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. |
  3. sql_boolean

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
1084 def self.from_value_pairs(pairs, op=:AND, negate=false)
1085   pairs = pairs.map{|l,r| from_value_pair(l, r)}
1086   pairs.map!{|ce| invert(ce)} if negate
1087   pairs.length == 1 ? pairs[0] : new(op, *pairs)
1088 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
1149 def self.invert(ce)
1150   case ce
1151   when BooleanExpression
1152     case op = ce.op
1153     when :AND, :OR
1154       BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1155     when :IN, :"NOT IN"
1156       BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1157     else
1158       if ce.args.length == 2
1159         case ce.args[1]
1160         when Function, LiteralString, PlaceholderLiteralString
1161           # Special behavior to not push down inversion in this case because doing so
1162           # can result in incorrect behavior for ANY/SOME/ALL operators.
1163           BooleanExpression.new(:NOT, ce)
1164         else
1165           BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1166         end
1167       else
1168         BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1169       end
1170     end
1171   when StringExpression, NumericExpression
1172     raise(Sequel::Error, "cannot invert #{ce.inspect}")
1173   when Constant
1174     CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1175   else
1176     BooleanExpression.new(:NOT, ce)
1177   end
1178 end

Public Instance methods

&(ce)

Always use an AND operator for & on BooleanExpressions

[show source] 
     # File lib/sequel/sql.rb
1181 def &(ce)
1182   BooleanExpression.new(:AND, self, ce)
1183 end
|(ce)

Always use an OR operator for | on BooleanExpressions

[show source] 
     # File lib/sequel/sql.rb
1186 def |(ce)
1187   BooleanExpression.new(:OR, self, ce)
1188 end
sql_boolean()

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

[show source] 
     # File lib/sequel/sql.rb
1191 def sql_boolean
1192   self
1193 end