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Class Zql.ZExpression 

java.lang.Object
   |
   +----Zql.ZExpression
public class ZExpression
extends Object
implements ZExp
ZExpression: an SQL Expression An SQL expression is an operator and one or more operands Example: a AND b AND c -> operator = AND, operands = (a, b, c)

Constructor Index

o ZExpression(String)
Create an SQL Expression given the operator
o ZExpression(String, ZExp)
Create an SQL Expression given the operator and 1st operand
o ZExpression(String, ZExp, ZExp)
Create an SQL Expression given the operator, 1st and 2nd operands

Method Index

o addOperand(ZExp)
Add an operand to the current expression.
o getOperand(int)
Get an operand according to its index (position).
o getOperands()
Get this expression's operands.
o getOperator()
Get this expression's operator.
o nbOperands()
Get the number of operands
o setOperands(Vector)
Set the operands list
o toReversePolish()
String form of the current expression (reverse polish notation).
o toString()

Constructors

o ZExpression 
 public ZExpression(String op)
Create an SQL Expression given the operator

Parameters:
op - The operator
o ZExpression 
 public ZExpression(String op,
                    ZExp o1)
Create an SQL Expression given the operator and 1st operand

Parameters:
op - The operator
o1 - The 1st operand
o ZExpression 
 public ZExpression(String op,
                    ZExp o1,
                    ZExp o2)
Create an SQL Expression given the operator, 1st and 2nd operands

Parameters:
op - The operator
o1 - The 1st operand
o2 - The 2nd operand

Methods

o getOperator 
 public String getOperator()
Get this expression's operator.

Returns:
the operator.
o setOperands 
 public void setOperands(Vector v)
Set the operands list

Parameters:
v - A vector that contains all operands (ZExp objects).
o getOperands 
 public Vector getOperands()
Get this expression's operands.

Returns:
the operands (as a Vector of ZExp objects).
o addOperand 
 public void addOperand(ZExp o)
Add an operand to the current expression.

Parameters:
o - The operand to add.
o getOperand 
 public ZExp getOperand(int pos)
Get an operand according to its index (position).

Parameters:
pos - The operand index, starting at 0.
Returns:
The operand at the specified index, null if out of bounds.
o nbOperands 
 public int nbOperands()
Get the number of operands

Returns:
The number of operands
o toReversePolish 
 public String toReversePolish()
String form of the current expression (reverse polish notation). Example: a > 1 AND b = 2 -> (AND (> a 1) (= b 2))

Returns:
The current expression in reverse polish notation (a String)
o toString 
 public String toString()
Overrides:
toString in class Object 
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