/*
Apply mapper to where condition expressions.
*/
func (this *MergeDelete) MapExpressions(mapper expression.Mapper) (err error) {
	if this.where != nil {
		this.where, err = mapper.Map(this.where)
	}

	return
}

/*
This method maps all the constituent clauses, namely the from,
let, where, group by and projection(select) within a Subselect
statement.
*/
func (this *Subselect) MapExpressions(mapper expression.Mapper) (err error) {
	if this.from != nil {
		err = this.from.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.let != nil {
		err = this.let.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.where != nil {
		this.where, err = mapper.Map(this.where)
		if err != nil {
			return
		}
	}

	if this.group != nil {
		err = this.group.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	return this.projection.MapExpressions(mapper)
}

/*
Applies mapper to all the expressions in the upsert statement.
*/
func (this *Upsert) MapExpressions(mapper expression.Mapper) (err error) {
	if this.key != nil {
		this.key, err = mapper.Map(this.key)
		if err != nil {
			return
		}
	}

	if this.value != nil {
		this.value, err = mapper.Map(this.value)
		if err != nil {
			return
		}
	}

	if this.values != nil {
		err = this.values.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.query != nil {
		err = this.query.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.returning != nil {
		err = this.returning.MapExpressions(mapper)
	}

	return
}

/*
Map the input expression of the result expr.
*/
func (this *ResultTerm) MapExpression(mapper expression.Mapper) (err error) {
	if this.expr != nil {
		this.expr, err = mapper.Map(this.expr)
	}

	return
}

/*
Applies mapper to the key and value expressions.
*/
func (this *Pair) MapExpressions(mapper expression.Mapper) (err error) {
	this.Key, err = mapper.Map(this.Key)
	if err != nil {
		return
	}

	this.Value, err = mapper.Map(this.Value)
	return
}

/*
Maps the source array of the unnest if the parent object(left)
is mapped successfully.
*/
func (this *Unnest) MapExpressions(mapper expression.Mapper) (err error) {
	err = this.left.MapExpressions(mapper)
	if err != nil {
		return
	}

	this.expr, err = mapper.Map(this.expr)
	return
}

/*
Map Expressions for all sort terms in the receiver.
*/
func (this SortTerms) MapExpressions(mapper expression.Mapper) (err error) {
	for _, term := range this {
		term.expr, err = mapper.Map(term.expr)
		if err != nil {
			return
		}
	}

	return
}

/*
Applies mapper to the path expressions and update for in
the unset Term.
*/
func (this *UnsetTerm) MapExpressions(mapper expression.Mapper) (err error) {
	path, err := mapper.Map(this.path)
	if err != nil {
		return err
	}

	this.path = path.(expression.Path)

	if this.updateFor != nil {
		err = this.updateFor.MapExpressions(mapper)
	}

	return
}

/*
It is a utility function that takes in as input parameter
a mapper and maps the involved expressions to an expression.
If there is an error during the mapping, an error is returned.
*/
func (this *AggregateBase) MapChildren(mapper expression.Mapper) error {
	children := this.Children()

	for i, c := range children {
		expr, err := mapper.Map(c)
		if err != nil {
			return err
		}

		children[i] = expr
	}

	return nil
}

/*
This method maps all the constituent clauses, namely the
by, letting and having within a group by clause.
*/
func (this *Group) MapExpressions(mapper expression.Mapper) (err error) {
	if this.by != nil {
		err = this.by.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.letting != nil {
		err = this.letting.MapExpressions(mapper)
		if err != nil {
			return
		}
	}

	if this.having != nil {
		this.having, err = mapper.Map(this.having)
	}

	return
}

/*
Applies mapper to all the expressions in the delete statement.
*/
func (this *Delete) MapExpressions(mapper expression.Mapper) (err error) {
	if this.keys != nil {
		this.keys, err = mapper.Map(this.keys)
		if err != nil {
			return err
		}
	}

	if this.where != nil {
		this.where, err = mapper.Map(this.where)
		if err != nil {
			return err
		}
	}

	if this.limit != nil {
		this.limit, err = mapper.Map(this.limit)
		if err != nil {
			return err
		}
	}

	if this.returning != nil {
		err = this.returning.MapExpressions(mapper)
	}

	return
}

/*
This method maps all the constituent clauses, namely the expression,
partition and where clause within a create index statement.
*/
func (this *CreateIndex) MapExpressions(mapper expression.Mapper) (err error) {
	err = this.exprs.MapExpressions(mapper)
	if err != nil {
		return
	}

	if this.partition != nil {
		this.partition, err = mapper.Map(this.partition)
		if err != nil {
			return
		}
	}

	if this.where != nil {
		this.where, err = mapper.Map(this.where)
		if err != nil {
			return
		}
	}

	return
}