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

package org.eclipse.equinox.p2.metadata.expression
Provides a simple expression language used to represent requirements and filters in the metadada

## Package Specification

This package defines a simple expression language that is used to define requirements and filters in the metadata, but also form the base of the p2 query language.

Since:
  2.0

Related Packages
Package
Description
org.eclipse.equinox.p2.metadata
Defines the metadata being handled by p2.
org.eclipse.equinox.p2.metadata.index
Provides classes for metadata query indexing
Class
Description
ExpressionParseException
An exception used by an expression parser that indicates that something went wrong when parsing.
ExpressionUtil
Global access to factory, parser, and methods for introspection
IContextExpression<T>
This is an expression that will need access to the global variable `everything`.
IEvaluationContext
The evaluation context.
IExpression
A node in the expression tree
IExpressionFactory
This interface provides all the factory methods needed to create the nodes of the expression tree.
IExpressionParser
A parser that produces an expression tree based on a string representation.
IExpressionVisitor
A general purpose visitor that will visit each node in an expression tree.
IFilterExpression
An interface that combines the IExpression with the LDAP filter.
IMatchExpression<T>
A match expression is a boolean expression matching a candidate of a specific type.
IMemberProvider
This interface may be implemented by any class that wants to provide easy (high performance) access to its member to the expression evaluator.
SimplePattern
A simple compiled pattern.