class Sequel::SQL::BooleanExpression

  1. lib/sequel/sql.rb
Superclass: ComplexExpression

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

Methods

Public Class

  1. from_value_pairs
  2. invert

Public Instance

  1. &
  2. sql_boolean
  3. |

Included modules

  1. BooleanMethods

Public Class methods

from_value_pairs (pairs, op=:AND, negate=false)

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)
[show source]
     # File lib/sequel/sql.rb
1079 def self.from_value_pairs(pairs, op=:AND, negate=false)
1080   pairs = pairs.map{|l,r| from_value_pair(l, r)}
1081   pairs.map!{|ce| invert(ce)} if negate
1082   pairs.length == 1 ? pairs[0] : new(op, *pairs)
1083 end
invert (ce)

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"
[show source]
     # File lib/sequel/sql.rb
1126 def self.invert(ce)
1127   case ce
1128   when BooleanExpression
1129     case op = ce.op
1130     when :AND, :OR
1131       BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1132     when :IN, :"NOT IN"
1133       BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1134     else
1135       if ce.args.length == 2
1136         case ce.args[1]
1137         when Function, LiteralString, PlaceholderLiteralString
1138           # Special behavior to not push down inversion in this case because doing so
1139           # can result in incorrect behavior for ANY/SOME/ALL operators.
1140           BooleanExpression.new(:NOT, ce)
1141         else
1142           BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1143         end
1144       else
1145         BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1146       end
1147     end
1148   when StringExpression, NumericExpression
1149     raise(Sequel::Error, "cannot invert #{ce.inspect}")
1150   when Constant
1151     CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1152   else
1153     BooleanExpression.new(:NOT, ce)
1154   end
1155 end

Public Instance methods

& (ce)

Always use an AND operator for & on BooleanExpressions

[show source]
     # File lib/sequel/sql.rb
1158 def &(ce)
1159   BooleanExpression.new(:AND, self, ce)
1160 end
sql_boolean ()

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

[show source]
     # File lib/sequel/sql.rb
1168 def sql_boolean
1169   self
1170 end
| (ce)

Always use an OR operator for | on BooleanExpressions

[show source]
     # File lib/sequel/sql.rb
1163 def |(ce)
1164   BooleanExpression.new(:OR, self, ce)
1165 end