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;; Copyright (c) Nicola Mometto, Rich Hickey & contributors.
;; The use and distribution terms for this software are covered by the
;; Eclipse Public License 1.0 (
;; which can be found in the file epl-v10.html at the root of this distribution.
;; By using this software in any fashion, you are agreeing to be bound by
;; the terms of this license.
;; You must not remove this notice, or any other, from this software.
"Analyzer for clojure code, host agnostic.
Entry point:
* analyze
Platform implementers must provide dynamic bindings for:
* macroexpand-1
* parse
* create-var
* var?
See for an example on how to setup the analyzer."
(:refer-clojure :exclude [macroexpand-1 macroexpand var? record?])
(:require [ :refer :all]))
(defmulti -analyze (fn [op form env & _] op))
(defmulti -parse
"Takes a form and an env map and dispatches on the head of the form, a special
(fn [[op & rest] env] op))
(defn analyze
"Given a form to analyze and an environment, a map containing:
* :locals a map from binding symbol to AST of the binding value
* :context a keyword describing the form's context, one of:
** :return the form is in return position
** :statement the return value of the form is not needed
** :expr everything else
* :ns a symbol representing the current namespace of the form to be
analyzed, must be present in the :namespaces map
* :namespaces an atom containing a map from namespace symbol to namespace map,
the namespace map contains the following keys:
** :mappings a map of mappings of the namespace, symbol to var
** :aliases a map of the aliases of the namespace, symbol to symbol
** :ns a symbol representing the namespace
returns an AST for that form.
The AST is a map that is *guaranteed* to have the following keys:
* :op a keyword describing the AST node
* :form the form represented by the AST node
* :env the environment map of the AST node
Additionaly if the AST node contains sub-nodes, it is guaranteed to have:
* :children a vector of the keys of the AST node mapping to the sub-nodes"
[form env]
(let [form (if (seq? form)
(or (seq form) ()) ;; force evaluation for analysis
(symbol? form) (-analyze :symbol form env)
(type? form) (-analyze :const form env :type)
(record? form) (-analyze :const form env :record)
(and (seq? form)
(not (empty? form))) (-analyze :seq form env)
(vector? form) (-analyze :vector form env)
(map? form) (-analyze :map form env)
(set? form) (-analyze :set form env)
:else (-analyze :const form env))))
(defn empty-env
"Returns an empty env"
{:context :expr
:locals {}
:ns 'user
:namespaces (atom
{'user {:mappings {}
:aliases {}
:ns 'user}})})
(defn analyze-in-env
"Takes an env map and returns a function that analyzes a form in that env"
(fn [form] (analyze form env)))
(def ^{:dynamic true
:arglists '([form env])
:doc "If form represents a macro form, returns its expansion,
else returns form."}
(def ^{:dynamic true
:arglists '([[op & args] env])
:doc "Multimethod that dispatches on op, should default to -parse"}
(def ^{:dynamic true
:arglists '([sym env])
:doc "Creates a var for sym and returns it"}
(def ^{:dynamic true
:arglists '([obj])
:doc "Returns true if obj represent a var form as returned by create-var"}
(defn wrapping-meta [{:keys [form env] :as expr}]
(let [meta (meta form)]
(if (and (obj? form)
(seq meta))
{:op :with-meta
:env env
:form form
:meta (analyze meta (ctx env :expr))
:expr (assoc-in expr [:env :context] :expr)
:children [:meta :expr]}
(defmethod -analyze :const
[_ form env & [type]]
(let [type (or type (classify form))
m (meta form)]
{:op :const
:env env
:type type
:literal? true
:val form
:form form}
(when (seq m)
{:meta (-analyze :const m (ctx env :expr) :map)
:children [:meta]}))))
(defmethod -analyze :vector
[_ form env]
(let [items-env (ctx env :expr)
items (mapv (analyze-in-env items-env) form)]
{:op :vector
:env env
:items items
:form form
:children [:items]})))
(defmethod -analyze :map
[_ form env]
(let [kv-env (ctx env :expr)
[keys vals] (reduce-kv (fn [[keys vals] k v]
[(conj keys k) (conj vals v)])
[[] []] form)
ks (mapv (analyze-in-env kv-env) keys)
vs (mapv (analyze-in-env kv-env) vals)]
{:op :map
:env env
:keys ks
:vals vs
:form form
:children [:keys :vals]})))
(defmethod -analyze :set
[_ form env]
(let [items-env (ctx env :expr)
items (mapv (analyze-in-env items-env) form)]
{:op :set
:env env
:items items
:form form
:children [:items]})))
(def specials
"Set of special forms common to every clojure variant"
'#{do if new quote set! try
catch throw finally & def .
