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jsonld.php
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jsonld.php
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<?php
/**
* PHP implementation of the JSON-LD API.
* Version: 0.4.9-dev
*
* @author Dave Longley
*
* BSD 3-Clause License
* Copyright (c) 2011-2014 Digital Bazaar, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* Neither the name of the Digital Bazaar, Inc. nor the names of its
* contributors may be used to endorse or promote products derived from
* this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
* PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
* TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* Performs JSON-LD compaction.
*
* @param mixed $input the JSON-LD object to compact.
* @param mixed $ctx the context to compact with.
* @param assoc [$options] options to use:
* [base] the base IRI to use.
* [graph] true to always output a top-level graph (default: false).
* [documentLoader(url)] the document loader.
*
* @return mixed the compacted JSON-LD output.
*/
function jsonld_compact($input, $ctx, $options=array()) {
$p = new JsonLdProcessor();
return $p->compact($input, $ctx, $options);
}
/**
* Performs JSON-LD expansion.
*
* @param mixed $input the JSON-LD object to expand.
* @param assoc[$options] the options to use:
* [base] the base IRI to use.
* [documentLoader(url)] the document loader.
*
* @return array the expanded JSON-LD output.
*/
function jsonld_expand($input, $options=array()) {
$p = new JsonLdProcessor();
return $p->expand($input, $options);
}
/**
* Performs JSON-LD flattening.
*
* @param mixed $input the JSON-LD to flatten.
* @param mixed $ctx the context to use to compact the flattened output, or
* null.
* @param [options] the options to use:
* [base] the base IRI to use.
* [documentLoader(url)] the document loader.
*
* @return mixed the flattened JSON-LD output.
*/
function jsonld_flatten($input, $ctx, $options=array()) {
$p = new JsonLdProcessor();
return $p->flatten($input, $ctx, $options);
}
/**
* Performs JSON-LD framing.
*
* @param mixed $input the JSON-LD object to frame.
* @param stdClass $frame the JSON-LD frame to use.
* @param assoc [$options] the framing options.
* [base] the base IRI to use.
* [embed] default @embed flag (default: true).
* [explicit] default @explicit flag (default: false).
* [requireAll] default @requireAll flag (default: true).
* [omitDefault] default @omitDefault flag (default: false).
* [documentLoader(url)] the document loader.
*
* @return stdClass the framed JSON-LD output.
*/
function jsonld_frame($input, $frame, $options=array()) {
$p = new JsonLdProcessor();
return $p->frame($input, $frame, $options);
}
/**
* **Experimental**
*
* Links a JSON-LD document's nodes in memory.
*
* @param mixed $input the JSON-LD document to link.
* @param mixed $ctx the JSON-LD context to apply or null.
* @param assoc [$options] the options to use:
* [base] the base IRI to use.
* [expandContext] a context to expand with.
* [documentLoader(url)] the document loader.
*
* @return the linked JSON-LD output.
*/
function jsonld_link($input, $ctx, $options) {
// API matches running frame with a wildcard frame and embed: '@link'
// get arguments
$frame = new stdClass();
if($ctx) {
$frame->{'@context'} = $ctx;
}
$frame->{'@embed'} = '@link';
return jsonld_frame($input, $frame, $options);
};
/**
* Performs RDF dataset normalization on the given input. The input is
* JSON-LD unless the 'inputFormat' option is used. The output is an RDF
* dataset unless the 'format' option is used.
*
* @param mixed $input the JSON-LD object to normalize.
* @param assoc [$options] the options to use:
* [base] the base IRI to use.
* [intputFormat] the format if input is not JSON-LD:
* 'application/nquads' for N-Quads.
* [format] the format if output is a string:
* 'application/nquads' for N-Quads.
* [documentLoader(url)] the document loader.
*
* @return mixed the normalized output.
*/
function jsonld_normalize($input, $options=array()) {
$p = new JsonLdProcessor();
return $p->normalize($input, $options);
}
/**
* Converts an RDF dataset to JSON-LD.
*
* @param mixed $input a serialized string of RDF in a format specified
* by the format option or an RDF dataset to convert.
* @param assoc [$options] the options to use:
* [format] the format if input not an array:
* 'application/nquads' for N-Quads (default).
* [useRdfType] true to use rdf:type, false to use @type
* (default: false).
