This is the formal syntax of BCPL (Richards & Whitby-Strevens 1980:161-165). The grammar is written in ISO/IEC 14977 EBNF notation (ISO/IEC 1996).
- 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' ;
- octal digit =
- '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' ;
- hex digit =
- '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' | 'A' | 'B' | 'C' | 'D' | 'E' | 'F' ;
- digit =
- '0' | '1' | '2' | '3' | '4' | '5' | '6' | '7' | '8' | '9' ;
- string constant =
- '"', ? 255 or fewer characters ?, '"' ;
- character constant =
- "'", ? one character ?, "'" ;
- octal number =
- '#', octal digit, {octal digit} ;
- hex number =
- '#X', hex digit, {hex digit} ;
- number =
- octal number | hex number | digit, {digit} ;
- identifier =
- letter, {letter | digit | '.'} ;
- address op =
- '@' | '!' ;
- mult op =
- '*' | '/' | 'REM' ;
- add op =
- '+' | '-' ;
- rel op =
- '=' | '¬=' | '<=' | '>=' | '<' | '>' ;
- shift op =
- '<<' | '>>' ;
- and op =
- '&' ;
- or op =
- '|' ;
- eqv op =
- 'EQV' | 'NEQV' ;
- not op =
- '¬' ;
- element =
- character constant | string constant | number | identifier | 'TRUE' | 'FALSE' ;
- primary E =
- primary E, '(', expression list, ')' | primary E, '(', ')' | '(', expression, ')' | element ;
- vector E =
- vector E, '!', primary E | primary E ;
- address E =
- address op, address E | vector E ;
- mult E =
- mult E, mult op, address E | address E ;
- add E =
- add E, add op, mult E | add op, mult E | mult E ;
- rel E =
- add E, {rel op, add E} ;
- shift E =
- shift E, shift op, add E | rel E ;
- not E =
- not op, shift E | shift E ;
- and E =
- not E, {and op, not E} ;
- or E =
- and E, {or op, and E} ;
- eqv E =
- or E, {eqv op, or E} ;
- conditional E =
- eqv E, '->', conditional E, ',', conditional E | eqv E ;
- expression =
- conditional E | 'TABLE', constant expression, {',', constant expression} | 'VALOF', command ;
- c element =
- character constant | number | identifier | 'TRUE' | 'FALSE' | '(', constant expression, ')' ;
- c mult E =
- c mult E, mult op, c element | c element ;
- c add E =
- c add E, add op, c mult E | add op, c mult E | c mult E ;
- c shift E =
- c shift E, shift op, c add E | c add E ;
- c and E =
- c and E, and op, c shift E | c shift E ;
- constant expression =
- constant expression, or op, c and E | c and E ;
- expression list =
- expression, {',', expression} ;
- name list =
- name, {',', name} ;
- manifest item =
- identifier, '=', constant expression ;
- manifest list =
- manifest item, {';', manifest item} ;
- manifest declaration =
- 'MANIFEST', '$(', manifest list, '$)' ;
- static declaration =
- 'STATIC', '$(', manifest list, '$)' ;
- global item =
- identifier, ':', constant expression ;
- global list =
- global item, {';', global item} ;
- global declaration =
- 'GLOBAL', '$(', global list, '$)' ;
- simple definition =
- name list, '=', expression list ;
- vector definition =
- identifier, '=', 'VEC', constant expression ;
- function definition =
- identifier, '(', name list, ')', '=', expression | identifier, '(', ')', '=', expression ;
- routine definition =
- identifier, '(', name list, ')', 'BE', command | identifier, '(', ')', 'BE', command ;
- definition =
- simple definition | vector definition | function definition | routine definition ;
- simultaneous declaration =
- 'LET', definition, {'AND', definition} ;
- declaration =
- simultaneous declaration | manifest declaration | static declaration | global declaration ;
- lhse =
- identifier | vector E, '!', primary E | '!', primary E ;
- left hand side list =
- lhse, {',', lhse} ;
- assignment =
- left hand side list, ':=', expression list ;
- simple command =
- 'BREAK' | 'LOOP' | 'ENDCASE' | 'RETURN' | 'FINISH' ;
- goto command =
- 'GOTO', expression ;
- routine command =
- primary E, '(', expression list, ')' | primary E, '(', ')' ;
- resultis command =
- 'RESULTIS', expression ;
- switchon command =
- 'SWITCHON', expression, 'INTO', compound command ;
- repeatable command =
- assignment | simple command | goto command | routine command | resultis command | repeated command | switchon command | compound command | block ;
- repeated command =
- repeatable command, 'REAPEAT' | repeatable command, 'REPEATUNTIL', expression | repeatable command, 'REPEATWHILE', expression ;
- until command =
- 'UNTIL', expression, 'DO', command ;
- while command =
- 'WHILE', expression, 'DO', command ;
- for command =
- 'FOR', identifier, '=', expression, 'TO', expression, 'BY', constant expression, 'DO', command | 'FOR', identifier, '=', expression, 'TO', expression, 'DO', command ;
- repetitive command =
- repeated command | until command | while command | for command ;
- test command =
- 'TEST', expression, 'THEN', command, 'ELSE', command ;
- if command =
- 'IF', expression, 'THEN', command ;
- unless command =
- 'UNLESS', expression, 'THEN', command ;
- unlabelled command =
- repeatable command | repetitive command | test command | if command ;
- label prefix =
- identifier, ':' ;
- case prefix =
- 'CASE', constant expression, ':' ;
- default prefix =
- 'DEFAULT', ':' ;
- prefix =
- label prefix | case prefix | default prefix ;
- command =
- unlabelled command | prefix, command | prefix ;
- command list =
- command, {';', command} ;
- declaration part =
- declaration, {';', declaration} ;
- block =
- '$(', declaration part, ';', command list, '$)' ;
- compound command =
- '$(', command list, '$)' ;
- program =
- declaration part ;
Grammar
- '!'
