tuffy.ra
Class Expression

java.lang.Object
  tuffy.ra.Expression

All Implemented Interfaces:

java.lang.Cloneable

public final class Expression
extends java.lang.Object
implements java.lang.Cloneable

An expression to a function is like a literal to a predicate. The interesting part is that expressions can be nested. The value of an expression can be numeric/string/boolean.

Author:

Feng Niu

Field Summary

private java.util.ArrayList<Expression>	args_
boolean	changeName
private Function	func_
private java.lang.String	val
private java.lang.String	valBinding

Constructor Summary

Expression(Function func)
Construct a new expression based on the function func_

Method Summary

void	addArgument(Expression expr) Append an argument to the underlying function
static Expression	and(Expression e1, Expression e2) Boolean AND
void	bindVariables(java.util.Map<java.lang.String,java.lang.String> mapVarVal) Bind variable references to their values in the symbol table.
Expression	clone()
static Expression	exprConstInteger(int n) Atomic expression representing a constant integer
static Expression	exprConstNum(double num) Atomic expression representing a constant number
static Expression	exprConstString(java.lang.String str) Atomic expression representing a constant string
static Expression	exprVariableBinding(java.lang.String var) Atomic expression representing a variable binding
java.util.ArrayList<Expression>	getArgs()
Function	getFunction()
private java.lang.String	getStringForm(boolean inSQL) Compute the SQL representation of this expression.
java.util.HashSet<java.lang.String>	getVars() Get the variables referenced by this expression.
boolean	isBoolean() Test if this expression returns a boolean value
boolean	isNumeric() Test if this expression returns a numeric value
boolean	isString() Test if this expression returns a string value
private boolean	needEnclosure() For aesthetics, check if we need a pair of parenthses for this experession.
static Expression	not(Expression e) Boolean negation
static Expression	or(Expression e1, Expression e2) Boolean OR
java.lang.String	renameVariables(java.util.Map<java.lang.String,java.lang.String> mapVarVar) Bind variable references to their values in the symbol table.
java.lang.String	toSQL() Get the SQL snippet for this expression
java.lang.String	toString()

Methods inherited from class java.lang.Object

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

Field Detail

func_

private Function func_

args_

private java.util.ArrayList<Expression> args_

val

private java.lang.String val

valBinding

private java.lang.String valBinding

changeName

public boolean changeName

Constructor Detail

Expression

public Expression(Function func)

Construct a new expression based on the function func_

Parameters:

func - the underlying function

Method Detail

getArgs

public java.util.ArrayList<Expression> getArgs()

getFunction

public Function getFunction()

getVars

public java.util.HashSet<java.lang.String> getVars()

Get the variables referenced by this expression.

needEnclosure

private boolean needEnclosure()

For aesthetics, check if we need a pair of parenthses for this experession.

not

public static Expression not(Expression e)

Boolean negation

Parameters:

e -

and

public static Expression and(Expression e1,
                             Expression e2)

Boolean AND

Parameters:

e1 -

e2 -

or

public static Expression or(Expression e1,
                            Expression e2)

Boolean OR

Parameters:

e1 -

e2 -

isBoolean

public boolean isBoolean()

Test if this expression returns a boolean value

isString

public boolean isString()

Test if this expression returns a string value

isNumeric

public boolean isNumeric()

Test if this expression returns a numeric value

addArgument

public void addArgument(Expression expr)

Append an argument to the underlying function

Parameters:

expr - the new argument

exprConstInteger

public static Expression exprConstInteger(int n)

Atomic expression representing a constant integer

Parameters:

n -

exprConstNum

public static Expression exprConstNum(double num)

Atomic expression representing a constant number

exprConstString

public static Expression exprConstString(java.lang.String str)

Atomic expression representing a constant string

exprVariableBinding

public static Expression exprVariableBinding(java.lang.String var)

Atomic expression representing a variable binding

clone

public Expression clone()

Overrides:

clone in class java.lang.Object

renameVariables

public java.lang.String renameVariables(java.util.Map<java.lang.String,java.lang.String> mapVarVar)

Bind variable references to their values in the symbol table. Variable name in the clause -> attribute name in SQL representing the value column of the symbol table.

Parameters:

mapVarVar -

bindVariables

public void bindVariables(java.util.Map<java.lang.String,java.lang.String> mapVarVal)

Bind variable references to their values in the symbol table. Variable name in the clause -> attribute name in SQL representing the value column of the symbol table.

Parameters:

mapVarVal -

toSQL

public java.lang.String toSQL()

Get the SQL snippet for this expression

getStringForm

private java.lang.String getStringForm(boolean inSQL)

Compute the SQL representation of this expression. Call bindVariables(Map) first.

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object