Package org.eclipse.equinox.p2.metadata.expression

Interface IExpressionFactory

public interface IExpressionFactory
This interface provides all the factory methods needed to create the nodes of the expression tree.
Since:
2.0
Restriction:
This interface is not intended to be implemented directly by clients.
Restriction:
This interface is not intended to be extended directly by clients.

  • Field Details

  • Method Details

    • all

      IExpression all(IExpression collection, IExpression lambda)
      Create a collection filter that yields true if the lambda yields true for all of the elements of the collection
      Parameters:
      collection - The collection providing the elements to test
      lambda - The lambda that performs the test
      Returns:
      A boolean expression

    • and

      IExpression and(IExpression... operands)
      Create a logical and of its operands.
      Parameters:
      operands - The boolean operands
      Returns:
      A boolean expression

    • assignment

      IExpression assignment(IExpression variable, IExpression expression)
      Creates an expression that represents a variable assignment
      Parameters:
      variable - The variable
      expression - The expression that yields the value to assign to the variable
      Returns:
      An assignment expression

    • collect

      IExpression collect(IExpression collection, IExpression lambda)
      Create an expression that collects the result of evaluating each element in a new collection.
      Parameters:
      collection - The collection providing the elements to evaluate
      lambda - The lambda that creates each new element
      Returns:
      A collection expression

    • condition

      IExpression condition(IExpression test, IExpression ifTrue, IExpression ifFalse)
      Create an expression that first evaluates a test and then, depending on the outcome, evaluates either ifTrue or ifFalse. The expression yields the result of the ifTrue or ifFalse evaluation.
      Parameters:
      test - The test
      ifTrue - The code to evaluate when the test evaluates to true
      ifFalse - The code to evaluate when the test evaluates to false
      Returns:
      The conditional expression

    • first

      IExpression first(IExpression collection, IExpression lambda)
      Create an expression that yields the first element of the collection for which the lambda yields true.
      Parameters:
      collection - The collection providing the elements to test
      lambda - The lambda that performs the test
      Returns:
      An element expression

    • flatten

      IExpression flatten(IExpression collection)
      Intended to be applied on collections of collections. Yields a single collection with all elements from the source collections, in the order they are evaluated.
      Parameters:
      collection - The collection providing the collections that provides all elements
      Returns:
      A collection expression

    • lambda

      IExpression lambda(IExpression variable, IExpression[] initialAssignments, IExpression body)
      Creates a lambda expression that takes more then one variable (currying). Suitable for use in most collection expressions.
      Parameters:
      variable - The element variable that the lambda uses
      body - The body of the lambda
      initialAssignments - Assignments to evaluate once before calling the body for each element.
      Returns:
      A lambda expression with currying

    • memberCall

      IExpression memberCall(IExpression target, String name, IExpression... args)
      Creates a member call expression.
      Parameters:
      target - The target for the member call
      name - The name of the member
      args - The arguments to use for the call
      Returns:
      A member expression

    • traverse

      IExpression traverse(IExpression collection, IExpression lambda)

      Recursively traverse and collect elements based on a condition

      A common scenario in p2 is that you want to start with a set of roots and then find all items that fulfill the root requirements. Those items in turn introduce new requirements so you want to find them too. The process continues until no more requirements can be satisfied. This type of query can be performed using the traverse function.

      The function will evaluate an expression, once for each element, collect elements for which the evaluation returned true, then then re-evaluate using the collected result as source of elements. No element is evaluated twice. This continues until no more elements are found.

      Parameters:
      collection - The collection providing the elements to test
      lambda - The lambda that collects the children for the next iteration
      Returns:
      A collection expression

    • unique

      IExpression unique(IExpression collection, IExpression cache)
      Create an expression that yields a new collection where each element is unique. An optional cache can be provided if the uniqueness should span a larger scope then just the source collection.
      Parameters:
      collection - The source collection
      cache - Optional cache to use when uniqueness should span over several invocations
      Returns:
      A collection expression

    • array

      IExpression array(IExpression... elements)
      Create an array of elements.
      Parameters:
      elements - The elements of the array
      Returns:
      An array expression

    • at

      IExpression at(IExpression target, IExpression key)
      Create an lookup of key in the target. The key expression should evaluate to a string or an integer.
      Parameters:
      target - The target for the lookup
      key - The key to use for the lookup
      Returns:
      A lookup expression

    • createContext

      IEvaluationContext createContext(Object... params)
      Create an evaluation context with one single variable
      Parameters:
      params - Indexed parameters to use in the expression
      Returns:
      the context

    • createContext

      IEvaluationContext createContext(IExpression[] variables, Object... params)
      Create an evaluation context with one single variable
      Parameters:
      params - Indexed parameters to use in the expression
      variables - The variables that will be maintained by the context
      Returns:
      the context

    • constant

      IExpression constant(Object value)
      Creates an expression that evaluates to the constant value.
      Parameters:
      value - The constant
      Returns:
      A constant expression

    • contextExpression

      <T> IContextExpression<T> contextExpression(IExpression expr, Object... parameters)
      Creates a top level expression that represents a full query.
      Parameters:
      expr - The query
      parameters - The parameters of the query
      Returns:
      A top level query expression

    • equals

      IExpression equals(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs is equal to rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • exists

