A3 Syntax

Summary

The following syntax rules are taken from Annex P of the ARM. The rules have been reordered to correspond to the order of introduction of the topics in this book but individual rules have not been changed.

It should be noted that the rules for the construction of lexical elements, which are under the subheading of Chapter 5, have a slightly different status from the other rules since spaces and newlines may be freely inserted between lexical elements but not within lexical elements.

The rules have been sequentially numbered for ease of reference; an index to them will be found in Section A3.2. Note that in rules 74 (discrete_choice_list), 98 (component_choice_list), 111 (membership choice_list), 201 (exception_handler), and 226 (discriminant_association), the vertical bar following the brace stands for itself and is not a metasymbol.

Syntax rules

Chapter 5

• 1 identifier ::= identifier_start ﹛identifier_start | identifier_extend﹜

• 2 identifier_start ::= letter_uppercase | letter_lowercase | letter_titlecase | letter_modifier | letter_other | number_letter

• 3 identifier_extend ::= mark_nonspacing | mark_spacing_combining | number_decimal | punctuation_connector

• 4 numeric_literal ::= decimal_literal | based_literal

• 5 decimal_literal ::= numeral [. numeral] [exponent]

• 6 numeral ::= digit ﹛[underline] digit﹜

• 7 exponent ::= E [+] numeral | E - numeral

• 8 digit ::= 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9

• 9 based_literal ::= base # based_numeral [. based_numeral] # [exponent]

• 10 base ::= numeral

• 11 based_numeral ::= extended_digit ﹛[underline] extended_digit﹜

• 12 extended_digit ::= digit | A | B | C | D | E | F

• 13 character_literal ::= ‘graphic_character'

• 14 string_literal ::= “﹛string_element﹜“

• 15 string_element ::= “” | non_quotation_mark_graphic_character

• 16 comment ::= -- ﹛non_end_of_line_character﹜

• 17 pragma ::= pragma identifier [(pragma_argument_association ﹛, pragma_argument_association﹜)];

• 18 pragma_argument_association ::=

• | [pragma_argument_identifier =>] name

• | [pragma_argument_identifier =>] expression

• | pragma_argument_aspect_mark => name

• | pragma_argument_aspect_mark => expression

• Chapter 6

• 19 basic_declaration ::=

• type_declaration | subtype_declaration

• | object_declaration | number_declaration

• | subprogram_declaration | abstract_subprogram_declaration

• | null_procedure_declaration | expression_function_declaration

• | package_declaration | renaming_declaration

• | exception_declaration | generic_declaration

• | generic_instantiation

• 20 object_declaration ::=

• | defining_identifier_list : [aliased] [constant] subtype_indication [:= expression] [aspect_specification];

• | defining_identifier_list : [aliased] [constant] access_definition [:= expression] [aspect_specification];

• | defining_identifier_list : [aliased] [constant] array_type_definition [:= expression] [aspect_specification];

• | single_task_declaration

• | single_protected_declaration

• 21 number_declaration ::=

• defining_identifier_list : constant := static_expression;

• 22 defining_identifier_list ::= defining_identifier ﹛, defining_identifier﹜

• 23 defining_identifier ::= identifier

• 24 assignment_statement ::= variable_name := expression;