let* letfn* loop* recur fn*})
(defn macroexpand
"Repeatedly calls macroexpand-1 on form until it no longer
represents a macro form, then returns it."
[form env]
(loop [mform (macroexpand-1 form env)]
(if (= mform form)
(recur mform))))
(defmethod -analyze :symbol
[_ sym env]
(let [mform (macroexpand-1 sym env)] ;; t.a.j/macroexpand-1 macroexpands Class/Field into (. Class Field)
(if (= mform sym)
(merge (if-let [{:keys [mutable children] :as local-binding} (-> env :locals sym)]
(merge (dissoc local-binding :init)
{:op :local
:assignable? (boolean mutable)
:children (vec (remove #{:init} children))})
(if-let [var (let [v (resolve-var sym env)]
(and (var? v) v))]
{:op :var
:assignable? (dynamic? var)
:var var}
(if-let [maybe-class (namespace sym)] ;; e.g. js/ or Long/MAX_VALUE
(let [maybe-class (symbol maybe-class)]
(if-not (resolve-ns maybe-class env)
{:op :maybe-host-form
:class maybe-class
:field (symbol (name sym))}
(throw (ex-info (str "Could not resolve var: " sym)
(merge {:var mform}
(-source-info sym env))))))
{:op :maybe-class ;; e.g. java.lang.Integer or Long
:class mform})))
{:env env
:form mform})
(analyze (if (obj? mform)
(with-meta mform (meta sym))
(defmethod -analyze :seq
[_ form env]
(let [op (first form)]
(when (nil? op)
(throw (ex-info "Can't call nil" {:form form})))
(let [mform (macroexpand-1 form env)]
(if (= form mform)
(parse mform env) ;; invoke == :default
(analyze (if (obj? mform)
(with-meta mform (meta form))
(defn analyze-block
[exprs env]
(let [statements-env (ctx env :statement)
[statements ret] (loop [statements [] [e & exprs] exprs]
(if (seq exprs)
(recur (conj statements e) exprs)
[statements e]))
statements (mapv (analyze-in-env statements-env) statements)
ret (analyze ret env)]
{:statements statements
:ret ret
:children [:statements :ret]}))
(defmethod -parse 'do
[[_ & exprs :as form] env]
(into {:op :do
:env env
:form form}
(analyze-block exprs env)))
(defmethod -parse 'if
[[_ test then else :as form] env]
(when-not (<= 3 (count form) 4)
(throw (ex-info (str "Wrong number of args to if, had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
(let [test-expr (analyze test (ctx env :expr))
then-expr (analyze then env)
else-expr (analyze else env)]
{:op :if
:form form
:env env
:test test-expr
:then then-expr
:else else-expr
:children [:test :then :else]}))
(defmethod -parse 'new
[[_ class & args :as form] env]
(when-not (>= (count form) 2)
(throw (ex-info (str "Wrong number of args to new, had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
(let [args-env (ctx env :expr)
args (mapv (analyze-in-env args-env) args)]
{:op :new
:env env
:form form
:class class
:args args
:children [:args]}))
(defmethod -parse 'quote
[[_ expr :as form] env]
(when-not (<= 1 (count form) 2)
(throw (ex-info (str "Wrong number of args to quote, had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
(let [const (-analyze :const expr (assoc env :quoted? true))]
{:op :quote
:expr const
:form form
:env env
:literal? true
:children [:expr]}))
(defmethod -parse 'set!
[[_ target val :as form] env]
(when-not (= 3 (count form))
(throw (ex-info (str "Wrong number of args to set!, had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
(let [target (analyze target (ctx env :expr))
val (analyze val (ctx env :expr))]
{:op :set!
