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
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) 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
1143 def self.invert(ce)
1144   case ce
1145   when BooleanExpression
1146     case op = ce.op
1147     when :AND, :OR
1148       BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
1149     when :IN, :"NOT IN"
1150       BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1151     else
1152       if ce.args.length == 2
1153         case ce.args[1]
1154         when Function, LiteralString, PlaceholderLiteralString
1155           # Special behavior to not push down inversion in this case because doing so
1156           # can result in incorrect behavior for ANY/SOME/ALL operators.
1157           BooleanExpression.new(:NOT, ce)
1158         else
1159           BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1160         end
1161       else
1162         BooleanExpression.new(OPERATOR_INVERSIONS[op], *ce.args.dup)
1163       end
1164     end
1165   when StringExpression, NumericExpression
1166     raise(Sequel::Error, "cannot invert #{ce.inspect}")
1167   when Constant
1168     CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
1169   else
1170     BooleanExpression.new(:NOT, ce)
1171   end
1172 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
1091 def self.from_value_pair(l, r)
1092   case r
1093   when Range
1094     unless r.begin.nil?
1095       begin_expr = new(:>=, l, r.begin)
1096     end
1097     unless r.end.nil?
1098       end_expr = new(r.exclude_end? ? :< : :<=, l, r.end)
1099     end
1100     if begin_expr
1101       if end_expr
1102         new(:AND, begin_expr, end_expr)
1103       else
1104         begin_expr
1105       end
1106     elsif end_expr
1107       end_expr
1108     else
1109       new(:'=', 1, 1)
1110     end
1111   when ::Array
1112     r = r.dup.freeze unless r.frozen?
1113     new(:IN, l, r)
1114   when ::String
1115     r = r.dup.freeze unless r.frozen?
1116     new(:'=', l, r)
1117   when ::Sequel::Dataset
1118     new(:IN, l, r)
1119   when NegativeBooleanConstant
1120     new(:"IS NOT", l, r.constant)
1121   when BooleanConstant
1122     new(:IS, l, r.constant)
1123   when NilClass, TrueClass, FalseClass
1124     new(:IS, l, r)
1125   when Regexp
1126     StringExpression.like(l, r)
1127   when DelayedEvaluation
1128     Sequel.delay{|ds| from_value_pair(l, r.call(ds))}
1129   when Dataset::PlaceholderLiteralizer::Argument
1130     r.transform{|v| from_value_pair(l, v)}
1131   else
1132     new(:'=', l, r)
1133   end
1134 end

Public Instance Methods

&(ce) click to toggle source

Always use an AND operator for & on BooleanExpressions

     # File lib/sequel/sql.rb
1175 def &(ce)
1176   BooleanExpression.new(:AND, self, ce)
1177 end
sql_boolean() click to toggle source

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

     # File lib/sequel/sql.rb
1185 def sql_boolean
1186   self
1187 end
|(ce) click to toggle source

Always use an OR operator for | on BooleanExpressions

     # File lib/sequel/sql.rb
1180 def |(ce)
1181   BooleanExpression.new(:OR, self, ce)
1182 end