Package org.openrefine.grel.ast

Class VariableExpr

java.lang.Object

org.openrefine.grel.ast.VariableExpr

All Implemented Interfaces:

Serializable, GrelExpr

public class VariableExpr
extends Object
implements GrelExpr

An abstract syntax tree node encapsulating the retrieval of a variable's content.

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field	Description
protected String	_name

Constructor Summary

Constructors

Constructor	Description
VariableExpr(String name)

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object other)
Object	evaluate(Properties bindings)	Returns the value of the expression in a given context.
Set<String>	getColumnDependencies(String baseColumn)	Returns the names of the columns this expression depends on.
String	getName()
boolean	isLocal()
VariableExpr	renameColumnDependencies(Map<String,String> substitutions)	Translates this expression by simultaneously substituting column names as the supplied map specifies.
String	toString()	For GREL expressions, toString should return the source code of the expression, or a source code for an equivalent expression.

Methods inherited from class java.lang.Object

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

Field Detail

_name

protected final String _name

Constructor Detail

VariableExpr

public VariableExpr(String name)

Method Detail

evaluate

public Object evaluate(Properties bindings)

Description copied from interface: GrelExpr

Returns the value of the expression in a given context.

Specified by:

evaluate in interface GrelExpr

Parameters:

bindings - the evaluation context, mapping variable names to their values

Returns:

the result of the evaluation of the expression

toString

public String toString()

Description copied from interface: GrelExpr

For GREL expressions, toString should return the source code of the expression, or a source code for an equivalent expression. (without the "grel:" prefix).

Specified by:

toString in interface GrelExpr

Overrides:

toString in class Object

getName

public String getName()

equals

public boolean equals(Object other)

Overrides:

equals in class Object

getColumnDependencies

public Set<String> getColumnDependencies(String baseColumn)

Description copied from interface: GrelExpr

Returns the names of the columns this expression depends on.

Specified by:

getColumnDependencies in interface GrelExpr

Parameters:

baseColumn - the name of the column this expression is based on (null if none)

Returns:

null if the columns could not be isolated: in this case, the expression might depend on all columns in the project.

renameColumnDependencies

public VariableExpr renameColumnDependencies(Map<String,String> substitutions)

Description copied from interface: GrelExpr

Translates this expression by simultaneously substituting column names as the supplied map specifies.

This is only possible if the extraction of column dependencies with GrelExpr.getColumnDependencies(String) succeeds (return a non-null value).

Specified by:

renameColumnDependencies in interface GrelExpr

Parameters:

substitutions - a map specifying new names for some columns. If a column name is not present in the map, it is assumed that the column is not renamed.

Returns:

a new expression with updated column names.

isLocal

public boolean isLocal()

Specified by:

isLocal in interface GrelExpr

Returns:

true when the expression can be evaluated purely based on the local context (see Evaluable).