:env env
:form form
:target target
:val val
:children [:target :val]}))
(defn analyze-body [body env]
(assoc (parse (cons 'do body) env) :body? true))
(defmethod -parse 'try
[[_ & body :as form] env]
(let [catch? (every-pred seq? #(= (first %) 'catch))
finally? (every-pred seq? #(= (first %) 'finally))
[body tail] (split-with (complement (some-fn catch? finally?)) body)
[cblocks tail] (split-with catch? tail)
[[fblock & fbs :as fblocks] tail] (split-with finally? tail)]
(when-not (empty? tail)
(throw (ex-info "Only catch or finally clause can follow catch in try expression"
(merge {:expr tail
:form form}
(-source-info form env)))))
(when-not (empty? fbs)
(throw (ex-info "Only one finally clause allowed in try expression"
(merge {:expr fblocks
:form form}
(-source-info form env)))))
(let [body (analyze-body body (assoc env :in-try true :no-recur true))
cenv (ctx env :expr)
cblocks (mapv #(parse % cenv) cblocks)
fblock (when-not (empty? fblock)
(analyze-body (rest fblock) (ctx env :statement)))]
(merge {:op :try
:env env
:form form
:body body
:catches cblocks}
(when fblock
{:finally fblock})
{:children `[:body :catches ~@(when fblock [:finally])]}))))
(defmethod -parse 'catch
[[_ etype ename & body :as form] env]
(when (or (not (symbol? ename))
(namespace ename))
(throw (ex-info (str "Bad binding form: " ename)
(merge {:sym ename
:form form}
(-source-info form env)))))
(let [local {:op :binding
:env env
:form ename
:name ename
:local :catch
:tag etype}]
{:op :catch
:class etype
:local local
:env env
:form form
:body (analyze-body body (assoc-in env [:locals ename] local))
:children [:local :body]}))
(defmethod -parse 'throw
[[_ throw :as form] env]
(when-not (= 2 (count form))
(throw (ex-info (str "Wrong number of args to throw, had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
{:op :throw
:env env
:form form
:exception (analyze throw (ctx env :expr))
:children [:exception]})
(defn validate-bindings
[[op bindings & _ :as form] env]
(when-let [error-msg
(not (vector? bindings))
(str op " requires a vector for its bindings, had: "
(class bindings))
(not (even? (count bindings)))
(str op " requires an even number of forms in binding vector, had: "
(count bindings)))]
(throw (ex-info error-msg
(merge {:form form
:bindings bindings}
(-source-info form env))))))
(defmethod -parse 'letfn*
[[_ bindings & body :as form] env]
(validate-bindings form env)
(let [bindings (apply hash-map bindings)
fns (keys bindings)]
(when-not (every? #(and (symbol? %)
(not (namespace %)))
(let [sym (first (remove symbol? fns))]
(throw (ex-info (str "Bad binding form: " sym)
(merge {:form form
:sym sym}
(-source-info form env))))))
(let [binds (reduce (fn [binds name]
(assoc binds name
{:op :binding
:env env
:name name
:form name
:local :letfn}))
{} fns)
e (update-in env [:locals] merge binds)
binds (reduce-kv (fn [binds name bind]
(assoc binds name
(merge bind
{:init (analyze (bindings name)
(ctx e :expr))
:children [:init]})))
{} binds)
e (update-in env [:locals] merge binds)
body (analyze-body body e)]
{:op :letfn
:env env
:form form
:bindings (vec (vals binds))
:body body
:children [:bindings :body]})))
(defn analyze-let
[[op bindings & body :as form] {:keys [context loop-id] :as env}]
(validate-bindings form env)
(let [loop? (= 'loop* op)
env (if loop? (dissoc env :once) env)]
(loop [bindings (partition 2 bindings)
env (ctx env :expr)
binds []]
(if-let [[name init] (first bindings)]
(if (or (not (symbol name))
(namespace name)
(.contains (str name) "."))
(throw (ex-info (str "Bad binding form: " name)
(merge {:form form
:sym name}
(-source-info form env))))
(let [init-expr (analyze init (update-in env [:name] str "$" name))
bind-expr {:op :binding
:env env
:name name
:init init-expr
:form name
:local (if loop? :loop :let)
:children [:init]}]
(recur (next bindings)
(assoc-in env [:locals name] bind-expr)
(conj binds bind-expr))))
(let [body-env (assoc env
:context (if loop? :return context))
body (analyze-body body
(if loop?