* [useNativeTypes] true to convert XSD types into native types
* (boolean, integer, double), false not to (default: false).
*
* @return array the JSON-LD output.
*/
function jsonld_from_rdf($input, $options=array()) {
$p = new JsonLdProcessor();
return $p->fromRDF($input, $options);
}
/**
* Outputs the RDF dataset found in the given JSON-LD object.
*
* @param mixed $input the JSON-LD object.
* @param assoc [$options] the options to use:
* [base] the base IRI to use.
* [format] the format to use to output a string:
* 'application/nquads' for N-Quads.
* [produceGeneralizedRdf] true to output generalized RDF, false
* to produce only standard RDF (default: false).
* [documentLoader(url)] the document loader.
*
* @return mixed the resulting RDF dataset (or a serialization of it).
*/
function jsonld_to_rdf($input, $options=array()) {
$p = new JsonLdProcessor();
return $p->toRDF($input, $options);
}
/**
* JSON-encodes (with unescaped slashes) the given stdClass or array.
*
* @param mixed $input the native PHP stdClass or array which will be
* converted to JSON by json_encode().
* @param int $options the options to use.
* [JSON_PRETTY_PRINT] pretty print.
* @param int $depth the maximum depth to use.
*
* @return the encoded JSON data.
*/
function jsonld_encode($input, $options=0, $depth=512) {
// newer PHP has a flag to avoid escaped '/'
if(defined('JSON_UNESCAPED_SLASHES')) {
return json_encode($input, JSON_UNESCAPED_SLASHES | $options, $depth);
}
// use a simple string replacement of '\/' to '/'.
return str_replace('\\/', '/', json_encode($input, $options, $depth));
}
/**
* Decodes a serialized JSON-LD object.
*
* @param string $input the JSON-LD input.
*
* @return mixed the resolved JSON-LD object, null on error.
*/
function jsonld_decode($input) {
return json_decode($input);
}
/**
* Parses a link header. The results will be key'd by the value of "rel".
*
* Link: <http://json-ld.org/contexts/person.jsonld>; rel="http://www.w3.org/ns/json-ld#context"; type="application/ld+json"
*
* Parses as: {
* 'http://www.w3.org/ns/json-ld#context': {
* target: http://json-ld.org/contexts/person.jsonld,
* type: 'application/ld+json'
* }
* }
*
* If there is more than one "rel" with the same IRI, then entries in the
* resulting map for that "rel" will be arrays of objects, otherwise they will
* be single objects.
*
* @param string $header the link header to parse.
*
* @return assoc the parsed result.
*/
function jsonld_parse_link_header($header) {
$rval = array();
// split on unbracketed/unquoted commas
if(!preg_match_all(
'/(?:<[^>]*?>|"[^"]*?"|[^,])+/', $header, $entries, PREG_SET_ORDER)) {
return $rval;
}
$r_link_header = '/\s*<([^>]*?)>\s*(?:;\s*(.*))?/';
foreach($entries as $entry) {
if(!preg_match($r_link_header, $entry[0], $match)) {
continue;
}
$result = (object)array('target' => $match[1]);
$params = $match[2];
$r_params = '/(.*?)=(?:(?:"([^"]*?)")|([^"]*?))\s*(?:(?:;\s*)|$)/';
preg_match_all($r_params, $params, $matches, PREG_SET_ORDER);
foreach($matches as $match) {
$result->{$match[1]} = $match[2] ?: $match[3];
}
$rel = property_exists($result, 'rel') ? $result->rel : '';
if(!isset($rval[$rel])) {
$rval[$rel] = $result;
} else if(is_array($rval[$rel])) {
$rval[$rel][] = $result;
} else {
$rval[$rel] = array($rval[$rel], $result);
}
}
return $rval;
}
/**
* Relabels all blank nodes in the given JSON-LD input.
*
* @param mixed input the JSON-LD input.
*/
function jsonld_relabel_blank_nodes($input) {
$p = new JsonLdProcessor();
return $p->_labelBlankNodes(new UniqueNamer('_:b'), $input);
}
/** JSON-LD shared in-memory cache. */
global $jsonld_cache;
$jsonld_cache = new stdClass();
/** The default active context cache. */
$jsonld_cache->activeCtx = new ActiveContextCache();
/** Stores the default JSON-LD document loader. */
global $jsonld_default_load_document;
$jsonld_default_load_document = 'jsonld_default_document_loader';
/**
* Sets the default JSON-LD document loader.
