productionset
productionset — A set of EBNF productions.
Synopsis
productionset ::=
Attributes
Additional Constraints
- If this element is the root element, it must have a version attribute.
Description
A productionset
is a collection of
Extended Backus-Naur Form (EBNF)
production
s.
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.
Processing expectations
Formatted as a displayed block. The detailed processing expectations with respect to individual productions, lefthand sides, and righthand sides are quite complex.
The production
s should be numbered.
Children
The following elements occur in productionset: info
(db.titleforbidden.info), info
(db.titleonly.info), production
, productionrecap
, title
, titleabbrev
.
Examples
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:
Division by zero is an error.
</constraintdef>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>