Class CastNode

All Implemented Interfaces:
Visitable

class CastNode extends ValueNode
An CastNode represents a cast expression.
  • Field Details

    • castOperand

      ValueNode castOperand
    • targetCharType

      private int targetCharType
    • sourceCTI

      TypeId sourceCTI
    • forDataTypeFunction

      private boolean forDataTypeFunction
    • targetUDT

      private DataTypeDescriptor targetUDT
      The original, unbound descriptor for the target type, if it is a UDT.
    • externallyGeneratedCastNode

      private boolean externallyGeneratedCastNode
      This variable gets set by the parser to indicate that this CAST node has been generated by the parser. This means that we should use the collation info of the current compilation schema for this node's collation setting. If this variable does not get set to true, then it means that this CAST node has been an internally generated node and we should not touch the collation info set for this CAST node because it has been already set correctly by the class that generated this CAST node. Collation info is part of the DataTypeDescriptor that's defined on the ValueNode (the super class of this CastNode class)
    • assignmentSemantics

      private boolean assignmentSemantics
      Method calls: Argument type has the same semantics as assignment: Section 9.2 (Store assignment). There, General Rule 2.b.v.2 says that the database should raise an exception if truncation occurs when stuffing a string value into a VARCHAR, so make sure CAST doesn't issue warning only.
    • udtTargetName

      private TableName udtTargetName
      The name of the target type if it's a UDT. It is partly redundant, as the name can also be retrieved from the type descriptor. Additionally, it contains information about the location of the UDT name in the query text, which is useful if the query text needs to be rewritten. (Useful for example when rewriting a CHECK constraint definition to have fully qualified names before storing it in the dictionary.) This field is only set for explicit casts to a UDT.
  • Constructor Details

    • CastNode

      CastNode(ValueNode castOperand, DataTypeDescriptor castTarget, ContextManager cm) throws StandardException
      Constructor for a CastNode
      Parameters:
      castOperand - The operand of the node
      castTarget - DataTypeServices (target type of cast)
      cm - The context manager
      Throws:
      StandardException - Thrown on error
    • CastNode

      CastNode(ValueNode castOperand, int charType, int charLength, ContextManager cm) throws StandardException
      Constructor for a CastNode
      Parameters:
      castOperand - The operand of the node
      charType - CHAR or VARCHAR JDBC type as target
      charLength - target type length
      cm - The context manager
      Throws:
      StandardException - Thrown on error
  • Method Details

    • toString

      public String toString()
      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
    • getOrderableVariantType

      protected int getOrderableVariantType() throws StandardException
      Description copied from class: ValueNode
      Return the variant type for the underlying expression. The variant type can be: VARIANT - variant within a scan (method calls and non-static field access) SCAN_INVARIANT - invariant within a scan (column references from outer tables) QUERY_INVARIANT - invariant within the life of a query (constant expressions)
      Overrides:
      getOrderableVariantType in class ValueNode
      Returns:
      The variant type for the underlying expression.
      Throws:
      StandardException - Thrown on error
    • bindExpression

      ValueNode bindExpression(FromList fromList, SubqueryList subqueryList, List<AggregateNode> aggregates) throws StandardException
      Bind this expression. This means binding the sub-expressions, as well as figuring out what the return type is for this expression.
      Overrides:
      bindExpression in class ValueNode
      Parameters:
      fromList - The FROM list for the query this expression is in, for binding columns.
      subqueryList - The subquery list being built as we find SubqueryNodes
      aggregates - The aggregate list being built as we find AggregateNodes
      Returns:
      The new top of the expression tree.
      Throws:
      StandardException - Thrown on error
    • bindCastNodeOnly

      void bindCastNodeOnly() throws StandardException
      Bind this node but not its child. Caller has already bound the child. This is useful for when we generate a CastNode during binding after having already bound the child.
      Throws:
      StandardException - Thrown on error
    • getCastFromCharConstant

      private ValueNode getCastFromCharConstant(int destJDBCTypeId) throws StandardException
      Get a constant representing the cast from a CHAR to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- char boolean char date/time/ts char non-decimal numeric
      Parameters:
      destJDBCTypeId - The destination JDBC TypeId
      Returns:
      The new top of the tree (this CastNode or a new Constant)
      Throws:
      StandardException - Thrown on error
    • getCastFromIntegralType

      private ValueNode getCastFromIntegralType(long longValue, int destJDBCTypeId) throws StandardException
      Get a constant representing the cast from an integral type to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- integral type non-decimal numeric integral type char
      Parameters:
      longValue - integral type as a long to cast from
      destJDBCTypeId - The destination JDBC TypeId
      Returns:
      The new top of the tree (this CastNode or a new Constant)
      Throws:
      StandardException - Thrown on error
    • getCastFromNumericType

      private ValueNode getCastFromNumericType(DataValueDescriptor constantValue, int destJDBCTypeId) throws StandardException
      Get a constant representing the cast from a non-integral type to another type. If this is not an "easy" cast to perform, then just return this cast node. Here's what we think is "easy": source destination ------ ----------- non-integral type non-decimal numeric non-integral type char
      Parameters:
      constantValue - non-integral type a a double to cast from
      destJDBCTypeId - The destination JDBC TypeId
      Returns:
      The new top of the tree (this CastNode or a new Constant)
      Throws:
      StandardException - Thrown on error
    • preprocess

