Style Script
Style script is a language for customizing the visual display of graphs. The main building blocks of style script are expressions and directives. Style script files are a sequence of expressions and directives.
Expressions are used to combine values to create new values using functions. For example expression
Add(2, 5)-> 7
creates a new value 7 from values 2 and 5. There are a lot of functions built into style script so there are even more ways to combine values. There is even a function to create new functions.
When expressions are evaluated, values are created. There are several types of style script values: Boolean, Color, Number, String, Array, Dictionary, Functionand Null.
An expression can be either literal expressions, name expressions or function applications. Literal expressions exist for Colors, Numbers and Strings.
This is a literal expression for Strings.
"Hello"-> Hello
It evaluates to the value "Hello" of type String. The newline character and double quotes can be escaped in strings using \ (backslash).
"In the end he said: \"I am Iron Man!\""-> In the end he said: "I am Iron Man!"
These are literal expressions for Numbers.
123-> 1233.14159-> 3.14159
Literal expressions for colors are hex strings starting with '#'. This is a literal expression for the color red.
#ff0000-> #ff0000
Name expressions are names that can be evaluated if there are values bound to them in the environment (lexical scope). Names can start with any of the lower case or upper case letters of the English alphabet and apart from those can contain digits and the following characters: ?, !, $, -, _, ., *. Names can be defined using the Define function.
Define(superhero, "Iron Man")superhero-> Iron Man
In the previous example the value "Iron Man" was bound to the name superhero. After that name expression superhero evaluates to the value "Iron Man" fo type String.
There are many built-in names that are bound to useful values. Most used are boolean values which are bound to True and False and null value which is bound to Null. Also, all the CSS web colors are bound to their names.
dodgerblue-> #1e90ffforestgreen-> #228b22
The third type of expressions are function application expressions. A function can be applied to the list of expressions (arguments) in the following way.
Concat("Agents", " ", "of", " ", "S.H.I.E.L.D.")-> Agents of S.H.I.E.L.D.
Here the function Concat was applied to the list of string literal expressions to produce their concatenation. Any expression can be an argument.
Not all expressions have to be evaluated. For example, when calling If function one argument will not be evaluated.
Define(mood, "happy")Define(name, "Happy Hogan")If(Equals?(mood, "happy"),Format("{} is happy today.", name),Format("{} is not happy today.", name))-> Happy Hogan is happy today.
In the previous example expression Format("{} is not happy today", name) will not be evaluated because its value is not needed.
Some other function will not evaluate their arguments because they are interested in their names and not values. For example, when creating a new function argument names aren't evaluated, but are remembered to be later bound to the function arguments when the function is called.
Define(square, Fucntion(x, Mul(x, x)))square(2)-> 4
In the previous example the name x isn't evaluated in the first line, and neither is the expression Mul(x, x). In the second line when the function square is called number 2 will be bound to the name x and only then will Mul(x, x) be evaluated.
Directives are the second building block of style script. Directive names start with '@'. The name is followed by the optional expression (filter) which is followed by an opening curly brace, directive body and a closing curly brace. The directive body is a list of pairs of property names and expressions. Property names and expressions are separated by a colon and after every expression a newline must follow. The directive structure is the following.
@<DirectiveName> <expression>? {<property-name-1>: <expression-1>......<property-name-n>: <expression-n>}
Like in CSS, directives defined later override properties of the previous directives.
Style script currently has two directives: @NodeStyle, for defining visual style of graph nodes, and @EdgeStyle for defining visual style of graph edges.
An example of a directive is @NodeStyle directive which can be used to specify style properties of a graph node.
@NodeStyle {border-width: 2color: #abcdeflabel: "Hello, World!"}
@NodeStyle directive is used for defining style properties of a graph node. It is possible to filter the nodes to which the directive applies by providing an optional predicate after directive name and before the opening curly brace.
Before any expressions are evaluated (including the predicate) the name node is bound to the graph node for which the directive is being evaluated. Graph node is of type Dictionary and has all information about the node (properties, labels).
