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

Class ExpressionUtil

java.lang.Object

org.eclipse.equinox.p2.metadata.expression.ExpressionUtil

public final class ExpressionUtil
extends Object

Global access to factory, parser, and methods for introspection

Since:

2.0

Restriction:

This class is not intended to be subclassed by clients.

Restriction:

This class is not intended to be instantiated by clients.

Field Summary

Fields

Modifier and Type	Field	Description
static IExpression	FALSE_EXPRESSION
static IExpression	TRUE_EXPRESSION

Method Summary

Modifier and Type	Method	Description
static IExpressionFactory	getFactory()	Returns the global expression factory
static IExpression	getLHS(IExpression expression)	Obtains the Left Hand Side (LHS) of a binary expression.
static String	getName(IExpression expression)	Obtains the name of a variable or member expression.
static IExpression	getOperand(IExpression expression)	Obtains the operand of an unary expression
static IExpression[]	getOperands(IExpression expression)	Obtains the operands of an n-ary expression
static IExpressionParser	getParser()	Creates and returns a new expression parser
static IExpression	getRHS(IExpression expression)	Obtains the Right Hand Side (RHS) of a binary expression.
static Object	getValue(IExpression expression)	Obtains the value of a literal expression
static IExpression	parse(String expression)	Create a new expression.
static IFilterExpression	parseLDAP(String filter)	Parse an LDAP filter from the filter string.
static IExpression	parseQuery(String expression)	Create an arbitrary expression.
static String	trimmedOrNull(String str)	If str is null, then this method returns null.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TRUE_EXPRESSION

public static final IExpression TRUE_EXPRESSION

FALSE_EXPRESSION

public static final IExpression FALSE_EXPRESSION

Method Detail

getFactory

public static IExpressionFactory getFactory()

Returns the global expression factory

Returns:

The global expression factory.

getParser

public static IExpressionParser getParser()

Creates and returns a new expression parser

Returns:

The new parser

parseLDAP

public static IFilterExpression parseLDAP(String filter)
                                   throws IllegalArgumentException

Parse an LDAP filter from the filter string. If filter is null or a string that is empty or only consists of whitespace, then this method returns null.

Parameters:

filter - The filter to parse. Can be null or empty.

Returns:

An expression that corresponds to the LDAP filter or null.

Throws:

ExpressionParseException - If the syntax was invalid

IllegalArgumentException

parse

public static IExpression parse(String expression)

Create a new expression. The expression will have access to the global variable 'this' and to the context parameters.

Parameters:

expression - The string representing the boolean expression.

Returns:

The resulting expression tree.

Throws:

ExpressionParseException - If the syntax was invalid

parseQuery

public static IExpression parseQuery(String expression)

Create an arbitrary expression. The expression will have access to the global variable 'everything' and to the context parameters.

Parameters:

expression - The string representing the boolean expression.

Returns:

The resulting expression tree.

Throws:

ExpressionParseException - If the syntax was invalid

trimmedOrNull

public static String trimmedOrNull(String str)

If str is null, then this method returns null. Otherwise str is trimmed from whitespace at both ends. If the result of the trim is an empty string, then null is returned, otherwise the result of the trim is returned.

Parameters:

str - The string to trim. Can be null.

Returns:

The trimmed string or null.

getLHS

public static IExpression getLHS(IExpression expression)

Obtains the Left Hand Side (LHS) of a binary expression.

Parameters:

expression - The expression to introspect

Returns:

The left hand side operator

Throws:

IllegalArgumentException - if the expression is not a binary expression

See Also:

IExpression.TYPE_AT, IExpression.TYPE_EQUALS, IExpression.TYPE_GREATER, IExpression.TYPE_GREATER_EQUAL, IExpression.TYPE_LESS, IExpression.TYPE_LESS_EQUAL, IExpression.TYPE_MATCHES, IExpression.TYPE_NOT_EQUALS

getName

public static String getName(IExpression expression)

Obtains the name of a variable or member expression.

Parameters:

expression - The expression to introspect

Returns:

The name of the expression

Throws:

IllegalArgumentException - if the expression is not a variable or a member

See Also:

IExpression.TYPE_MEMBER, IExpression.TYPE_VARIABLE

getOperand

public static IExpression getOperand(IExpression expression)

Obtains the operand of an unary expression

Parameters:

expression - The expression to introspect

Returns:

The expression operand

Throws:

IllegalArgumentException - if the expression is not an unary expression

See Also:

IExpression.TYPE_ALL, IExpression.TYPE_EXISTS, IExpression.TYPE_LAMBDA, IExpression.TYPE_NOT

getOperands

public static IExpression[] getOperands(IExpression expression)

Obtains the operands of an n-ary expression

Parameters:

expression - The expression to introspect

Returns:

The expression operand

Throws:

IllegalArgumentException - if the expression is not a n-ary expression

See Also:

IExpression.TYPE_AND, IExpression.TYPE_OR

getRHS

public static IExpression getRHS(IExpression expression)

Obtains the Right Hand Side (RHS) of a binary expression.

Parameters:

expression - The expression to introspect

Returns:

The right hand side operator

Throws:

IllegalArgumentException - if the expression is not a binary expression

See Also:

IExpression.TYPE_AT, IExpression.TYPE_EQUALS, IExpression.TYPE_GREATER, IExpression.TYPE_GREATER_EQUAL, IExpression.TYPE_LESS, IExpression.TYPE_LESS_EQUAL, IExpression.TYPE_MATCHES, IExpression.TYPE_NOT_EQUALS

getValue

public static Object getValue(IExpression expression)

Obtains the value of a literal expression

Parameters:

expression - The expression to introspect

Returns:

The literal value

Throws:

IllegalArgumentException - if the expression is not a literal

See Also:

IExpression.TYPE_LITERAL