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Java example source code file (xml.clj)

This example Java source code file (xml.clj) is included in the "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

attributes, contenthandler, copyright, hickey, inputstream, license, public, rich, saxexception, saxparserfactory, string, stringbuilder, the, xml

The xml.clj Java example source code

;   Copyright (c) Rich Hickey. All rights reserved.
;   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.

(ns ^{:doc "XML reading/writing."
       :author "Rich Hickey"}
  (:import (org.xml.sax ContentHandler Attributes SAXException)
           (javax.xml.parsers SAXParser SAXParserFactory)))

(def ^:dynamic *stack*)
(def ^:dynamic *current*)
(def ^:dynamic *state*) ; :element :chars :between
(def ^:dynamic *sb*)

(defstruct element :tag :attrs :content)

(def tag (accessor element :tag))
(def attrs (accessor element :attrs))
(def content (accessor element :content))

(def content-handler
  (let [push-content (fn [e c]
                       (assoc e :content (conj (or (:content e) []) c)))
        push-chars (fn []
                     (when (and (= *state* :chars)
                                (some (complement #(Character/isWhitespace (char %))) (str *sb*)))
                       (set! *current* (push-content *current* (str *sb*)))))]
    (new clojure.lang.XMLHandler
         (proxy [ContentHandler] []
           (startElement [uri local-name q-name ^Attributes atts]
             (let [attrs (fn [ret i]
                           (if (neg? i)
                             (recur (assoc ret
                                           (clojure.lang.Keyword/intern (symbol (.getQName atts i)))
                                           (.getValue atts (int i)))
                                    (dec i))))
                   e (struct element
                             (. clojure.lang.Keyword (intern (symbol q-name)))
                             (when (pos? (.getLength atts))
                               (attrs {} (dec (.getLength atts)))))]
               (set! *stack* (conj *stack* *current*))
               (set! *current* e)
               (set! *state* :element))
           (endElement [uri local-name q-name]
             (set! *current* (push-content (peek *stack*) *current*))
             (set! *stack* (pop *stack*))
             (set! *state* :between)
           (characters [^chars ch start length]
             (when-not (= *state* :chars)
               (set! *sb* (new StringBuilder)))
             (let [^StringBuilder sb *sb*]
               (.append sb ch (int start) (int length))
               (set! *state* :chars))
           (setDocumentLocator [locator])
           (startDocument [])
           (endDocument [])
           (startPrefixMapping [prefix uri])
           (endPrefixMapping [prefix])
           (ignorableWhitespace [ch start length])
           (processingInstruction [target data])
           (skippedEntity [name])

(defn startparse-sax [s ch]
  (.. SAXParserFactory (newInstance) (newSAXParser) (parse s ch)))

(defn parse
  "Parses and loads the source s, which can be a File, InputStream or
  String naming a URI. Returns a tree of the xml/element struct-map,
  which has the keys :tag, :attrs, and :content. and accessor fns tag,
  attrs, and content. Other parsers can be supplied by passing
  startparse, a fn taking a source and a ContentHandler and returning
  a parser"
  {:added "1.0"}
  ([s] (parse s startparse-sax))
  ([s startparse]
    (binding [*stack* nil
              *current* (struct element)
              *state* :between
              *sb* nil]
      (startparse s content-handler)
      ((:content *current*) 0)))) 

(defn emit-element [e]
  (if (instance? String e)
    (println e)
      (print (str "<" (name (:tag e))))
      (when (:attrs e)
	(doseq [attr (:attrs e)]
	  (print (str " " (name (key attr)) "='" (val attr)"'"))))
      (if (:content e)
	  (println ">")
	  (doseq [c (:content e)]
	    (emit-element c))
	  (println (str "</" (name (:tag e)) ">")))
	(println "/>")))))

(defn emit [x]
  (println "<?xml version='1.0' encoding='UTF-8'?>")
  (emit-element x))

;(export '(tag attrs content parse element emit emit-element))

;(load-file "/Users/rich/dev/clojure/src/xml.clj")
;(def x (xml/parse ""))

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