      ValueNode preprocess(int numTables, FromList outerFromList, SubqueryList outerSubqueryList, PredicateList outerPredicateList) throws StandardException
      Preprocess an expression tree. We do a number of transformations here (including subqueries, IN lists, LIKE and BETWEEN) plus subquery flattening. NOTE: This is done before the outer ResultSetNode is preprocessed.
      Overrides:
      preprocess in class ValueNode
      Parameters:
      numTables - Number of tables in the DML Statement
      outerFromList - FromList from outer query block
      outerSubqueryList - SubqueryList from outer query block
      outerPredicateList - PredicateList from outer query block
      Returns:
      The modified expression
      Throws:
      StandardException - Thrown on error
    • categorize

      boolean categorize(JBitSet referencedTabs, boolean simplePredsOnly) throws StandardException
      Categorize this predicate. Initially, this means building a bit map of the referenced tables for each predicate. If the source of this ColumnReference (at the next underlying level) is not a ColumnReference or a VirtualColumnNode then this predicate will not be pushed down. For example, in: select * from (select 1 from s) a (x) where x = 1 we will not push down x = 1. NOTE: It would be easy to handle the case of a constant, but if the inner SELECT returns an arbitrary expression, then we would have to copy that tree into the pushed predicate, and that tree could contain subqueries and method calls. RESOLVE - revisit this issue once we have views.
      Overrides:
      categorize in class ValueNode
      Parameters:
      referencedTabs - JBitSet with bit map of referenced FromTables
      simplePredsOnly - Whether or not to consider method calls, field references and conditional nodes when building bit map
      Returns:
      boolean Whether or not source.expression is a ColumnReference or a VirtualColumnNode.
      Throws:
      StandardException - Thrown on error
    • remapColumnReferencesToExpressions

      ValueNode remapColumnReferencesToExpressions() throws StandardException
      Remap all ColumnReferences in this tree to be clones of the underlying expression.
      Overrides:
      remapColumnReferencesToExpressions in class ValueNode
      Returns:
      ValueNode The remapped expression tree.
      Throws:
      StandardException - Thrown on error
    • isConstantExpression

      boolean isConstantExpression()
      Return whether or not this expression tree represents a constant expression.
      Overrides:
      isConstantExpression in class ValueNode
      Returns:
      Whether or not this expression tree represents a constant expression.
    • constantExpression

      boolean constantExpression(PredicateList whereClause)
      Description copied from class: ValueNode
      Return whether or not this expression tree represents a constant value. In this case, "constant" means that it will always evaluate to the same thing, even if it includes columns. A column is constant if it is compared to a constant expression.
      Overrides:
      constantExpression in class ValueNode
      Returns:
      True means this expression tree represents a constant value.
      See Also:
    • getConstantValueAsObject

      Object getConstantValueAsObject() throws StandardException
      Return an Object representing the bind time value of this expression tree. If the expression tree does not evaluate to a constant at bind time then we return null. This is useful for bind time resolution of VTIs. RESOLVE: What do we do for primitives?
      Overrides:
      getConstantValueAsObject in class ValueNode
      Returns:
      An Object representing the bind time value of this expression tree. (null if not a bind time constant.)
      Throws:
      StandardException - Thrown on error
    • generateExpression

      void generateExpression(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
      Do code generation for this unary operator.
      Overrides:
      generateExpression in class ValueNode
      Parameters:
      acb - The ExpressionClassBuilder for the class we're generating
      mb - The method the code to place the code
      Throws:
      StandardException - Thrown on error
    • genDataValueConversion

      private void genDataValueConversion(ExpressionClassBuilder acb, MethodBuilder mb) throws StandardException
      Throws:
      StandardException
    • acceptChildren

      void acceptChildren(Visitor v) throws StandardException
      Accept the visitor for all visitable children of this node.
      Overrides:
      acceptChildren in class QueryTreeNode
      Parameters:
      v - the visitor
      Throws:
      StandardException - on error
    • setForExternallyGeneratedCASTnode

      void setForExternallyGeneratedCASTnode()
      This method gets called by the parser to indiciate that this CAST node has been generated by the parser. This means that we should use the collation info of the current compilation schmea for this node's collation setting. If this method does not get called, then it means that this CAST node has been an internally generated node and we should not touch the collation of this CAST node because it has been already set correctly by the class that generated this CAST node.
    • setForDataTypeFunction

      void setForDataTypeFunction(boolean b)
      set this to be a dataTypeScalarFunction
      Parameters:
      b - true to use function conversion rules
    • setAssignmentSemantics

      void setAssignmentSemantics()
      Set assignmentSemantics to true. Used by method calls for casting actual arguments
    • isEquivalent

      boolean isEquivalent(ValueNode o) throws StandardException
      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:
      o - the node to compare this ValueNode against.
      Returns:
      true if the two nodes are equivalent, false otherwise.
      Throws:
      StandardException
    • setTargetUDTName

      void setTargetUDTName(TableName name)
      Set the target type name if this is a cast to a UDT.
      Parameters:
      name - the name of the target type