package com.fasterxml.jackson.core;
import com.fasterxml.jackson.core.io.NumberInput;
/**
* Implementation of
* <a href="http://tools.ietf.org/html/draft-ietf-appsawg-json-pointer-03">JSON Pointer</a>
* specification.
* Pointer instances can be used to locate logical JSON nodes for things like
* tree traversal (see {@link TreeNode#at}).
* It may be used in future for filtering of streaming JSON content
* as well (not implemented yet for 2.3).
*<p>
* Instances are fully immutable and can be shared, cached.
*
* @author Tatu Saloranta
*
* @since 2.3
*/
public class JsonPointer
{
/**
* Marker instance used to represent segment that matches current
* node or position.
*/
protected final static JsonPointer EMPTY = new JsonPointer();
/**
* Reference to rest of the pointer beyond currently matching
* segment (if any); null if this pointer refers to a matching
* segment.
*/
protected final JsonPointer _nextSegment;
/**
* We will retain representation of the pointer, as a String,
* so that {@link #toString} should be as efficient as possible.
*/
protected final String _asString;
protected final String _matchingPropertyName;
protected final int _matchingElementIndex;
/*
/**********************************************************
/* Cosntruction
/**********************************************************
*/
/**
* Constructor used for creating "empty" instance, used to represent
* state that matches current node.
*/
protected JsonPointer() {
_nextSegment = null;
_matchingPropertyName = "";
_matchingElementIndex = -1;
_asString = "";
}
/**
* Constructor used for creating non-empty Segments
*/
protected JsonPointer(String fullString, String segment, JsonPointer next) {
_asString = fullString;
_nextSegment = next;
// Ok; may always be a property
_matchingPropertyName = segment;
_matchingElementIndex = _parseIndex(segment);
}
/*
/**********************************************************
/* Factory methods
/**********************************************************
*/
/**
* Factory method that parses given input and construct matching pointer
* instance, if it represents a valid JSON Pointer: if not, a
* {@link IllegalArgumentException} is thrown.
*
* @throws IllegalArgumentException Thrown if the input does not present a valid JSON Pointer
* expression: currently the only such expression is one that does NOT start with
* a slash ('/').
*/
public static JsonPointer compile(String input) throws IllegalArgumentException
{
// First quick checks for well-known 'empty' pointer
if ((input == null) || input.length() == 0) {
return EMPTY;
}
// And then quick validity check:
if (input.charAt(0) != '/') {
throw new IllegalArgumentException("Invalid input: JSON Pointer expression must start with '/': "+"\""+input+"\"");
}
return _parseTail(input);
}
/**
* Alias for {@link #compile}; added to make instances automatically
* deserializable by Jackson databind.
*/
public static JsonPointer valueOf(String input) { return compile(input); }
/* Factory method that composes a pointer instance, given a set
* of 'raw' segments: raw meaning that no processing will be done,
* no escaping may is present.
*
* @param segments
*
* @return Constructed path instance
*/
/* TODO!
public static JsonPointer fromSegment(String... segments)
{
if (segments.length == 0) {
return EMPTY;
}
JsonPointer prev = null;
for (String segment : segments) {
JsonPointer next = new JsonPointer()
}
}
*/
/*
/**********************************************************
/* Public API
/**********************************************************
*/
public boolean matches() { return _nextSegment == null; }
public String getMatchingProperty() { return _matchingPropertyName; }
public int getMatchingIndex() { return _matchingElementIndex; }
public boolean mayMatchProperty() { return _matchingPropertyName != null; }
public boolean mayMatchElement() { return _matchingElementIndex >= 0; }
public JsonPointer matchProperty(String name) {
if (_nextSegment == null || !_matchingPropertyName.equals(name)) {
return null;
}
return _nextSegment;
}
public JsonPointer matchElement (int index) {
if ((index != _matchingElementIndex) || (index < 0)) {
return null;
}
return _nextSegment;
}
/**
* Accessor for getting a "sub-pointer", instance where current segment
* has been removed and pointer includes rest of segments;
*/
public JsonPointer tail() {
return _nextSegment;
}
/*
/**********************************************************
/* Standard method overrides
/**********************************************************
*/
@Override public String toString() { return _asString; }
@Override public int hashCode() { return _asString.hashCode(); }
@Override public boolean equals(Object o) {
if (o == this) return true;
if (o == null) return false;
if (!(o instanceof JsonPointer)) return false;
return _asString.equals(((JsonPointer) o)._asString);
}
/*
/**********************************************************
/* Internal methods
/**********************************************************
*/
private final static int _parseIndex(String str) {
final int len = str.length();
// [core#133]: beware of super long indexes; assume we never
// have arrays over 2 billion entries so ints are fine.
if (len == 0 || len > 10) {
return -1;
}
// [core#176]: no leading zeroes allowed
char c = str.charAt(0);
if (c <= '0') {
return (len == 1 && c == '0') ? 0 : -1;
}
if (c > '9') {
return -1;
}
for (int i = 1; i < len; ++i) {
c = str.charAt(i);
if (c > '9' || c < '0') {
return -1;
}
}
if (len == 10) {
long l = NumberInput.parseLong(str);
if (l > Integer.MAX_VALUE) {
return -1;
}
}
return NumberInput.parseInt(str);
}
protected static JsonPointer _parseTail(String input) {
final int end = input.length();
// first char is the contextual slash, skip
for (int i = 1; i < end; ) {
char c = input.charAt(i);
if (c == '/') { // common case, got a segment
return new JsonPointer(input, input.substring(1, i),
_parseTail(input.substring(i)));
}
++i;
// quoting is different; offline this case
if (c == '~' && i < end) { // possibly, quote
return _parseQuotedTail(input, i);
}
// otherwise, loop on
}
// end of the road, no escapes
return new JsonPointer(input, input.substring(1), EMPTY);
}
/**
* Method called to parse tail of pointer path, when a potentially
* escaped character has been seen.
*
* @param input Full input for the tail being parsed
* @param i Offset to character after tilde
*/
protected static JsonPointer _parseQuotedTail(String input, int i) {
final int end = input.length();
StringBuilder sb = new StringBuilder(Math.max(16, end));
if (i > 2) {
sb.append(input, 1, i-1);
}
_appendEscape(sb, input.charAt(i++));
while (i < end) {
char c = input.charAt(i);
if (c == '/') { // end is nigh!
return new JsonPointer(input, sb.toString(),
_parseTail(input.substring(i))); // need to push back slash
}
++i;
if (c == '~' && i < end) {
_appendEscape(sb, input.charAt(i++));
continue;
}
sb.append(c);
}
// end of the road, last segment
return new JsonPointer(input, sb.toString(), EMPTY);
}
private static void _appendEscape(StringBuilder sb, char c) {
if (c == '0') {
c = '~';
} else if (c == '1') {
c = '/';
} else {
sb.append('~');
}
sb.append(c);
}
}