(assoc body-env
:loop-id loop-id
:loop-locals (mapv :form binds))
{:body body
:bindings binds
:children [:bindings :body]})))))
(defmethod -parse 'let*
[form env]
(into {:op :let
:form form
:env env}
(analyze-let form env)))
(defmethod -parse 'loop*
[form env]
(let [loop-id (gensym "loop_")
env (dissoc (assoc env :loop-id loop-id) :no-recur)]
(into {:op :loop
:form form
:env env
:loop-id loop-id}
(analyze-let form env))))
(defmethod -parse 'recur
[[_ & exprs :as form] {:keys [context loop-locals loop-id no-recur]
:as env}]
(when-let [error-msg
(not (= :return context))
"Can only recur from tail position"
"Cannot recur across try"
(not (= (count exprs) (count loop-locals)))
(str "Mismatched argument count to recur, expected: " (count loop-locals)
" args, had: " (count exprs)))]
(throw (ex-info error-msg
(merge {:exprs exprs
:form form}
(-source-info form env)))))
(let [exprs (mapv (analyze-in-env (ctx env :expr))
{:op :recur
:env env
:form form
:exprs exprs
:loop-id loop-id
:children [:exprs]}))
(defn analyze-fn-method [[params & body :as form] {:keys [locals local] :as env}]
(when-let [error-msg
(not (every? symbol? params))
(str "Params must be symbols, had: "
(mapv class params))
(some namespace params)
(str "Unexpected namespace in parameter(s) name: "
(seq (filter namespace params))))]
(throw (ex-info error-msg
(merge {:params params
:form form}
(-source-info form env)
(-source-info params env))))) ;; more specific
(let [variadic? (boolean (some '#{&} params))
params-names (vec (remove '#{&} params))
env (dissoc env :local)
arity (count params-names)
params-expr (mapv (fn [name id]
{:env env
:form name
:name name
:variadic? (and variadic?
(= id (dec arity)))
:op :binding
:arg-id id
:local :arg})
params-names (range))
fixed-arity (if variadic?
(dec arity)
loop-id (gensym "loop_")
body-env (into (update-in env [:locals]
merge (zipmap params-names params-expr))
{:context :return
:loop-id loop-id
:loop-locals (mapv :form params-expr)})
body (analyze-body body body-env)]
(when variadic?
(let [x (drop-while #(not= % '&) params)]
(when (= '& (second x))
(throw (ex-info "Invalid parameter list"
(merge {:params params
:form form}
(-source-info form env)
(-source-info params env)))))
(when (not= 2 (count x))
(throw (ex-info (str "Unexpected parameter: " (first (drop 2 x))
" after variadic parameter: " (second x))
(merge {:params params
:form form}
(-source-info form env)
(-source-info params env)))))))
{:op :fn-method
:form form
:loop-id loop-id
:env env
:variadic? variadic?
:params params-expr
:fixed-arity fixed-arity
:body body
:children [:params :body]}
(when local
{:local (dissoc local :env)}))))
(defmethod -parse 'fn*
[[op & args :as form] env]
(let [[n meths] (if (symbol? (first args))
[(first args) (next args)]
[nil (seq args)])
name (or n "fn")
full-name (str (when-let [n (:name env)]
(str n "$")) name (gensym "__"))
name-expr {:op :binding
:env env
:form name
:local :fn
:name name}
env (assoc (dissoc env :once) :name full-name)
e (if n (assoc (assoc-in env [:locals name] name-expr) :local name-expr) env)
menv (assoc (dissoc e :no-recur)
:once (-> op meta :once boolean))
meths (if (vector? (first meths)) (list meths) meths) ;;turn (fn [] ...) into (fn ([]...))
methods-exprs (mapv #(analyze-fn-method % menv) meths)
variadic (seq (filter :variadic? methods-exprs))
variadic? (boolean variadic)
fixed-arities (seq (map :fixed-arity (remove :variadic? methods-exprs)))
max-fixed-arity (when fixed-arities (apply max fixed-arities))]
(when (>= (count variadic) 2)
(throw (ex-info "Can't have more than 1 variadic overload"
(merge {:variadics (mapv :form variadic)
:form form}
(-source-info form env)))))
(when (not= (seq (distinct fixed-arities)) fixed-arities)
(throw (ex-info "Can't have 2 or more overloads with the same arity"
(merge {:form form}
(-source-info form env)))))
(when (and variadic?
