1.1 --- /dev/null	Thu Jan 01 00:00:00 1970 +0000
     1.2 +++ b/src/clojure/contrib/json.clj	Sat Aug 21 06:25:44 2010 -0400
     1.3 @@ -0,0 +1,341 @@
     1.4 +;;; json.clj: JavaScript Object Notation (JSON) parser/writer
     1.5 +
     1.6 +;; by Stuart Sierra, http://stuartsierra.com/
     1.7 +;; January 30, 2010
     1.8 +
     1.9 +;; Copyright (c) Stuart Sierra, 2010. All rights reserved.  The use
    1.10 +;; and distribution terms for this software are covered by the Eclipse
    1.11 +;; Public License 1.0 (http://opensource.org/licenses/eclipse-1.0.php)
    1.12 +;; which can be found in the file epl-v10.html at the root of this
    1.13 +;; distribution.  By using this software in any fashion, you are
    1.14 +;; agreeing to be bound by the terms of this license.  You must not
    1.15 +;; remove this notice, or any other, from this software.
    1.16 +
    1.17 +(ns ^{:author "Stuart Sierra"
    1.18 +       :doc "JavaScript Object Notation (JSON) parser/writer.
    1.19 +  See http://www.json.org/
    1.20 +  To write JSON, use json-str, write-json, or write-json.
    1.21 +  To read JSON, use read-json."}
    1.22 +    clojure.contrib.json
    1.23 +  (:use [clojure.contrib.pprint :only (write formatter-out)]
    1.24 +        [clojure.contrib.string :only (as-str)])
    1.25 +  (:import (java.io PrintWriter PushbackReader StringWriter
    1.26 +                    StringReader Reader EOFException)))
    1.27 +
    1.28 +;;; JSON READER
    1.29 +
    1.30 +(declare read-json-reader)
    1.31 +
    1.32 +(defn- read-json-array [^PushbackReader stream keywordize?]
    1.33 +  ;; Expects to be called with the head of the stream AFTER the
    1.34 +  ;; opening bracket.
    1.35 +  (loop [i (.read stream), result (transient [])]
    1.36 +    (let [c (char i)]
    1.37 +      (cond
    1.38 +       (= i -1) (throw (EOFException. "JSON error (end-of-file inside array)"))
    1.39 +       (Character/isWhitespace c) (recur (.read stream) result)
    1.40 +       (= c \,) (recur (.read stream) result)
    1.41 +       (= c \]) (persistent! result)
    1.42 +       :else (do (.unread stream (int c))
    1.43 +                 (let [element (read-json-reader stream keywordize? true nil)]
    1.44 +                   (recur (.read stream) (conj! result element))))))))
    1.45 +
    1.46 +(defn- read-json-object [^PushbackReader stream keywordize?]
    1.47 +  ;; Expects to be called with the head of the stream AFTER the
    1.48 +  ;; opening bracket.
    1.49 +  (loop [i (.read stream), key nil, result (transient {})]
    1.50 +    (let [c (char i)]
    1.51 +      (cond
    1.52 +       (= i -1) (throw (EOFException. "JSON error (end-of-file inside object)"))
    1.53 +
    1.54 +       (Character/isWhitespace c) (recur (.read stream) key result)
    1.55 +
    1.56 +       (= c \,) (recur (.read stream) nil result)
    1.57 +
    1.58 +       (= c \:) (recur (.read stream) key result)
    1.59 +
    1.60 +       (= c \}) (if (nil? key)
    1.61 +                  (persistent! result)
    1.62 +                  (throw (Exception. "JSON error (key missing value in object)")))
    1.63 +
    1.64 +       :else (do (.unread stream i)
    1.65 +                 (let [element (read-json-reader stream keywordize? true nil)]
    1.66 +                   (if (nil? key)
    1.67 +                     (if (string? element)
    1.68 +                       (recur (.read stream) element result)
    1.69 +                       (throw (Exception. "JSON error (non-string key in object)")))
    1.70 +                     (recur (.read stream) nil
    1.71 +                            (assoc! result (if keywordize? (keyword key) key)
    1.72 +                                    element)))))))))
    1.73 +
    1.74 +(defn- read-json-hex-character [^PushbackReader stream]
    1.75 +  ;; Expects to be called with the head of the stream AFTER the
    1.76 +  ;; initial "\u".  Reads the next four characters from the stream.
