sequel.rb in bmg-0.10.0

- old
+ new
@@ -1,11 +1,62 @@
+require 'bmg/sql'
 require 'sequel'
 require 'predicate/sequel'
 module Bmg
 
-  def sequel(dataset, type = Type::ANY)
-    Sequel::Relation.new(type, dataset).spied(main_spy)
+  module Sequel
+
+    def sequel(*args, &bl)
+      source, sequel_db, type = sequel_params(*args, &bl)
+      builder = Sql::Builder.new
+      sexpr = builder.select_all(type.to_attrlist, source)
+      Sequel::Relation.new(type, builder, sexpr, sequel_db).spied(Bmg.main_spy)
+    end
+    module_function :sequel
+
+    def sequel_params(source, sequel_db = nil, type = nil)
+      sequel_db, type = nil, sequel_db if sequel_db.nil? or sequel_db.is_a?(Type)
+      sequel_db = source.db if sequel_db.nil? and source.is_a?(::Sequel::Dataset)
+      raise ArgumentError, "A Sequel::Database object is required" if sequel_db.nil?
+      raise ArgumentError, "Type's attrlist must be known (#{type})" if type && !type.knows_attrlist?
+      type = infer_type!(sequel_db, source) if type.nil?
+      [source, sequel_db, type]
+    end
+    module_function :sequel_params
+
+    def infer_type!(sequel_db, source)
+      raise "Sequel::Relation requires a type for `#{source}`" unless source.is_a?(Symbol)
+      TypeInference.new(sequel_db).call(source)
+    end
+    module_function :infer_type!
+
   end
+
+  # Builds a Relation that uses Sequel for managing real data
+  # accesses.
+  #
+  # Supported signatures:
+  #
+  #   # Table name, providing the Sequel's Database object
+  #   Bmg.sequel(:suppliers, DB)
+  #
+  #   # Sequel dataset object, embedding the Database object
+  #   # `from_self` will be used at compilation time, you don't
+  #   # need to call it yourself.
+  #   Bmg.sequel(DB[:suppliers])
+  #
+  #   # Similar, but with with a pure SQL query
+  #   Bmg.sequel(DB[%Q{SELECT ... FROM ...}])
+  #
+  #   # All signatures above with an explicit type object, e.g.:
+  #   Bmg.sequel(:suppliers, DB, Type::ANY)
+  #   Bmg.sequel(DB[:suppliers], Type::ANY)
+  #
+  def sequel(source, sequel_db = nil, type = nil)
+    Sequel.sequel(source, sequel_db, type)
+  end
   module_function :sequel
 
 end
+require_relative 'sequel/translator'
+require_relative 'sequel/type_inference'
 require_relative 'sequel/relation'