Here is an example of @NodeStyle directive that is applied to all graph nodes with the label superhero
@NodeStyle HasLabel?(node, vehicle) {label: Format("{}, horsepower: {}",Property(node, "model"),Property(node, "horsepower"))}
Predicate can be any expression that returns a value of type Boolean. It should depend on node, because if it doesn't, it will either be applied to all nodes or to no nodes.
@NodeStyle And(HasProperty(node, "name"),Equals?(Property(node, "name"), "Tony Stark")) {color: goldshadow-color: redlabel: "You know who I am"}
Here is the list of all properties that can be defined in the @NodeStyle directive, along with their expected types.
border-color:Colorborder-color-hover:Colorborder-color-selected:Colorborder-width:Numberborder-width-selected:Numbercolor:Colorcolor-hover:Colorcolor-selected:Colorfont-background-color:Colorfont-color:Colorfont-family:Stringfont-size:Numberimage-url:Stringimage-url-selected:Stringlabel:Stringshadow-color:Colorshadow-size:Numbershadow-offset-x:Numbershadow-offset-y:Numbershape:String("dot","square","diamond","triangle","triangleDown","star")size:Number
@EdgeStyle directive is used for defining style properties of a graph edge. Most things work like @NodeStyle directive with one exception: the directive will bind the name edge to the edge for which the directive is being evaluated (@NodeStyle binds the name node).
Here is the list of all properties that can be defined in the @EdgeStyle directive, along with their expected types.
arrow-size:Numbercolor:Colorcolor-hover:Colorcolor-selected:Colorfont-background-color:Colorfont-color:Colorfont-family:Stringfont-size:Numberlabel:Stringshadow-color:Colorshadow-size:Numbershadow-offset-x:Numbershadow-offset-y:Numbertype:String("straight"or"smooth")width:Numberwidth-hover:Numberwidth-selected:Number
Style script files are composed of expressions and directives. All expressions outside directives are evaluated first in the global environment. This is useful for defining names using function Define. After that @NodeStyle and @EdgeStyle directives are evaluated for each node and edge, respectively. All the names in the global environment are visible while applying the directives so they can be used for defining property values inside directives.
Example.
Define(square, Function(x, Mul(x, x)))Define(maxAllowedDebt, 10000)​@NodeStyle HasLabel?(node, "BankUser") {size: square(Property(node, "debt"))color: If(Greater?(Property(node, "debt"), maxAllowedDebt),red,lightblue)}
Names square and maxAllowedDebt are visible inside @NodeStyle directive.
value1,value2,value3,...:NumberReturns:
Number
Returns the sum of given values.
value1,value2,value3,...:BooleanReturns:
Boolean
Returns True if all of the given values are True. Returns False otherwise. Expressions after first expression that evaluates to False are not evaluated.
value1,value2,...:AnyReturns:
Array
Creates and returns an array of given values.
value:StringReturns:
Number
Parses the given string and returns a number. The string should contain only one number in base 10 and nothing else.
value:AnyReturns:
String
Returns a textual representation of given value.
color:ColorReturns:
Number
Returns blue component of given color. The value will be between 0 and 255 (both inclusive).
f:Functionarg1,arg2,...:Any
Calls function f with given arguments and returns f(arg1, arg2,...).
array:Arrayvalue:AnyReturns:
Boolean
Returns True if array contains value, False otherwise.
string1,string2,string3,...:StringReturns:
String
Concatanetes given strings.
color:ColorReturns:
Color
Returns a darker version of the given color.
name:Namevalue:Any
Binds the given value to the given name. Names cannot be redefined.
value1:Numbervalue2:NumberReturns:
Number
Returns value1 divided by value2.
exp1,exp2,exp3,...:AnyReturns:
Any
Evaluates all given expressions and returns the value of last one.
val1:Anyval2:AnyReturns:
Any
Returns True if given values are equal, False otherwise. Numbers, Strings and Booleans are compared by value, while objects of all other types are compared by identity.
message:StringReturns:
Never
Throws an error with the given message.
value:NumberReturns:
Number
Returns 2.71828... raised to the power value.
formatString:Stringval1,val2,...:AnyReturns: `String``
Substitutes occurences of curly brace pairs in formatString with textual representations of given values. First occurrence is substituted with first value, second occurrence with second value and so on.
