org.jclarion.clarion.runtime.expr
Class CExpr

java.lang.Object
  org.jclarion.clarion.runtime.expr.CExpr

Direct Known Subclasses:

BoolExpr, CmpExpr, ConcatExpr, ConstExpr, LabelExpr, NegExpr, NotExpr, PowExpr, ProdExpr, SumExpr

public abstract class CExpr
extends java.lang.Object

Nested Class Summary

static class	CExpr.DeepIterator
protected static class	CExpr.GenericOp
static class	CExpr.JoinIterator
static class	CExpr.OneIterator
static class	CExpr.OpIterable
static class	CExpr.OpIterator
static class	CExpr.TwoIterator
static class	CExpr.ZeroIterator

Constructor Summary

CExpr()

Method Summary

abstract void	cast(CExprType type) Force expr type to a new cast
protected void	cast(java.lang.Iterable<CExpr> in, CExprType type)
abstract java.util.Iterator<CExpr>	directChildren()
abstract ClarionObject	eval() Generate result
abstract boolean	generateString(java.lang.StringBuilder out, boolean strict) Generate SQL capable string.
abstract CExprType	getType() Work out expression type
abstract boolean	isRecastableType() Return whether or not expression type is fixed.
protected boolean	isRecastableType(java.lang.Iterable<CExpr> in)
java.util.Iterator<CExpr>	iterator()
abstract int	precendence() Return order of precendence.
protected CExprType	resolveCasts(java.lang.Iterable<CExpr> in)

Methods inherited from class java.lang.Object

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

Constructor Detail

CExpr

public CExpr()

Method Detail

getType

public abstract CExprType getType()

Work out expression type

Returns:

cast

public abstract void cast(CExprType type)

Force expr type to a new cast

isRecastableType

public abstract boolean isRecastableType()

Return whether or not expression type is fixed. i.e. cannot be easily recast

eval

public abstract ClarionObject eval()

Generate result

Returns:

precendence

public abstract int precendence()

Return order of precendence. Low number = low order of precedence (i.e. bool etc) Hi number = high order of precendence (i.e. * % / etc ). Highest is constants When rebuilding expressions (i.e. SQL) you need to paran anything whose precendence is lower then yourself i.e. Sum(Prod,Prod) = 2*3 + 6*3 Prod(Sum,Sum) = (2+3) * (6+3)

directChildren

public abstract java.util.Iterator<CExpr> directChildren()

generateString

public abstract boolean generateString(java.lang.StringBuilder out,
                                       boolean strict)

Generate SQL capable string. if strict is false (not strict mode) then it will generate expression faithfully without consideration as to whether or not it will yield legal SQL If strict mode is set - then only faithful SQL will be yielded return result in this case will indicate whether or not this call of generateString yielded SQL. If a method returns false it must preserve StringBuilder as is e.g. Pow() will always return false. e.g. BoolExpr will return false if there are any 'OR' components which are not strict SQL

iterator

public java.util.Iterator<CExpr> iterator()

resolveCasts

protected CExprType resolveCasts(java.lang.Iterable<CExpr> in)

isRecastableType

protected boolean isRecastableType(java.lang.Iterable<CExpr> in)

cast

protected void cast(java.lang.Iterable<CExpr> in,
                    CExprType type)