class Sequel::SQL::BooleanExpression

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

Public Class Methods

from_value_pairs(pairs, op=:AND, negate=false) click to toggle source

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)
     # 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) click to toggle source

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"
     # 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

Private Class Methods

from_value_pair(l, r) click to toggle source

Return a BooleanExpression based on the right side of the pair.

     # File lib/sequel/sql.rb
1086 def self.from_value_pair(l, r)
1087   case r
1088   when Range
1089     expr = new(:>=, l, r.begin)
1090     unless r.end.nil?
1091       expr = new(:AND, expr, new(r.exclude_end? ? :< : :<=, l, r.end))
1092     end
1093     expr
1094   when ::Array
1095     r = r.dup.freeze unless r.frozen?
1096     new(:IN, l, r)
1097   when ::String
1098     r = r.dup.freeze unless r.frozen?
1099     new(:'=', l, r)
1100   when ::Sequel::Dataset
1101     new(:IN, l, r)
1102   when NegativeBooleanConstant
1103     new(:"IS NOT", l, r.constant)
1104   when BooleanConstant
1105     new(:IS, l, r.constant)
1106   when NilClass, TrueClass, FalseClass
1107     new(:IS, l, r)
1108   when Regexp
1109     StringExpression.like(l, r)
1110   when DelayedEvaluation
1111     Sequel.delay{|ds| from_value_pair(l, r.call(ds))}
1112   when Dataset::PlaceholderLiteralizer::Argument
1113     r.transform{|v| from_value_pair(l, v)}
1114   else
1115     new(:'=', l, r)
1116   end
1117 end

Public Instance Methods

&(ce) click to toggle source

Always use an AND operator for & on BooleanExpressions

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

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

     # File lib/sequel/sql.rb
1168 def sql_boolean
1169   self
1170 end
|(ce) click to toggle source

Always use an OR operator for | on BooleanExpressions

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