    1.77 +  (let [digits [(.read stream)
    1.78 +                (.read stream)
    1.79 +                (.read stream)
    1.80 +                (.read stream)]]
    1.81 +    (when (some neg? digits)
    1.82 +      (throw (EOFException. "JSON error (end-of-file inside Unicode character escape)")))
    1.83 +    (let [chars (map char digits)]
    1.84 +      (when-not (every? #{\0 \1 \2 \3 \4 \5 \6 \7 \8 \9 \a \b \c \d \e \f \A \B \C \D \E \F}
    1.85 +                        chars)
    1.86 +        (throw (Exception. "JSON error (invalid hex character in Unicode character escape)")))
    1.87 +      (char (Integer/parseInt (apply str chars) 16)))))
    1.88 +
    1.89 +(defn- read-json-escaped-character [^PushbackReader stream]
    1.90 +  ;; Expects to be called with the head of the stream AFTER the
    1.91 +  ;; initial backslash.
    1.92 +  (let [c (char (.read stream))]
    1.93 +    (cond
    1.94 +     (#{\" \\ \/} c) c
    1.95 +     (= c \b) \backspace
    1.96 +     (= c \f) \formfeed
    1.97 +     (= c \n) \newline
    1.98 +     (= c \r) \return
    1.99 +     (= c \t) \tab
   1.100 +     (= c \u) (read-json-hex-character stream))))
   1.101 +
   1.102 +(defn- read-json-quoted-string [^PushbackReader stream]
   1.103 +  ;; Expects to be called with the head of the stream AFTER the
   1.104 +  ;; opening quotation mark.
   1.105 +  (let [buffer (StringBuilder.)]
   1.106 +    (loop [i (.read stream)]
   1.107 +      (let [c (char i)]
   1.108 +        (cond
   1.109 +         (= i -1) (throw (EOFException. "JSON error (end-of-file inside string)"))
   1.110 +         (= c \") (str buffer)
   1.111 +         (= c \\) (do (.append buffer (read-json-escaped-character stream))
   1.112 +                      (recur (.read stream)))
   1.113 +         :else (do (.append buffer c)
   1.114 +                   (recur (.read stream))))))))
   1.115 +
   1.116 +(defn- read-json-reader
   1.117 +  ([^PushbackReader stream keywordize? eof-error? eof-value]
   1.118 +     (loop [i (.read stream)]
   1.119 +       (let [c (char i)]
   1.120 +         (cond
   1.121 +          ;; Handle end-of-stream
   1.122 +          (= i -1) (if eof-error?
   1.123 +                     (throw (EOFException. "JSON error (end-of-file)"))
   1.124 +                     eof-value)
   1.125 +
   1.126 +          ;; Ignore whitespace
   1.127 +          (Character/isWhitespace c) (recur (.read stream))
   1.128 +
   1.129 +          ;; Read numbers, true, and false with Clojure reader
   1.130 +          (#{\- \0 \1 \2 \3 \4 \5 \6 \7 \8 \9} c)
   1.131 +          (do (.unread stream i)
   1.132 +              (read stream true nil))
   1.133 +
   1.134 +          ;; Read strings
   1.135 +          (= c \") (read-json-quoted-string stream)
   1.136 +
   1.137 +          ;; Read null as nil
   1.138 +          (= c \n) (let [ull [(char (.read stream))
   1.139 +                              (char (.read stream))
   1.140 +                              (char (.read stream))]]
   1.141 +                     (if (= ull [\u \l \l])
   1.142 +                       nil
   1.143 +                       (throw (Exception. (str "JSON error (expected null): " c ull)))))
   1.144 +
   1.145 +          ;; Read true
   1.146 +          (= c \t) (let [rue [(char (.read stream))
   1.147 +                              (char (.read stream))
   1.148 +                              (char (.read stream))]]
   1.149 +                     (if (= rue [\r \u \e])
   1.150 +                       true
   1.151 +                       (throw (Exception. (str "JSON error (expected true): " c rue)))))
   1.152 +
   1.153 +          ;; Read false
   1.154 +          (= c \f) (let [alse [(char (.read stream))
   1.155 +                               (char (.read stream))
   1.156 +                               (char (.read stream))
   1.157 +                               (char (.read stream))]]
   1.158 +                     (if (= alse [\a \l \s \e])
   1.159 +                       false
   1.160 +                       (throw (Exception. (str "JSON error (expected false): " c alse)))))
   1.161 +
   1.162 +          ;; Read JSON objects
   1.163 +          (= c \{) (read-json-object stream keywordize?)
