Subclass of ComplexExpression where the expression results in a boolean value in SQL.
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
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, line 887 887: def self.from_value_pairs(pairs, op=:AND, negate=false) 888: pairs = pairs.collect do |l,r| 889: ce = case r 890: when Range 891: new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end)) 892: when ::Array, ::Sequel::Dataset 893: new(:IN, l, r) 894: when NegativeBooleanConstant 895: new(:"IS NOT", l, r.constant) 896: when BooleanConstant 897: new(:IS, l, r.constant) 898: when NilClass, TrueClass, FalseClass 899: new(:IS, l, r) 900: when Regexp 901: StringExpression.like(l, r) 902: else 903: new(:'=', l, r) 904: end 905: negate ? invert(ce) : ce 906: end 907: pairs.length == 1 ? pairs.at(0) : new(op, *pairs) 908: end
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, line 916 916: def self.invert(ce) 917: case ce 918: when BooleanExpression 919: case op = ce.op 920: when :AND, :OR 921: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)}) 922: else 923: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) 924: end 925: when StringExpression, NumericExpression 926: raise(Sequel::Error, "cannot invert #{ce.inspect}") 927: when Constant 928: CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}") 929: else 930: BooleanExpression.new(:NOT, ce) 931: end 932: end
Always use an AND operator for & on BooleanExpressions
# File lib/sequel/sql.rb, line 935 935: def &(ce) 936: BooleanExpression.new(:AND, self, ce) 937: end
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