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Namespaces

One important feature of IQL is the integration of Java types. The DSL can refer to Java types from Java standard libraries, Odysseus Bundles or other external libraries. Namespaces are useful in this context to refer Java types by a simple name and not by a fully qualified name. The static-keyword allows the static methods of a java class to be referenced without qualifying the class name.

Code Block
titleGrammar
ID                      ::= ("a".."z"|"A".."Z"|"_")("a".."z"|"A".."Z"|"_"|"0".."9")*.
QName                   ::= ID ("::" ID)*
Namespace              ::= "use" ("static")? QualifiedNameWithWildcard ";".
QualifiedNameWildcard  ::= QualifiedName ("::*")?
Code Block
titleExample
use java::util::*;
use de::uniol::inf::is::odysseus::core::ISubscription;
use com::google::common::collect::ImmutableMap;
use static java::lang::System;

Class, Interface

Besides the integration of Java types it is also possible to create your own classes and interfaces.

Code Block
titleGrammar
Class                  ::= "class" ID ("extends" QName)? ("implements" QName ("," QName)*)? "{" (Attribute | Method)* "}". 
Interface              ::= "interface" ID ("extends" QName ("," QName)*)? "{" (MethodDeclaration)* "}".
Attribute              ::= VariableDeclaration (VariableInit)? ";".
VariableDeclaration    ::= Type ID.
Type                   ::= (PrimitiveType | QName) ("[" "]")*.
PrimitiveType          ::= "boolean" | "byte" | "char" | "short" | "int" | "float" | "long" | "double".
Method                 ::= ("override")? MethodDeclaration StatementBlock.  
MethodDeclaration      ::= ID (MethodParameters)? (":" Type)?.
MethodParameters       ::= "(" (VariableDeclaration ("," VariableDeclaration)*)? ")".
Code Block
titleExample Class
class Point implements IPoint{
    int x;
    int y;
    
    Point(int x, int y) {
        this.x = x;
        this.y = y;
    }
    
    override getX() : int{
        return this.x;
    }
    
    override getY() : int{
        return this.y;
    }    
}
Code Block
titleExample Interface
interface IPoint {
	getX() : int;
    getY() :  int;
}
Code Block
titleExample Interface
interface IPoint {
	getX() : int;
    getY() : int;
}

...

Statements

Methods, constructors and other blocks are sequences of statements. They can be divided into atomic and compound statements. Atomic statements are not made up of other statements and end with a semicolon (e.g. VariableStatement). Compound statements (also called control structures) contain other statements (e.g. WhileStatement).

Code Block
titleGrammar
Statement              ::= ( StatementBlock | IfStatement | SwitchStatement | WhileStatement | DoWhileStatement | ForStatement | ForEachStatement
                           | VariableStatement | ConstructorStatement | ExpressionStatement | BreakStatement | ContinueStatement | ReturnStatement ).
StatementBlock         ::= "{" (Statement)* "}".
IfStatement            ::= "if" "(" Expression ")" Statement ("else" Statement)?.
SwitchStatement        ::= "switch" "(" Expression ")" "{" ("case" Expression ":" (Statement)*)* ("default" ":" (Statement)*)? "}"
WhileStatement         ::= "while" "(" Expression ")" Statement.
DoWhileStatement       ::= "do" Statement "while" "(" Expression ")" ";".
ForStatement           ::= "for" "(" VariableDeclaration ";" Expression ";" Expression ")" Statement.
ForEachStatement       ::= "for" "(" VariableDeclaration ":" Expression ")" Statement.
VariableStatement      ::= VariableDeclaration VariableInit ";".
ConstructorStatement   ::= ("super" | "this") "(" (ArgsList)? ")" ";".
ExpressionStatement    ::= Expression ";".
BreakStatement         ::= "break" ";".
ContinueStatement      ::= "continue" ";".
ReturnStatement        ::= "return" (Expression)? ";".

...

Code Block
titleExample for-Statement
for (int j = 0; j<10; j++) {

} 
        
List list = [1,2,3];
for (Object element : list)  
List list = [1,2,3];
for (Object element : list) {

}{

}

 

A new object can be created by calling a constructor. It is also possible to assign values to attributes in this context. This makes it easier to configure operators when building a query with QDL because it is not necessary to create a new statement for each parameter.

