();
-
- /**
- * Creates a {@code JSONPointer} instance using the tokens previously set using the
- * {@link #append(String)} method calls.
- */
- public JSONPointer build() {
- return new JSONPointer(this.refTokens);
- }
-
- /**
- * Adds an arbitrary token to the list of reference tokens. It can be any non-null value.
- *
- * Unlike in the case of JSON string or URI fragment representation of JSON pointers, the
- * argument of this method MUST NOT be escaped. If you want to query the property called
- * {@code "a~b"} then you should simply pass the {@code "a~b"} string as-is, there is no
- * need to escape it as {@code "a~0b"}.
- *
- * @param token the new token to be appended to the list
- * @return {@code this}
- * @throws NullPointerException if {@code token} is null
- */
- public Builder append(String token) {
- if (token == null) {
- throw new NullPointerException("token cannot be null");
- }
- this.refTokens.add(token);
- return this;
- }
-
- /**
- * Adds an integer to the reference token list. Although not necessarily, mostly this token will
- * denote an array index.
- *
- * @param arrayIndex the array index to be added to the token list
- * @return {@code this}
- */
- public Builder append(int arrayIndex) {
- this.refTokens.add(String.valueOf(arrayIndex));
- return this;
- }
- }
-
- /**
- * Static factory method for {@link Builder}. Example usage:
- *
- *
- * JSONPointer pointer = JSONPointer.builder()
- * .append("obj")
- * .append("other~key").append("another/key")
- * .append("\"")
- * .append(0)
- * .build();
- *
- *
- * @return a builder instance which can be used to construct a {@code JSONPointer} instance by chained
- * {@link Builder#append(String)} calls.
- */
- public static Builder builder() {
- return new Builder();
- }
-
- // Segments for the JSONPointer string
- private final List refTokens;
-
- /**
- * Pre-parses and initializes a new {@code JSONPointer} instance. If you want to
- * evaluate the same JSON Pointer on different JSON documents then it is recommended
- * to keep the {@code JSONPointer} instances due to performance considerations.
- *
- * @param pointer the JSON String or URI Fragment representation of the JSON pointer.
- * @throws IllegalArgumentException if {@code pointer} is not a valid JSON pointer
- */
- public JSONPointer(final String pointer) {
- if (pointer == null) {
- throw new NullPointerException("pointer cannot be null");
- }
- if (pointer.isEmpty() || pointer.equals("#")) {
- this.refTokens = Collections.emptyList();
- return;
- }
- String refs;
- if (pointer.startsWith("#/")) {
- refs = pointer.substring(2);
- try {
- refs = URLDecoder.decode(refs, ENCODING);
- } catch (UnsupportedEncodingException e) {
- throw new RuntimeException(e);
- }
- } else if (pointer.startsWith("/")) {
- refs = pointer.substring(1);
- } else {
- throw new IllegalArgumentException("a JSON pointer should start with '/' or '#/'");
- }
- this.refTokens = new ArrayList();
- int slashIdx = -1;
- int prevSlashIdx = 0;
- do {
- prevSlashIdx = slashIdx + 1;
- slashIdx = refs.indexOf('/', prevSlashIdx);
- if(prevSlashIdx == slashIdx || prevSlashIdx == refs.length()) {
- // found 2 slashes in a row ( obj//next )
- // or single slash at the end of a string ( obj/test/ )
- this.refTokens.add("");
- } else if (slashIdx >= 0) {
- final String token = refs.substring(prevSlashIdx, slashIdx);
- this.refTokens.add(unescape(token));
- } else {
- // last item after separator, or no separator at all.
- final String token = refs.substring(prevSlashIdx);
- this.refTokens.add(unescape(token));
- }
- } while (slashIdx >= 0);
- // using split does not take into account consecutive separators or "ending nulls"
- //for (String token : refs.split("/")) {
- // this.refTokens.add(unescape(token));
- //}
- }
-
- public JSONPointer(List refTokens) {
- this.refTokens = new ArrayList(refTokens);
- }
-
- private String unescape(String token) {
- return token.replace("~1", "/").replace("~0", "~")
- .replace("\\\"", "\"")
- .replace("\\\\", "\\");
- }
-
- /**
- * Evaluates this JSON Pointer on the given {@code document}. The {@code document}
- * is usually a {@link JSONObject} or a {@link JSONArray} instance, but the empty
- * JSON Pointer ({@code ""}) can be evaluated on any JSON values and in such case the
- * returned value will be {@code document} itself.
- *
- * @param document the JSON document which should be the subject of querying.
- * @return the result of the evaluation
- * @throws JSONPointerException if an error occurs during evaluation
- */
- public Object queryFrom(Object document) throws JSONPointerException {
- if (this.refTokens.isEmpty()) {
- return document;
- }
- Object current = document;
- for (String token : this.refTokens) {
- if (current instanceof JSONObject) {
- current = ((JSONObject) current).opt(unescape(token));
- } else if (current instanceof JSONArray) {
- current = readByIndexToken(current, token);
- } else {
- throw new JSONPointerException(format(
- "value [%s] is not an array or object therefore its key %s cannot be resolved", current,
- token));
- }
- }
- return current;
- }
-
- /**
- * Matches a JSONArray element by ordinal position
- * @param current the JSONArray to be evaluated
- * @param indexToken the array index in string form
- * @return the matched object. If no matching item is found a
- * @throws JSONPointerException is thrown if the index is out of bounds
- */
- private Object readByIndexToken(Object current, String indexToken) throws JSONPointerException {
- try {
- int index = Integer.parseInt(indexToken);
- JSONArray currentArr = (JSONArray) current;
- if (index >= currentArr.length()) {
- throw new JSONPointerException(format("index %d is out of bounds - the array has %d elements", index,
- currentArr.length()));
- }
- try {
- return currentArr.get(index);
- } catch (JSONException e) {
- throw new JSONPointerException("Error reading value at index position " + index, e);
- }
- } catch (NumberFormatException e) {
- throw new JSONPointerException(format("%s is not an array index", indexToken), e);
- }
- }
-
- /**
- * Returns a string representing the JSONPointer path value using string
- * representation
- */
- @Override
- public String toString() {
- StringBuilder rval = new StringBuilder("");
- for (String token: this.refTokens) {
- rval.append('/').append(escape(token));
- }
- return rval.toString();
- }
-
- /**
- * Escapes path segment values to an unambiguous form.
- * The escape char to be inserted is '~'. The chars to be escaped
- * are ~, which maps to ~0, and /, which maps to ~1. Backslashes
- * and double quote chars are also escaped.
- * @param token the JSONPointer segment value to be escaped
- * @return the escaped value for the token
- */
- private String escape(String token) {
- return token.replace("~", "~0")
- .replace("/", "~1")
- .replace("\\", "\\\\")
- .replace("\"", "\\\"");
- }
-
- /**
- * Returns a string representing the JSONPointer path value using URI
- * fragment identifier representation
- */
- public String toURIFragment() {
- try {
- StringBuilder rval = new StringBuilder("#");
- for (String token : this.refTokens) {
- rval.append('/').append(URLEncoder.encode(token, ENCODING));
- }
- return rval.toString();
- } catch (UnsupportedEncodingException e) {
- throw new RuntimeException(e);
- }
- }
-
-}