Syntax highlighting for fenced code blocks, in command help output, on macOS works

[nazmulidris]

Current behavior

Currently, for Ockam Command CLI help output, the syntax highlighting for fenced code blocks has been disabled. It didn't work properly on macOS.

This commit removes the use of the use of FencedCodeBlockHighlighter::process_line().

Here's an example on macOS of the current behavior. Run ockam project ticket --help. It produces the following output in the Examples section. Note that it does not have any syntax highlighting.

Desired behavior

With syntax highlighting via syntect crate, it should be whatever syntect produces for sh syntax set.

Here are some places to get started in the code.

• process_terminal_docs() - This function is responsible for taking the CLAP help text output and formatting it just before displaying it to stdout.

• FencedCodeBlockHighlighter::process_line() - This is the function that is generating the unexpected and undefined color spans and newlines in the output.

[YorickdeJong]

Hey I can take a look at this one if it's still free

[nazmulidris]

@YorickdeJong That's awesome, this is all yours. Please let us know if you have any questions as you explore. You can also ask questions on the contributors discord https://discord.ockam.io

[YorickdeJong]

Cool thanks! I checked out the podcasts online and I really like the project! Combining rust, swift and microservices, awesome

[YorickdeJong]

Quick question, it seems that a few years ago this project stopped using the main branch. can I assume that the developer branch is the production branch?

[nazmulidris]

@YorickdeJong That's right. The develop branch is the "main" branch 👍🏽

[YorickdeJong]

Quick update, I ran a test and debugged the FencedCodeBlockHighlighter struct. It seems that the problem arises from the THEME variable. On MacOS it cannot determine the terminal background and sets it to None. In turn, this causes the process_line() function to panic, as the FencedCodeBlockHighlighter.inner variable is also set to None.

static THEME: Lazy<Option<Theme>> = Lazy::new(|| {
    let theme_name = match TerminalBackground::detect_background_color() {
        TerminalBackground::Light => "base16-ocean.light",
        TerminalBackground::Dark => "base16-ocean.dark",
        TerminalBackground::Unknown => "base16-ocean.dark" //return None,
    };
    let mut theme_set = ThemeSet::load_defaults();
    let theme = theme_set.themes.remove(theme_name).unwrap();
    Some(theme)
});

When I ran the test with:

TerminalBackground::Unknown => "base16-ocean.dark"

instead of

TerminalBackground::Unknown => None

I did get colors to show on macOS

I also managed to get the correct coloring for the issue at hand in the test:

However, it seems that running ockam project ticket --help seems to not be affected by the implemented changes. This arises from the fact that it has is_markdown() configured, which doesn't have syntax_highlighted enabled

if is_markdown() {
        Box::leak(body.to_string().into_boxed_str())
    } else {
        let syntax_highlighted = process_terminal_docs(body.to_string());
        Box::leak(syntax_highlighted.into_boxed_str())
    }
}

[nazmulidris]

@YorickdeJong Good job examining the code 👍🏽 .

process_terminal_docs()

You might not see ockam project ticket --help produce syntect highlighted output in the help / examples section at the bottom of the output because currently the call to process_line() has been removed from here process_terminal_docs().

This is what the old (removed) code used to look like here:

...
    for line in LinesWithEndings::from(input.as_str()) {
        // Try to process fenced code blocks
        if code_highlighter.process_line(line, &mut output) {
            continue;
        }

        // Replace headers with bold and underline text
        if HEADER_RE.is_match(line) {
...

is_markdown()

docs.rs is used to post process clap help text output (before it is displayed to stdout), as well as generate the MD manual that is can be seen here: https://command.ockam.io/manual/. Here's more info on this: build-trust/ockam-documentation#16

The code path that you're looking for is the else block:

pub(crate) fn render(body: &str) -> &'static str {
    if is_markdown() {
        Box::leak(body.to_string().into_boxed_str())
    } else {
        let syntax_highlighted = process_terminal_docs(body.to_string());
        Box::leak(syntax_highlighted.into_boxed_str())
    }
}

static THEME

I think the expression assigned to needs some updating.

If it isn't possible to determine what the background color is (based on those heuristics), ie, the theme_name is TerminalBackground::Unknown, then it should default to base16-ocean.dark. That heuristic to determine the background isn't really reliable. It's a heuristic after all. What are your thoughts on this?

call process_line() from process_terminal_docs()

Let's say the fallback theme is base16-ocean.dark, and process_line() is called (currently the call to this function has been removed).

• The implementation of process_line() itself needs to be examined as well. For eg, it uses the as_24_bit_terminal_escaped(). It states in the docs for this function that is is meant for debugging and testing only. With the use of this function there's a need to append a RESET ANSI escape code as well (output.push("\x1b[0m".to_string());). You might try getting the syntax highlighting to work with this existing implementation though. Just to confirm that we are heading in the right direction.