Code Block
titleExample Variables
// Constructor Call
Point p1 = new Point(2, 5);
Point p2(2,5);

// Assigning attributesvalues ofto objectattributes
Point p3 = new Point{x = 2, y = 5};
Point p4{x = 2, y = 5};

Expressions


Point p4{x = 2, y = 5};

Select sel{predicate="bid.price <=200"};
Project proj(sel){attributes=[bid.PRICE]};

Expressions

An expression is used as part of other expressions or statements and produces a value as result.

Code Block
titleGrammar
Expression           ::= ( AssignmentExpression | LogicalExpression | EqualityExpression | ArithmeticExpression | UnaryExpression | CastExpression
							| PrefixExpression | PostfixExpression | InstanceOfExpression | CreateExpression | AttributeExpression | MethodExpression
							| ArrayExpression | "this" | "super" | ID | LiteralExpression | ("(" Expression ")").
AssignmentExpression
Code Block
titleGrammar
Expression           ::= ( AssignmentExpression | LogicalExpression | EqualityExpression | ArithmeticExpression | UnaryExpression | CastExpression
							| PrefixExpression | PostfixExpression | InstanceOfExpression | CreateExpression | AttributeExpression | MethodExpression
							| ArrayExpression | "this" | "super" | ID | LiteralExpression | ("(" Expression ")").
AssignmentExpression ::= Expression ("=" | "+=" | "-=" | "*=" | "/=" | "%=") Expression.
LogicalExpression    ::= Expression ("&&" | "||") Expression.
EqualityExpression   ::= Expression ("==" | "!=" | ">" | ">=" | "<" | "<=") Expression.
ArithmeticExpression ::= Expression ("=" | "+=" | "-=" | "*=" | "/=" | "%=") Expression.
LogicalExpression    ::= Expression ("&&" | "||") Expression.
EqualityExpression   ::= Expression ("==" | "!=" | ">"    
UnaryExpression     | ">=" | "<" | "<=") Expression.
ArithmeticExpression ::= Expression ("+" | "-" | "*" | "!/"| "%") Expression.
CastExpression        ::= "(" Type ")" Expression.
PrefixExpression     ::= ("++" | "--") Expression.
PostfixExpression  
UnaryExpression      ::= Expression ("++" | "--").
InstanceOfExpression ::= Expression | "instanceof!") TypeExpression.
NewExpression CastExpression       ::= "new" QName (("[" "]") | (("(" (ArgsList)? ")")? ("{" ArgsMap "}")?)).
MemberCallExpression= "(" Type ")" Expression.
PrefixExpression     ::= (Expression ".++")? ID| ("(--" (ArgsList)? ")")?Expression.
ArrayExpression  PostfixExpression    ::= Expression ("[++" ArgsList| "]--")+.
LiteralExpression   InstanceOfExpression ::= IntegerExpression | Double | Boolean | Char | String | Range | List | Map | Null
VariableInit         ::= ("instanceof" Type.
NewExpression        ::= "new" QName (("[" "]") | (("(" (ArgsList)? ")")? ("{" ArgsMap "}")?)).
MemberCallExpression ::= (Expression ".") |? ID ("(" (ArgsList)? ")")?.
ArrayExpression      ::= Expression ("[" Expression))ArgsList "]")+.
ArgsListLiteralExpression    ::= Integer | Double | Boolean | Char | ::=String Expression ("," Expression)*.
ArgsMap     | Range | List | Map | Null
VariableInit         ::= ArgsMapKeyValue (((",(" ArgsMapKeyValue)*.
ArgsMapKeyValue      ::= ID (ArgsList)? ")")? ("{" ArgsMap "}")?) | ("=" Expression

Metadata

Code Block
titleGrammar
Metadata  )).
ArgsList             ::= IDExpression ("=," MetadataValueExpression)*.
MetadataValue   ArgsMap       ::= MetadataValueSingle | MetadataValueList | MetadataValueMap.
MetadataValueSingle    ::= INTEGER | Double | CHAR | STRING | BOOLEAN | QName.
MetadataValueList      ::= "[" (MetadataValue ("," MetadataValue)*)? "]".
MetadataValueMap       ::= "[" (MetadataValueMapEntry ("," MetadataValueMapEntry)*)? "]".
MetadataValueMapEntry  ::= MetadataValue ":" MetadataValue.

