org.codehaus.groovy.ast.expr
Class DeclarationExpression

java.lang.Object
  org.codehaus.groovy.ast.ASTNode
      org.codehaus.groovy.ast.AnnotatedNode
          org.codehaus.groovy.ast.expr.Expression
              org.codehaus.groovy.ast.expr.BinaryExpression
                  org.codehaus.groovy.ast.expr.DeclarationExpression

public class DeclarationExpression
extends BinaryExpression

Represents one or more local variables. Typically it is a single local variable declared by name with an expression like "def foo" or with type "String foo". However, the multiple assignment feature allows you to create two or more variables using an expression like: def (x, y) = [1, 2].

You can access the left hand side of a declaration using the "Expression getLeftExpression()" method. In which case you might then use instanceof and casting to perform operations specific to a single local variable (VariableExpression) or for the multiple assignment case (TupleExpression).

Alternatively, if isMultipleAssignmentDeclaration() is false you can use the method "VariableExpression getVariableExpression()" method. Similarly, if isMultipleAssignmentDeclaration() is true you can use the method "TupleExpression getTupleExpression()" method. Calling either of these expression getters when the "isMultipleAssignment" condition is not appropriate is unsafe and will result in a ClassCastException.

Version:

$Revision$

Author:

Jochen Theodorou, Hamlet D'Arcy

Constructor Summary

DeclarationExpression(Expression left, Token operation, Expression right)
Creates a DeclarationExpression for Expressions like "def (x, y) = [1, 2]"

DeclarationExpression(VariableExpression left, Token operation, Expression right)
Creates a DeclarationExpression for VariableExpressions like "def x" or "String y = 'foo'".

Method Summary

TupleExpression	getTupleExpression() This method returns the left hand side of the declaration cast to the TupleExpression type.
VariableExpression	getVariableExpression() This method returns the left hand side of the declaration cast to the VariableExpression type.
boolean	isMultipleAssignmentDeclaration() This method tells you if this declaration is a multiple assignment declaration, which has the form "def (x, y) = ..." in Groovy.
void	setLeftExpression(Expression leftExpression) This method sets the leftExpression for this BinaryExpression.
void	setRightExpression(Expression rightExpression)
Expression	transformExpression(ExpressionTransformer transformer) Return a copy of the expression calling the transformer on any nested expressions
void	visit(GroovyCodeVisitor visitor)

Methods inherited from class org.codehaus.groovy.ast.expr.BinaryExpression

getLeftExpression, getOperation, getRightExpression, getText, newAssignmentExpression, newInitializationExpression, toString

Methods inherited from class org.codehaus.groovy.ast.expr.Expression

getType, setType, transformExpressions, transformExpressions

Methods inherited from class org.codehaus.groovy.ast.AnnotatedNode

addAnnotation, addAnnotations, getAnnotations, getAnnotations, getDeclaringClass, hasNoRealSourcePosition, isSynthetic, setDeclaringClass, setHasNoRealSourcePosition, setSynthetic

Methods inherited from class org.codehaus.groovy.ast.ASTNode

copyNodeMetaData, getColumnNumber, getLastColumnNumber, getLastLineNumber, getLineNumber, getNodeMetaData, putNodeMetaData, removeNodeMetaData, setColumnNumber, setLastColumnNumber, setLastLineNumber, setLineNumber, setNodeMetaData, setSourcePosition

Methods inherited from class java.lang.Object

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

Constructor Detail

DeclarationExpression

public DeclarationExpression(VariableExpression left,
                             Token operation,
                             Expression right)

Creates a DeclarationExpression for VariableExpressions like "def x" or "String y = 'foo'".

Parameters:

left - the left hand side of a variable declaration

operation - the operation, typically an assignment operator

right - the right hand side of a declaration

DeclarationExpression

public DeclarationExpression(Expression left,
                             Token operation,
                             Expression right)

Creates a DeclarationExpression for Expressions like "def (x, y) = [1, 2]"

Parameters:

left - the left hand side of a declaration. Must be either a VariableExpression or a TupleExpression with at least one element.

operation - the operation, typically an assignment operator

right - the right hand side of a declaration

Method Detail

visit

public void visit(GroovyCodeVisitor visitor)

Overrides:

visit in class BinaryExpression

getVariableExpression

public VariableExpression getVariableExpression()

This method returns the left hand side of the declaration cast to the VariableExpression type. This is an unsafe method to call. In a multiple assignment statement, the left hand side will be a TupleExpression and a ClassCastException will occur. If you invoke this method then be sure to invoke isMultipleAssignmentDeclaration() first to check that it is safe to do so. If that method returns true then this method is safe to call.

Returns:

left hand side of normal variable declarations

Throws:

ClassCastException - if the left hand side is not a VariableExpression (and is probably a multiple assignment statement).

getTupleExpression

public TupleExpression getTupleExpression()

This method returns the left hand side of the declaration cast to the TupleExpression type. This is an unsafe method to call. In a single assignment statement, the left hand side will be a VariableExpression and a ClassCastException will occur. If you invoke this method then be sure to invoke isMultipleAssignmentDeclaration() first to check that it is safe to do so. If that method returns true then this method is safe to call.

Returns:

left hand side of multiple assignment declarations

Throws:

ClassCastException - if the left hand side is not a TupleExpression (and is probably a VariableExpression).

setLeftExpression

public void setLeftExpression(Expression leftExpression)

This method sets the leftExpression for this BinaryExpression. The parameter must be either a VariableExpression or a TupleExpression with one or more elements.

Overrides:

setLeftExpression in class BinaryExpression

Parameters:

leftExpression - either a VariableExpression or a TupleExpression with one or more elements.

setRightExpression

public void setRightExpression(Expression rightExpression)

Overrides:

setRightExpression in class BinaryExpression

transformExpression

public Expression transformExpression(ExpressionTransformer transformer)

Description copied from class: Expression

Return a copy of the expression calling the transformer on any nested expressions

Overrides:

transformExpression in class BinaryExpression

isMultipleAssignmentDeclaration

public boolean isMultipleAssignmentDeclaration()

This method tells you if this declaration is a multiple assignment declaration, which has the form "def (x, y) = ..." in Groovy. If this method returns true, then the left hand side is an ArgumentListExpression. Do not call "getVariableExpression()" on this object if this method returns true, instead use "getLeftExpression()".

Returns:

true if this declaration is a multiple assignment declaration, which means the left hand side is an ArgumentListExpression.