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module Arel
module Predicates
class Predicate
def or(other_predicate)
Or.new(self, other_predicate)
end
def and(other_predicate)
And.new(self, other_predicate)
end
def complement
Not.new(self)
end
def not
self.complement
end
end
class Polyadic < Predicate
attr_reader :predicates
def initialize(*predicates)
@predicates = predicates
end
# Build a Polyadic predicate based on:
# * <tt>operator</tt> - The Predicate subclass that defines the type of operation
# (LessThan, Equality, etc)
# * <tt>operand1</tt> - The left-hand operand (normally an Arel::Attribute)
# * <tt>additional_operands</tt> - All possible right-hand operands
def self.build(operator, operand1, *additional_operands)
new(
*additional_operands.uniq.inject([]) do |predicates, operand|
predicates << operator.new(operand1, operand)
end
)
end
def ==(other)
super || predicates == other.predicates
end
def bind(relation)
self.class.new(
*predicates.map {|p| p.find_correlate_in(relation)}
)
end
def eval(row)
predicates.send(compounder) do |operation|
operation.eval(row)
end
end
def to_sql(formatter = nil)
"(" +
predicates.map {|p| p.to_sql(formatter)}.join(" #{predicate_sql} ") +
")"
end
end
class Any < Polyadic
def complement
All.new(*predicates.map {|p| p.complement})
end
def compounder; :any? end
def predicate_sql; "OR" end
end
class All < Polyadic
def complement
Any.new(*predicates.map {|p| p.complement})
end
def compounder; :all? end
def predicate_sql; "AND" end
end
class Unary < Predicate
attr_reader :operand
def initialize operand
@operand = operand
end
def bind(relation)
self.class.new(operand.find_correlate_in(relation))
end
def == other
super || self.class === other && operand == other.operand
end
def eval(row)
operand.eval(row).send(operator)
end
def to_sql(formatter = nil)
"#{predicate_sql} (#{operand.to_sql(formatter)})"
end
end
class Not < Unary
def complement
operand
end
def eval(row)
!operand.eval(row)
end
def predicate_sql; "NOT" end
end
class Binary < Unary
attr_reader :operand2
alias :operand1 :operand
def initialize left, right
super(left)
@operand2 = right
end
def ==(other)
super && @operand2 == other.operand2
end
def bind(relation)
self.class.new(operand1.find_correlate_in(relation), operand2.find_correlate_in(relation))
end
def eval(row)
operand1.eval(row).send(operator, operand2.eval(row))
end
def to_sql(formatter = nil)
"#{operand1.to_sql} #{predicate_sql} #{operand1.format(operand2)}"
end
end
class CompoundPredicate < Binary
def eval(row)
eval "operand1.eval(row) #{operator} operand2.eval(row)"
end
def to_sql(formatter = nil)
"(#{operand1.to_sql(formatter)} #{predicate_sql} #{operand2.to_sql(formatter)})"
end
end
class And < CompoundPredicate
def complement
Or.new(operand1.complement, operand2.complement)
end
def operator; :and end
def predicate_sql; "AND" end
end
class Or < CompoundPredicate
def complement
And.new(operand1.complement, operand2.complement)
end
def operator; :or end
def predicate_sql; "OR" end
end
class Equality < Binary
def ==(other)
self.class === other and
((operand1 == other.operand1 and operand2 == other.operand2) or
(operand1 == other.operand2 and operand2 == other.operand1))
end
def complement
Inequality.new(operand1, operand2)
end
def operator; :== end
def predicate_sql
operand2.equality_predicate_sql
end
end
class Inequality < Equality
def complement
Equality.new(operand1, operand2)
end
def eval(row)
operand1.eval(row) != operand2.eval(row)
end
def predicate_sql
operand2.inequality_predicate_sql
end
end
class GreaterThanOrEqualTo < Binary
def complement
LessThan.new(operand1, operand2)
end
def operator; :>= end
def predicate_sql; '>=' end
end
class GreaterThan < Binary
def complement
LessThanOrEqualTo.new(operand1, operand2)
end
def operator; :> end
def predicate_sql; '>' end
end
class LessThanOrEqualTo < Binary
def complement
GreaterThan.new(operand1, operand2)
end
def operator; :<= end
def predicate_sql; '<=' end
end
class LessThan < Binary
def complement
GreaterThanOrEqualTo.new(operand1, operand2)
end
def operator; :< end
def predicate_sql; '<' end
end
class Match < Binary
def complement
NotMatch.new(operand1, operand2)
end
def operator; :=~ end
def predicate_sql; 'LIKE' end
end
class NotMatch < Binary
def complement
Match.new(operand1, operand2)
end
def eval(row)
operand1.eval(row) !~ operand2.eval(row)
end
def predicate_sql; 'NOT LIKE' end
end
class In < Binary
def complement
NotIn.new(operand1, operand2)
end
def eval(row)
operand2.eval(row).include?(operand1.eval(row))
end
def to_sql(formatter = nil)
if operand2.is_a?(Range) && operand2.exclude_end?
GreaterThanOrEqualTo.new(operand1, operand2.begin).and(
LessThan.new(operand1, operand2.end)
).to_sql(formatter)
else
super
end
end
def predicate_sql; operand2.inclusion_predicate_sql end
end
class NotIn < Binary
def complement
In.new(operand1, operand2)
end
def eval(row)
!(operand2.eval(row).include?(operand1.eval(row)))
end
def predicate_sql; operand2.exclusion_predicate_sql end
end
end
end
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