utils.cljc

(ns schema.utils
  "Private utilities used in schema implementation."
  (:refer-clojure :exclude [record?])
  #?(:clj (:require [clojure.string :as string])
     :cljs (:require
             goog.string.format
             [goog.object :as gobject]
             [goog.string :as gstring]
             [clojure.string :as string]))
  #?(:cljs (:require-macros [schema.utils :refer [char-map]])))

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;;; Miscellaneous helpers

(defn assoc-when
  "Like assoc but only assocs when value is truthy.  Copied from plumbing.core so that
   schema need not depend on plumbing."
  [m & kvs]
  (assert (even? (count kvs)))
  (into (or m {})
        (for [[k v] (partition 2 kvs)
              :when v]
          [k v])))

(defn type-of [x]
  #?(:clj (class x)
     :cljs (js* "typeof ~{}" x)))

(defn fn-schema-bearer
  "What class can we associate the fn schema with? In Clojure use the class of the fn; in
   cljs just use the fn itself."
  [f]
  #?(:clj (class f)
     :cljs f))

(defn format* [fmt & args]
  (apply #?(:clj format :cljs gstring/format) fmt args))

(def max-value-length (atom 19))

(defn value-name
  "Provide a descriptive short name for a value."
  [value]
  (let [t (type-of value)]
    (if (<= (count (str value)) @max-value-length)
      value
      (symbol (str "a-" #?(:clj (.getName ^Class t) :cljs t))))))

#?(:clj
(defmacro char-map []
  clojure.lang.Compiler/CHAR_MAP))

#?(:clj
(defn unmunge
  "TODO: eventually use built in demunge in latest cljs."
  [s]
  (->> (char-map)
       (sort-by #(- (count (second %))))
       (reduce (fn [^String s [to from]] (string/replace s from (str to))) s))))

(defn fn-name
  "A meaningful name for a function that looks like its symbol, if applicable."
  [f]
  #?(:cljs
     (let [[_ s] (re-matches #"#object\[(.*)\]" (pr-str f))]
       (if (= "Function" s)
         "function"
         (->> s demunge (re-find #"[^/]+(?:$|(?=/+$))"))))
     :clj (let [s (.getName (class f))
                slash (.lastIndexOf s "$")
                raw (unmunge
                      (if (>= slash 0)
                        (str (subs s 0 slash) "/" (subs s (inc slash)))
                        s))]
            (string/replace raw #"^clojure.core/" ""))))

(defn record? [x]
  #?(:clj (instance? clojure.lang.IRecord x)
     :cljs (satisfies? IRecord x)))


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;;; Error descriptions

;; A leaf schema validation error, describing the schema and value and why it failed to
;; match the schema.  In Clojure, prints like a form describing the failure that would
;; return true.

(declare validation-error-explain)

(deftype ValidationError [schema value expectation-delay fail-explanation]
  #?(:cljs IPrintWithWriter)
  #?(:cljs (-pr-writer [this writer opts]
             (-pr-writer (validation-error-explain this) writer opts))))

(defn validation-error-explain [^ValidationError err]
  (list (or (.-fail-explanation err) 'not) @(.-expectation-delay err)))

#?(:clj ;; Validation errors print like forms that would return false
(defmethod print-method ValidationError [err writer]
  (print-method (validation-error-explain err) writer)))

(defn make-ValidationError
  "for cljs sake (easier than normalizing imports in macros.clj)"
  [schema value expectation-delay fail-explanation]
  (ValidationError. schema value expectation-delay fail-explanation))


;; Attach a name to an error from a named schema.
(declare named-error-explain)

(deftype NamedError [name error]
  #?(:cljs IPrintWithWriter)
  #?(:cljs (-pr-writer [this writer opts]
             (-pr-writer (named-error-explain this) writer opts))))

(defn named-error-explain [^NamedError err]
  (list 'named (.-error err) (.-name err)))

#?(:clj ;; Validation errors print like forms that would return false
(defmethod print-method NamedError [err writer]
  (print-method (named-error-explain err) writer)))


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;;; Monoidish error containers, which wrap errors (to distinguish from success values).

(defrecord ErrorContainer [error])

(defn error
  "Distinguish a value (must be non-nil) as an error."
  [x] (assert x) (->ErrorContainer x))

(defn error? [x]
  (instance? ErrorContainer x))

(defn error-val [x]
  (when (error? x)
    (.-error ^ErrorContainer x)))


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;;; Registry for attaching schemas to classes, used for defn and defrecord

#?(:clj
(let [^java.util.Map +class-schemata+ (java.util.Collections/synchronizedMap (java.util.WeakHashMap.))]
  (defn declare-class-schema! [klass schema]
    "Globally set the schema for a class (above and beyond a simple instance? check).
   Use with care, i.e., only on classes that you control.  Also note that this
   schema only applies to instances of the concrete type passed, i.e.,
   (= (class x) klass), not (instance? klass x)."
    (assert (class? klass)
            (format* "Cannot declare class schema for non-class %s" (class klass)))
    (.put +class-schemata+ klass schema))

  (defn class-schema [klass]
    "The last schema for a class set by declare-class-schema!, or nil."
    (.get +class-schemata+ klass))))

#?(:cljs
(do
  (defn declare-class-schema! [klass schema]
    (gobject/set klass "schema$utils$schema" schema))

  (defn class-schema [klass]
    (gobject/get klass "schema$utils$schema"))))


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;;; Utilities for fast-as-possible reference to use to turn fn schema validation on/off

(def use-fn-validation
  "Turn on run-time function validation for functions compiled when
   s/compile-fn-validation was true -- has no effect for functions compiled
   when it is false."
  ;; specialize in Clojure for performance
  #?(:clj (java.util.concurrent.atomic.AtomicReference. false)
     :cljs (atom false)))