Class: Sequel::SQL::BooleanExpression

Inherits:
ComplexExpression show all
Includes:
BooleanMethods
Defined in:
lib/sequel/sql.rb

Overview

Subclass of ComplexExpression where the expression results in a boolean value in SQL.

Constant Summary

Constants inherited from ComplexExpression

ComplexExpression::ASSOCIATIVE_OPERATORS, ComplexExpression::BITWISE_OPERATORS, ComplexExpression::BOOLEAN_OPERATOR_METHODS, ComplexExpression::CONSTANT_INVERSIONS, ComplexExpression::CUSTOM_EXPRESSIONS, ComplexExpression::EQUALITY_OPERATORS, ComplexExpression::INEQUALITY_OPERATORS, ComplexExpression::IN_OPERATORS, ComplexExpression::IS_OPERATORS, ComplexExpression::LIKE_OPERATORS, ComplexExpression::MATHEMATICAL_OPERATORS, ComplexExpression::N_ARITY_OPERATORS, ComplexExpression::ONE_ARITY_OPERATORS, ComplexExpression::OPERTATOR_INVERSIONS, ComplexExpression::REGEXP_OPERATORS, ComplexExpression::TWO_ARITY_OPERATORS

Instance Attribute Summary

Attributes inherited from ComplexExpression

#args, #op

Class Method Summary collapse

Instance Method Summary collapse

Methods included from BooleanMethods

#~

Methods inherited from ComplexExpression

#initialize, #sql_number, #sql_string

Methods included from SubscriptMethods

#sql_subscript

Methods included from PatternMatchMethods

#!~, #=~

Methods included from OrderMethods

#asc, #desc

Methods included from CastMethods

#cast, #cast_numeric, #cast_string

Methods included from AliasMethods

#as

Methods inherited from Expression

#==, attr_reader, #clone, #eql?, #hash, inherited, #inspect

Constructor Details

This class inherits a constructor from Sequel::SQL::ComplexExpression

Class Method Details

.from_value_pairs(pairs, op = :AND, negate = false) ⇒ Object

Take pairs of values (e.g. a hash or array of two element arrays) and converts it to a BooleanExpression. The operator and args used depends on the case of the right (2nd) argument:

0..10

left >= 0 AND left <= 10

1,2

left IN (1,2)

nil

left IS NULL

true

left IS TRUE

false

left IS FALSE

/as/

left ~ ‘as’

:blah

left = blah

‘blah’

left = ‘blah’

If multiple arguments are given, they are joined with the op given (AND by default, OR possible). If negate is set to true, all subexpressions are inverted before used. Therefore, the following expressions are equivalent:

~from_value_pairs(hash)
from_value_pairs(hash, :OR, true)



1079
1080
1081
1082
1083
 
# File 'lib/sequel/sql.rb', line 1079

def self.from_value_pairs(pairs, op=:AND, negate=false)
  pairs = pairs.map{|l,r| from_value_pair(l, r)}
  pairs.map!{|ce| invert(ce)} if negate
  pairs.length == 1 ? pairs[0] : new(op, *pairs)
end

.invert(ce) ⇒ Object

Invert the expression, if possible. If the expression cannot be inverted, raise an error. An inverted expression should match everything that the uninverted expression did not match, and vice-versa, except for possible issues with SQL NULL (i.e. 1 == NULL is NULL and 1 != NULL is also NULL).

BooleanExpression.invert(:a) # NOT "a"



1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
 
# File 'lib/sequel/sql.rb', line 1126

def self.invert(ce)
  case ce
  when BooleanExpression
    case op = ce.op
    when :AND, :OR
      BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
    when :IN, :"NOT IN"
      BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
    else
      if ce.args.length == 2
        case ce.args[1]
        when Function, LiteralString, PlaceholderLiteralString
          # Special behavior to not push down inversion in this case because doing so
          # can result in incorrect behavior for ANY/SOME/ALL operators.
          BooleanExpression.new(:NOT, ce)
        else
          BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
        end
      else
        BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
      end
    end
  when StringExpression, NumericExpression
    raise(Sequel::Error, "cannot invert #{ce.inspect}")
  when Constant
    CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
  else
    BooleanExpression.new(:NOT, ce)
  end
end

Instance Method Details

#&(ce) ⇒ Object

Always use an AND operator for & on BooleanExpressions



1158
1159
1160
 
# File 'lib/sequel/sql.rb', line 1158

def &(ce)
  BooleanExpression.new(:AND, self, ce)
end

#sql_boolean ⇒ Object

Return self instead of creating a new object to save on memory.



1168
1169
1170
 
# File 'lib/sequel/sql.rb', line 1168

def sql_boolean
  self
end

#|(ce) ⇒ Object

Always use an OR operator for | on BooleanExpressions



1163
1164
1165
 
# File 'lib/sequel/sql.rb', line 1163

def |(ce)
  BooleanExpression.new(:OR, self, ce)
end