# File:
#   pascal-grammar.txt
# Author:
#   Samuel A. Rebelsky
#   Based on the official Pascal grammar taken from pp. 110-118
#   of Jensen and Wirth.
# Summary:
#   A grammar for Pascal.  
# Notation:
#   Nonterminals are represented as 
#     less-than sign, nonterminal name, greater-than sign.
#   erminals are represented as all-caps.
#   Comments begin with hash signs.
# Differences from Standard Pascal Grammar:
#   Identifiers are treated as terminals rather than nonterminals.
#    Unsigned integers and unsigned reals are treated as terminals
#      rather than nonterminals.
#    Strings are treated as terminals rather than nonterminals.
#    Nonterminals are presented in alphabetical order.
#    No or (|) symbols are used.  Instead, multiple rules are presented.

<array_type> ::= ARRAY 
	OPENBRACKET <index_type> { , <index_type> } CLOSEBRACKET
	OF <component_type>

<block> ::= <label_declarations> 
	<constant_definitions>
	<type_definitions>
	<variable_declarations>
	<procedure_declarations>
	<statements>

<component_type> ::= <type>

<constant> ::= <unsigned_number>
<constant> ::= <sign> <unsigned_number>
<constant> ::= <constant_identifier>
<constant> ::= <sign> <constant_identifier>
<constant> ::= SRING

<constant_definition> ::= PIDENTIFIER = <constant>

<constant_definitions> ::= <empty>
<constant_definitions> ::= CONS <constant_definition> SEMI
	{ <constant_definition> SEMI }

<constant_identifier> ::= PIDENTIFIER

<empty> ::=

<field_list> ::= <fixed_part>
<field_list> ::= <fixed_part> SEMI <variant_part>
<field_list> ::= <variant_part>

<file_identifier> ::= PIDENTIFIER

<fixed_part> ::= <record_section> { SEMI <record_section> }

<index_type> ::= <simple_type>

<label> ::= UIN

<label_declarations> ::= <empty>
<label_declarations> ::= LABEL <label> { COMMA <label } SEMI

<program> ::= <program_heading> <block> PERIOD

<program_heading> ::= PROGRAM PIDENTIFIER 
	OPENPAREN <file_identifier> { COMMA <file_identifier> } CLOSEPAREN
	SEMI

<record_section> ::= <field_identifier> { COMMA <field_identifier> }
	COLON <type>

<record_type> ::= RECORD <field_list> END

<scalar_type> ::= OPEN PIDENTIFIER { COMMA PIDENTIFIER }

<sign> ::= PLUS
<sign> ::= MINUS

<simple_type> ::= <scalar_type>
<simple_type> ::= <subrange_type>
<simple_type> ::= <type_identifier>

<structured_type> ::= <unpacked_structured_type>
<structured_type> ::= PACKED <unpacked_structured_type>

<subrange_type> ::= <constant> ELLIPSES <constant>

<type> ::= <simple_type>
<type> ::= <structured_type>
<type> ::= <pointer_type>

<type_definitions> ::= <empty>
<type_definitions> ::= TYPE <type_definition> SEMI
	{ <type_definition SEMI }

<type_identifier> ::= PIDENTIFIER

<unpacked_structured_type> ::= <array_type>
<unpacked_structured_type> ::= <record_type>
<unpacked_structured_type> ::= <set_type>
<unpacked_structured_type> ::= <file_type>

<unsigned_number> ::= PINT
<unsigned_number> ::= PREAL