/
macros.clj
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/
macros.clj
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(ns schema.macros
"Macros and macro helpers used in schema.core."
(:require
[clojure.string :as str]
[schema.utils :as utils]))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Helpers used in schema.core.
(defn cljs-env?
"Take the &env from a macro, and tell whether we are expanding into cljs."
[env]
(boolean (:ns env)))
(defmacro if-cljs
"Return then if we are generating cljs code and else for Clojure code.
https://groups.google.com/d/msg/clojurescript/iBY5HaQda4A/w1lAQi9_AwsJ"
[then else]
(if (cljs-env? &env) then else))
(defmacro try-catchall
"A cross-platform variant of try-catch that catches all* exceptions.
Does not (yet) support finally, and does not need or want an exception class.
*On the JVM certain fatal exceptions are not caught."
[& body]
(let [try-body (butlast body)
[catch sym & catch-body :as catch-form] (last body)]
(assert (= catch 'catch))
(assert (symbol? sym))
`(if-cljs
(try ~@try-body (~'catch js/Object ~sym ~@catch-body))
(try
~@try-body
;; this whitelist is shamelessly copied from scala
;; https://github.com/scala/scala/blob/2.13.x/src/library/scala/util/control/NonFatal.scala#L42
(~'catch VirtualMachineError e# (throw e#))
(~'catch ThreadDeath e# (throw e#))
(~'catch InterruptedException e# (throw e#))
(~'catch LinkageError e# (throw e#))
(~'catch Throwable ~sym ~@catch-body)))))
(defmacro error!
"Generate a cross-platform exception appropriate to the macroexpansion context"
([s]
`(if-cljs
(throw (js/Error. ~s))
(throw (RuntimeException. ~(with-meta s `{:tag java.lang.String})))))
([s m]
(let [m (merge {:type :schema.core/error} m)]
`(if-cljs
(throw (ex-info ~s ~m))
(throw (clojure.lang.ExceptionInfo. ~(with-meta s `{:tag java.lang.String}) ~m))))))
(defmacro safe-get
"Like get but throw an exception if not found. A macro just to work around cljx function
placement restrictions. "
[m k]
`(let [m# ~m k# ~k]
(if-let [pair# (find m# k#)]
(val pair#)
(error! (utils/format* "Key %s not found in %s" k# m#)))))
(defmacro assert!
"Like assert, but throws a RuntimeException (in Clojure) and takes args to format."
[form & format-args]
`(when-not ~form
(error! (utils/format* ~@format-args))))
(defmacro validation-error [schema value expectation & [fail-explanation]]
`(schema.utils/error
(utils/make-ValidationError ~schema ~value (delay ~expectation) ~fail-explanation)))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Helpers for processing and normalizing element/argument schemas in s/defrecord and s/(de)fn
(defn maybe-split-first [pred s]
(if (pred (first s))
[(first s) (next s)]
[nil s]))
(def primitive-sym? '#{float double boolean byte char short int long
floats doubles booleans bytes chars shorts ints longs objects})
(defn valid-tag? [env tag]
(and (symbol? tag) (or (primitive-sym? tag) (class? (resolve env tag)))))
(defn normalized-metadata
"Take an object with optional metadata, which may include a :tag,
plus an optional explicit schema, and normalize the
object to have a valid Clojure :tag plus a :schema field."
[env imeta explicit-schema]
(let [{:keys [tag s s? schema]} (meta imeta)]
(assert! (not (or s s?)) "^{:s schema} style schemas are no longer supported.")
(assert! (< (count (remove nil? [schema explicit-schema])) 2)
"Expected single schema, got meta %s, explicit %s" (meta imeta) explicit-schema)
(let [schema (or explicit-schema schema tag `schema.core/Any)]
(with-meta imeta
(-> (or (meta imeta) {})
(dissoc :tag)
(utils/assoc-when :schema schema
:tag (let [t (or tag schema)]
(when (valid-tag? env t)
t))))))))
(defn extract-schema-form
"Pull out the schema stored on a thing. Public only because of its use in a public macro."