      IExpression exists(IExpression collection, IExpression lambda)
      Create a collection filter that yields true if the lambda yields true for at least one of the elements of the collection
      Parameters:
      collection - The collection providing the elements to test
      lambda - The lambda that performs the test
      Returns:
      A boolean expression

    • filterExpression

      IFilterExpression filterExpression(IExpression expression)
      Creates a top level expression suitable for predicate matching
      Parameters:
      expression - The boolean expression
      Returns:
      A top level predicate expression

    • function

      IExpression function(Object function, IExpression... args)
      Given one of the values in the map returned by getFunctionMap(), this method returns a function expression.
      Parameters:
      function - The value obtained from the map.
      args - The arguments to evaluate and pass when evaluating the function.
      Returns:
      A function expression

    • getFunctionMap

      Map<String,? extends Object> getFunctionMap()
      Returns a map of functions supported by this factory. The map is keyed by function names and the value is an object suitable to pass to the function(Object, IExpression[]) method.
      Returns:
      A key/function map.

    • greater

      IExpression greater(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs is greater than rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • greaterEqual

      IExpression greaterEqual(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs is greater than or equal to rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • indexedParameter

      IExpression indexedParameter(int index)
      Creates an indexed parameter expression
      Parameters:
      index - The index to use
      Returns:
      a parameter expression

    • intersect

      IExpression intersect(IExpression c1, IExpression c2)
      Create an intersection of c1 and c2
      Parameters:
      c1 - first collection
      c2 - second collection
      Returns:
      An intersect expression

    • lambda

      IExpression lambda(IExpression variable, IExpression body)
      Creates a lambda expression that takes exactly one variable. Suitable for use in most collection expressions.
      Parameters:
      variable - The element variable that the lambda uses
      body - The body of the lambda
      Returns:
      A lambda expression

    • latest

      IExpression latest(IExpression collection)
      Create an expression that yields a new collection consisting of the latest version of the elements of the collection. Each element in collection must implement the IVersionedId interface.
      Parameters:
      collection - The collection providing the versioned elements
      Returns:
      A collection expression

    • less

      IExpression less(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs is less than rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • lessEqual

      IExpression lessEqual(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs is less than or equal to rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • limit

      IExpression limit(IExpression collection, int count)
      Create an expression that yields a new collection consisting of the count first elements of the source collection.
      Parameters:
      collection - The source collection
      count - The element count limit
      Returns:
      A collection expression

    • limit

      IExpression limit(IExpression collection, IExpression limit)
      Create an expression that yields a new collection consisting of the n first elements of the source collection where n is determined by limit.
      Parameters:
      collection - The source collection
      limit - The expression that evaluates to the element count limit
      Returns:
      A collection expression

    • normalize

      IExpression normalize(List<? extends IExpression> operands, int expressionType)
      Performs boolean normalization on the expression to create a canonical form.
      Parameters:
      operands - The operands to normalize
      expressionType - The type (must be either IExpression.TYPE_AND or IExpression.TYPE_OR.
      Returns:
      The normalized expression

    • matches

      IExpression matches(IExpression lhs, IExpression rhs)
      Create an expression that tests if lhs matches rhs.
      Parameters:
      lhs - The left hand side value.
      rhs - The right hand side value.
      Returns:
      A boolean expression

    • matchExpression

      <T> IMatchExpression<T> matchExpression(IExpression expression, Object... parameters)
      Creates a parameterized top level expression suitable for predicate matching
      Parameters:
      expression - The boolean expression
      parameters - The parameters to use in the call
      Returns:
      A top level predicate expression

    • member

      IExpression member(IExpression target, String name)
      Creates a member accessor expression.
      Parameters:
      target - The target for the member access
      name - The name of the member
      Returns:
      A member expression

    • not

      IExpression not(IExpression operand)
      Creates an expression that negates the result of evaluating its operand.
      Parameters:
      operand - The boolean expression to negate
      Returns:
      A boolean expression

    • or

      IExpression or(IExpression... operands)
      Create a logical or of its operands.
      Parameters:
      operands - The boolean operands
      Returns:
      A boolean expression

    • pipe

      IExpression pipe(IExpression... expressions)
      Create a pipe of expressions.
      Parameters:
      expressions - The expressions that make out the pipe
      Returns:
      A pipe expression

    • select

      IExpression select(IExpression collection, IExpression lambda)
      Create an expression that yields a new collection consisting of all elements of the collection for which the lambda yields true.
      Parameters:
      collection - The collection providing the elements to test
      lambda - The lambda that performs the test
      Returns:
      A collection expression

    • thisVariable

      IExpression thisVariable()
      Returns the variable that represents this in an expression
      Returns:
      The this variable.

    • toExpression

      IExpression toExpression(IQuery<?> query)
      Wrap an IQuery as an expression.
      Parameters:
      query - The query to wrap.
      Returns:
      An expression that wraps the query

    • union

      IExpression union(IExpression c1, IExpression c2)
      Create a union of c1 and c2
      Parameters:
      c1 - first collection
      c2 - second collection
      Returns:
      A union expression

    • variable

      IExpression variable(String name)
      Creates an expression that represents a variable
      Parameters:
      name - The name of the variable
      Returns:
      A variable expression