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
1081 def self.from_value_pairs(pairs, op=:AND, negate=false)
1082   pairs = pairs.map{|l,r| from_value_pair(l, r)}
1083   pairs.map!{|ce| invert(ce)} if negate
1084   pairs.length == 1 ? pairs[0] : new(op, *pairs)
1085 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
1140 def self.invert(ce)
1141   case ce
1142   when BooleanExpression
1143     case op = ce.op
1144     when :AND, :OR
1145       BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1146     when :IN, :"NOT IN"
1147       BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1148     else
1149       if ce.args.length == 2
1150         case ce.args[1]
1151         when Function, LiteralString, PlaceholderLiteralString
1152           # Special behavior to not push down inversion in this case because doing so
1153           # can result in incorrect behavior for ANY/SOME/ALL operators.
1154           BooleanExpression.new(:NOT, ce)
1155         else
1156           BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1157         end
1158       else
1159         BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
1160       end
1161     end
1162   when StringExpression, NumericExpression
1163     raise(Sequel::Error, "cannot invert #{ce.inspect}")
1164   when Constant
1165     CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1166   else
1167     BooleanExpression.new(:NOT, ce)
1168   end
1169 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
1088 def self.from_value_pair(l, r)
1089   case r
1090   when Range
1091     unless r.begin.nil?
1092       begin_expr = new(:>=, l, r.begin)
1093     end
1094     unless r.end.nil?
1095       end_expr = new(r.exclude_end? ? :< : :<=, l, r.end)
1096     end
1097     if begin_expr
1098       if end_expr
1099         new(:AND, begin_expr, end_expr)
1100       else
1101         begin_expr
1102       end
1103     elsif end_expr
1104       end_expr
1105     else
1106       new(:'=', 1, 1)
1107     end
1108   when ::Array
1109     r = r.dup.freeze unless r.frozen?
1110     new(:IN, l, r)
1111   when ::String
1112     r = r.dup.freeze unless r.frozen?
1113     new(:'=', l, r)
1114   when ::Sequel::Dataset
1115     new(:IN, l, r)
1116   when NegativeBooleanConstant
1117     new(:"IS NOT", l, r.constant)
1118   when BooleanConstant
1119     new(:IS, l, r.constant)
1120   when NilClass, TrueClass, FalseClass
1121     new(:IS, l, r)
1122   when Regexp
1123     StringExpression.like(l, r)
1124   when DelayedEvaluation
1125     Sequel.delay{|ds| from_value_pair(l, r.call(ds))}
1126   when Dataset::PlaceholderLiteralizer::Argument
1127     r.transform{|v| from_value_pair(l, v)}
1128   else
1129     new(:'=', l, r)
1130   end
1131 end

Public Instance Methods

&(ce) click to toggle source

Always use an AND operator for & on BooleanExpressions

     # File lib/sequel/sql.rb
1172 def &(ce)
1173   BooleanExpression.new(:AND, self, ce)
1174 end
sql_boolean() click to toggle source

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

     # File lib/sequel/sql.rb
1182 def sql_boolean
1183   self
1184 end
|(ce) click to toggle source

Always use an OR operator for | on BooleanExpressions

     # File lib/sequel/sql.rb
1177 def |(ce)
1178   BooleanExpression.new(:OR, self, ce)
1179 end