com.mapr.ojai.store.impl

Class Expression

java.lang.Object

com.mapr.ojai.store.impl.Expression

Direct Known Subclasses:

FieldExpression, LiteralExpression, OperatorExpression

public abstract class Expression
extends java.lang.Object

Query expression. The QueryAnalyzer builds a tree of these, with the leaves being either literals or field references; inner nodes are relational or logical operators. New leaf derived classes need to be added to ExpressionVisitor in order for tree visits to work correctly.

Constructor Summary

Constructors

Constructor and Description
Expression()

Method Summary

Modifier and Type	Method and Description
abstract void	emitSql(java.lang.StringBuilder sb, java.lang.String tableAlias) Deprecated.
void	gatherExpressions(int depth, java.util.Map<org.ojai.FieldPath,java.util.List<NaryOperator>> topRelations, java.util.Set<Expression> otherPredicates) TODO: doc
abstract boolean	structuralEquals(Expression e) Check to see if the two expressions are equal.
abstract int	structuralHashCode() Generate the hash code for the Expression.
java.lang.String	toString()
abstract void	visit(ExpressionVisitor ev) Visit this node.

Methods inherited from class java.lang.Object

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

Constructor Detail

Expression

public Expression()

Method Detail

emitSql

@Deprecated
public abstract void emitSql(java.lang.StringBuilder sb,
                                         java.lang.String tableAlias)

Deprecated.

Emit this expression's contribution to the string (where clause).

Parameters:

sb - where to write to

tableAlias - the table alias to use for field names

structuralEquals

public abstract boolean structuralEquals(Expression e)

Check to see if the two expressions are equal. Two expressions are considered equal if they have the same shape, fields, and operators, but the literal values do not need to match.

Parameters:

e - the other expression to compare with

structuralHashCode

public abstract int structuralHashCode()

Generate the hash code for the Expression. Note that hashCodes do not depend on the values of literals; this is to aid in finding queries that are the same except for their constants (which could be replaced with bind variables, if they were supported).

Returns:

the hash code

visit

public abstract void visit(ExpressionVisitor ev)

Visit this node. For nodes that have children, this will be expected to visit those in post-order.

Parameters:

ev - the visitor

gatherExpressions

public void gatherExpressions(int depth,
                              java.util.Map<org.ojai.FieldPath,java.util.List<NaryOperator>> topRelations,
                              java.util.Set<Expression> otherPredicates)

TODO: doc

Parameters:

depth -

topPredicates -

otherPredicates -

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object