Information

This information is part of the Modelica Standard Library maintained by the Modelica Association.

Modelica 3.4 Grammar

This is the grammar of Modelica 3.4 in EBNF form. Each non-terminal appearing on the right hand side of a production is a link to the production for that non-terminal. This grammar is identical to that in the Modelica 3.4 specification except for removal of some unnecessary parentheses, grouping of some common terms, and reformatting for easier readability. The following typographic conventions are used:

Keywords are set in boldface.
Literals other than keywords are "quoted-monospaced" text.
Non-terminals are set in italics, with blue italics used for links.
EBNF meta-characters are green.

Stored Definition

stored_definition:
[ within [ name ] ";" ] { [ final ] class_definition ";" }

Class Definition

class_definition:
[ encapsulated ] class_prefixes class_specifier

class_specifier:
long_class_specifier | short_class_specifier | der_class_specifier

long_class_specifier:
IDENT string_comment composition end IDENT
| extends IDENT [ class_modification ] string_comment composition end IDENT

short_class_specifier:
IDENT "=" base_prefix type_specifier [ array_subscripts ] [ class_modification ] comment
| IDENT "=" enumeration "(" ( [ enum_list ] | ":" ) ")" comment

der_class_specifier:
IDENT "=" der "(" type_specifier "," IDENT { "," IDENT } ")" comment

base_prefix:
[ input | output ]

enum_list:
enumeration_literal { "," enumeration_literal }

enumeration_literal:
IDENT comment

composition:
        element_list
        { public element_list | protected element_list | equation_section | algorithm_section }
        [ external [ language_specification ]
          [ external_function_call ] [ annotation_comment ] ";" ]
        [ annotation_comment ";" ]

language_specification:
STRING

external_function_call:
[ component_reference "=" ] IDENT "(" [ expression_list ] ")"

element_list:
{ element ";" }

element:
        import_clause
        | extends_clause
        | [ redeclare ] [ final ] [ inner ] [ outer ]
          ( class_definition
            | component_clause
            | replaceable ( class_definition | component_clause )
              [ constraining_clause comment ] )

import_clause:
import ( IDENT "=" name | name [ "." "*" | ".*" | "{" import_list "}" ] ) comment

import_list:
IDENT { "," IDENT }

Extends

extends_clause:
extends type_specifier [ class_modification ] [ annotation_comment ]

constraining_clause:
constrainedby type_specifier [ class_modification ]

Component Clause

component_clause:
type_prefix type_specifier [ array_subscripts ] component_list

type_prefix:
[ flow | stream ] [ discrete | parameter | constant ] [ input | output ]

component_list:
component_declaration { "," component_declaration }

component_declaration:
declaration [ condition_attribute ] comment

condition_attribute:
if expression

declaration:
IDENT [ array_subscripts ] [ modification ]

Modification

modification:
        class_modification [ "=" expression ]
        | "=" expression
        | ":=" expression

class_modification:
"(" [ argument_list ] ")"

argument_list:
argument { "," argument }

argument:
element_modification_or_replaceable | element_redeclaration

element_modification_or_replaceable:
[ each ] [ final ] ( element_modification | element_replaceable )

element_modification:
name [ modification ] string_comment

element_redeclaration:
redeclare [ each ] [ final ]
( short_class_definition | component_clause1 | element_replaceable )

element_replaceable:
replaceable ( short_class_definition | component_clause1 )
[ constraining_clause ]

component_clause1:
type_prefix type_specifier component_declaration1

component_declaration1:
declaration comment

short_class_definition:
class_prefixes short_class_specifier

Equation

equation_section:
[ initial ] equation { equation ";" }

algorithm_section:
[ initial ] algorithm { statement ";" }

if_equation:
        if expression then { equation ";" }
        { elseif expression then { equation ";" } }
        [ else { equation ";" } ]
        end if

if_statement:
        if expression then { statement ";" }
        { elseif expression then { statement ";" } }
        [ else { statement ";" } ]
        end if

for_equation:
for for_indices loop { equation ";" } end for

for_statement:
for for_indices loop { statement ";" } end for

for_indices:
for_index { "," for_index }

for_index:
IDENT [ in expression ]

while_statement:
while expression loop { statement ";" } end while

when_equation:
        when expression then { equation ";" }
        { elsewhen expression then { equation ";" } }
        end when

when_statement:
        when expression then { statement ";" }
        { elsewhen expression then { statement ";" } }
        end when

connect_clause:
connect "(" component_reference "," component_reference ")"

Expression

expression:
        simple_expression
        | if expression then expression
          { elseif expression then expression }
          else expression

simple_expression:
logical_expression [ ":" logical_expression [ ":" logical_expression ] ]

logical_expression:
logical_term { or logical_term }

logical_term:
logical_factor { and logical_factor }

logical_factor:
[ not ] relation

relation:
arithmetic_expression [ relational_operator arithmetic_expression ]

relational_operator:
"<" | "<=" | ">" | ">=" | "==" | "<>"

arithmetic_expression:
[ add_operator ] term { add_operator term }

add_operator:
"+" | "-" | ".+" | ".-"

term:
factor { mul_operator factor }

mul_operator:
"*" | "/" | ".*" | "./"

factor:
primary [ ( "^" | ".^" ) primary ]

primary:
        UNSIGNED_NUMBER
        | STRING
        | false
        | true
        | component_reference
        | ( component_reference | der | initial | pure ) function_call_args
        | "(" output_expression_list ")"
        | "[" expression_list { ";" expression_list } "]"
        | "{" array_arguments "}"
        | end