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     1 ;;  Copyright (c) Jeffrey Straszheim. All rights reserved.  The use and

     2 ;;  distribution terms for this software are covered by the Eclipse Public

     3 ;;  License 1.0 (http://opensource.org/licenses/eclipse-1.0.php) which can

     4 ;;  be found in the file epl-v10.html at the root of this distribution.  By

     5 ;;  using this software in any fashion, you are agreeing to be bound by the

     6 ;;  terms of this license.  You must not remove this notice, or any other,

     7 ;;  from this software.

     8 ;;

     9 ;;  datalog.clj

    10 ;;

    11 ;;  A Clojure implementation of Datalog

    12 ;;

    13 ;;  straszheimjeffrey (gmail)

    14 ;;  Created 2 March 2009

    15 

    16 

    17 ;;; Please see the example.clj file in the datalog folder

    18 

    19 

    20 (ns 

    21   ^{:author "Jeffrey Straszheim",

    22      :doc "A Clojure implementation of Datalog"} 

    23   clojure.contrib.datalog

    24   (:use clojure.contrib.datalog.rules

    25         clojure.contrib.datalog.softstrat

    26         clojure.contrib.datalog.database)

    27   (:use [clojure.set :only (intersection)]

    28         [clojure.contrib.except :only (throwf)]))

    29 

    30 (defstruct work-plan

    31   :work-plan        ; The underlying structure

    32   :rules            ; The original rules

    33   :query            ; The original query

    34   :work-plan-type)  ; The type of plan

    35 

    36 (defn- validate-work-plan

    37   "Ensure any top level semantics are not violated"

    38   [work-plan database]

    39   (let [common-relations (-> work-plan :rules (intersection (-> database keys set)))]

    40     (when (-> common-relations

    41               empty?

    42               not)

    43       (throwf "The rules and database define the same relation(s): %s" common-relations))))

    44   ; More will follow

    45 

    46 (defn build-work-plan

    47   "Given a list of rules and a query, build a work plan that can be

    48    used to execute the query."

    49   [rules query]

    50   (struct-map work-plan

    51     :work-plan (build-soft-strat-work-plan rules query)

    52     :rules rules

    53     :query query

    54     :work-plan-type ::soft-stratified))

    55 

    56 (defn run-work-plan

    57   "Given a work plan, a database, and some query bindings, run the

    58    work plan and return the results."

    59   [work-plan database query-bindings]

    60   (validate-work-plan work-plan database)

    61   (evaluate-soft-work-set (:work-plan work-plan) database query-bindings))

    62 

    63 

    64 ;; End of file
author	Robert McIntyre <rlm@mit.edu>
date	Sat, 21 Aug 2010 06:25:44 -0400
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