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(ns clojure.tools.nrepl.middleware
(:require clojure.tools.nrepl
[clojure.tools.nrepl.transport :as transport]
[clojure.tools.nrepl.misc :as misc]
[clojure.set :as set])
(:refer-clojure :exclude (comparator)))
(defn- var-name
[^clojure.lang.Var v]
(str (.ns v) \/ (.sym v)))
(defn- wrap-conj-descriptor
[descriptor-map h]
(fn [{:keys [op descriptors] :as msg}]
(h (if-not (= op "describe")
msg
(assoc msg :descriptors (merge descriptor-map descriptors))))))
(defn set-descriptor!
"Sets the given [descriptor] map as the ::descriptor metadata on
the provided [middleware-var], after assoc'ing in the var's
fully-qualified name as the descriptor's \"implemented-by\" value."
[middleware-var descriptor]
(let [descriptor (-> descriptor
(assoc :implemented-by (-> middleware-var var-name symbol))
(update-in [:expects] (fnil conj #{}) "describe"))]
(alter-meta! middleware-var assoc ::descriptor descriptor)
(alter-var-root middleware-var #(comp (partial wrap-conj-descriptor
(:handles descriptor)) %))))
(defn- safe-version
[m]
(into {} (filter (fn [[_ v]] (or (number? v) (string? v))) m)))
(defn wrap-describe
[h]
(fn [{:keys [op descriptors verbose? transport] :as msg}]
(if (= op "describe")
(transport/send transport (misc/response-for msg
{:ops (if verbose?
descriptors
(into {} (map #(vector (key %) {}) descriptors)))
:versions {:nrepl (safe-version clojure.tools.nrepl/version)
:clojure (safe-version *clojure-version*)}
:status :done}))
(h msg))))
(set-descriptor! #'wrap-describe
{:handles {"describe"
{:doc "Produce a machine- and human-readable directory and documentation for the operations supported by an nREPL endpoint."
:requires {}
:optional {"verbose?" "Include informational detail for each \"op\"eration in the return message."}
:returns {"ops" "Map of \"op\"erations supported by this nREPL endpoint"
"versions" "Map containing version maps (like *clojure-version*, e.g. major, minor, incremental, and qualifier keys) for values, component names as keys. Common keys include \"nrepl\" and \"clojure\"."}}}})
; eliminate implicit expectation of "describe" handler; this is the only
; special case introduced by the conj'ing of :expects "describe" by set-descriptor!
(alter-meta! #'wrap-describe update-in [::descriptor :expects] disj "describe")
(defn- dependencies
[set start dir]
(let [ops (start dir)
deps (set/select
(comp seq (partial set/intersection ops) :handles)
set)]
(when (deps start)
(throw (IllegalArgumentException.
(format "Middleware %s depends upon itself via %s"
(:implemented-by start)
dir))))
(concat ops
(mapcat #(dependencies set % dir) deps))))
(defn- comparator
[{a-requires :requires a-expects :expects a-handles :handles}
{b-requires :requires b-expects :expects b-handles :handles}]
(or (->> (into {} [[[a-requires b-handles] -1]
[[a-expects b-handles] 1]
[[b-requires a-handles] 1]
[[b-expects a-handles] -1]])
(map (fn [[sets ret]]
(and (seq (apply set/intersection sets)) ret)))
(some #{-1 1}))
0))
(defn- extend-deps
[middlewares]
(let [descriptor #(-> % meta ::descriptor)
middlewares (concat middlewares
(->> (map descriptor middlewares)
(mapcat (juxt :expects :requires))
(mapcat identity)
(filter var?)))]
(doseq [m (remove descriptor middlewares)]
(binding [*out* *err*]
(printf "[WARNING] No nREPL middleware descriptor in metadata of %s, see clojure.tools.middleware/set-descriptor!" m)))
(let [middlewares (set (for [m middlewares]
(-> (descriptor m)
; only conj'ing m here to support direct reference to
; middleware dependencies in :expects and :requires,
; e.g. interruptable-eval's dep on
; clojure.tools.nrepl.middleware.pr-values/pr-values
(update-in [:handles] (comp set #(conj % m) keys))
(assoc :implemented-by m))))]
(set (for [m middlewares]
(reduce
#(update-in % [%2] into (dependencies middlewares % %2))
m #{:expects :requires}))))))
(defn- conj-sorted
[stack comparator x]
(let [comparisons (->> stack
(map-indexed #(vector % (comparator x %2)))
(remove (comp zero? second)))
lower (ffirst (filter (comp neg? second) comparisons))
upper (ffirst (reverse (filter (comp pos? second) comparisons)))
; default conj'ing at the end, a good default for descriptor-less middlewares
[before after] (split-at (or (and upper (inc upper)) lower (count stack)) stack)]
(into [] (concat before [x] after))))
;; TODO throw exception when the stack doesn't satisfy the requirements of the descriptors involved
(defn linearize-middleware-stack
[middlewares]
(->> middlewares
extend-deps
(sort-by (comp count (partial apply concat) (juxt :expects :requires)))
reverse
(reduce #(conj-sorted % comparator %2) [])
(map :implemented-by)))
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