   1.164 +
   1.165 +          ;; Read JSON arrays
   1.166 +          (= c \[) (read-json-array stream keywordize?)
   1.167 +
   1.168 +          :else (throw (Exception. (str "JSON error (unexpected character): " c))))))))
   1.169 +
   1.170 +(defprotocol Read-JSON-From
   1.171 +  (read-json-from [input keywordize? eof-error? eof-value]
   1.172 +                  "Reads one JSON value from input String or Reader.
   1.173 +  If keywordize? is true, object keys will be converted to keywords.
   1.174 +  If eof-error? is true, empty input will throw an EOFException; if
   1.175 +  false EOF will return eof-value. "))
   1.176 +
   1.177 +(extend-protocol
   1.178 + Read-JSON-From
   1.179 + String
   1.180 + (read-json-from [input keywordize? eof-error? eof-value]
   1.181 +                 (read-json-reader (PushbackReader. (StringReader. input))
   1.182 +                                   keywordize? eof-error? eof-value))
   1.183 + PushbackReader
   1.184 + (read-json-from [input keywordize? eof-error? eof-value]
   1.185 +                 (read-json-reader input
   1.186 +                                   keywordize? eof-error? eof-value))
   1.187 + Reader
   1.188 + (read-json-from [input keywordize? eof-error? eof-value]
   1.189 +                 (read-json-reader (PushbackReader. input)
   1.190 +                                   keywordize? eof-error? eof-value)))
   1.191 +
   1.192 +(defn read-json
   1.193 +  "Reads one JSON value from input String or Reader.
   1.194 +  If keywordize? is true (default), object keys will be converted to
   1.195 +  keywords.  If eof-error? is true (default), empty input will throw
   1.196 +  an EOFException; if false EOF will return eof-value. "
   1.197 +  ([input]
   1.198 +     (read-json-from input true true nil))
   1.199 +  ([input keywordize?]
   1.200 +     (read-json-from input keywordize? true nil))
   1.201 +  ([input keywordize? eof-error? eof-value]
   1.202 +     (read-json-from input keywordize? eof-error? eof-value)))
   1.203 +
   1.204 +
   1.205 +;;; JSON PRINTER
   1.206 +
   1.207 +(defprotocol Write-JSON
   1.208 +  (write-json [object out]
   1.209 +              "Print object to PrintWriter out as JSON"))
   1.210 +
   1.211 +(defn- write-json-string [^CharSequence s ^PrintWriter out]
   1.212 +  (let [sb (StringBuilder. ^Integer (count s))]
   1.213 +    (.append sb \")
   1.214 +    (dotimes [i (count s)]
   1.215 +      (let [cp (Character/codePointAt s i)]
   1.216 +        (cond
   1.217 +         ;; Handle printable JSON escapes before ASCII
   1.218 +         (= cp 34) (.append sb "\\\"")
   1.219 +         (= cp 92) (.append sb "\\\\")
   1.220 +         (= cp 47) (.append sb "\\/")
   1.221 +         ;; Print simple ASCII characters
   1.222 +         (< 31 cp 127) (.append sb (.charAt s i))
   1.223 +         ;; Handle non-printable JSON escapes
   1.224 +         (= cp 8) (.append sb "\\b")
   1.225 +         (= cp 12) (.append sb "\\f")
   1.226 +         (= cp 10) (.append sb "\\n")
   1.227 +         (= cp 13) (.append sb "\\r")
   1.228 +         (= cp 9) (.append sb "\\t")
   1.229 +         ;; Any other character is Hexadecimal-escaped
   1.230 +         :else (.append sb (format "\\u%04x" cp)))))
   1.231 +    (.append sb \")
   1.232 +    (.print out (str sb))))
   1.233 +
   1.234 +(defn- write-json-object [m ^PrintWriter out] 
   1.235 +  (.print out \{)
   1.236 +  (loop [x m]
   1.237 +    (when (seq m)
   1.238 +      (let [[k v] (first x)]
   1.239 +        (when (nil? k)
   1.240 +          (throw (Exception. "JSON object keys cannot be nil/null")))
   1.241 +        (.print out \")
   1.242 +        (.print out (as-str k))
   1.243 +        (.print out \")
   1.244 +        (.print out \:)
