    | DocBook: The Definitive Guide 0.0.12 for DocBook V5.0b1 (Alpha) |
| | DocBook: The Definitive Guide 0.0.12 for DocBook V5.0b1 (Alpha) |
productionset — A set of EBNF productions
A ProductionSet is a collection of
Extended Backus-Naur Form (EBNF)
Productions.
EBNF is a notation for describing the grammar of context-free languages. Even if you aren't conversant in the programming language concepts of context-free languages and grammars, it's not really as hard to understand as it sounds.
Formatted as a displayed block. The detailed processing expecations with respect to individual productions, left-hand sides, and right-hand sides are quite complex.
Productions should be numbered.
These elements contain productionset: annotation, answer, appendix, article, bibliodiv, bibliography, bibliolist, blockquote, callout, calloutlist, caption (db.caption), caution, chapter, colophon, constraintdef, dedication, entry, example, figure, footnote, glossary, glossdef, glossdiv, glosslist, html:fieldset, html:form, important, index, indexdiv, informalexample, informalfigure, itemizedlist, legalnotice, listitem, msgexplan, msgtext, note, orderedlist, para, partintro, preface, procedure, qandadiv, qandaset, question, refsect1, refsect2, refsect3, refsection, refsynopsisdiv, revdescription, sect1, sect2, sect3, sect4, sect5, section, setindex, sidebar, simplesect, step, taskprerequisites, taskrelated, tasksummary, td, textobject, th, tip, toc, tocdiv, variablelist, warning.
The following elements occur in productionset: info (db.titleforbidden.info), info (db.titleonly.info), production, productionrecap, title, titleabbrev.
A set of EBNF productions describes the legal arrangements of tokens in a language. Consider arithmetic expressions as a simple example.
The expression
“3 + 4”
is valid and so is
“3 + 4 - 5”, but
“3 - + - 4” is not, nor is
“3 + 4 6”. We can use EBNF to
describe all the possible legal arrangements:
| Arithemetic Expressions | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
That is expressed in DocBook like this:
<article xmlns='http://docbook.org/ns/docbook'>
<title>Example productionset</title>
<simplesect><title>EBNF Grammar</title>
<productionset><title>Arithemetic Expressions</title>
<production xml:id="ebnf.expression">
<lhs>Expression</lhs>
<rhs><nonterminal def="#ebnf.arith">ArithExpression</nonterminal> |
<nonterminal def="#ebnf.mult">MultExpression</nonterminal>
<lineannotation>Does this grammar actually get precedence right?
</lineannotation>
</rhs>
</production>
<production xml:id="ebnf.arith">
<lhs>ArithExpression</lhs>
<rhs><nonterminal def="#ebnf.expression">Expression</nonterminal>
'+'
<nonterminal def="#ebnf.mult">MultExpression</nonterminal> |
<nonterminal def="#ebnf.expression">Expression</nonterminal>
'-'
<nonterminal def="#ebnf.mult">MultExpression</nonterminal>
</rhs>
</production>
<production xml:id="ebnf.mult">
<lhs>MultExpression</lhs>
<rhs><nonterminal def="#ebnf.mult">MultExpression</nonterminal>
'*'
<nonterminal def="#ebnf.mult">MultExpression</nonterminal> |
<nonterminal def="#ebnf.mult">MultExpression</nonterminal>
'/'
<nonterminal def="#ebnf.mult">MultExpression</nonterminal> |
<nonterminal def="#ebnf.number">Number</nonterminal>
</rhs>
<constraint linkend="div0"/>
</production>
<production xml:id="ebnf.number">
<lhs>Number</lhs>
<rhs>[0-9]+</rhs>
</production>
</productionset>
<constraintdef xml:id="div0">
<title>Division by Zero</title>
<para>Division by zero is an error.</para>
</constraintdef>
</simplesect>
</article>
| | | |
| productionrecap | | productname |