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Define <-tagged-SQLite and tagged-SQLite-to-JS to do tag-aware value transforms.

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Richard Newman 2016-08-15 13:31:21 -07:00
parent ff9a75ae09
commit 22fc2ce201
1 changed files with 61 additions and 16 deletions
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77
src/datomish/sqlite_schema.cljc
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@ -17,21 +17,6 @@
(def current-version 1)
;; Datomish rows are tagged with a numeric representation of :db/valueType:
;; The tag is used to limit queries, and therefore is placed carefully in the relevant indices to
;; allow searching numeric longs and doubles quickly. The tag is also used to convert SQLite values
;; to the correct Datomish value type on query egress.
(def value-type-tag-map
{:db.type/ref 0
:db.type/boolean 1
:db.type/instant 4
:db.type/long 5 ;; SQLite distinguishes integral from decimal types, allowing long and double to share a tag.
:db.type/double 5 ;; SQLite distinguishes integral from decimal types, allowing long and double to share a tag.
:db.type/string 10
:db.type/uuid 11
:db.type/uri 12
:db.type/keyword 13})
(def v1-statements
["CREATE TABLE datoms (e INTEGER NOT NULL, a SMALLINT NOT NULL, v BLOB NOT NULL, tx INTEGER NOT NULL,
value_type_tag SMALLINT NOT NULL,
@ -176,7 +161,8 @@
number
(->SQLite [x] x)]))
(defn <-SQLite "Transforms SQLite values to Clojure{Script}."
(defn <-SQLite
"Transforms SQLite values to Clojure{Script}."
[valueType value]
(case valueType
:db.type/ref value
@ -186,8 +172,67 @@
:db.type/long value
:db.type/double value))
;; Datomish rows are tagged with a numeric representation of :db/valueType:
;; The tag is used to limit queries, and therefore is placed carefully in the relevant indices to
;; allow searching numeric longs and doubles quickly. The tag is also used to convert SQLite values
;; to the correct Datomish value type on query egress.
(def value-type-tag-map
{:db.type/ref 0
:db.type/boolean 1
:db.type/instant 4
:db.type/long 5 ;; SQLite distinguishes integral from decimal types, allowing long and double to share a tag.
:db.type/double 5 ;; SQLite distinguishes integral from decimal types, allowing long and double to share a tag.
:db.type/string 10
:db.type/uuid 11
:db.type/uri 12
:db.type/keyword 13})
(defn ->tag [valueType]
(or
(valueType value-type-tag-map)
(raise "Unknown valueType " valueType ", expected one of " (sorted-set (keys value-type-tag-map))
{:error :SQLite/tag, :valueType valueType})))
#?(:clj
(defn <-tagged-SQLite
"Transforms SQLite values to Clojure with tag awareness."
[tag value]
(case tag
;; In approximate commonality order.
0 value ; ref.
1 (= value 1) ; boolean
4 (java.util.Date. value) ; instant
13 (keyword (subs value 1)) ; keyword
12 (java.net.URI. value) ; URI
11 (java.util.UUID/fromString value) ; UUID
; 5 value ; numeric
; 10 value ; string
value
)))
#?(:cljs
(defn <-tagged-SQLite
"Transforms SQLite values to ClojureScript with tag awareness."
[tag value]
;; In approximate commonality order.
(case tag
0 value ; ref.
1 (= value 1) ; boolean
4 (new Date value) ; instant
13 (keyword (subs value 1)) ; keyword
; 12 value ; URI
; 11 value ; UUID
; 5 value ; numeric
; 10 value ; string
value
)))
(defn tagged-SQLite-to-JS
"Transforms SQLite values to JavaScript-compatible values."
[tag value]
(case tag
1 (= value 1) ; boolean.
; 0 value ; No point trying to ident.
; 4 value ; JS doesn't have a Date representation.
; 13 value ; Return the keyword string from the DB: ":foobar".
value))