   1.245 +        (write-json v out))
   1.246 +      (let [nxt (next x)]
   1.247 +        (when (seq nxt)
   1.248 +          (.print out \,)
   1.249 +          (recur nxt)))))
   1.250 +  (.print out \}))
   1.251 +
   1.252 +(defn- write-json-array [s ^PrintWriter out]
   1.253 +  (.print out \[)
   1.254 +  (loop [x s]
   1.255 +    (when (seq x)
   1.256 +      (let [fst (first x)
   1.257 +            nxt (next x)]
   1.258 +        (write-json fst out)
   1.259 +        (when (seq nxt)
   1.260 +          (.print out \,)
   1.261 +          (recur nxt)))))
   1.262 +  (.print out \]))
   1.263 +
   1.264 +(defn- write-json-bignum [x ^PrintWriter out]
   1.265 +  (.print out (str x)))
   1.266 +
   1.267 +(defn- write-json-plain [x ^PrintWriter out]
   1.268 +  (.print out x))
   1.269 +
   1.270 +(defn- write-json-null [x ^PrintWriter out]
   1.271 +  (.print out "null"))
   1.272 +
   1.273 +(defn- write-json-named [x ^PrintWriter out]
   1.274 +  (write-json-string (name x) out))
   1.275 +
   1.276 +(defn- write-json-generic [x out]
   1.277 +  (if (.isArray (class x))
   1.278 +    (write-json (seq x) out)
   1.279 +    (throw (Exception. (str "Don't know how to write JSON of " (class x))))))
   1.280 +  
   1.281 +(extend nil Write-JSON
   1.282 +        {:write-json write-json-null})
   1.283 +(extend clojure.lang.Named Write-JSON
   1.284 +        {:write-json write-json-named})
   1.285 +(extend java.lang.Boolean Write-JSON
   1.286 +        {:write-json write-json-plain})
   1.287 +(extend java.lang.Number Write-JSON
   1.288 +        {:write-json write-json-plain})
   1.289 +(extend java.math.BigInteger Write-JSON
   1.290 +        {:write-json write-json-bignum})
   1.291 +(extend java.math.BigDecimal Write-JSON
   1.292 +        {:write-json write-json-bignum})
   1.293 +(extend java.lang.CharSequence Write-JSON
   1.294 +        {:write-json write-json-string})
   1.295 +(extend java.util.Map Write-JSON
   1.296 +        {:write-json write-json-object})
   1.297 +(extend java.util.Collection Write-JSON
   1.298 +        {:write-json write-json-array})
   1.299 +(extend clojure.lang.ISeq Write-JSON
   1.300 +        {:write-json write-json-array})
   1.301 +(extend java.lang.Object Write-JSON
   1.302 +        {:write-json write-json-generic})
   1.303 +
   1.304 +(defn json-str
   1.305 +  "Converts x to a JSON-formatted string."
   1.306 +  [x]
   1.307 +  (let [sw (StringWriter.)
   1.308 +        out (PrintWriter. sw)]
   1.309 +    (write-json x out)
   1.310 +    (.toString sw)))
   1.311 +
   1.312 +(defn print-json
   1.313 +  "Write JSON-formatted output to *out*"
   1.314 +  [x]
   1.315 +  (write-json x *out*))
   1.316 +
   1.317 +
   1.318 +;;; JSON PRETTY-PRINTER
   1.319 +
   1.320 +;; Based on code by Tom Faulhaber
   1.321 +
   1.322 +(defn- pprint-json-array [s] 
   1.323 +  ((formatter-out "~<[~;~@{~w~^, ~:_~}~;]~:>") s))
   1.324 +
   1.325 +(defn- pprint-json-object [m]
   1.326 +  ((formatter-out "~<{~;~@{~<~w:~_~w~:>~^, ~_~}~;}~:>") 
   1.327 +   (for [[k v] m] [(as-str k) v])))
   1.328 +
   1.329 +(defn- pprint-json-generic [x]
   1.330 +  (if (.isArray (class x))
   1.331 +    (pprint-json-array (seq x))
   1.332 +    (print (json-str x))))
   1.333 +  
   1.334 +(defn- pprint-json-dispatch [x]
   1.335 +  (cond (nil? x) (print "null")
   1.336 +        (instance? java.util.Map x) (pprint-json-object x)
   1.337 +        (instance? java.util.Collection x) (pprint-json-array x)
   1.338 +        (instance? clojure.lang.ISeq x) (pprint-json-array x)
   1.339 +        :else (pprint-json-generic x)))
   1.340 +
   1.341 +(defn pprint-json
   1.342 +  "Pretty-prints JSON representation of x to *out*"
   1.343 +  [x]
   1.344 +  (write x :dispatch pprint-json-dispatch))