• Instead it may be better to create an implementation to generate these ANSI escape sequences manually using the r3bl_ansi_color crate. Here's an example of how this might be done (from a different crate that also does something similar): here.

[YorickdeJong]

Hi @nazmulidris,

Thank you for the detailed feedback. I've reintroduced the call to process_line() within process_terminal_docs() to ensure that code blocks are processed and highlighted correctly.

/// Use a shell syntax highlighter to render the fenced code blocks in terminals
fn process_terminal_docs(input: String) -> String {
    let mut output: Vec<String> = Vec::new();
    let mut code_highlighter = FencedCodeBlockHighlighter::new();

    for line in LinesWithEndings::from(&input) {
        
        // Check if the current line is a code block start/end or content.
        let is_code_line = code_highlighter.process_line(line, &mut output);
        if !is_code_line {
            // The line was not part of a code block, so process normally.

            // Replace headers with bold and underline text
            if HEADER_RE.is_match(line) {
                output.push(line.to_string().bold().underlined().to_string());
            }
            // Replace subheaders with underlined text
            else if line.starts_with("#### ") {
                output.push(line.replace("#### ", "").underlined().to_string());
            }
            // Catch all other lines
            else {
                output.push(line.to_string());
            }
        }
    }
    output.join("")
}

Such that my tests are able to include color into the output for shell commands. I should have mentioned that, apologies.

is_markdown(): I think the reason we aren't seeing any colors for the markdown menu is that syntax_highlight isn't configured for it

static THEME: I agree with your suggestion that we should default "base16-ocean.dark" if no background can be determined, as most developers use dark mode anyways.

Manual ANSI Sequences: I plan to explore the use of the r3bl_ansi_color crate to manually generate ANSI escape sequences for syntax highlighting tomorrow. Will keep you posted.

[nazmulidris]

@YorickdeJong Thanks for the clarification 🙏🏽 . That's great that you are calling
let is_code_line = code_highlighter.process_line(line, &mut output);.

Re: is_markdown()

We actually do not want those ANSI escape sequences to be generated for Markdown generation. We only want them to be generated for stdout display output. So the is_markdown() check is working as intended 👍🏽 .

Re: static THEME

That's great that you agree with that too 👏🏽 .

Manual ANSI sequences

Please let me know if you have any questions about this. The example I shared with you is from the r3bl_tui crate which does not output to r3bl_ansi_color.

• However, it does have the algorithm that can be copied in order to port that implementation so that it goes from syntect -> r3bl_ansi_color output -> stdout.
• The AnsiStyledText struct implements Display trait, so you can just use println!("{}... or format!("{}... to send it to stdout.

[YorickdeJong]

Hi @nazmulidris,

Thanks for your suggestions.

Re: Manual ANSI sequences

I implemented the r3bl_ansi_color library:

    #[allow(dead_code)]
    pub fn process_line(&mut self, line: &str, output: &mut Vec<String>) -> bool {

        if let Some(highlighter) = &mut self.inner {
            if line == "```sh\n" {
                self.in_fenced_block = true;
                return true;
            }

            if !self.in_fenced_block {
                return false;
            }

            if line == "```\n" {
                // Push a reset to clear the coloring.
                output.push("\x1b[0m".to_string());
                self.in_fenced_block = false;
                return true;
            }

            // Highlight the code line
            let ranges: Vec<(Style, &str)> = highlighter
                .highlight_line(line, &SYNTAX_SET)
                .unwrap_or_default();

            // Convert each syntect range to an ANSI styled string
            convert_syntect_style_to_ansi(output, &ranges);

            true
        } else {
            false
        }
    }
}

With a converted function:

pub fn convert_syntect_style_to_ansi(output: &mut Vec<String>, ranges: &Vec<(Style, &str)>) {
    for (style, text) in ranges {
        let ansi_styled_text = AnsiStyledText {
            text: text,
            style: &[
                StyleAnsi::Foreground(Color::Rgb(style.foreground.r, style.foreground.g, style.foreground.b)),
            ],
        };

        output.push(ansi_styled_text.to_string());
    }
}

My tests come back positively. It should be noted that I currently only add Foreground coloring, but if needed bold, italic, underlining and background options can also be set.

Running ockam project ticket --help

I'm still having problems coloring the results from running the command ockam project ticket --help. These results still don't show color, whereas the test I'm running do show color. It seems that when running the code in debug mode, text is colored as well. I included a picture, on the left in debug mode and on the right in normal mode, to show case what I mean.

Would you happen to know why the color is still missing in the normal mode? Thanks!