Class: Sequel::SQL::BooleanExpression
- Inherits:
-
ComplexExpression
- Object
- Expression
- ComplexExpression
- Sequel::SQL::BooleanExpression
- Includes:
- BooleanMethods
- Defined in:
- lib/sequel/sql.rb
Overview
Subclass of ComplexExpression
where the expression results in a boolean value in SQL.
Constant Summary
Constants inherited from ComplexExpression
ComplexExpression::BITWISE_OPERATORS, ComplexExpression::BOOLEAN_OPERATOR_METHODS, ComplexExpression::INEQUALITY_OPERATORS, ComplexExpression::IN_OPERATORS, ComplexExpression::IS_OPERATORS, ComplexExpression::MATHEMATICAL_OPERATORS, ComplexExpression::N_ARITY_OPERATORS, ComplexExpression::ONE_ARITY_OPERATORS, ComplexExpression::OPERTATOR_INVERSIONS, ComplexExpression::TWO_ARITY_OPERATORS
Instance Attribute Summary
Attributes inherited from ComplexExpression
Class Method Summary collapse
-
.from_value_pairs(pairs, op = :AND, negate = false) ⇒ Object
Take pairs of values (e.g. a hash or array of two element arrays) and converts it to a
BooleanExpression
. -
.invert(ce) ⇒ Object
Invert the expression, if possible.
Methods included from BooleanMethods
Methods inherited from ComplexExpression
Methods included from SubscriptMethods
Methods included from OrderMethods
Methods included from CastMethods
#cast, #cast_numeric, #cast_string
Methods included from AliasMethods
Methods inherited from Expression
#==, attr_reader, comparison_attrs, #eql?, #hash, #inspect, #lit, #sql_literal
Constructor Details
This class inherits a constructor from Sequel::SQL::ComplexExpression
Class Method Details
.from_value_pairs(pairs, op = :AND, negate = false) ⇒ Object
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)
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# File 'lib/sequel/sql.rb', line 558 def self.from_value_pairs(pairs, op=:AND, negate=false) pairs = pairs.collect do |l,r| ce = case r when Range new(:AND, new(:>=, l, r.begin), new(r.exclude_end? ? :< : :<=, l, r.end)) when ::Array, ::Sequel::Dataset new(:IN, l, r) when NegativeBooleanConstant new(:"IS NOT", l, r.constant) when BooleanConstant new(:IS, l, r.constant) when NilClass, TrueClass, FalseClass new(:IS, l, r) when Regexp StringExpression.like(l, r) else new(:'=', l, r) end negate ? invert(ce) : ce end pairs.length == 1 ? pairs.at(0) : new(op, *pairs) end |
.invert(ce) ⇒ Object
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"
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# File 'lib/sequel/sql.rb', line 587 def self.invert(ce) case ce when BooleanExpression case op = ce.op when :AND, :OR BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.collect{|a| BooleanExpression.invert(a)}) else BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup) end when StringExpression, NumericExpression raise(Sequel::Error, "cannot invert #{ce.inspect}") else BooleanExpression.new(:NOT, ce) end end |