[symbol]
(let [s (:schema (meta symbol))]
(assert! s "%s is missing a schema" symbol)
s))
(defn extract-arrow-schematized-element
"Take a nonempty seq, which may start like [a ...] or [a :- schema ...], and return
a list of [first-element-with-schema-attached rest-elements]"
[env s]
(assert (seq s))
(let [[f & more] s]
(if (= :- (first more))
[(normalized-metadata env f (second more)) (drop 2 more)]
[(normalized-metadata env f nil) more])))
(defn process-arrow-schematized-args
"Take an arg vector, in which each argument is followed by an optional :- schema,
and transform into an ordinary arg vector where the schemas are metadata on the args."
[env args]
(loop [in args out []]
(if (empty? in)
out
(let [[arg more] (extract-arrow-schematized-element env in)]
(recur more (conj out arg))))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Helpers for schematized fn/defn
(defn split-rest-arg [env bind]
(let [[pre-& [_ rest-arg :as post-&]] (split-with #(not= % '&) bind)]
(if (seq post-&)
(do (assert! (= (count post-&) 2) "& must be followed by a single binding" (vec post-&))
(assert! (or (symbol? rest-arg)
(and (vector? rest-arg)
(not-any? #{'&} rest-arg)))
"Bad & binding form: currently only bare symbols and vectors supported" (vec post-&))
[(vec pre-&)
(if (vector? rest-arg)
(with-meta (process-arrow-schematized-args env rest-arg) (meta rest-arg))
rest-arg)])
[bind nil])))
(defn single-arg-schema-form [rest? [index arg]]
`(~(if rest? `schema.core/optional `schema.core/one)
~(extract-schema-form arg)
~(if (symbol? arg)
`'~arg
`'~(symbol (str (if rest? "rest" "arg") index)))))
(defn simple-arglist-schema-form [rest? regular-args]
(mapv (partial single-arg-schema-form rest?) (map-indexed vector regular-args)))
(defn rest-arg-schema-form [arg]
(let [s (extract-schema-form arg)]
(if (= s `schema.core/Any)
(if (vector? arg)
(simple-arglist-schema-form true arg)
[`schema.core/Any])
(do (assert! (vector? s) "Expected seq schema for rest args, got %s" s)
s))))
(defn input-schema-form [regular-args rest-arg]
(let [base (simple-arglist-schema-form false regular-args)]
(if rest-arg
(vec (concat base (rest-arg-schema-form rest-arg)))
base)))
(defn apply-prepost-conditions
"Replicate pre/postcondition logic from clojure.core/fn."
[body]
(let [[conds body] (maybe-split-first #(and (map? %) (next body)) body)]
(concat (map (fn [c] `(assert ~c)) (:pre conds))
(if-let [post (:post conds)]
`((let [~'% (do ~@body)]
~@(map (fn [c] `(assert ~c)) post)
~'%))
body))))
(def ^:dynamic *compile-fn-validation* (atom true))
(defn compile-fn-validation?
"Returns true if validation should be included at compile time, otherwise false.
Validation is elided for any of the following cases:
* function has :never-validate metadata
* *compile-fn-validation* is false
* *assert* is false AND function is not :always-validate"
[env fn-name]
(let [fn-meta (meta fn-name)]
(and
@*compile-fn-validation*
(not (:never-validate fn-meta))
(or (:always-validate fn-meta)
*assert*))))
(defn process-fn-arity
"Process a single (bind & body) form, producing an output tag, schema-form,
and arity-form which has asserts for validation purposes added that are
executed when turned on, and have very low overhead otherwise.
tag? is a prospective tag for the fn symbol based on the output schema.
schema-bindings are bindings to lift eval outwards, so we don't build the schema
every time we do the validation."