*
* @param callable load_document(url) the document loader.
*/
function jsonld_set_document_loader($load_document) {
global $jsonld_default_load_document;
$jsonld_default_load_document = $load_document;
}
/**
* Retrieves JSON-LD at the given URL.
*
* @param string $url the URL to retrieve.
*
* @return the JSON-LD.
*/
function jsonld_get_url($url) {
global $jsonld_default_load_document;
if($jsonld_default_load_document !== null) {
$document_loader = $jsonld_default_load_document;
} else {
$document_loader = 'jsonld_default_document_loader';
}
$remote_doc = call_user_func($document_loader, $url);
if($remote_doc) {
return $remote_doc->document;
}
return null;
}
/**
* The default implementation to retrieve JSON-LD at the given URL.
*
* @param string $url the URL to to retrieve.
*
* @return stdClass the RemoteDocument object.
*/
function jsonld_default_document_loader($url) {
$doc = (object)array(
'contextUrl' => null, 'document' => null, 'documentUrl' => $url);
$redirects = array();
$opts = array(
'http' => array(
'method' => 'GET',
'header' =>
"Accept: application/ld+json\r\n"),
/* Note: Use jsonld_default_secure_document_loader for security. */
'ssl' => array(
'verify_peer' => false,
'allow_self_signed' => true)
);
$context = stream_context_create($opts);
$content_type = null;
stream_context_set_params($context, array('notification' =>
function($notification_code, $severity, $message) use (
&$redirects, &$content_type) {
switch($notification_code) {
case STREAM_NOTIFY_REDIRECTED:
$redirects[] = $message;
break;
case STREAM_NOTIFY_MIME_TYPE_IS:
$content_type = $message;
break;
};
}));
$result = @file_get_contents($url, false, $context);
if($result === false) {
throw new JsonLdException(
'Could not retrieve a JSON-LD document from the URL: ' . $url,
'jsonld.LoadDocumentError', 'loading document failed');
}
$link_header = array();
foreach($http_response_header as $header) {
if(strpos($header, 'link') === 0) {
$value = explode(': ', $header);
if(count($value) > 1) {
$link_header[] = $value[1];
}
}
}
$link_header = jsonld_parse_link_header(join(',', $link_header));
if(isset($link_header['http://www.w3.org/ns/json-ld#context'])) {
$link_header = $link_header['http://www.w3.org/ns/json-ld#context'];
} else {
$link_header = null;
}
if($link_header && $content_type !== 'application/ld+json') {
// only 1 related link header permitted
if(is_array($link_header)) {
throw new JsonLdException(
'URL could not be dereferenced, it has more than one ' .
'associated HTTP Link Header.', 'jsonld.LoadDocumentError',
'multiple context link headers', array('url' => $url));
}
$doc->{'contextUrl'} = $link_header->target;
}
// update document url based on redirects
$redirs = count($redirects);
if($redirs > 0) {
$url = $redirects[$redirs - 1];
}
$doc->document = $result;
$doc->documentUrl = $url;
return $doc;
}
/**
* The default implementation to retrieve JSON-LD at the given secure URL.
*
* @param string $url the secure URL to to retrieve.
*
* @return stdClass the RemoteDocument object.
