Hide lines in code block (#1453)

* hide lines

* test hide ines

* add documentation

* fix test

* factor shared code with hl_lines

components/rendering/src/markdown/codeblock.rs

@@ -17,6 +17,8 @@ pub struct CodeBlock<'config> {
 
     /// List of ranges of lines to highlight.
     highlight_lines: Vec<Range>,
+    /// List of ranges of lines to hide.
+    hide_lines: Vec<Range>,
     /// The number of lines in the code block being processed.
     num_lines: usize,
 }
@@ -52,6 +54,7 @@ impl<'config> CodeBlock<'config> {
             theme,
 
             highlight_lines: fence_info.highlight_lines,
+            hide_lines: fence_info.hide_lines,
             num_lines: 0,
         }
     }
@@ -77,6 +80,9 @@ impl<'config> CodeBlock<'config> {
         let hl_lines = self.get_highlighted_lines();
         color_highlighted_lines(&mut highlighted, &hl_lines, hl_background);
 
+        let hide_lines = self.get_hidden_lines();
+        let highlighted = hide_hidden_lines(highlighted, &hide_lines);
+
         styled_line_to_highlighted_html(&highlighted, self.background)
     }
 
@@ -94,8 +100,16 @@ impl<'config> CodeBlock<'config> {
     }
 
     fn get_highlighted_lines(&self) -> HashSet<usize> {
+        self.ranges_to_lines(&self.highlight_lines)
+    }
+
+    fn get_hidden_lines(&self) -> HashSet<usize> {
+        self.ranges_to_lines(&self.hide_lines)
+    }
+
+    fn ranges_to_lines(&self, range: &Vec<Range>) -> HashSet<usize> {
         let mut lines = HashSet::new();
-        for range in &self.highlight_lines {
+        for range in range {
             for line in range.from..=min(range.to, self.num_lines) {
                 // Ranges are one-indexed
                 lines.insert(line.saturating_sub(1));
@@ -196,3 +210,29 @@ fn color_highlighted_lines(data: &mut [(Style, &str)], lines: &HashSet<usize>, b
         }
     }
 }
+
+fn hide_hidden_lines<'a>(
+    data: Vec<(Style, &'a str)>,
+    lines: &HashSet<usize>,
+) -> Vec<(Style, &'a str)> {
+    if lines.is_empty() {
+        return data;
+    }
+
+    let mut current_line = 0;
+
+    let mut to_keep = Vec::new();
+
+    for item in data {
+        if !lines.contains(&current_line) {
+            to_keep.push(item);
+        }
+
+        // We split the lines such that every newline is at the end of an item.
+        if item.1.ends_with('\n') {
+            current_line += 1;
+        }
+    }
+
+    to_keep
+}

components/rendering/src/markdown/fence.rs

@@ -28,16 +28,23 @@ pub struct FenceSettings<'a> {
     pub language: Option<&'a str>,
     pub line_numbers: bool,
     pub highlight_lines: Vec<Range>,
+    pub hide_lines: Vec<Range>,
 }
 impl<'a> FenceSettings<'a> {
     pub fn new(fence_info: &'a str) -> Self {
-        let mut me = Self { language: None, line_numbers: false, highlight_lines: Vec::new() };
+        let mut me = Self {
+            language: None,
+            line_numbers: false,
+            highlight_lines: Vec::new(),
+            hide_lines: Vec::new(),
+        };
 
         for token in FenceIter::new(fence_info) {
             match token {
                 FenceToken::Language(lang) => me.language = Some(lang),
                 FenceToken::EnableLineNumbers => me.line_numbers = true,
                 FenceToken::HighlightLines(lines) => me.highlight_lines.extend(lines),
+                FenceToken::HideLines(lines) => me.hide_lines.extend(lines),
             }
         }
 
