SIMULA 67(ID:301/sim053)

 EBNF - Syntax of SIMULA
67

  1 <program> ::
{<block prefix>}<block> | {<block prefix>}<compound
statement>
  2  <block prefix> ::= <class
identifier>{(<actual paremeter list>)}
 
3   <block> ::= <block head>;<compound
tail>
  4    <block head> ::= <block
head>;<declaration> | BEGIN <declaration>

  5 <declaration> ::=
<type declaration> | <array declaration> | <switch
declaration> | <procedure declaration> | <class declaration> |
<external declaration>
  6  <type declaration> ::=
<type><identifier list>
  7   <type>
::= BOOLEAN | CHARACTER | INTEGER | REAL | REF(<class declaration>) |
TEXT
  8   <identifier list> ::= {<identifier
list>,}<identifier>
  9  <array declaration>
::= {<type>} ARRAY <array
list>
 10   <array list> ::={<array
list>,} <array segment>
 11    <array
segment> ::= <identifier list>[<bound pair
list>]
 12     <bound pair list> ::=
{<bound pair list>,}<arithmetic expression>:<arithmetic
expression>
 13  <switch declaration> ::= SWITCH
<switch identifier> := <switch
list>
 14   <switch identifier> ::=
<identifier>
 15   <switch list> ::=
{<switch list>,}<designational
expression>
 16  <procedure declaration> ::=
{<type>} PROCEDURE <procedure heading>;<proceduere
body>
 17   <procedure heading> ::=
<procedure identifier>{<formal parameter part>;{<mode
part>;}<specification
part>}
 18    <formal parameter part> ::=
(<identifier list>)
 19    <mode part>
::= {<value part>;}<name part> | {<name part>;}<value
part>
 20     <value part> ::= VALUE
<identifier list>
 21     <name
part> ::= NAME <identifier
list>
 22    <specification part> ::=
{<specification part>;}<specifier><identifier
list>
 23     <specifier> ::=
{<type>} ARRAY | LABEL | {<virtual part>;}<identifier
list>
 24   <procedure body> ::=
<statement>
 25  <class declaration> ::
{<prefix>} CLASS <class heding>;{<virtual part>;}<class
body>
 26   <prefix> ::= <class
identifier>
 27   <class heading> ::= <class
identifier>{<formal paremeter part>;{<value
part>;}<specification
part>}
 28    <class identifier> ::=
<identifier>
 29   <virtual part> ::=
VIRTUAL: <virtual specification
part>
 30    <virtual specification part>
::= {<virtual specification part>;}<virtual specifier><identifier
list>
 31     <virtual specifier> ::=
LABEL | {<type>} PROCEDURE | SWITCH
 32   <class
body> ::= <split body> |
<statement>
 33    <split body> ::
<initial part> INNER; <compound
tail>
 34     <initial part> ::= BEGIN
| <block head>; | <initial
part><statement>
 35  <external declaration>
::= EXTERNAL {<type>} PROCEDURE <external list> | EXTERNAL CLASS
<external list>
 36   <external list> ::=
{<external list>,}<external
item>
 37    <external item> ::=
<external identifier> | <identifier> = <external
identifier>