*/
function jsonld_default_secure_document_loader($url) {
if(strpos($url, 'https') !== 0) {
throw new JsonLdException(
"Could not GET url: '$url'; 'https' is required.",
'jsonld.LoadDocumentError', 'loading document failed');
}
$doc = (object)array(
'contextUrl' => null, 'document' => null, 'documentUrl' => $url);
$redirects = array();
// default JSON-LD https GET implementation
$opts = array(
'http' => array(
'method' => 'GET',
'header' =>
"Accept: application/ld+json\r\n"),
'ssl' => array(
'verify_peer' => true,
'allow_self_signed' => false,
'cafile' => '/etc/ssl/certs/ca-certificates.crt'));
$context = stream_context_create($opts);
$content_type = null;
stream_context_set_params($context, array('notification' =>
function($notification_code, $severity, $message) use (
&$redirects, &$content_type) {
switch($notification_code) {
case STREAM_NOTIFY_REDIRECTED:
$redirects[] = $message;
break;
case STREAM_NOTIFY_MIME_TYPE_IS:
$content_type = $message;
break;
};
}));
$result = @file_get_contents($url, false, $context);
if($result === false) {
throw new JsonLdException(
'Could not retrieve a JSON-LD document from the URL: ' + $url,
'jsonld.LoadDocumentError', 'loading document failed');
}
$link_header = array();
foreach($http_response_header as $header) {
if(strpos($header, 'link') === 0) {
$value = explode(': ', $header);
if(count($value) > 1) {
$link_header[] = $value[1];
}
}
}
$link_header = jsonld_parse_link_header(join(',', $link_header));
if(isset($link_header['http://www.w3.org/ns/json-ld#context'])) {
$link_header = $link_header['http://www.w3.org/ns/json-ld#context'];
} else {
$link_header = null;
}
if($link_header && $content_type !== 'application/ld+json') {
// only 1 related link header permitted
if(is_array($link_header)) {
throw new JsonLdException(
'URL could not be dereferenced, it has more than one ' .
'associated HTTP Link Header.', 'jsonld.LoadDocumentError',
'multiple context link headers', array('url' => $url));
}
$doc->{'contextUrl'} = $link_header->target;
}
// update document url based on redirects
foreach($redirects as $redirect) {
if(strpos($redirect, 'https') !== 0) {
throw new JsonLdException(
"Could not GET redirected url: '$redirect'; 'https' is required.",
'jsonld.LoadDocumentError', 'loading document failed');
}
$url = $redirect;
}
$doc->document = $result;
$doc->documentUrl = $url;
return $doc;
}
/** Registered global RDF dataset parsers hashed by content-type. */
global $jsonld_rdf_parsers;
$jsonld_rdf_parsers = new stdClass();
/**
* Registers a global RDF dataset parser by content-type, for use with
* jsonld_from_rdf. Global parsers will be used by JsonLdProcessors that do
* not register their own parsers.
*
* @param string $content_type the content-type for the parser.
* @param callable $parser(input) the parser function (takes a string as
* a parameter and returns an RDF dataset).
*/
function jsonld_register_rdf_parser($content_type, $parser) {
global $jsonld_rdf_parsers;
$jsonld_rdf_parsers->{$content_type} = $parser;
}
/**
* Unregisters a global RDF dataset parser by content-type.
*
* @param string $content_type the content-type for the parser.
*/
function jsonld_unregister_rdf_parser($content_type) {
global $jsonld_rdf_parsers;
if(property_exists($jsonld_rdf_parsers, $content_type)) {
unset($jsonld_rdf_parsers->{$content_type});
}
}
/**
* Parses a URL into its component parts.
*
* @param string $url the URL to parse.
*
* @return assoc the parsed URL.
*/
function jsonld_parse_url($url) {
if($url === null) {
$url = '';
}
$keys = array(
'href', 'protocol', 'scheme', '?authority', 'authority',
'?auth', 'auth', 'user', 'pass', 'host', '?port', 'port', 'path',
'?query', 'query', '?fragment', 'fragment');
$regex = "/^(([^:\/?#]+):)?(\/\/(((([^:@]*)(?::([^:@]*))?)?@)?([^:\/?#]*)(:(\d*))?))?([^?#]*)(\?([^#]*))?(#(.*))?/";
preg_match($regex, $url, $match);
$rval = array();
$flags = array();
$len = count($keys);
for($i = 0; $i < $len; ++$i) {
$key = $keys[$i];
if(strpos($key, '?') === 0) {
$flags[substr($key, 1)] = !empty($match[$i]);
} else if(!isset($match[$i])) {
$rval[$key] = null;
} else {
$rval[$key] = $match[$i];
}
}
if(!$flags['authority']) {
$rval['authority'] = null;
}
if(!$flags['auth']) {
$rval['auth'] = $rval['user'] = $rval['pass'] = null;
}
if(!$flags['port']) {
$rval['port'] = null;
}
if(!$flags['query']) {
$rval['query'] = null;
}
if(!$flags['fragment']) {
$rval['fragment'] = null;
}
$rval['normalizedPath'] = jsonld_remove_dot_segments(
$rval['path'], !!$rval['authority']);
return $rval;
}
/**
* Removes dot segments from a URL path.
*
* @param string $path the path to remove dot segments from.
