Algol 60 grammar (tncy)

empty

Basic Symbols

basic symbol: letter; digit; logical value; delimiter

Letters

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; 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

Digits

digit: 0; 1; 2; 3; 4; 5; 6; 7; 8; 9

Logical values

logical value: true; false

Delimiters

delimiter: operator; separator; bracket; declarator; specificator
operator: arithmetic operator; relational operator; logical operator; sequential operator
arithmetic operator: +; −; ×; /; ÷; ↑
relational operator: <; ≤; =; ≥; >; ≠
logical operator: ≡; ⊃; ∨; ∧; ¬
sequential operator: go to; if; then; else; for; do
separator: ,; .; ⏨; :; ;; ≔; ␣; step; until; while; comment
bracket: (; ); [; ]; ⸢; ⸣; begin; end
declarator: own; Boolean; integer; real; array; switch; procedure
specificator: string; label; value

The sequence	is equivalent to
; comment any sequence of zero or more characters not containing ; ;	;
begin comment any sequence of zero or more characters not containing ; ;	begin

Identifiers

identifier: letter; identifier letter; identifier digit

Numbers

unsigned integer: digit; unsigned integer digit
integer: unsigned integer; + unsigned integer; − unsigned integer
decimal fraction: . unsigned integer
exponential part: ⏨ integer
decimal number: unsigned integer; decimal fraction; unsigned integer decimal fraction
unsigned number: decimal number; decimal number exponential part
number: unsigned number; + unsigned number; − unsigned number

Strings

proper string: any sequence of characters not containing ⸢ or ⸣; empty
open string: proper string; proper string closed string open string
closed string: ⸢ open string ⸣
string: closed string; closed string string

Expressions

expression: arithmetic expression; Boolean expression; designational expression

Variables

variable identifier: identifier
simple variable: variable identifier
subscript expression: arithmetic expression
subscript list: subscript expression; subscript list , subscript expression
array identifier: identifier
subscripted variable: array identifier [ subscript list ]
variable: simple variable; subscripted variable

Function designators

procedure identifier: identifier
actual parameter: string; expression; array identifier; switch identifier; procedure identifier
letter string: letter; letter string letter
parameter delimiter: ,; ) letter string : (
actual parameter list: actual parameter; actual parameter list parameter delimiter actual parameter
actual parameter part: empty; ( actual parameter list )
function designator: procedure identifier actual parameter part

Arithmetic expressions

adding operator: +; −
multiplying operator: ×; /; ÷
primary: unsigned number; variable; function designator; ( arithmetic expression )
factor: primary; factor ↑ primary
term: factor; term multiplying operator factor
simple arithmetic expression: term; adding operator term; simple arithmetic expression adding operator term
if clause: if Boolean expression then
arithmetic expression: simple arithmetic expression; if clause simple arithmetic expression else arithmetic expression

Boolean expressions

relational operator: <; ≤; =; ≥; >; ≠
relation: simple arithmetic expression relational operator simple arithmetic expression
Boolean primary: logical value; variable; function designator; relation; ( Boolean expression )
Boolean secondary: Boolean primary; ¬ Boolean primary
Boolean factor: Boolean secondary; Boolean factor ∧ Boolean secondary
Boolean term: Boolean factor; Boolean term ∨ Boolean factor
implication: Boolean term; implication ⊃ Boolean term
simple Boolean: implication; simple Boolean ≡ implication
Boolean expression: simple Boolean; if clause simple Boolean else Boolean expression

Designational expressions

label: identifier; unsigned integer
switch identifier: identifier
switch designator: switch identifier [ subscript expression ]
simple designational expression: label; switch designator; ( designational expression )
designational expression: simple designational expression; if clause simple designational expression else designational expression

Statements

Compound statements and blocks

unlabelled basic statement: assignment statement; go to statement; dummy statement; procedure statement
basic statement: unlabelled basic statement; label : basic statement
unconditional statement: basic statement; compound statement; block
statement: unconditional statement; conditional statement; for statement
compound tail: statement end; statement ; compound tail
block head: begin declaration; block head ; declaration
unlabelled block: block head ; compound tail
unlabelled compound: begin compound tail
compound statement: unlabelled compound; label : compound statement
block: unlabelled block; label : block
program: block; compound statement

Assignment statements

destination: variable; procedure identifier
left part: destination ≔
left part list: left part; left part list left part
assignment statement: left part list arithmetic expression; left part list Boolean expression

Go to statements

go to statement: go to designational expression

Dummy statements

dummy statement: empty

Conditional statements

if clause: if Boolean expression then
unconditional statement: basic statement; compound statement; block
if statement: if clause unconditional statement
conditional statement: if statement; if statement else statement; if clause for statement; label : conditional statement

For statements

for list element: arithmetic expression; arithmetic expression step arithmetic expression until arithmetic expression; arithmetic expression while Boolean expression
for list: for list element; for list , for list element
for clause: for variable ≔ for list do
for statement: for clause statement; label : for statement

Procedure statements

actual parameter: string; expression; array identifier; switch identifier; procedure identifier
letter string: letter; letter string letter
parameter delimiter: ,; ) letter string : (
actual parameter list: actual parameter; actual parameter list parameter delimiter actual parameter
actual parameter part: empty; ( actual parameter list )
procedure statement: procedure identifier actual parameter part

Declarations

declaration: type declaration; array declaration; switch declaration; procedure declaration

Type declarations

type list: simple variable; simple variable , type list
type: real; integer; Boolean
local or own: empty; own
type declaration: local or own type type list

Array declarations

lower bound: arithmetic expression
upper bound: arithmetic expression
bound pair: lower bound : upper bound
bound pair list: bound pair; bound pair list , bound pair
array segment: array identifier [ bound pair list ]; array identifier , array segment
array list: array segment; array list , array segment
array declarer: type array; array
array declaration: local or own array declarer array list

Switch declarations

switch list: designational expression; switch list , designational expression
switch declaration: switch switch identifier ≔ switch list

Procedure declarations

formal parameter: identifier
formal parameter list: formal parameter; formal parameter list parameter delimiter formal parameter
formal parameter part: empty; ( formal parameter list )
identifier list: identifier; identifier list , identifier
value part: value identifier list ;; empty
specifier: string; type; array declarer; label; switch; procedure; type procedure
specification part: empty; specifier identifier list ;; specification part specifier identifier list ;
procedure heading: procedure identifier formal parameter part ; value part specification part
procedure body: statement
procedure declaration: procedure procedure heading procedure body; type procedure procedure heading procedure body

Transcription of basic symbols

The UTF-8 symbol	is replaced by the ASCII symbol
(	(
)	)
[	[
]	]
,	,
;	;
:	:
≔	:=
≡	<=>
⊃	=>
∨	\/
∧	/\
¬	~
=	=
≠	<>
<	<
≥	>=
>	>
≤	<=
+	+
−	-
×	*
/	/
÷	//
↑	**
⸢	`
⸣	'
.	.
⏨	e
␣