(not-every? #(<= (:fixed-arity %)
(:fixed-arity (first variadic)))
(remove :variadic? methods-exprs)))
(throw (ex-info "Can't have fixed arity overload with more params than variadic overload"
(merge {:form form}
(-source-info form env)))))
(merge {:op :fn
:env env
:form form
:name full-name
:variadic? variadic?
:max-fixed-arity max-fixed-arity
:methods methods-exprs}
(when n
{:local name-expr})
{:children `[~@(when n [:local]) :methods]})))
(defmethod -parse 'def
[[_ sym & expr :as form] {:keys [ns namespaces] :as env}]
(when (not (symbol? sym))
(throw (ex-info (str "First argument to def must be a symbol, had: " (class sym))
(merge {:form form}
(-source-info form env)))))
(when (and (namespace sym)
(not= *ns* (the-ns (symbol (namespace sym)))))
(throw (ex-info "Cannot def namespace qualified symbol"
(merge {:form form
:sym sym}
(-source-info form env)))))
(let [pfn (fn
{:init init})
([doc init]
{:pre [(string? doc)]}
{:init init :doc doc}))
args (apply pfn expr)
doc (or (:doc args) (-> sym meta :doc))
arglists (when-let [arglists (:arglists (meta sym))]
(second arglists)) ;; drop quote
sym (with-meta (symbol (name sym)) (meta sym))
meta (merge (meta sym)
(-source-info form env)
(when doc {:doc doc}))
var (create-var sym env)
_ (swap! namespaces assoc-in [ns :mappings sym] var)
sym (with-meta sym meta)
sym (if arglists
(vary-meta sym assoc :arglists arglists)
env (assoc env :name sym)
meta-expr (when meta (analyze meta
(ctx env :expr)))
args (when-let [[_ init] (find args :init)]
(merge args {:init (analyze init (ctx env :expr))}))
children `[~@(when meta [:meta])
~@(when (:init args) [:init])]]
(merge {:op :def
:env env
:form form
:name sym
:var var}
(when meta
{:meta meta-expr}) ;; or meta?
(when-not (empty? children)
{:children children}))))
(defmethod -parse '.
[[_ target & [m-or-f & args] :as form] env]
(when-not (>= (count form) 3)
(throw (ex-info (str "Wrong number of args to ., had: " (dec (count form)))
(merge {:form form}
(-source-info form env)))))
(let [[m-or-f field?] (if (and (symbol? m-or-f)
(= \- (first (name m-or-f))))
[(-> m-or-f name (subs 1) symbol) true]
[(if args (cons m-or-f args) m-or-f) false])
target-expr (analyze target (ctx env :expr))
call? (and (not field?) (seq? m-or-f))]
(when (and call? (not (symbol? (first m-or-f))))
(throw (ex-info (str "Method name must be a symbol, had: " (class (first m-or-f)))
(merge {:form form
:method m-or-f}
(-source-info form env)))))
(merge {:form form
:env env}
{:op :host-call
:target target-expr
:method (symbol (name (first m-or-f)))
:args (mapv (analyze-in-env (ctx env :expr)) (next m-or-f))
:children [:target :args]}
{:op :host-field
:target target-expr
:field (symbol (name m-or-f))
:children [:target]}
{:op :host-interop ;; either field access or single method call
:target target-expr
:m-or-f (symbol (name m-or-f))
:children [:target]}))))
;; invoke
(defmethod -parse :default
[[f & args :as form] env]
(let [e (ctx env :expr)
fn-expr (analyze f e)
args-expr (mapv (analyze-in-env e) args)
m (meta form)]
(merge {:op :invoke
:form form
:env env
:fn fn-expr
:args args-expr}
(when m
{:meta m}) ;; this implies it's not going to be evaluated
{:children [:fn :args]})))
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