### HighLight ###

HighLight (HL) is a small domain-specific language for encoding basic
syntax-highlighting information in-line with source code. Here is an example:

	%Tint %Vx = %N3 ;
	%Tstring %Vs = %{S"line 1%{E\n%}line 2"%} ;

HL has only 3 syntax rules:
	* `%A` applies rule `A` from the next character until before the next
	  whitespace character or at the start/end of another rule, or a
	  "word style".
	* `%{A...%}` applies rule `A` across all of `...`, or a "region style".
	* `%%` applies no rule but instead simply expands to a literal `%`
	  character.

Rules only have a "start" and "end" and will not modify any text that is not
part of a rule marker. Rule identifiers are single characters in the range
`A-Za-z`.

Config files store rules in this format:

	<identifier>\t<start>\t<end>[\t<comment>]

For example, a config file that converts the example at the top into HTML using
`<span>` tags might look like this:

	T	<span class="type">	</span>	A type
	V	<span class="var">	</span>	A variable
	N	<span class="num">	</span> A numeric literal
	S	<span class="str">	</span>	A string literal
	E	<span class="escape">	</span>	An escape sequence

For configs that will not work properly when "nested" e.g. with an ANSI escape
sequence based config that uses "\x1b[0m" as the end markers, the first (and
only the first) line of the config file can be given as `#nonest`. This will
mean that this:

	%{Aaaa%{Bbbb%}ccc%}

will be treated as though it is this:

	%{Aaaa%}%{Bbbb%}%{Accc%}

# USAGE

hl -c|--config <config> [-o|--output <output>] [<input>]

	-c|--config <config>
		Use the given config file. This has no default.
	-o|--output <output>
		Write output to the given file. If not provided, will write to stdout.
	<input>
		Read from the given input file. If not provided, will read from stdin.

# INSTALLING

Where $PREFIX is somewhere in your $PATH (e.g. "~/.bin"):

	dmd hl.d -of="$PREFIX/hl"

# EXAMPLES

Use the `test.src` example source file with the two provided example config
files like this:

	hl -c term.conf test.src
	hl -c html.conf test.src

`term.conf` uses escape sequences so the output to your terminal will be
coloured. `html.conf` uses `<span>` tags instead and can be used e.g. for adding
syntax-highlighted code snippets to websites.