288 lines
11 KiB
Java
288 lines
11 KiB
Java
package org.json;
|
|
|
|
import static net.lax1dude.eaglercraft.v1_8.HString.format;
|
|
|
|
import java.io.UnsupportedEncodingException;
|
|
import java.net.URLDecoder;
|
|
import java.net.URLEncoder;
|
|
import java.util.ArrayList;
|
|
import java.util.Collections;
|
|
import java.util.List;
|
|
|
|
/*
|
|
Public Domain.
|
|
*/
|
|
|
|
/**
|
|
* A JSON Pointer is a simple query language defined for JSON documents by
|
|
* <a href="https://tools.ietf.org/html/rfc6901">RFC 6901</a>.
|
|
*
|
|
* 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.
|
|
*
|
|
* @author JSON.org
|
|
* @version 2016-05-14
|
|
*/
|
|
public class JSONPointer {
|
|
|
|
// 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 {
|
|
|
|
/**
|
|
* Constructs a new Builder object.
|
|
*/
|
|
public 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.
|
|
* @return a JSONPointer object
|
|
*/
|
|
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:
|
|
*
|
|
* <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();
|
|
}
|
|
|
|
// 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.
|
|
*
|
|
* @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));
|
|
//}
|
|
}
|
|
|
|
/**
|
|
* Constructs a new JSONPointer instance with the provided list of reference tokens.
|
|
*
|
|
* @param refTokens A list of strings representing the reference tokens for the JSON Pointer.
|
|
* Each token identifies a step in the path to the targeted value.
|
|
*/
|
|
public JSONPointer(List<String> refTokens) {
|
|
this.refTokens = new ArrayList<String>(refTokens);
|
|
}
|
|
|
|
/**
|
|
* @see <a href="https://tools.ietf.org/html/rfc6901#section-3">rfc6901 section 3</a>
|
|
*/
|
|
private static String unescape(String token) {
|
|
return token.replace("~1", "/").replace("~0", "~");
|
|
}
|
|
|
|
/**
|
|
* 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 static 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 %s is out of bounds - the array has %d elements", indexToken,
|
|
Integer.valueOf(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.
|
|
* @param token the JSONPointer segment value to be escaped
|
|
* @return the escaped value for the token
|
|
*
|
|
* @see <a href="https://tools.ietf.org/html/rfc6901#section-3">rfc6901 section 3</a>
|
|
*/
|
|
private static String escape(String token) {
|
|
return token.replace("~", "~0")
|
|
.replace("/", "~1");
|
|
}
|
|
|
|
/**
|
|
* Returns a string representing the JSONPointer path value using URI
|
|
* fragment identifier representation
|
|
* @return a uri fragment string
|
|
*/
|
|
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);
|
|
}
|
|
}
|
|
|
|
}
|