class Sequel::SQL::BooleanExpression

  1. lib/sequel/sql.rb
Superclass: ComplexExpression

Subclass of ComplexExpression where the expression results in a boolean value in SQL.

Methods

Public Class

  1. from_value_pairs
  2. invert

Public Instance

  1. &
  2. sql_boolean
  3. |

Included modules

  1. BooleanMethods

Public Class methods

from_value_pairs (pairs, op=:AND, negate=false)

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)
[show source]
# File lib/sequel/sql.rb, line 1072
def self.from_value_pairs(pairs, op=:AND, negate=false)
  pairs = pairs.map{|l,r| from_value_pair(l, r)}
  pairs.map!{|ce| invert(ce)} if negate
  pairs.length == 1 ? pairs[0] : new(op, *pairs)
end
invert (ce)

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"
[show source]
# File lib/sequel/sql.rb, line 1119
def self.invert(ce)
  case ce
  when BooleanExpression
    case op = ce.op
    when :AND, :OR
      BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.map{|a| BooleanExpression.invert(a)})
    when :IN, :"NOT IN"
      BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
    else
      if ce.args.length == 2
        case ce.args[1]
        when Function, LiteralString, PlaceholderLiteralString
          # Special behavior to not push down inversion in this case because doing so
          # can result in incorrect behavior for ANY/SOME/ALL operators.
          BooleanExpression.new(:NOT, ce)
        else
          BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
        end
      else
        BooleanExpression.new(OPERTATOR_INVERSIONS[op], *ce.args.dup)
      end
    end
  when StringExpression, NumericExpression
    raise(Sequel::Error, "cannot invert #{ce.inspect}")
  when Constant
    CONSTANT_INVERSIONS[ce] || raise(Sequel::Error, "cannot invert #{ce.inspect}")
  else
    BooleanExpression.new(:NOT, ce)
  end
end

Public Instance methods

& (ce)

Always use an AND operator for & on BooleanExpressions

[show source]
# File lib/sequel/sql.rb, line 1151
def &(ce)
  BooleanExpression.new(:AND, self, ce)
end
sql_boolean ()

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

[show source]
# File lib/sequel/sql.rb, line 1161
def sql_boolean
  self
end
| (ce)

Always use an OR operator for | on BooleanExpressions

[show source]
# File lib/sequel/sql.rb, line 1156
def |(ce)
  BooleanExpression.new(:OR, self, ce)
end