Implement basic fulltext binding.
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Richard Newman
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5f04a48c2a
commit
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2 changed files with 168 additions and 2 deletions
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@ -5,6 +5,7 @@
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(ns datomish.query.clauses
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(:require
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[datomish.query.cc :as cc]
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[datomish.query.functions :as functions]
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[datomish.query.source
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:refer [attribute-in-source
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constant-in-source
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@ -170,8 +171,9 @@
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;; TODO: handle And within the Or patterns.
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(raise "Non-simple `or` clauses not yet supported." {:clause orc})))
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(apply-function-clause [cc function]
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cc)
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(defn apply-function-clause [cc function]
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(or (functions/apply-sql-function cc function)
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(raise "Unknown function expression." {:clause function})))
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;; We're keeping this simple for now: a straightforward type switch.
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(defn apply-clause [cc it]
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164
src/datomish/query/functions.cljc
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164
src/datomish/query/functions.cljc
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@ -0,0 +1,164 @@
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;; This Source Code Form is subject to the terms of the Mozilla Public
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;; License, v. 2.0. If a copy of the MPL was not distributed with this
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;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
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(ns datomish.query.functions
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(:require
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[honeysql.format :as fmt]
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[datomish.query.cc :as cc]
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[datomish.query.source :as source]
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[datomish.util :as util #?(:cljs :refer-macros :clj :refer) [raise raise-str cond-let]]
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[datascript.parser :as dp
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#?@(:cljs
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[:refer
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[
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BindColl
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BindScalar
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BindTuple
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BindIgnore
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Constant
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Function
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PlainSymbol
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SrcVar
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Variable
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]])]
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[honeysql.core :as sql]
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[clojure.string :as str]
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)
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#?(:clj
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(:import
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[datascript.parser
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BindColl
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BindScalar
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BindTuple
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BindIgnore
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Constant
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Function
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PlainSymbol
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SrcVar
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Variable
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])))
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;; honeysql's MATCH handler doesn't work for sqlite. This does.
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(defmethod fmt/fn-handler "match" [_ col val]
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(str (fmt/to-sql col) " MATCH " (fmt/to-sql val)))
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(defn fulltext-attribute? [source attribute]
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;; TODO: schema lookup.
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true)
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(defn- validate-fulltext-clause [cc function]
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(let [[src attr search] (:args function)]
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(when-not (and (instance? SrcVar src)
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(= "$" (name (:symbol src))))
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(raise "Non-default sources not supported." {:arg src}))
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(when-not (instance? Constant attr)
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(raise "Non-constant fulltext attributes not supported." {:arg attr}))
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(when-not (fulltext-attribute? (:source cc) (:value attr))
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(raise-str "Attribute " (:value attr) " is not a fulltext-indexed attribute."))
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(when-not (and (instance? BindColl (:binding function))
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(instance? BindTuple (:binding (:binding function)))
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(every? (fn [s]
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(or (instance? BindIgnore s)
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(and (instance? BindScalar s)
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(instance? Variable (:variable s)))))
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(:bindings (:binding (:binding function)))))
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(raise "Unexpected binding value." {:binding (:binding function)}))))
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(defn apply-fulltext-clause [cc function]
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(validate-fulltext-clause cc function)
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;; A fulltext search string is either a constant string or a variable binding.
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;; The search string and the attribute are used to generate a SQL MATCH expression:
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;; table MATCH 'search string'
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;; This is then joined against an ordinary pattern to yield entity, value, and tx.
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;; We do not currently support scoring; the score value will always be 0.
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(let [[src attr search] (:args function)
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;; Pull out the symbols for the binding array.
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[entity value tx score]
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(map (comp :symbol :variable) ; This will nil-out placeholders.
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(get-in function [:binding :binding :bindings]))
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;; Find the FTS table name and alias. We might have multiple fulltext
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;; expressions so we will generate a query like
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;; SELECT ttt.a FROM t1 AS ttt WHERE ttt.t1 MATCH 'string'
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[fts-table fts-alias] (source/source->fts-from (:source cc)) ; [:t1 :ttt]
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match-column (sql/qualify fts-alias fts-table) ; :ttt.t1
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match-value (cc/argument->value cc search)
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[datom-table datom-alias] (source/source->non-fts-from (:source cc))
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;; The following will end up being added to the CC.
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from [[fts-table fts-alias]
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[datom-table datom-alias]]
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wheres [[:match match-column match-value] ; The FTS match.
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;; The FTS rowid to datom correspondence.
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[:=
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(sql/qualify datom-alias :v)
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(sql/qualify fts-alias :rowid)]
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;; The attribute itself must match.
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[:=
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(sql/qualify datom-alias :a)
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(source/attribute-in-source (:source cc) (:value attr))]]
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;; Now compose any bindings for entity, value, tx, and score.
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;; TODO: do we need to examine existing bindings to capture
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;; wheres for any of these? We shouldn't, because the CC will
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;; be internally cross-where'd when everything is done...
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bindings (into {}
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(filter
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(comp not nil? first)
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[[entity [(sql/qualify datom-alias :e)]]
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[value [match-column]]
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[tx [(sql/qualify datom-alias :tx)]]
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;; Future: use matchinfo to compute a score
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;; if this is a variable rather than a placeholder.
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[score [0]]]))]
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(cc/augment-cc cc from bindings wheres)))
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(def sql-functions
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;; Future: versions of this that uses snippet() or matchinfo().
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{"fulltext" apply-fulltext-clause})
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(defn apply-sql-function
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"Either returns an application of `function` to `cc`, or nil to
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encourage you to try a different application."
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[cc function]
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(when (and (instance? Function function)
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(instance? PlainSymbol (:fn function)))
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(when-let [apply-f (get sql-functions (name (:symbol (:fn function))))]
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(apply-f cc function))))
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;; A fulltext expression parses to:
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;;
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;; Function ( :fn, :args )
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;;
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;; The args begin with a SrcVar, and then are attr and search.
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;;
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;; This binds a relation of [?entity ?value ?tx ?score]:
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;;
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;; BindColl
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;; :binding BindTuple
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;; :bindings [BindScalar...]
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;;
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;; #datascript.parser.Function
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;; {:fn #datascript.parser.PlainSymbol{:symbol fulltext},
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;; :args [#datascript.parser.SrcVar{:symbol $}
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;; #datascript.parser.Constant{:value :artist/name}
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;; #datascript.parser.Variable{:symbol ?search}],
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;; :binding #datascript.parser.BindColl
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;; {:binding #datascript.parser.BindTuple
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;; {:bindings [
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;; #datascript.parser.BindScalar{:variable #datascript.parser.Variable{:symbol ?entity}}
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;; #datascript.parser.BindScalar{:variable #datascript.parser.Variable{:symbol ?name}}
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;; #datascript.parser.BindScalar{:variable #datascript.parser.Variable{:symbol ?tx}}
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;; #datascript.parser.BindScalar{:variable #datascript.parser.Variable{:symbol ?score}}]}}}
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