = tokens
+        .windows(N)
+        .map(|slice| <&[Token<'a>; N]>::try_from(slice).ok().unwrap());
+
+    let split_at = match windows.position(pattern) {
+        Some(i) => i + N,
+        None => tokens.len(), // consume everything
+    };
+
+    let (consume, keep) = tokens.split_at(split_at);
+    *tokens = keep;
+
+    consume
+        .iter()
+        .fold(token.span.clone(), |span: Span<'_>, token| {
+            span.try_merge(&token.span).unwrap()
+        })
+}
+
+pub fn highlight_easymark_old(
     egui_style: &egui::Style,
     mut text: &str,