@@ -50,6 +57,7 @@ enum FenceToken<'a> {
     Language(&'a str),
     EnableLineNumbers,
     HighlightLines(Vec<Range>),
+    HideLines(Vec<Range>),
 }
 
 struct FenceIter<'a> {
@@ -59,6 +67,16 @@ impl<'a> FenceIter<'a> {
     fn new(fence_info: &'a str) -> Self {
         Self { split: fence_info.split(',') }
     }
+
+    fn parse_ranges(token: Option<&str>) -> Vec<Range> {
+        let mut ranges = Vec::new();
+        for range in token.unwrap_or("").split(' ') {
+            if let Some(range) = Range::parse(range) {
+                ranges.push(range);
+            }
+        }
+        ranges
+    }
 }
 
 impl<'a> Iterator for FenceIter<'a> {
@@ -73,14 +91,13 @@ impl<'a> Iterator for FenceIter<'a> {
                 "" => continue,
                 "linenos" => return Some(FenceToken::EnableLineNumbers),
                 "hl_lines" => {
-                    let mut ranges = Vec::new();
-                    for range in tok_split.next().unwrap_or("").split(' ') {
-                        if let Some(range) = Range::parse(range) {
-                            ranges.push(range);
-                        }
-                    }
+                    let ranges = Self::parse_ranges(tok_split.next());
                     return Some(FenceToken::HighlightLines(ranges));
                 }
+                "hide_lines" => {
+                    let ranges = Self::parse_ranges(tok_split.next());
+                    return Some(FenceToken::HideLines(ranges));
+                }
                 lang => {
                     return Some(FenceToken::Language(lang));
                 }

components/rendering/tests/codeblock_hide_lines.rs

@@ -0,0 +1,61 @@
+use std::collections::HashMap;
+
+use tera::Tera;
+
+use config::Config;
+use front_matter::InsertAnchor;
+use rendering::{render_content, RenderContext};
+
+macro_rules! colored_html_line {
+    ( $s:expr ) => {{
+        let mut result = "<span style=\"color:#c0c5ce;\">".to_string();
+        result.push_str($s);
+        result.push_str("\n</span>");
+        result
+    }};
+}
+
+macro_rules! colored_html {
+    ( $($s:expr),* $(,)* ) => {{
+        let mut result = "<pre style=\"background-color:#2b303b;\">\n<code>".to_string();
+        $(
+            result.push_str(colored_html_line!($s).as_str());
+        )*
+        result.push_str("</code></pre>");
+        result
+    }};
+}
+
+#[test]
+fn hide_lines_simple() {
+    let tera_ctx = Tera::default();
+    let permalinks_ctx = HashMap::new();
+    let mut config = Config::default();
+    config.markdown.highlight_code = true;
+    let context = RenderContext::new(
+        &tera_ctx,
+        &config,
+        &config.default_language,
+        "",
+        &permalinks_ctx,
+        InsertAnchor::None,
+    );
+    let res = render_content(
+        r#"
+```hide_lines=2
+foo
+bar
+baz
+bat
+```
+    "#,
+        &context,
+    )
+    .unwrap();
+    assert_eq!(
+        res.body,
+        colored_html!(
+            "foo\nbaz\nbat",
+        )
+    );
+}

docs/content/documentation/content/syntax-highlighting.md

@@ -150,7 +150,6 @@ Here is a full list of supported languages and their short names:
 ```
 
 Note: due to some issues with the JavaScript syntax, the TypeScript syntax will be used instead.
-If 
 
 If you want to highlight a language not on this list, please open an issue or a pull request on the [Zola repo](https://github.com/getzola/zola).
 Alternatively, the `extra_syntaxes` configuration option can be used to add additional syntax files.
@@ -173,3 +172,40 @@ If your site source is laid out as follows:
 ```
 
 you would set your `extra_syntaxes` to `["syntaxes", "syntaxes/Sublime-Language1"]` to load `lang1.sublime-syntax` and `lang2.sublime-syntax`.
+
+## Annotations
+
+You can use additional annotations to customize how code blocks are displayed:
+
+- `linenos` to enable line numbering.
+````md
+
+```rust,linenos
+use highlighter::highlight;
+let code = "...";
+highlight(code);
+```
+
+````
+- `hl_lines` to highlight lines. You must specify a list of ranges of lines to highlight,
+separated by ` `. Ranges are 1-indexed.
+````md
+
+```rust,hl_lines=3
+use highlighter::highlight;
+let code = "...";
+highlight(code);
+```
+
+````
+- `hide_lines` to hide lines. You must specify a list of ranges of lines to hide,
+separated by ` `. Ranges are 1-indexed.
+````md
+
+```rust,hide_lines=1-2
+use highlighter::highlight;
+let code = "...";
+highlight(code);
+```
+
+````