* @param bool $has_authority true if the URL has an authority, false if not.
*/
function jsonld_remove_dot_segments($path, $has_authority) {
$rval = '';
if(strpos($path, '/') === 0) {
$rval = '/';
}
// RFC 3986 5.2.4 (reworked)
$input = explode('/', $path);
$output = array();
while(count($input) > 0) {
if($input[0] === '.' || ($input[0] === '' && count($input) > 1)) {
array_shift($input);
continue;
}
if($input[0] === '..') {
array_shift($input);
if($has_authority ||
(count($output) > 0 && $output[count($output) - 1] !== '..')) {
array_pop($output);
} else {
// leading relative URL '..'
$output[] = '..';
}
continue;
}
$output[] = array_shift($input);
}
return $rval . implode('/', $output);
}
/**
* Prepends a base IRI to the given relative IRI.
*
* @param mixed $base a string or the parsed base IRI.
* @param string $iri the relative IRI.
*
* @return string the absolute IRI.
*/
function jsonld_prepend_base($base, $iri) {
// skip IRI processing
if($base === null) {
return $iri;
}
// already an absolute IRI
if(strpos($iri, ':') !== false) {
return $iri;
}
// parse base if it is a string
if(is_string($base)) {
$base = jsonld_parse_url($base);
}
// parse given IRI
$rel = jsonld_parse_url($iri);
// per RFC3986 5.2.2
$transform = array('protocol' => $base['protocol']);
if($rel['authority'] !== null) {
$transform['authority'] = $rel['authority'];
$transform['path'] = $rel['path'];
$transform['query'] = $rel['query'];
} else {
$transform['authority'] = $base['authority'];
if($rel['path'] === '') {
$transform['path'] = $base['path'];
if($rel['query'] !== null) {
$transform['query'] = $rel['query'];
} else {
$transform['query'] = $base['query'];
}
} else {
if(strpos($rel['path'], '/') === 0) {
// IRI represents an absolute path
$transform['path'] = $rel['path'];
} else {
// merge paths
$path = $base['path'];
// append relative path to the end of the last directory from base
if($rel['path'] !== '') {
$idx = strrpos($path, '/');
$idx = ($idx === false) ? 0 : $idx + 1;
$path = substr($path, 0, $idx);
if(strlen($path) > 0 && substr($path, -1) !== '/') {
$path .= '/';
}
$path .= $rel['path'];
}
$transform['path'] = $path;
}
$transform['query'] = $rel['query'];
}
}
// remove slashes and dots in path
$transform['path'] = jsonld_remove_dot_segments(
$transform['path'], !!$transform['authority']);
// construct URL
$rval = $transform['protocol'];
if($transform['authority'] !== null) {
$rval .= '//' . $transform['authority'];
}
$rval .= $transform['path'];
if($transform['query'] !== null) {
$rval .= '?' . $transform['query'];
}
if($rel['fragment'] !== null) {
$rval .= '#' . $rel['fragment'];
}
// handle empty base
if($rval === '') {
$rval = './';
}
return $rval;
}
/**
* Removes a base IRI from the given absolute IRI.
*
* @param mixed $base the base IRI.
* @param string $iri the absolute IRI.
*
* @return string the relative IRI if relative to base, otherwise the absolute
* IRI.
*/
function jsonld_remove_base($base, $iri) {
// skip IRI processing
if($base === null) {
return $iri;
}
if(is_string($base)) {
$base = jsonld_parse_url($base);
}
// establish base root
$root = '';
if($base['href'] !== '') {
$root .= "{$base['protocol']}//{$base['authority']}";
} else if(strpos($iri, '//') === false) {
// support network-path reference with empty base
$root .= '//';
}
// IRI not relative to base
if($root === '' || strpos($iri, $root) !== 0) {
return $iri;
}
// remove root from IRI
$rel = jsonld_parse_url(substr($iri, strlen($root)));
// remove path segments that match (do not remove last segment unless there
// is a hash or query)
$base_segments = explode('/', $base['normalizedPath']);
$iri_segments = explode('/', $rel['normalizedPath']);
$last = ($rel['query'] || $rel['fragment']) ? 0 : 1;
while(count($base_segments) > 0 && count($iri_segments) > $last) {
if($base_segments[0] !== $iri_segments[0]) {
break;
}
array_shift($base_segments);
array_shift($iri_segments);
}
// use '../' for each non-matching base segment
$rval = '';
if(count($base_segments) > 0) {
// don't count the last segment (if it ends with '/' last path doesn't
// count and if it doesn't end with '/' it isn't a path)
array_pop($base_segments);
foreach($base_segments as $segment) {
$rval .= '../';
}
}
// prepend remaining segments
$rval .= implode('/', $iri_segments);
// add query and hash
if($rel['query'] !== null) {
$rval .= "?{$rel['query']}";
}
if($rel['fragment'] !== null) {
$rval .= "#{$rel['fragment']}";
}
if($rval === '') {
$rval = './';
}
return $rval;
}
/**
* A JSON-LD processor.
