Class GenerationClauseNode

  • All Implemented Interfaces:
    Visitable

    class GenerationClauseNode
    extends ValueNode
    This node describes a Generation Clause in a column definition.
    • Field Detail

      • _generationExpression

        private ValueNode _generationExpression
      • _expressionText

        private java.lang.String _expressionText
      • _boundExpression

        private ValueNode _boundExpression
    • Constructor Detail

      • GenerationClauseNode

        GenerationClauseNode​(ValueNode generationExpression,
                             java.lang.String expressionText,
                             ContextManager cm)
    • Method Detail

      • getExpressionText

        public java.lang.String getExpressionText()
        Get the defining text of this generation clause
      • setAuxiliaryProviderList

        void setAuxiliaryProviderList​(ProviderList apl)
        Set the auxiliary provider list.
      • getAuxiliaryProviderList

        ProviderList getAuxiliaryProviderList()
        Return the auxiliary provider list.
      • isEquivalent

        boolean isEquivalent​(ValueNode other)
                      throws StandardException
        Description copied from class: ValueNode
        Tests if this node is equivalent to the specified ValueNode. Two ValueNodes are considered equivalent if they will evaluate to the same value during query execution.

        This method provides basic expression matching facility for the derived class of ValueNode and it is used by the language layer to compare the node structural form of the two expressions for equivalence at bind phase.

        Note that it is not comparing the actual row values at runtime to produce a result; hence, when comparing SQL NULLs, they are considered to be equivalent and not unknown.

        One usage case of this method in this context is to compare the select column expression against the group by expression to check if they are equivalent. e.g.:

        SELECT c1+c2 FROM t1 GROUP BY c1+c2

        In general, node equivalence is determined by the derived class of ValueNode. But they generally abide to the rules below:

        • The two ValueNodes must be of the same node type to be considered equivalent. e.g.: CastNode vs. CastNode - equivalent (if their args also match), ColumnReference vs CastNode - not equivalent.
        • If node P contains other ValueNode(s) and so on, those node(s) must also be of the same node type to be considered equivalent.
        • If node P takes a parameter list, then the number of arguments and its arguments for the two nodes must also match to be considered equivalent. e.g.: CAST(c1 as INTEGER) vs CAST(c1 as SMALLINT), they are not equivalent.
        • When comparing SQL NULLs in this context, they are considered to be equivalent.
        • If this does not apply or it is determined that the two nodes are not equivalent then the derived class of this method should return false; otherwise, return true.
        Specified by:
        isEquivalent in class ValueNode
        Parameters:
        other - the node to compare this ValueNode against.
        Returns:
        true if the two nodes are equivalent, false otherwise.
        Throws:
        StandardException
      • toString

        public java.lang.String toString()
        Description copied from class: ValueNode
        Convert this object to a String. See comments in QueryTreeNode.java for how this should be done for tree printing.
        Overrides:
        toString in class ValueNode
        Returns:
        This object as a String
      • printSubNodes

        void printSubNodes​(int depth)
        Prints the sub-nodes of this object. See QueryTreeNode.java for how tree printing is supposed to work.
        Overrides:
        printSubNodes in class QueryTreeNode
        Parameters:
        depth - The depth of this node in the tree