 38 <compound statement> ::=
BEGIN <compound tail>
 39  <compound tail> ::= END
| <statement>;<compound
tail>
 40   <statement> ::= <label
list><statement> | <conditional statement> | <connection
statement> | <repetition statement> | <unconditional
statement>
 41    <label list> ::=
{<label
list>}<label>:
 42     <label>
::= <identifier>
 43    <conditional
statement> ::= <if clause><connection statement> | <if
clause><repetition statement> | <if clause><unconditional
statement>{ELSE
<statement>}
 44     <if clause>
::= IF <Boolean expression>
THEN
 45    <connection statement> ::= INSPECT
<object expression><connection part>{OTHERWISE
<statement>}
 46     <connection
part> ::= DO <statement> | <selective
part>
 47      <selective part>
::= {<selective part>} WHEN <class identifier> DO
<statement>
 48    <repetition
statement> ::=<for statement> | <while
statement>
 49     <for statement> ::=
FOR <variable> :- <reference list> DO <statement> | FOR
<variable> := <value list> DO
<statement>
 50      <reference
list> ::= {<reference list>,}<reference expression> {WHILE
<Boolean
expression>}
 51      <value
list> ::= {<value list>,}<value list
element>
 52       <value list
element> ::= <value expression>{WHILE <Boolean expression>} |
<arithmetic expression> STEP <arithmetic expression> UNTIL
<arithmetic expression>
 53     <while
statement> ::= WHILE <Boolean expression> DO
<statement>
 54    <unconditional
statement> ::= <basic statement> | {<block prefix>}<block>
| {<block prefix>}<compound
statement>
 55     <basic statement>
::= <activation statement> | <assignment statement> | <dummy
statement> | <goto statement> | <object generator> |
<procedure
satement>
 56      <activation
statement> ::=<activator><object expression>{<scheduling
part>}
 57       <activator>
::= ACTIVATE |
REACTIVATE
 58       <scheduling
part> ::= AT <arithmetic expression>{PRIOR} | DELAY <arithmetic
expression> {PRIOR} | BEFORE <object expression> | AFTER <object
expression>
 59      <assignment
statement> ::= <reference assignment> | <value
assignment>
 60       <reference
assignment> ::= <reference left part> :- <reference right
part>
 61        <reference
left part> ::= <variable> | <procedure
identifiere>
 62        <reference
right part> ::= <reference expression> | <reference
assignment>
 63       <value
assignment> ::= <value left part> := <value right
part>
 64        <value
left part> ::= <variable> | <procedure identifier> | <simple
text
expression>
 65        <value
right part> ::= <value expression> | <value
assignment>
 66      <dummy
statement> ::=
<empty>
 67      <goto
statement> ::= GOTO <designational
expression>
 68      <object
generator> ::= NEW <class identifier> {(<actual parameter
list>)}
 69      <procedure
statement> ::= {<simple reference expression>,}<procedure
identifier>{(<actual parameter
list>)}
 70       <simple
reference expression> ::= <simple object expression> | <simple text
expression>
 71       <actual
parameter list> ::= {<actual parameter list>,}<actual
parameter>
 72        <actual
parameter> ::= <expression> | <array identifier> | <procedure
identifier> | <switch
identifier>
 73         <array
identifier> ::= {<simple object
expression>.}<identifier>
 74         <procedure
identifier> ::= {<simple reference
expression>.}<identifier>

