org.eclipse.birt.data.engine.api
Interface IBaseExpression

All Known Subinterfaces:
IConditionalExpression, IScriptExpression
All Known Implementing Classes:
BaseExpression, ConditionalExpression, ScriptExpression

public interface IBaseExpression

Base type to represent a generic data expression used in a report design. An expression has an optional return data type. Each expression can also be associated with a handle, which is used by the Data Engine to store the compiled evaluation plan for the expression.


Method Summary
 int getDataType()
          Gets the data type of the expression.
 java.lang.Object getHandle()
          Returns the handle associated with the expression.
 java.lang.String getID()
          Every expression has its own unique id.
 void setHandle(java.lang.Object handle)
          Associates the expression with the provided handle.
 void setID(java.lang.String exprID)
          ID can be automatically generated by expression concrete class or be set externally.
 

Method Detail

getID

public java.lang.String getID()
Every expression has its own unique id. A typical use case is in presentation time. An expression id will be used as the key to retrieve expression value rather than to evaluate expression handle

Returns:
unique expression id

setID

public void setID(java.lang.String exprID)
ID can be automatically generated by expression concrete class or be set externally. In expression preparation process, the latter approach is used since a unique ID needs to be guranteed.

Parameters:
exprID -

getDataType

public int getDataType()
Gets the data type of the expression. Acceptable return values are those enumeration constants defined in the org.eclipse.birt.core.data.DataType class. If the result data type of the expression is not known, return UNKNOWN_TYPE.

See Also:
DataType

getHandle

public java.lang.Object getHandle()
Returns the handle associated with the expression.

Returns:
the expression execution handle.

setHandle

public void setHandle(java.lang.Object handle)
Associates the expression with the provided handle.



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