- address op
- lhse
- vector E
- '#'
- octal number
- '#X'
- hex number
- '$('
- block
- compound command
- global declaration
- manifest declaration
- static declaration
- '$)'
- block
- compound command
- global declaration
- manifest declaration
- static declaration
- '&'
- and op
- '¬'
- not op
- '¬='
- rel op
- "'"
- character constant
- '('
- c element
- function definition
- primary E
- routine command
- routine definition
- ')'
- c element
- function definition
- primary E
- routine command
- routine definition
- '"'
- string constant
- '*'
- mult op
- '+'
- add op
- ','
- conditional E
- expression list
- expression
- left hand side list
- name list
- '-'
- add op
- '->'
- conditional E
- '.'
- identifier
- '/'
- mult op
- '0'
- digit
- hex digit
- octal digit
- '1'
- digit
- hex digit
- octal digit
- '2'
- digit
- hex digit
- octal digit
- ? 255 or fewer characters ?
- string constant
- '3'
- digit
- hex digit
- octal digit
- '4'
- digit
- hex digit
- octal digit
- '5'
- digit
- hex digit
- octal digit
- '6'
- digit
- hex digit
- octal digit
- '7'
- digit
- hex digit
- octal digit
- '8'
- digit
- hex digit
- '9'
- digit
- hex digit
- ':'
- case prefix
- default prefix
- global item
- label prefix
- ':='
- assignment
- ';'
- block
- command list
- declaration part
- global list
- manifest list
- '<'
- rel op
- '<<'
- shift op
- '<='
- rel op
- '='
- for command
- function definition
- manifest item
- rel op
- simple definition
- vector definition
- '>'
- rel op
- '>='
- rel op
- '>>'
- shift op
- '@'
- address op
- 'A'
- hex digit
- letter
- 'AND'
- simultaneous declaration
- 'B'
- hex digit
- letter
- 'BE'
- routine definition
- 'BREAK'
- simple command
- 'BY'
- for command
- 'C'
- hex digit
- letter
- 'CASE'
- case prefix
- 'D'
- hex digit
- letter
- 'DEFAULT'
- default prefix
- 'DO'
- for command
- until command
- while command
- 'E'
- hex digit
- letter
- 'ELSE'
- test command
- 'ENDCASE'
- simple command
- 'EQV'
- eqv op
- 'F'
- hex digit
- letter
- 'FALSE'
- c element
- element
- 'FINISH'
- simple command
- 'FOR'
- for command
- 'G'
- letter
- 'GLOBAL'
- global declaration
- 'GOTO'
- goto command
- 'H'
- letter
- 'I'
- letter
- 'IF'
- if command
- 'INTO'
- switchon command
- 'J'
- letter
- 'K'
- letter
- 'L'
- letter
- 'LET'
- simultaneous declaration
- 'LOOP'
- simple command
- 'M'
- letter
- 'MANIFEST'
- manifest declaration
- 'N'
- letter
- 'NEQV'
- eqv op
- 'O'
- letter
- 'P'
- letter
- 'Q'
- letter
- 'R'
- letter
- 'REAPEAT'
- repeated command
- 'REM'
- mult op
- 'REPEATUNTIL'
- repeated command
- 'REPEATWHILE'
- repeated command
- 'RESULTIS'
- resultis command
- 'RETURN'
- simple command
- 'S'
- letter
- 'STATIC'
- static declaration
- 'SWITCHON'
- switchon command
- 'T'
- letter
- 'TABLE'
- expression
- 'TEST'
- test command
- 'THEN'
- if command
- test command
- unless command
- 'TO'
- for command
- 'TRUE'
- c element
- element
- 'U'
- letter
- 'UNLESS'
- unless command
- 'UNTIL'
- until command
- 'V'
- letter
- 'VALOF'
- expression
- 'VEC'
- vector definition
- 'W'
- letter
- 'WHILE'
- while command
- 'X'
- letter
- 'Y'
- letter
- 'Z'
- letter
- add E
- add E
- rel E
- shift E
- add op
- add E
- add op
- c add E
- address E
- address E
- mult E
- address op
- address E
- address op
- and E
- and E
- or E
- and op
- and E
- and op
- c and E
- assignment
- assignment
- repeatable command
- block
- block
- repeatable command
- c add E
- c add E
- c shift E
- c and E
- c and E
- constant expression
- c element
- c element
- c mult E
- c mult E
- c add E
- c mult E
- c shift E
- c and E
- c shift E
- case prefix
- case prefix
- prefix
- character constant
- c element
- character constant
- element
- command list
- block
- command list
- compound command
- command
- command list
- command
- expression
- for command
- if command
- routine definition
- test command
- unless command
- until command
- while command
- compound command
