Filetype detection

We'll write a function named selectSyntax to detect and set the buffer syntax. This function will be invoked in two places:

• in openFile():

    B.filename = try e.updateString(B.filename, path);

    B.syntax = try e.selectSyntax();

• in saveFile(), so that we can set a syntax for newly created files, after we give them a name:

    B.syntax = try e.selectSyntax();

    // determine number of bytes to write, make room for \n characters
    var fsize: usize = B.rows.items.len;

The selectSyntax() function

I put this in the "Syntax highlighting" section.

We start by freeing the old syntax, then we try to assign it again. For now unnamed buffers can't set a syntax, but it will be selected when the buffer is named and saved.

/// Return the syntax name for the current file, or null.
fn selectSyntax(e: *Editor) !?[]const u8 {
    var B = &e.buffer;

    // free the old syntax, if any
    t.freeOptional(e.alc, B.syntax);
    B.syntax = null;

    // we might allow setting a syntax even without a filename, actually...
    // but for now it's not possible
    if (B.filename == null) {
        return null;
    }

    // code to come...
}

We get the extension of the syntax, then we loop over all syntax definitions and we see if any of them matches for that extension.

If none of the extension matches, we match against the tail of the filename.

    const fileExt = str.getExtension(B.filename.?);

    for (&syndefs.Syntaxes) |*syntax| {
        if (fileExt) |extension| {
            for (syntax.ft_ext) |ext| {
                if (str.eql(ext, extension)) {
                    B.syndef = syntax;
                    return try e.alc.dupe(u8, syntax.ft_name);
                }
            }
        }
        for (syntax.ft_fntails) |name| {
            if (str.isTail(B.filename.?, name)) {
                B.syndef = syntax;
                return try e.alc.dupe(u8, syntax.ft_name);
            }
        }
    }
    return null;

Needed constants:

const syndefs = @import("syndefs.zig");