;;-----------------------------------------------------------------------------
;; Pascal.ebnf
;; Transcribed from The Pascal User Manual and Report 4th ed.

program = programheading semicolon block dot.
programheading = proglit identifier [ programparameterlist ] .
programparameterlist = lparen identifierlist rparen .
block = label-declaration-part const-declaration-part type-definition-part variable-declaration-part procedure-declaration-part procedure-and-function-declaration-part statement-part.
label-declaration-part = ["label" number {"," number} semicolon].
const-declaration-part = ["const" constant-definition semicolon {constant-definition semicolon}].
type-definition-part = ["type" type-definition ";"  {type-definition ";"}].
variable-declaration-part = ["var" variable-declaration semicolon {variable-declaration semicolon}].
procedure-and-function-declaration-part = {(procedure-declaration | function-declaration) semicolon}.
statement-part = compound-statement.
constant-definition   = identifier "=" constant.
type-definition       = identifier "=" type.
variable-declaration  = identifierlist ":" type.
procedure-declaration = procedure-heading semicolon directive
                       | procedure-identification semicolon block.
function-declaration  = function-heading semicolon block
                       | function-heading semicolon directive
                       | function-identification semicolon block.
procedure-heading = "procedure" identifier [formal-parameters-list].
procedure-identification = "procedure" procedure-identifier.
function-heading = "function" identifier [formal-parameters-list] colon result-type.
formal-parameters-list = lparen formal-parameters-section {semicolon formal-parameters-section} rparen.
formal-parameters-section = value-parameter-specification
                           | variable-parameter-specification
                           | procedural-parameter-specification
                           | functional-parameter-specification .
value-parameter-specification = identifier-list ":" (type-identifier | conformat-array-schema).
variable-parameter-specification = "var" identifier-list ":" (type-identifier | conformat-array-schema).
procedural-parameter-specification = procedure-heading.
functional-parameter-specification = function-heading.
conformat-array-schema = packed-constant-array-schema
                        | unpacked-constant-array-schema.
packed-constant-array-schema = "packed" "array" "[" index-type-specification "]" "of" type-identifier.
unpacked-constant-array-schema = "array" "[" index-type-specification { ";" index-type-specification } "]" "of" (type-identifier | conformat-array-schema).
index-type-specification = identifier ".." identifier ":" ordinal-type-identifier.
compound-statement = "begin" statement-sequence "end".
statement-sequence = statement {";" statement}.
statement          = [label ":"] (simple-statement | structured-statement).
simple-statement   = empty-statement
                    | assignment-statement
                    | procedure-statement
                    | goto-statement.
structured-statement = compound-statement
                      | conditional-statement
                      | repetitive-statement
                      | with-statement.
conditional-statement = if-statement
                       | case-statement.
repetitive-statement  = while-statement
                       | repeat-statement
                       | for-statement.
empty-statement = empty.
assignment-statement = (variable | function-identifier) ":=" expression.
procedure-statement = procedure-identifier [actual-parameter-list | write-parameter-list].
goto-statement = "goto" label.
if-statement = "if" boolean-expression "then" statement ["else" statement].
case-statement = "case" case-index "of" case {semicolon case} [semicolon] end.
repeat-statement = "repeat" statement-sequence "until" boolean-expression.
while-statement = "while" boolean-expression "do" statement.
for-statement = "for" control-variable ":=" initial-value ("to" | "downto") final-value "do" statement.
with-statement = "with" record-variable-list "do" statement.
record-variable-list = record-variable {comma record-variable}.
case-index = ordinal-expression.
case = constant {comma constant} semicolon statement.
control-variable = variable-identifier.
initial-value = ordinal-expression.
final-value = ordinal-expression.
type = simple-type | structured-type | pointer-type.
simple-type = ordinal-type | real-type-identifier.
structured-type = ["packed"] unpacked-structure-type | structured-type-identifier.
pointer-type = "^" domain-type | pointer-type-identifier.
ordinal-type = enumerated-type | subrange-type | ordinal-type-identifier.
unpacked-structure-type = array-type | record-type | set-type | file-type.
domain-type = type-identifier.
enumerated-type = lparen identifier-list rparen.
subrange-type = constant dotdot constant.
array-type = "array" "[" index-type {comma index-type} "]" "of" component-type.
record-type = "record" field-list "end".
set-type = "set" "of" basetype.
file-type = "file" "of" component-type.
index-type = ordinal-type.
component-type = type.
base-type = ordinal-type.
result-type = ordinal-type-identifier
             | real-type-identifier
             | pointer-type-identifier.
field-list = [(fixed-part [";" variant-part] | variant-part) [";"]].
fixed-part = record-section {";" record-section}.
variant-part = "case" variant-selector "of" variant {";" variant}.
record-section = identifier-list colon type.
variant-selector = [tag-field colon] tag-type.
variant = constant {comma constant} colon lparen field-list rparen.
tag-type = ordinal-type-identifier.
tag-field = identifier.
constant = [sign] (unsigned-number | constant-identifier | character-string).
expression = simple-expression [relational-operator simple-expression].
simple-expression = [sign] term {adding-operator term}.
term = factor {multiplying-operator factor}.
factor = unsigned-constant | bound-identifier | variable | set-constructor | function-designator | "not" factor | lparen expression rparen.
relational-operator = op-eq | op-ne | op-lt | op-le | op-gt | op-ge | op-in.
adding-operator = op-add | op-sub | op-or.
multiplying-operator = op-mul | op-div | op-divdiv | op-mod | op-and.
unsigned-constant = unsigned-number | character-string | constant-identifier | "nil".
function-designator =  function-identifier [actual-parameter-list].
variable = entire-variable | component-variable | identified-variable | buffer-variable.
entire-variable = variable-identifier.
component-variable = indexed-variable | field-designator.
identified-variable = pointer-variable "^".
buffer-variable = file-variable "^".
indexed-variable = array-variable "[" index {"," index} "]".
field-designator = [record-variable "."] field-identifier.
set-constructor = "[" [ elememt-description {"," elememt-description} ] "]".
elememt-description = ordinal-expression [".." ordinal-expression].
actual-parameter-list = lparen actual-parameter {comma actual-parameter} rparen.
actual-parameter = expression | variable | procedure-identifier | function-identifier.
write-parameter-list = lparen (file-variable | write-parameter) rparen.
write-parameter = expression [colon integer-expression [colon integer-expression]].
array-variable = variable.
record-variable = variable.
file-variable = variable.
pointer-variable = variable.
integer-expression = ordinal-expression.
boolean-expression = ordinal-expression.
ordinal-expression = expression.
pointer-variable = type-identifier.
structured-type-identifier = type-identifier.
ordinal-type-identifier = type-identifier.
real-type-identifier = type-identifier.
constant-identifier = identifier.
type-identifier = identifier.
variable-identifier = identifier.
field-identifier = identifier.
procedure-identifier = identifier.
function-identifier = identifier.
bound-identifier = identifier.
unsigned-number = unsigned-integer | unsigned-real.
identifier-list = identifier {"," identifier}.