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@lambder
Forked from Chouser/externs_for_cljs.clj
Created April 6, 2016 15:23
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Generate an externs.js file for arbitrary JS libraries for use in advanced Google Closure compilation, based on the ClojureScript code that uses the libraries.
(ns n01se.externs-for-cljs
(:require [clojure.java.io :as io]
[cljs.compiler :as comp]
[cljs.analyzer :as ana]))
(defn read-file [file]
(let [eof (Object.)]
(with-open [stream (clojure.lang.LineNumberingPushbackReader. (io/reader file))]
(vec (take-while #(not= % eof)
(repeatedly #(read stream false eof)))))))
(defn file-analysis [file]
(binding [ana/*cljs-ns* 'cljs.user
ana/*cljs-file* file]
(mapv #(ana/analyze (ana/empty-env) %) (read-file file))))
(defn flat-file-analysis [file]
(mapcat #(tree-seq :children :children %)
(file-analysis file)))
(defn get-vars-used [ffa]
(->> ffa
(filter #(and (= (:op %) :var) (-> % :info :ns)))
(map #(-> % :info :name))
distinct))
(defn var-defined? [sym]
(contains? (:defs (get @ana/namespaces (symbol (namespace sym))))
(symbol (name sym))))
(defn get-undefined-vars [ffa]
(remove var-defined? (get-vars-used ffa)))
(defn externs-for-var [sym]
(if (= "js" (namespace sym))
(format "var %s={};\n" (name sym))
(format "var %s={};\n%s.%s=function(){};\n"
(namespace sym) (namespace sym) (name sym))))
(defn get-interop-used [ffa]
(->> ffa
(filter #(and (= (:op %) :dot)))
(map #(or (:method %) (:field %)))
distinct))
(defn externs-for-interop [sym]
(format "DummyExternClass.%s=function(){};\n" sym))
(defn externs-for-cljs [file]
(swap! ana/namespaces empty)
(ana/analyze-file "cljs/core.cljs")
(let [ffa (flat-file-analysis file)]
(apply str
(concat
(map externs-for-var (get-undefined-vars ffa))
["var DummyExternClass={};\n"]
(map externs-for-interop (get-interop-used ffa))))))
;; (externs-for-cljs "/home/chouser/proj/cljs-example/src/main.cljs")
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