Package edu.caltech.nanodb.expressions
Class InValuesOperator
- java.lang.Object
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- edu.caltech.nanodb.expressions.Expression
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- edu.caltech.nanodb.expressions.InValuesOperator
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- All Implemented Interfaces:
java.lang.Cloneable
public class InValuesOperator extends Expression
This class implements the expr IN (values) operator. This operation may be optimized out of a query, but if it is not, it can still be evaluated although it will be slow.
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Field Summary
Fields Modifier and Type Field Description (package private) Expression
expr
The expression to check against the set on the righthand side of the IN operator.private boolean
invert
If this is false, the operator computes expr IN (values); if true, the operator computes expr NOT IN (values).(package private) java.util.ArrayList<Expression>
values
If the righthand side of the IN operator is a list of values (expressions, specifically), this is the list of values.
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Constructor Summary
Constructors Constructor Description InValuesOperator(Expression expr, java.util.ArrayList<Expression> values)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected java.lang.Object
clone()
Creates a copy of expression.boolean
equals(java.lang.Object obj)
Checks if the argument is an expression with the same structure, but not necessarily the same references.java.lang.Object
evaluate(Environment env)
Evaluates this comparison expression and returns eitherBoolean.TRUE
orBoolean.FALSE
.ColumnInfo
getColumnInfo(Schema schema)
Returns aColumnInfo
object describing the type (and possibly the name) of the expression's result.java.util.ArrayList<Expression>
getValues()
If the IN operation has a list of values on the righthand side, this will be the list of values.int
hashCode()
Computes the hashcode of an Expression.void
setInvert(boolean invert)
java.lang.String
toString()
Returns a string representation of this comparison expression and its subexpressions.Expression
traverse(ExpressionProcessor p)
This method allows the entire expression tree to be traversed node by node, either for analysis or for transformation.-
Methods inherited from class edu.caltech.nanodb.expressions.Expression
duplicate, evaluate, evaluatePredicate, evaluatePredicate, getAllSymbols, hasSymbols, simplify
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Field Detail
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expr
Expression expr
The expression to check against the set on the righthand side of the IN operator.
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values
java.util.ArrayList<Expression> values
If the righthand side of the IN operator is a list of values (expressions, specifically), this is the list of values.
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invert
private boolean invert
If this is false, the operator computes expr IN (values); if true, the operator computes expr NOT IN (values).
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Constructor Detail
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InValuesOperator
public InValuesOperator(Expression expr, java.util.ArrayList<Expression> values)
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Method Detail
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setInvert
public void setInvert(boolean invert)
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getColumnInfo
public ColumnInfo getColumnInfo(Schema schema) throws SchemaNameException
Description copied from class:Expression
Returns aColumnInfo
object describing the type (and possibly the name) of the expression's result.- Specified by:
getColumnInfo
in classExpression
- Parameters:
schema
- a schema object that can be used to look up name and type details for symbols referenced by the expression.- Returns:
- a column-information object describing the type (and possibly the name and table-name) of this expression's result
- Throws:
SchemaNameException
- if a symbol cannot be resolved, either because it doesn't appear in the schema, or because the name is ambiguous.
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evaluate
public java.lang.Object evaluate(Environment env) throws ExpressionException
Evaluates this comparison expression and returns eitherBoolean.TRUE
orBoolean.FALSE
. If either the left-hand or right-hand expression evaluates tonull
(representing the SQL NULL value), then the expression's result is alwaysFALSE
.- Specified by:
evaluate
in classExpression
- Parameters:
env
- the environment to look up symbol-values from, when evaluating the expression- Returns:
- the result of the expression evaluation
- Throws:
ExpressionException
- if the expression cannot be evaluated for some reason.- Design Note:
- (Donnie) We have to suppress "unchecked operation" warnings on
this code, since
Comparable
is a generic (and thus allows us to specify the type of object being compared), but we want to use it without specifying any types.
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traverse
public Expression traverse(ExpressionProcessor p)
Description copied from class:Expression
This method allows the entire expression tree to be traversed node by node, either for analysis or for transformation. The
ExpressionProcessor
instance receives notifications as each node in the expression is entered and left.The expression tree can also be manipulated by this traversal process, depending on what the
ExpressionProcessor
wants to do. If the expression node thattraverse()
is invoked on, needs to be replaced with a new expression node, the replacement is returned by thetraverse()
method. (TheExpressionProcessor
specifies the replacement as the return-value from theExpressionProcessor.leave(Expression)
method.)- Specified by:
traverse
in classExpression
- Parameters:
p
- the object that performs analysis or transformation of the expression tree- Returns:
- an
Expression
node to replace this node, ornull
if no changes are to be made.
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toString
public java.lang.String toString()
Returns a string representation of this comparison expression and its subexpressions.- Overrides:
toString
in classjava.lang.Object
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getValues
public java.util.ArrayList<Expression> getValues()
If the IN operation has a list of values on the righthand side, this will be the list of values. Otherwise, this will be null.- Returns:
- the list of values on the righthand side of the IN operation, or null.
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equals
public boolean equals(java.lang.Object obj)
Checks if the argument is an expression with the same structure, but not necessarily the same references.- Specified by:
equals
in classExpression
- Parameters:
obj
- the object to which we are comparing
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hashCode
public int hashCode()
Description copied from class:Expression
Computes the hashcode of an Expression. This method is used to see if two expressions CAN be equal.- Specified by:
hashCode
in classExpression
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clone
protected java.lang.Object clone() throws java.lang.CloneNotSupportedException
Creates a copy of expression. This method is used by theExpression.duplicate()
method to make a deep copy of an expression tree.- Overrides:
clone
in classExpression
- Throws:
java.lang.CloneNotSupportedException
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