*
* In a nutshell, JSONPointer allows the user to navigate into a JSON document
* using strings, and retrieve targeted objects, like a simple form of XPATH.
- * Path segments are separated by the '/' char, which signifies the root of
- * the document when it appears as the first char of the string. Array
- * elements are navigated using ordinals, counting from 0. JSONPointer strings
- * may be extended to any arbitrary number of segments. If the navigation
- * is successful, the matched item is returned. A matched item may be a
- * JSONObject, a JSONArray, or a JSON value. If the JSONPointer string building
- * fails, an appropriate exception is thrown. If the navigation fails to find
- * a match, a JSONPointerException is thrown.
+ * Path segments are separated by the '/' char, which signifies the root of the
+ * document when it appears as the first char of the string. Array elements are
+ * navigated using ordinals, counting from 0. JSONPointer strings may be
+ * extended to any arbitrary number of segments. If the navigation is
+ * successful, the matched item is returned. A matched item may be a JSONObject,
+ * a JSONArray, or a JSON value. If the JSONPointer string building fails, an
+ * appropriate exception is thrown. If the navigation fails to find a match, a
+ * JSONPointerException is thrown.
*
* @author JSON.org
* @version 2016-05-14
*/
-public class JSONPointer {
+public class JSONPointer
+{
- // used for URL encoding and decoding
- private static final String ENCODING = "utf-8";
+ // used for URL encoding and decoding
+ private static final String ENCODING = "utf-8";
- /**
- * This class allows the user to build a JSONPointer in steps, using
- * exactly one segment in each step.
- */
- public static class Builder {
-
- // Segments for the eventual JSONPointer string
- private final List<String> refTokens = new ArrayList<String>();
-
- /**
- * 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);
- }
+ /**
+ * This class allows the user to build a JSONPointer in steps, using exactly
+ * one segment in each step.
+ */
+ public static class Builder
+ {
- /**
- * 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;
- }
+ // Segments for the eventual JSONPointer string
+ private final List<String> refTokens = new ArrayList<String>();
- /**
- * 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;
- }
+ /**
+ * 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);
}
/**
- * Static factory method for {@link Builder}. Example usage:
+ * Adds an arbitrary token to the list of reference tokens. It can be any
+ * non-null value.
*
- * <pre><code>
- * JSONPointer pointer = JSONPointer.builder()
- * .append("obj")
- * .append("other~key").append("another/key")
- * .append("\"")
- * .append(0)
- * .build();
- * </code></pre>
+ * 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"}.
*
- * @return a builder instance which can be used to construct a {@code JSONPointer} instance by chained
- * {@link Builder#append(String)} calls.
+ * @param token
+ * the new token to be appended to the list
+ * @return {@code this}
+ * @throws NullPointerException
+ * if {@code token} is null
*/
- public static Builder builder() {
- return new Builder();
+ public Builder append(String token)
+ {
+ if (token == null)
+ {
+ throw new NullPointerException("token cannot be null");
+ }
+ this.refTokens.add(token);
+ return this;
}
- // Segments for the JSONPointer string
- private final List<String> 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.
+ * Adds an integer to the reference token list. Although not necessarily,
+ * mostly this token will denote an array index.
*
- * @param pointer the JSON String or URI Fragment representation of the JSON pointer.
- * @throws IllegalArgumentException if {@code pointer} is not a valid JSON pointer
+ * @param arrayIndex
+ * the array index to be added to the token list
+ * @return {@code this}
*/
- 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<String>();
- 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 Builder append(int arrayIndex)
+ {
+ this.refTokens.add(String.valueOf(arrayIndex));
+ return this;
}
+ }
- public JSONPointer(List<String> refTokens) {
- this.refTokens = new ArrayList<String>(refTokens);
- }
+ /**
+ * Static factory method for {@link Builder}. Example usage:
+ *
+ * <pre>
+ * <code>
+ * JSONPointer pointer = JSONPointer.builder()
+ * .append("obj")
+ * .append("other~key").append("another/key")
+ * .append("\"")
+ * .append(0)
+ * .build();
+ * </code>
+ * </pre>
+ *
+ * @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();
+ }
- private String unescape(String token) {
- return token.replace("~1", "/").replace("~0", "~")
- .replace("\\\"", "\"")
- .replace("\\\\", "\\");
- }
+ // Segments for the JSONPointer string
+ private final List<String> refTokens;
- /**
- * 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;
+ /**
+ * 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<String>();
+ 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));
+ // }
+ }
- /**
- * 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);
- }
+ public JSONPointer(List<String> refTokens)
+ {
+ this.refTokens = new ArrayList<String>(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;
+ }
- /**
- * 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();
+ /**
+ * 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);
}
+ }
- /**
- * 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 string
+ * representation
+ */
+ @Override
+ public String toString()
+ {
+ StringBuilder rval = new StringBuilder("");
+ for (String token : this.refTokens)
+ {
+ rval.append('/').append(escape(token));
}
+ return rval.toString();
+ }
- /**
- * 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);
- }
+ /**
+ * 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);
}
-
+ }
+
}
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