Modelica Concrete Syntax¶
Lexical conventions¶
The following syntactic meta symbols are used (extended BNF):
[ ] optional
{ } repeat zero or more times
| or
"text" The text is treated as a single token (no whitespace between any characters)
The following lexical units are defined (the ones in boldface are the ones used in the grammar, the rest are just internal to the definition of other lexical units):
IDENT = NONDIGIT { DIGIT | NONDIGIT } | Q-IDENT
Q-IDENT = "'" ( Q-CHAR | S-ESCAPE ) { Q-CHAR | S-ESCAPE | """ } "'"
NONDIGIT = "_" | letters "a" to "z" | letters "A" to "Z"
STRING = """ { S-CHAR | S-ESCAPE } """
S-CHAR = see below
Q-CHAR = NONDIGIT | DIGIT | "!" | "#" | "$" | "%" | "&" | "(" | ")" | "*" | "+" | "," |
"-" | "." | "/" | ":" | ";" | "<" | ">" | "=" | "?" | "@" | "[" | "]" | "^" |
"{" | "}" | "|" | "~" | " "
S-ESCAPE = "\'" | "\"" | "\?" | "\\" |
"\a" | "\b" | "\f" | "\n" | "\r" | "\t" | "\v"
DIGIT = "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"
UNSIGNED-INTEGER = DIGIT { DIGIT }
UNSIGNED-NUMBER = UNSIGNED-INTEGER [ "." [ UNSIGNED-INTEGER ] ]
[ ( "e" | "E" ) [ "+" | "-" ] UNSIGNED-INTEGER ]
S-CHAR is any member of the Unicode character set (http://www.unicode.org; see for storing as UTF-8 on files) except double-quote “”“, and backslash “”
For identifiers the redundant escapes (’?’ and ’”’) are the same as the corresponding non-escaped variants (’?’ and ’”’). [The single quotes are part of an identifier. E.g. ’x’ and x are different IDENTs].
Note:
- Whitespace and comments can be used between separate lexical units and/or symbols, and also separates them. Whitespace and comments cannot be used inside other lexical units, except for STRING and Q-IDENT where they are treated as part of the STRING or Q-IDENT lexical unit.
- String constant concatenation “a” “b” becoming “ab” (as in C) is replaced by the “+” operator in Modelica.
- Modelica uses the same comment syntax as C++ and Java (i.e., // signals the start of a line comment and /* …. */ is a multi-line comment); comments may contain any Unicode character. Modelica also has structured comments in the form of annotations and string comments.
- Description strings (= production “string-comment” in the grammar) and strings in annotations (= STRING with production annotation in the grammar) may contain any member of the Unicode character set. All other strings have to contain only the sub-set of Unicode characters identical with the 7-bit US-ASCII character set. [As a consequence, operators like “>” or “<”, and external functions only operate on ASCII strings and not on Unicode-strings. Within a description string the tags <HTML> and </HTML> or <html> and </html> define optionally begin and end of content that is HTML encoded.]
- Boldface denotes keywords of the Modelica language. Keywords are reserved words and may not be used as identifiers.
- Productions use hyphen as separator both in the grammar and in the text. Previously the grammar used underscore.
Grammar¶
Stored Definition – Within¶
stored-definition:
[ within [ name ] ";" ]
{ [ final ] class-definition ";" }
Class Definition¶
class-definition :
[ encapsulated ] class-prefixes
class-specifier
class-prefixes :
[ partial ]
( class | model | [ operator ] record | block | [ expandable ] connector | type |
package | [ ( pure | impure ) ] [ operator ] function | operator )
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 ] ";" ]
[ annotation ";" ]
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]
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
Equations¶
equation-section :
[ initial ] equation { equation ";" }
algorithm-section :
[ initial ] algorithm { statement ";" }
equation :
( simple-expression "=" expression
| if-equation
| for-equation
| connect-clause
| when-equation
| component-reference function-call-args )
comment
statement :
( component-reference ( ":=" expression | function-call-args )
| "(" output-expression-list ")" ":=" component-reference function-call-args
| break
| return
| if-statement
| for-statement
| while-statement
| when-statement )
comment
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 ")"
Expressions¶
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 | der | initial | pure ) function-call-args
| component-reference
| "(" output-expression-list ")"
| "[" expression-list { ";" expression-list } "]"
| "{" array-arguments "}"
| end
type-specifier : ["."] name
name : IDENT { "." IDENT }
component-reference :
[ "." ] IDENT [ array-subscripts ] { "." IDENT [ array-subscripts ] }
function-call-args :
"(" [ function-arguments ] ")"
function-arguments :
expression [ "," function_arguments-non-first | for for_indices ]
| function name "(" [ named_arguments ] ")" [ "," function-arguments-non-first ]
| named-arguments
function-arguments-non-first :
function-argument [ "," function-arguments-non-first ]
| named-arguments
array-arguments :
expression [ "," array-arguments-non-first | for for-indices ]
array-arguments-non-first :
expression [ "," array-arguments-non-first ]
named-arguments: named-argument [ "," named-arguments ]
named-argument: IDENT "=" function-argument
function-argument :
function name "(" [ named-arguments ] ")" | expression
output-expression-list:
[ expression ] { "," [ expression ] }
expression-list :
expression { "," expression }
array-subscripts :
"[" subscript { "," subscript } "]"
subscript :
":" | expression
comment :
string-comment [ annotation ]
string-comment :
[ STRING { "+" STRING } ]
annotation :
annotation class-modification