 75 <expression> ::=
<designational expression> | <reference expression> | <value
expression>
 76  <designational expression> ::=
<simple designational expression> | <if clause> <simple
designational expression> ELSE <designational
expression>
 77   <simple designational
expression> ::= (<designational expression>) | <labal> |
<switch designator>
 78    <switch
designator> ::= <switch identifier>[<arithmetic
expression>]
 79  <reference expression> ::=
<object expression> | <text
expression>
 80   <object expression> ::=
<simple object expression> | <if clause><simple object
expression> ELSE <object
expression>
 81    <simple object
expression> ::= (<object expression>) | NONE | <function
designator> | <local object> | <object generator> | <qualified
object> |
<variable>
 82     <fuction
designator> ::= <procedure identifier> {(<actual parameter
list>)}
 83     <local object> ::=
THIS <class
identifier>
 84     <qualified object>
::= <simple object expression> QUA <class
identifier>
 85   <text expression> ::=
<simple text expression> | <if clause><simple text expression>
ELSE <text expression>
 86    <simple text
expression> ::= (<text expression>) | NOTEXT | <function
designator> | <variable>
 87   <value
expression> ::= <arithmetic expression> | <Boolean expression> |
<character expression> | <text value
expression>
 88    <simple arithmetic
expression> ::= <simple arithmetic expression> | <if
clause><simple arithmetic expression> ELSE <arithmetic
expression>
 89     <simple arithmetic
expression> ::= {{<simple arithmetic expression>}<adding
operator>}<arithmetic
term>
 90      <adding operator>
::= + | -
 91      <arithmetic term>
::= {<arithmetic term><multiplying operator>}<arithmetic
factor>
 92       <multiplying
operator> ::= x | / |
÷
 93       <arithmetic factor>
::= {<arithmetic factor>^}<arithmetic
primary>
 94        <arithmetic
primary> ::= (<arithmetic expression>) | <function designator> |
<unsigned number> |
<variable>
 95         <unsigned
number> ::= <decimal number> {<exponent part>} | <exponent
part>
 96          <decimal
number> ::= <unsigned integer>{<decimal fraction>} | <decimal
fraction>
 97           <unsigned
integer> ::= {<unsigned
integer>}<digit>
 98           <decimal
fraction> ::= .<unsigned
integer>
 99          <exponent
part> ::= \10{<adding operator>}<unsigned
integer>
100    <Boolean expression> ::=
<simple Boolean> | <if clause><simple Boolean> ELSE
<Boolean expression>
101     <simple
Boolean> ::= {<simple Boolean> \equ}
<implication>
102      <implication>
::= {<implication> \imp}<Boolean
term>
103       <Boolean term>
::= {<Boolean term> \or}<Boolean
factor>
104        <Boolean
factor> ::= {<Boolean factor> \and}{\not}<Boolean
primary>
105         <Boolean
primary> ::= (<Boolean expression>} | <logical value> |
<function designator> | <relation> |
<variable>
106          <logical
value> ::= TRUE |
FALSE
107          <relation>
::= <qualification relation> | <reference relation> | <value
expression>
108           <qualification
relation> ::= <simple object expression><qualification
tester><class
identifier>
109            <qualification
tester> ::= IS |
IN
110           <reference
releation> ::= <object reference relation> | <text reference
relation>
111            <object
reference relation> ::= <simple object expression> <reference
comparator><simple object
expression>
112             <reference
comparator> ::= == |
=/=
113            <text
reference relation> ::= <simple text expression><refernce
comparator><simple text
expression>
114           <value
relation> ::= <arithmetic relation> | <character relation> |
<text value
relation>
115            <arithmetic
relation> ::= <simple arithmetic expression><relational
operator><simple arithmetic
expression>
116             <relational
operator> ::= < | ¾ | = | „ | > |
‚
117            <chracter
relation> ::= <simple character expression><relational
operator><simple character
expression>
118            <text
value relation> ::= <simple text value><relational
operator><simple text
value>
119    <character expression> ::=
<simple character expression> | <if clause><simple character
expression> ELSE <character
expression>
120     <simple character
expression> ::= (<character expression> | <character constant> |
<function designator> |
<variable>
121     <character constant>
::= '<any basic symbol>'
122   <text value
expression> ::= <simple text value> | <if clause><simple text
value> 'ELSE' <text value
expression>
123    <simle text value> ::=
<simple text expression> | <text
constant>
124     <text constant> ::=
'<any sequence of basic symbols>'

125 <variable> ::= <simple
object expression>.<variable> | <simple variable> |
<subscripted variable>
126  <simple variable> ::=
<identifier>
127   <identifier ::=
{<identifier>}<letter> |
<identifier><digit>
128    <letter> ::=
A|B|C|D|E|F|G|H|I|J|K|L|M|N|O|P|Q|R|S|T|U|V|W|X|Y|Z
129    <digit>
::= 0|1|2|3|4|5|6|7|8|9|0
130  <subscripted variable> ::=
<array identifier>[<subscript
list>]
131   <subscript list> ::= {<subscript
list>,}<arithmetic expression>

 

# special signs:

÷    ... division - a line
between two dots aligned verticaly  (92)
^    ... power -
an up-arrow  (93)
\10  ... power of ten - a lowered "10" 
(99)
\equ ... logical equation - three strokes aligned verticaly 
(101)
\imp ... logical implication - a "U" turned counter-clockwise 
(102)
\or  ... logical or - a sign like a "v"  (103)
\and ...
logical and - like a flipped "v"  (104)
\not ... logical not "¬" - like
a flipped and conter-clockwise turned "L" (104)