com.github.sommeri.less4j

Interface LessFunction

public interface LessFunction

Implement this interface to create custom less function.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	canEvaluate(FunctionExpression input, List<Expression> parameters) Returns true if this function can evaluate the less function.
Expression	evaluate(FunctionExpression input, List<Expression> parameters, Expression evaluatedParameter, LessProblems problems) Evaluates less function in parameter.

Method Detail

canEvaluate

boolean canEvaluate(FunctionExpression input,
                  List<Expression> parameters)

Returns true if this function can evaluate the less function.

Parameters:

input - - function to be evaluated

parameters - - function parameters

Returns:

true only if the implementation can evaluate the input function.

evaluate

Expression evaluate(FunctionExpression input,
                  List<Expression> parameters,
                  Expression evaluatedParameter,
                  LessProblems problems)

Evaluates less function in parameter. Will be called only if canEvaluate(FunctionExpression, List) returns true. The evaluatedParameter contains function arguments as parsed into a single abstract syntax tree node. A function called with multiple arguments would be sent an instance of BinaryExpression with arguments bundled in as childs. The evaluatedParameter contains list of function arguments. It is convenience argument and contains evaluatedParameter expression split by commas.

Parameters:

input - - input function

parameters - - function arguments split (evaluated)

evaluatedParameter - - all function arguments as a single expression (evaluated)

problems - - errors and warnings collector

Returns:

result of function evaluation. Must NOT return null and should return correct abstract syntax tree node. Eg. * solved parent child relationships (both ways), * each node instance can appear in the three only once, * correctly filled underlying structure properties.