[env fn-name output-schema-sym bind-meta [bind & body]]
(assert! (vector? bind) "Got non-vector binding form %s" bind)
(when-let [bad-meta (seq (filter (or (meta bind) {}) [:tag :s? :s :schema]))]
(throw (RuntimeException. (str "Meta not supported on bindings, put on fn name" (vec bad-meta)))))
(let [original-arglist bind
bind (with-meta (process-arrow-schematized-args env bind) bind-meta)
[regular-args rest-arg] (split-rest-arg env bind)
input-schema-sym (gensym "input-schema")
input-checker-sym (gensym "input-checker")
output-checker-sym (gensym "output-checker")
compile-validation (compile-fn-validation? env fn-name)]
{:schema-binding [input-schema-sym (input-schema-form regular-args rest-arg)]
:more-bindings (when compile-validation
[input-checker-sym `(delay (schema.core/checker ~input-schema-sym))
output-checker-sym `(delay (schema.core/checker ~output-schema-sym))])
:arglist bind
:raw-arglist original-arglist
:arity-form (if compile-validation
(let [bind-syms (vec (repeatedly (count regular-args) gensym))
rest-sym (when rest-arg (gensym "rest"))
metad-bind-syms (with-meta (mapv #(with-meta %1 (meta %2)) bind-syms bind) bind-meta)]
(list
(if rest-arg
(into metad-bind-syms ['& rest-sym])
metad-bind-syms)
`(let [validate# ~(if (:always-validate (meta fn-name))
`true
`(if-cljs (deref ~'ufv__) (.get ~'ufv__)))]
(when validate#
(let [args# ~(if rest-arg
`(list* ~@bind-syms ~rest-sym)
bind-syms)]
(if schema.core/fn-validator
(schema.core/fn-validator :input
'~fn-name
~input-schema-sym
@~input-checker-sym
args#)
(when-let [error# (@~input-checker-sym args#)]
(error! (utils/format* "Input to %s does not match schema: \n\n\t \033[0;33m %s \033[0m \n\n"
'~fn-name (pr-str error#))
{:schema ~input-schema-sym :value args# :error error#})))))
(let [o# (loop ~(into (vec (interleave (map #(with-meta % {}) bind) bind-syms))
(when rest-arg [rest-arg rest-sym]))
~@(apply-prepost-conditions body))]
(when validate#
(if schema.core/fn-validator
(schema.core/fn-validator :output
'~fn-name
~output-schema-sym
@~output-checker-sym
o#)
(when-let [error# (@~output-checker-sym o#)]
(error! (utils/format* "Output of %s does not match schema: \n\n\t \033[0;33m %s \033[0m \n\n"
'~fn-name (pr-str error#))
{:schema ~output-schema-sym :value o# :error error#}))))
o#))))
(cons (into regular-args (when rest-arg ['& rest-arg]))
body))}))
(defn process-fn-
"Process the fn args into a final tag proposal, schema form, schema bindings, and fn form"
[env name fn-body]
(let [compile-validation (compile-fn-validation? env name)
output-schema (extract-schema-form name)
output-schema-sym (gensym "output-schema")
bind-meta (or (when-let [t (:tag (meta name))]
(when (primitive-sym? t)
{:tag t}))
{})
processed-arities (map (partial process-fn-arity env name output-schema-sym bind-meta)
(if (vector? (first fn-body))
[fn-body]
fn-body))
schema-bindings (map :schema-binding processed-arities)
fn-forms (map :arity-form processed-arities)]
{:outer-bindings (vec (concat
(when compile-validation
`[~(with-meta 'ufv__ {:tag 'java.util.concurrent.atomic.AtomicReference}) schema.utils/use-fn-validation])
[output-schema-sym output-schema]
(apply concat schema-bindings)
(mapcat :more-bindings processed-arities)))
:arglists (map :arglist processed-arities)
:raw-arglists (map :raw-arglist processed-arities)
:schema-form (if (= 1 (count processed-arities))
`(schema.core/->FnSchema ~output-schema-sym ~[(ffirst schema-bindings)])
`(schema.core/make-fn-schema ~output-schema-sym ~(mapv first schema-bindings)))
:fn-body fn-forms}))
(defn parse-arity-spec
"Helper for schema.core/=>*."