See operators in ODL or queries in QDL for examples.

 ArgsMapKeyValue ("," ArgsMapKeyValue)*.
ArgsMapKeyValue      ::= ID "=" Expression

If a data type has a getter- or setter-method there will always be a corresponding attribute to access. So it is often possible to use assignment expressions instead of method calls.

Code Block
titleExample
Tuple tuple = createTuple();

ITimeInterval time = tuple.metadata;
tuple.metadata = time;

//is equivalent to
ITimeInterval time1 = tuple.getMetadata();
tuple.setMetadata(time1);

Metadata

...

Code Block
titleGrammar
IntegerMetadata               ::= ID "=" MetadataValue.
MetadataValue          ::= (0..9)+.
Double             MetadataValueSingle | MetadataValueList | MetadataValueMap.
MetadataValueSingle    ::= INTEGER | Double | CHAR | STRING | BOOLEAN | QName.
MetadataValueList      ::= (0..9)* "." (0..9)+.
Boolean "[" (MetadataValue ("," MetadataValue)*)? "]".
MetadataValueMap       ::=        "[" (MetadataValueMapEntry ("," MetadataValueMapEntry)*)? "]".
MetadataValueMapEntry  ::= MetadataValue (":" MetadataValue.

See operators in ODL or queries in QDL for examples.

Literals

Literals are sequence of characters that represent constant values to be stored in variables.

Code Block
titleGrammar
Integertrue" | "false").
Char                    ::= "'" Unicode-Character "'".
String(0..9)+.
Double                  ::= '"' (Unicode-Character0..9)* '"'.   
Range  " (0..9)+.
Boolean                 ::= (0..9)+"true" | ".." (0..9)+false").
ListChar                    ::= "['" (ExpressionUnicode-Character ("," Expression)*)? "]".  
Map   '".
String                  ::= "[" (MapKeyValue ("," MapKeyValue)*)? "]".
MapKeyValue   ::= '"' (Unicode-Character)* '"'.   
Range          ::= Expression ":" Expression.
Null         ::= (0..9)+    ".." (0..9)+.
List      ::= "null".
Code Block
titleExample
Range r = 1..10;
List l  = [1, 2, 3];
Map m   ::= "["key1":1, "key2":2];

Identifier, Qualified Name, Namespace

Code Block
titleGrammar
ID  (Expression ("," Expression)*)? "]".  
Map                     ::= ("a".."z"|"A".."Z"|"_")("a".."z"|"A".."Z"|"_"|"0".."9")*.
QName:= "[" (MapKeyValue ("," MapKeyValue)*)? "]".
MapKeyValue             ::= Expression ":" Expression.
Null                    ::= ID ("::" ID)*
Namespace              ::= "use" QualifiedNameWithWildcard ";".
QualifiedNameWildcard  ::= QualifiedName ("::*")?
Code Block
titleExample
use java::util::*;
use de::uniol::inf::is::odysseus::core::ISubscription;
use com::google::common::collect::ImmutableMap;

...

null".
Code Block
titleExample
Range r = 1..10;
List l  = [1, 2, 3];
Map m   = ["key1":1, "key2":2];
Tuple t = [5, true, 3.4];
IPunctuation p = 100;

 

Java-Code

IQL-code is always translated into Java-code. Sometimes it might be useful to write Java-code directly instead of IQL-code.

Code Block
titleGrammar
GPLCode                ::= "$*" GPL Code "*$"
Code Block
titleExample
$*
public static void main(String[] args) {
         
}
*$

Comments

IQL supports single- and multi-line comments.

Code Block
titleGrammar
Comment                 ::= SingeLineComment | MultiLineComment.
SingeLineComment        ::= "//" Text (("\r")? "\n")?.
MultiLineComment        ::= "/*" Text "*/".

...