Class | Sequel::SQL::BooleanExpression |
In: |
lib/sequel/sql.rb
|
Parent: | ComplexExpression |
Subclass of ComplexExpression where the expression results in a boolean value in SQL.
Take pairs of values (e.g. a hash or array of arrays of two pairs) and converts it to a BooleanExpression. The operator and args used depends on the case of the right (2nd) argument:
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 423 423: def self.from_value_pairs(pairs, op=:AND, negate=false) 424: pairs = pairs.collect do |l,r| 425: ce = case r 426: when Range 427: new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end)) 428: when Array, ::Sequel::Dataset, SQLArray 429: new(:IN, l, r) 430: when NilClass, TrueClass, FalseClass 431: new(:IS, l, r) 432: when Regexp 433: StringExpression.like(l, r) 434: else 435: new('=''=', l, r) 436: end 437: negate ? invert(ce) : ce 438: end 439: pairs.length == 1 ? pairs.at(0) : new(op, *pairs) 440: 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).
# File lib/sequel/sql.rb, line 446 446: def self.invert(ce) 447: case ce 448: when BooleanExpression 449: case op = ce.op 450: when :AND, :OR 451: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)}) 452: else 453: BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) 454: end 455: when ComplexExpression 456: raise(Sequel::Error, "operator #{ce.op} cannot be inverted") 457: else 458: BooleanExpression.new(:NOT, ce) 459: end 460: end