[spec]
(assert! (vector? spec) "An arity spec must be a vector")
(let [[init more] ((juxt take-while drop-while) #(not= '& %) spec)
fixed (mapv (fn [i s] `(schema.core/one ~s '~(symbol (str "arg" i)))) (range) init)]
(if (empty? more)
fixed
(do (assert! (and (= (count more) 2) (vector? (second more)))
"An arity with & must be followed by a single sequence schema")
(into fixed (second more))))))
(defn emit-defrecord
[defrecord-constructor-sym env name field-schema & more-args]
(let [[extra-key-schema? more-args] (maybe-split-first map? more-args)
[extra-validator-fn? more-args] (maybe-split-first (complement symbol?) more-args)
field-schema (process-arrow-schematized-args env field-schema)]
`(do
(let [bad-keys# (seq (filter #(schema.core/required-key? %)
(keys ~extra-key-schema?)))]
(assert! (not bad-keys#) "extra-key-schema? can not contain required keys: %s"
(vec bad-keys#)))
~(when extra-validator-fn?
`(assert! (fn? ~extra-validator-fn?) "Extra-validator-fn? not a fn: %s"
(type ~extra-validator-fn?)))
(~defrecord-constructor-sym ~name ~field-schema ~@more-args)
(utils/declare-class-schema!
~name
(utils/assoc-when
(schema.core/record
~name
(merge ~(into {}
(for [k field-schema]
[(keyword (clojure.core/name k))
(do (assert! (symbol? k)
"Non-symbol in record binding form: %s" k)
(extract-schema-form k))]))
~extra-key-schema?)
~(symbol (str 'map-> name)))
:extra-validator-fn ~extra-validator-fn?))
~(let [map-sym (gensym "m")]
`(if-cljs
nil
(defn ~(symbol (str 'map-> name))
~(str "Factory function for class " name ", taking a map of keywords to field values, but not much\n"
" slower than ->x like the clojure.core version.\n"
" (performance is fixed in Clojure 1.7, so this should eventually be removed.)")
[~map-sym]
(let [base# (new ~(symbol (str name))
~@(map (fn [s] `(get ~map-sym ~(keyword s))) field-schema))
remaining# (dissoc ~map-sym ~@(map keyword field-schema))]
(if (seq remaining#)
(merge base# remaining#)
base#)))))
~(let [map-sym (gensym "m")]
`(defn ~(symbol (str 'strict-map-> name))
~(str "Factory function for class " name ", taking a map of keywords to field values. All"
" keys are required, and no extra keys are allowed. Even faster than map->")
[~map-sym & [drop-extra-keys?#]]
(when-not (or drop-extra-keys?# (= (count ~map-sym) ~(count field-schema)))
(error! (utils/format* "Wrong number of keys: expected %s, got %s"
(sort ~(mapv keyword field-schema)) (sort (keys ~map-sym)))))
(new ~(symbol (str name))
~@(map (fn [s] `(safe-get ~map-sym ~(keyword s))) field-schema)))))))
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; Public: helpers for schematized functions
(defn normalized-defn-args
"Helper for defining defn-like macros with schemas. Env is &env
from the macro body. Reads optional docstring, return type and
attribute-map and normalizes them into the metadata of the name,
returning the normalized arglist. Based on
clojure.tools.macro/name-with-attributes."
[env macro-args]
(let [[name macro-args] (extract-arrow-schematized-element env macro-args)
[maybe-docstring macro-args] (maybe-split-first string? macro-args)
[maybe-attr-map macro-args] (maybe-split-first map? macro-args)]
(cons (vary-meta name merge
(or maybe-attr-map {})
(when maybe-docstring {:doc maybe-docstring}))
macro-args)))
(defn set-compile-fn-validation!
"Globally turn on or off function validation from being compiled into s/fn and s/defn.
Enabled by default.
See (doc compile-fn-validation?) for all conditions which control fn validation compilation"
[on?]
(reset! *compile-fn-validation* on?))