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# Based on great work by Sam Smoot
# http://substantiality.net/archives/2007/4/16/datamapper-part-xiv-finder-block
module Sequel
class Dataset
class BlankSlate #:nodoc:
instance_methods.each { |m| undef_method m unless m =~ /^(__|instance_eval)/ }
end
# An Expression is made of a left side, an operator, and a right side.
class Expression < BlankSlate
attr_reader :left, :right
attr_accessor :op
def initialize(left)
@left = left
end
def method_missing(sym, *right)
@op = case sym
when :==, :===, :in, :in?: :eql
when :=~, :like, :like?: :like
when :"<=>", :is_not: :not
when :<: :lt
when :<=: :lte
when :>: :gt
when :>=: :gte
else
@left = "#{left}.#{sym}"
end
@right = right.first
self
end
def nil?
@op = :eql
@right = nil
self
end
end
# An ExpressionCompiler takes a Proc object and compiles it
# into an array of expressions using instance_eval magic.
class ExpressionCompiler < BlankSlate
def initialize(&block) #:nodoc:
@block = block
@expressions = []
end
# Converts the block into an array of expressions.
def __to_a__
instance_eval(&@block)
@expressions
rescue => e
raise SequelError, e.message
end
private
def __expr(sym) #:nodoc:
expr = Expression.new(sym)
@expressions << expr
expr
end
def method_missing(sym, *args); __expr(sym); end #:nodoc:
def test; __expr(:test); end #:nodoc:
def SUM(sym); __expr(sym.SUM); end #:nodoc:
end
end
end
class Proc
def to_expressions
Sequel::Dataset::ExpressionCompiler.new(&self).__to_a__
end
end
Version data entries
30 entries across 30 versions & 1 rubygems