| 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 |
| { |
| /** |
| * Character used to separate segments. |
| */ |
| public final static char SEPARATOR = '/'; |
| |
| /** |
| * Marker instance used to represent segment that matches current |
| * node or position (that is, returns true for |
| * {@link #matches()}). |
| */ |
| 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 the matching |
| * segment. |
| */ |
| protected final JsonPointer _nextSegment; |
| |
| /** |
| * Reference from currently matching segment (if any) to node |
| * before leaf. |
| * Lazily constructed if/as needed. |
| *<p> |
| * NOTE: we'll use `volatile` here assuming that this is unlikely to |
| * become a performance bottleneck. If it becomes one we can probably |
| * just drop it and things still should work (despite warnings as per JMM |
| * regarding visibility (and lack thereof) of unguarded changes). |
| * |
| * @since 2.5 |
| */ |
| protected volatile JsonPointer _head; |
| |
| /** |
| * 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; |
| |
| /* |
| /********************************************************** |
| /* Construction |
| /********************************************************** |
| */ |
| |
| /** |
| * 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; |
| // but could be an index, if parsable |
| _matchingElementIndex = _parseIndex(segment); |
| } |
| |
| /** |
| * @since 2.5 |
| */ |
| protected JsonPointer(String fullString, String segment, int matchIndex, JsonPointer next) { |
| _asString = fullString; |
| _nextSegment = next; |
| _matchingPropertyName = segment; |
| _matchingElementIndex = matchIndex; |
| } |
| |
| /* |
| /********************************************************** |
| /* 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; } |
| |
| /** |
| * Returns the leaf of current JSON Pointer expression. |
| * Leaf is the last non-null segment of current JSON Pointer. |
| * |
| * @since 2.5 |
| */ |
| public JsonPointer last() { |
| JsonPointer current = this; |
| if (current == EMPTY) { |
| return null; |
| } |
| JsonPointer next; |
| while ((next = current._nextSegment) != JsonPointer.EMPTY) { |
| current = next; |
| } |
| return current; |
| } |
| |
| public JsonPointer append(JsonPointer tail) { |
| if (this == EMPTY) { |
| return tail; |
| } |
| if (tail == EMPTY) { |
| return this; |
| } |
| String currentJsonPointer = _asString; |
| if (currentJsonPointer.endsWith("/")) { |
| //removes final slash |
| currentJsonPointer = currentJsonPointer.substring(0, currentJsonPointer.length()-1); |
| } |
| return compile(currentJsonPointer + tail._asString); |
| } |
| |
| /** |
| * Method that may be called to see if the pointer would match property |
| * (of a JSON Object) with given name. |
| * |
| * @since 2.5 |
| */ |
| public boolean matchesProperty(String name) { |
| return (_nextSegment != null) && _matchingPropertyName.equals(name); |
| } |
| |
| public JsonPointer matchProperty(String name) { |
| if ((_nextSegment != null) && _matchingPropertyName.equals(name)) { |
| return _nextSegment; |
| } |
| return null; |
| } |
| |
| /** |
| * Method that may be called to see if the pointer would match |
| * array element (of a JSON Array) with given index. |
| * |
| * @since 2.5 |
| */ |
| public boolean matchesElement(int index) { |
| return (index == _matchingElementIndex) && (index >= 0); |
| } |
| |
| /** |
| * @since 2.6 |
| */ |
| 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. |
| * For matching state, will return null. |
| */ |
| public JsonPointer tail() { |
| return _nextSegment; |
| } |
| |
| /** |
| * Accessor for getting a pointer instance that is identical to this |
| * instance except that the last segment has been dropped. |
| * For example, for JSON Point "/root/branch/leaf", this method would |
| * return pointer "/root/branch" (compared to {@link #tail()} that |
| * would return "/branch/leaf"). |
| * For leaf |
| * |
| * @since 2.5 |
| */ |
| public JsonPointer head() { |
| JsonPointer h = _head; |
| if (h == null) { |
| if (this != EMPTY) { |
| h = _constructHead(); |
| } |
| _head = h; |
| } |
| return h; |
| } |
| |
| /* |
| /********************************************************** |
| /* 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))); |
| } |
| ++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); |
| } |
| |
| protected JsonPointer _constructHead() |
| { |
| // ok; find out who we are to drop |
| JsonPointer last = last(); |
| if (last == this) { |
| return EMPTY; |
| } |
| // and from that, length of suffix to drop |
| int suffixLength = last._asString.length(); |
| JsonPointer next = _nextSegment; |
| return new JsonPointer(_asString.substring(0, _asString.length() - suffixLength), _matchingPropertyName, |
| _matchingElementIndex, next._constructHead(suffixLength, last)); |
| } |
| |
| protected JsonPointer _constructHead(int suffixLength, JsonPointer last) |
| { |
| if (this == last) { |
| return EMPTY; |
| } |
| JsonPointer next = _nextSegment; |
| String str = _asString; |
| return new JsonPointer(str.substring(0, str.length() - suffixLength), _matchingPropertyName, |
| _matchingElementIndex, next._constructHead(suffixLength, last)); |
| } |
| |
| private static void _appendEscape(StringBuilder sb, char c) { |
| if (c == '0') { |
| c = '~'; |
| } else if (c == '1') { |
| c = '/'; |
| } else { |
| sb.append('~'); |
| } |
| sb.append(c); |
| } |
| } |