From 09765c22460ee4aa3e2fbe5cf1af54aa3106e6a5 Mon Sep 17 00:00:00 2001
From: Philipp Gesang <phg42.2a@gmail.com>
Date: Mon, 29 Apr 2013 10:55:49 +0200
Subject: [doc] add font request syntax description
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For convenience it’s a notational bastard of BNF and ISO EBNF.
I couldn’t find a package for typesetting the latter, and
with my limited understanding of LaTeX I couldn’t have written
one within an acceptable time.
Anyways, I don’t think anybody will be confused by this.
---
luaotfload.dtx | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 77 insertions(+), 2 deletions(-)
diff --git a/luaotfload.dtx b/luaotfload.dtx
index 722a8d2..957dea1 100644
--- a/luaotfload.dtx
+++ b/luaotfload.dtx
@@ -160,6 +160,8 @@ and the derived files
\renewcommand\partname{Part}%% gets rid of the stupid “file” heading
+\usepackage{syntax}%% bnf for font request syntax
+
\VerbatimFootnotes
\begin{document}
\DocInput{luaotfload.dtx}%
@@ -256,8 +258,81 @@ and the derived files
%
% \noindent
% The curly brackets are optional and escape the spaces in the enclosed
-% font name (alternatively, double quotes serve the same purpose).
-% The individual parts of the syntax are:
+% font name.
+% Alternatively, double quotes serve the same purpose.
+% A selection of individual parts of the syntax are discussed below;
+% for a more formal description see figure \ref{font-syntax}.
+%
+% \begin{figure}[b]
+% \setlength\grammarparsep{12pt plus 2pt minus 2pt}
+% \setlength\grammarindent{5cm}
+% \begingroup
+% \small
+% \begin{grammar}
+% <definition> ::= `\\font', {\sc csname}, `=', <font request>, [ <size> ] ;
+%
+% <size> ::= `at', {\sc dimension} ;
+%
+% <font request> ::= `"', <unquoted font request> `"'
+% \alt `{', <unquoted font request> `}'
+% \alt <unquoted font request> ;
+%
+% <unquoted font request> ::= <specification>, [`:', <feature list> ]
+% \alt `[', <path lookup> `]', [ [`:'], <feature list> ] ;
+%
+% <specification> ::= <prefixed spec>, [ <subfont no> ], \{ <modifier> \}
+% \alt <anon lookup>, \{ <modifier> \} ;
+%
+% <prefixed spec> ::= `file:', <file lookup>
+% \alt `name:', <name lookup> ;
+%
+% <file lookup> ::= \{ <name character> \} ;
+%
+% <name lookup> ::= \{ <name character> \} ;
+%
+% <anon lookup> ::= {\sc tfmname} | <name lookup> ;
+%
+% <path lookup> ::= \{ {\sc all_characters} - `]' \} ;
+%
+% <modifier> ::= `/', (`i' | `b' | `bi' | `ib') ;
+%
+% <subfont no> ::= `(', \{ {\sc digit} \}, `)' ;
+%
+% <feature list> ::= <feature expr>, \{ `;', <feature expr> \} ;
+%
+% <feature expr> ::= {\sc feature_id}, `=', {\sc feature_value}
+% \alt <feature switch>, {\sc feature_id} ;
+%
+% <feature switch> ::= `+' | `-' ;
+%
+% <name character> ::= {\sc all_characters} - ( `(' | `/' | `:' ) ;
+% \end{grammar}
+% \endgroup
+% \caption{Font request syntax.
+% Braces or double quotes around the
+% \emphasis{specification} rule will
+% preserve whitespace in file names.
+% In addition to the font style modifiers
+% (\emphasis{slash-notation}) given above, there
+% are others that are recognized but will be silently
+% ignored: {\ttfamily aat},
+% {\ttfamily icu}, and
+% {\ttfamily gr}.
+% The special terminals are:
+% {\sc feature\textunderscore id} for a valid font
+% feature name and
+% {\sc feature\textunderscore value} for the corresponding
+% value.
+% {\sc tfmname} is the name of a \abbrev{tfm} file.
+% {\sc digit} again refers to bytes 48--57, and
+% {\sc all\textunderscore characters} to all byte values.
+% {\sc csname} and {\sc dimension} are the \TEX concepts.}
+% \label{font-syntax}
+% \end{figure}
+%
+% %(* braces around the specification will preserve whitespace *)
+% %(* file lookups do not allow paths *)
+% %(* others like `aat', `icu', and `gr' are silently ignored *)
%
% \paragraph{Prefix}
%
--
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