SvnWrapper.clj

(ns com.indeed.svnkit_wrapper.SvnWrapper
  (:import (org.basex.query QueryModule QueryModule$Requires QueryModule$Permission QueryModule$Deterministic))
  (:gen-class
    :main false
    :extends org.basex.query.QueryModule
    :methods [^{:static true
                QueryModule$Requires QueryModule$Permission/NONE}
              [cat [java.lang.String] java.lang.String]
              ^{:static true
                QueryModule$Deterministic {}
                QueryModule$Requires QueryModule$Permission/NONE}
              [catRev [java.lang.String int] java.lang.String]]))

(def instances (proxy [java.lang.ThreadLocal] [] (initialValue [] (ref {}))))

(defn build-url-seq [url-str] (seq (.split url-str "/")))

(defn build-trie [seed & kvs]
  (reduce
   (fn [trie [k v]]
     (assoc-in trie (concat k [:val]) v))
   seed
   (partition 2 kvs)))

(defn trie-prefix-match [target trie]
  (when (seq target)
    (when-let [node (trie (first target))]
      (or (:val node)
          (recur (rest target) node)))))

(defn get-instance [url-str]
	(dosync
		(if-let [repository (trie-prefix-match (build-url-seq url-str) @(.get instances))]
			repository
			(let [url (org.tmatesoft.svn.core.SVNURL/parseURIDecoded url-str)
			      repository (org.tmatesoft.svn.core.io.SVNRepositoryFactory/create url)
			      root-url (.getRepositoryRoot repository true)
			      root-url-str (.toString root-url)]
				(.setLocation repository root-url false)
				(alter (.get instances) build-trie (build-url-seq root-url-str) repository)
				repository))))

(defn cat
  ([filename] (cat filename -1))
  ([filename revision]
	(try
		(let [output-stream (java.io.ByteArrayOutputStream.)
		      repository (get-instance filename)
		      rel-loc (.substring filename (.. repository (getRepositoryRoot false) toString length))]
			(.getFile repository rel-loc -1 nil output-stream)
			(.toString output-stream))
		(catch org.tmatesoft.svn.core.SVNException e
			(if (= (.. e getErrorMessage getErrorCode)
                               org.tmatesoft.svn.core.SVNErrorCode/FS_NOT_FOUND)
                          nil
                          (throw e))))))

(defn -cat
  [filename] (cat filename))

(defn -catRev
  ([filename revision] (cat filename revision)))