- compound command
- repeatable command
- switchon command
- conditional E
- conditional E
- expression
- constant expression
- c element
- case prefix
- constant expression
- expression
- for command
- global item
- manifest item
- vector definition
- declaration part
- block
- declaration part
- program
- declaration
- declaration part
- declaration
- default prefix
- default prefix
- prefix
- definition
- definition
- simultaneous declaration
- digit
- digit
- identifier
- number
- element
- element
- primary E
- eqv E
- conditional E
- eqv E
- eqv op
- eqv E
- eqv op
- expression list
- assignment
- expression list
- primary E
- routine command
- simple definition
- expression
- expression list
- expression
- for command
- function definition
- goto command
- if command
- primary E
- repeated command
- resultis command
- switchon command
- test command
- unless command
- until command
- while command
- for command
- for command
- repetitive command
- function definition
- definition
- function definition
- global declaration
- declaration
- global declaration
- global item
- global item
- global list
- global list
- global declaration
- global list
- goto command
- goto command
- repeatable command
- hex digit
- hex digit
- hex number
- hex number
- hex number
- number
- identifier
- c element
- element
- for command
- function definition
- global item
- identifier
- label prefix
- lhse
- manifest item
- routine definition
- vector definition
- if command
- if command
- unlabelled command
- label prefix
- label prefix
- prefix
- left hand side list
- assignment
- left hand side list
- letter
- identifier
- letter
- lhse
- left hand side list
- lhse
- manifest declaration
- declaration
- manifest declaration
- manifest item
- manifest item
- manifest list
- manifest list
- manifest declaration
- manifest list
- static declaration
- mult E
- add E
- mult E
- mult op
- c mult E
- mult E
- mult op
- name list
- function definition
- name list
- routine definition
- simple definition
- name
- name list
- not E
- and E
- not E
- not op
- not E
- not op
- number
- c element
- element
- number
- octal digit
- octal digit
- octal number
- octal number
- number
- octal number
- ? one character ?
- character constant
- or E
- eqv E
- or E
- or op
- constant expression
- or E
- or op
- prefix
- command
- prefix
- primary E
- lhse
- primary E
- routine command
- vector E
- program
- program
- rel E
- rel E
- shift E
- rel op
- rel E
- rel op
- repeatable command
- repeatable command
- repeated command
- unlabelled command
- repeated command
- repeatable command
- repeated command
- repetitive command
- repetitive command
- repetitive command
- unlabelled command
- resultis command
- repeatable command
- resultis command
- routine command
- repeatable command
- routine command
- routine definition
- definition
- routine definition
- shift E
- not E
- shift E
- shift op
- c shift E
- shift E
- shift op
- simple command
- repeatable command
- simple command
- simple definition
- definition
- simple definition
- simultaneous declaration
- declaration
- simultaneous declaration
- static declaration
- declaration
- static declaration
- string constant
- element
- string constant
- switchon command
- repeatable command
- switchon command
- test command
- test command
- unlabelled command
- unlabelled command
- command
- unlabelled command
- unless command
- unless command
- until command
- repetitive command
- until command
- vector E
- address E
- lhse
- vector E
- vector definition
- definition
- vector definition
- while command
- repetitive command
- while command
- '|'
- or op
Index
References
- ISO/IEC. (1996). ISO/IEC 14977 : 1996(E). ISO/IEC. Retrieved Saturday, March 26, 2005 from http://www.cl.cam.ac.uk/~mgk25/iso-ebnf.html.
- Richards, Martin & Colin Whitby-Strevens. (1980). BCPL - the language and its compiler. Bristol: Cambridge University Press.