Examples:
Format("{}, {}!", "Hello", "World")-> Hello, World!
Text inside curly braces is ignored.
Format("{name}: {age}", "Antun", 23)-> Antun: 23
arg1,arg2,...:Namebody:AnyReturns:
Function
Creates a function. body is the expression to evaluate when the function is called. All arguments except body are argument names of the function to create. When the created function is called names arg1, arg2, ... are bound to function arguments and available in the body expression. This function is most useful in combination with Define.
Examples:
Define(makeGreeting, Function(firstName,Format("Hello, {}!", firstName)))makeGreeting("World")-> Hello, World!
Define(pow, Function(x, n,If(Equals?(n, 1),x,Mul(x, pow(x, Sub(n, 1))))))pow(2, 10)-> 1024
obj:ArrayorDictionarykey:NumberifobjisArray,StringifobjisDictionaryReturns:
Any
If obj is Array, returns the element with index key of array obj (indexing is zero based). If obj is Dictionary returns the value for key key.
value1:Numbervalue2:NumberReturns:
Boolean
Returns True if value1 is greater than value2, False otherwise.
color:ColorReturns:
Number
Returns green component of given color. The value will be between 0 and 255 (both inclusive).
node:Dictionarylabel:StringReturns:
Boolean
Returns True if given graph node node has label label, False otherwise.
nodeOrEdge:DictionarypropertyName:StringReturns:
Boolean
Returns True if given graph node or graph edge nodeOrEdge has property propertyName.
node:DictionaryReturns:
Number
Returns the id of the given graph node.
condition:Booleanthan:Anyelse:AnyReturns:
Any
If condition is True returns than, otherwise returns else.
node:DictionaryReturns:
Array
Returns the array of labels of the given graph node.
value1:Numbervalue2:NumberReturns:
Boolean
Returns True if value1 is less than value2, False otherwise.
color:ColorReturns:
Color
Returns a lighter version of the given color.
value:NumberReturns:
Number
Returns the logarithm (to the base e) of value.
value:NumberReturns:
Number
Returns the logarithm (to the base 10) of value.
string:StringReturns:
String
Returns the value of string converted to lower case.
color1:Colorcolor2:ColorReturns:
Color
Mixes given colors (performs linear interpolation).
value1,value2,value3,...:NumberReturns:
Number
Returns the product of given values.
value:BooleanReturns:
Boolean
Returns True if value is False, and returns False if value is True.
value1,value2,value3,...:BooleanReturns:
Boolean
Returns True if any of the given values is True. Returns False otherwise. Expressions after first expression that evaluates to True are not evaluated.
value1,value2,...:AnyReturns:
Null
Logs the given values to the console.
nodeOrEdge:DictionarypropertyName:StringReturns: `Any``
Returns the property with name propertyName of given graph node or graph edge.
Returns:
Number
Returns a random number between 0 (inclusive) and 1 (exclusive). All the possible numbers are equally likely to be returned.
array:ArrayReturns:
Any
Returns a random element of the given array. All the elements are equally likely to be chosen.
bound:NumberReturns:
Number
Returns a random integer between 0 (inclusive) and bound (exclusive). All the possible numbers are equally likely to be returned.
color:ColorReturns:
Number
Returns red component of given color. The value will be between 0 and 255 (both inclusive).
red:Numbergreen:Numberblue:NumberReturns:
Color
Creates a new color with given components.
value:Array,DictionaryorStringReturns:
Number
If value is of type Array or Dictionary, returns its size. If value is of type String, returns its length;
value:NumberReturns:
Number
Returns the square root of value.
value1:Numbervalue2:NumberReturns:
Number
Returns value1 minus value2.
edge:DictionaryReturns:
String
Returns the type of the given graph edge.
value:AnyReturns:
String
Returns the type of the given value.
string:StringReturns:
String
Returns the value of string converted to upper case.
