PLZ/SYS Grammar

module => module_identifier module declarations*
end module_identifier

declarations
=> constants
=> types
=> globals
=> internals
=> externals

constants => constant constant_definition*

types => type type_definition*

globals => global var_or_proc_declaration*

internals => internal var_or_proc_declaration*

externals => external restricted_var_or_proc_declaration*

constant_declaration => identifier := constant_expression

constant_expression => constant_term (add_op constant_term)*

constant_term => constant_factor (add_op constant_factor)*

constant_factor
=> ( constant_expression )
=> unary_op constant_expression
=> constant

constant
=> number
=> character_constant
=> constant_identifier
=> sizeof (static_variable | type_identifier | constant_identifier)

character_constant => ' character_text '

type_definition => identifier type

type
=> simple_type
=> structured_type

simple_type
=> byte
=> word
=> integer
=> short_integer
=> pointer_type
=> simple_type_identifier

pointer_type
=> ^ type
=> pointer_type_identifier

structured_type
=> array_type
=> record_type

array_type
=> array [ constant_expression+ type ]
=> array_type_identifier

record_type
=> record [ field_declaration+ ]
=> record_type_identifier

field_declaration => identifier+ type

var_or_proc_declaration
=> variable_declaration
=> procedure_declaration

restricted_var_or_proc_declaration
=> identifier+ type
=> restricted_procedure_declaration

variable_declaration
=> identifier simple_type [:= initial_value]
=> identifier identifier+ simple_type := [ initial_value* [...] ]]
=> identifier structured_type [:= constructor]
=> identifier identifier+ structured_type [:= [ constructor* [...] ]]
=> identifier array [ * simple_type ] := ([ initial_value+ ] | text_constant+)

constructor => [ initial_component* [...] ]

initial_component
=> initial_value
=> constructor

initial_value
=> type_converter initial_value
=> inc initial_value
=> dec initial_value
=> constant_expression
=> # (static_variable | text_constant)
=> nil
=> ?

text_constant => character_sequence

static_variable
=> simple_identifier
=> array_identifier
=> record_identifier
=> static_array_variable
=> static_record_variable

static_array_variable => static_array_designator [ constant_expression+ ]

static_array_designator
=> array_identifier
=> static_array_variable
=> static_record_variable

static_record_variable => static_record_designator . field_identifier

static_record_designator
=> record_identifier
=> static_array_variable
=> static_record_variable

procedure_declaration => procedure_identifier procedure [formal_parm_list]
[returns formal_parm_list]
locals*
[entry statement*]
end procedure_identifier

formal_parm_list => ( formal_parm* )

form_parm => identifier+ simple_type

locals => local (identifier+ type)*

restricted_procedure_declaration => procedure_identified procedure [parameter_type_list]
[returns parameter_type_list]

parameter_type_list => ( restricted_parm* )

restricted_parm => identifier* simple_type

statement
=> assignment_statement
=> if_statement
=> select_statement
=> loop_statement
=> exit_statement
=> repeat_statement
=> return_statement
=> procedure_statement

assignment_statement => variable assign_op arithmetic_expression

assign_op => := | += | -=

if_statement => if conditional_expression then statement* [else statement*] fi

select_statement => if arithmetic_expression select_element [else statement*] fi

select_element => case constant_expression+ then

loop_statement => [label] do statement* od

label => identifier

exit_statement => exit [from label]

repeat_statement => repeat [from label]

return_statement => return

procedure_statement => [variable variable+ :=] procedure_invocation

procedure_invocation => procedure_identifier [actual_parm_list]

actual_parm_list => ( parameter* )

parameter => arithmetic_expression

conditional_expression => conditional_term (orif conditional_term)*

conditional_term => conditional_factor (andif conditional_factor)*

conditional_factor => arithmetic_expression [rel_op arithmetic_expression]

arithmetic_expression => arithmetic_term (add_op arithmetic_term)*

arithmetic_term => arithmetic_factor (mult_op arithmetic_factor)*

arithmetic_factor
=> unary_operator arithmetic_factor
=> constant
=> variable
=> # (variable | text_constant)
=> nil
=> ( conditional_expression )

rel_op => = | <> | < | > | <= | >=

add_op => + | - | or | xor

mult_op => * | / | mod | and

unary_operator
=> unary_ops
=> type_converter

unary_op => + | - | abs | not | inc | dec

type_converter => simple_type

variable
=> identifier
=> procedure_invocation
=> array_variable
=> record_variable
=> pointer_variable

array_variable => array_designator [ arithmetic_expression ]

array_designator => variable

record_variable => record_designator . field_identifier

record_designator => variable

pointer_variable => pointer_designator ^

pointer_designator => variable

PLZ/SYS Lexical Grammar

PLZ_text => separator* [id_constant_text] (separator+ id_constant_text)*

id_constant_text
=> identifier
=> word_symbol
=> literal_constant

separator
=> delimeter_text
=> special_symbol

identifier => letter (letter | digit | _ )

literal_constant
=> number
=> character_sequence

delimiter_text
=> delimiter
=> comment

number
=> integer
=> hex_number

integer => digit+

hex_number => % hex_digit+

character_sequence => ' character_text+ '

character_text
=> character
=> special_character_text

character => any_character_except_%_or_

special_character_text => % (special_character | hex_digit hex_digit)

special_character => r | l | t | p | q

comment => comment_initiator comment_char* comment_terminator

comment_char => any_character_except_comment_terminator

comment_initiator => !

comment_terminator => !

letter
=> A | B | ... | Z
=> a | b | ... | z

digit => 0 | 1 | ... | 9

hex_digit
=> digit
=> A | B | ... | F
=> a | b | ... | f

special_symbol
=> = | <> | < | > | <= | >= | := | += | -= | ( | )
=> + | - | * | / | . | , | ^ | [ | ] | # | ? | ...

delimiter
=> , | ; | :
=> whitespace