The htmpl module provides runtime functions for the HTML template engine.

Functions herein are expected to be used by code generated by the same version
of htmplgen.

Many functions take an [[io::handle]], which represents the destination where
templates shall be rendered to.

use io;
use memio;
use strings;

// export type template = struct {
// 	writer: *fn(io::handle, const []u8) (size | io::error),
// };

// Writes a string to the destination.

export fn write(h: io::handle, s: str) (size | io::error) = {
	return io::write(h, strings::toutf8(s))?;
};

// Writes a string to the destination after HTML-escaping it.

export fn write_escape_html(h: io::handle, s: str) (size | io::error | nomem) = {
	let buf = memio::dynamic();
	defer io::close(&buf)!; // TODO: Might not want to abort for syscall interruptions

	let si = strings::iter(s);
	for (true) {
		match (strings::next(&si)) {
		case done =>
			break;
		case let c: rune =>
			switch (c) {
				case '<' =>
					memio::concat(&buf, "&lt;")?;
				case '>' =>
					memio::concat(&buf, "&gt;")?;
				case '&' =>
					memio::concat(&buf, "&amp;")?;
				case '"' =>
					memio::concat(&buf, "&quot;")?;
				case '\'' =>
					memio::concat(&buf, "&apos;")?;
				case =>
					memio::appendrune(&buf, c)?;
			};
		};
	};

	return io::write(h, memio::buffer(&buf))?;
};