*/
class JsonLdProcessor {
/** XSD constants */
const XSD_BOOLEAN = 'http://www.w3.org/2001/XMLSchema#boolean';
const XSD_DOUBLE = 'http://www.w3.org/2001/XMLSchema#double';
const XSD_INTEGER = 'http://www.w3.org/2001/XMLSchema#integer';
const XSD_STRING = 'http://www.w3.org/2001/XMLSchema#string';
/** RDF constants */
const RDF_LIST = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#List';
const RDF_FIRST = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#first';
const RDF_REST = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#rest';
const RDF_NIL = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#nil';
const RDF_TYPE = 'http://www.w3.org/1999/02/22-rdf-syntax-ns#type';
const RDF_LANGSTRING =
'http://www.w3.org/1999/02/22-rdf-syntax-ns#langString';
/** Restraints */
const MAX_CONTEXT_URLS = 10;
/** Processor-specific RDF dataset parsers. */
protected $rdfParsers = null;
/**
* Constructs a JSON-LD processor.
*/
public function __construct() {}
/**
* Performs JSON-LD compaction.
*
* @param mixed $input the JSON-LD object to compact.
* @param mixed $ctx the context to compact with.
* @param assoc $options the compaction options.
* [base] the base IRI to use.
* [compactArrays] true to compact arrays to single values when
* appropriate, false not to (default: true).
* [graph] true to always output a top-level graph (default: false).
* [skipExpansion] true to assume the input is expanded and skip
* expansion, false not to, defaults to false.
* [activeCtx] true to also return the active context used.
* [documentLoader(url)] the document loader.
*
* @return mixed the compacted JSON-LD output.
*/
public function compact($input, $ctx, $options) {
global $jsonld_default_load_document;
if($ctx === null) {
throw new JsonLdException(
'The compaction context must not be null.',
'jsonld.CompactError', 'invalid local context');
}
// nothing to compact
if($input === null) {
return null;
}
self::setdefaults($options, array(
'base' => is_string($input) ? $input : '',
'compactArrays' => true,
'graph' => false,
'skipExpansion' => false,
'activeCtx' => false,
'documentLoader' => $jsonld_default_load_document,
'link' => false));
if($options['link']) {
// force skip expansion when linking, "link" is not part of the
// public API, it should only be called from framing
$options['skipExpansion'] = true;
}
if($options['skipExpansion'] === true) {
$expanded = $input;
} else {
// expand input
try {
$expanded = $this->expand($input, $options);
} catch(JsonLdException $e) {
throw new JsonLdException(
'Could not expand input before compaction.',
'jsonld.CompactError', null, null, $e);
}
}
// process context
$active_ctx = $this->_getInitialContext($options);
try {
$active_ctx = $this->processContext($active_ctx, $ctx, $options);
} catch(JsonLdException $e) {
throw new JsonLdException(
'Could not process context before compaction.',
'jsonld.CompactError', null, null, $e);
}
// do compaction
$compacted = $this->_compact($active_ctx, null, $expanded, $options);
if($options['compactArrays'] &&
!$options['graph'] && is_array($compacted)) {
if(count($compacted) === 1) {
// simplify to a single item
$compacted = $compacted[0];
} else if(count($compacted) === 0) {
// simplify to an empty object
$compacted = new stdClass();
}
} else if($options['graph']) {
// always use array if graph option is on
$compacted = self::arrayify($compacted);
}
// follow @context key
if(is_object($ctx) && property_exists($ctx, '@context')) {
$ctx = $ctx->{'@context'};
}
// build output context
$ctx = self::copy($ctx);
$ctx = self::arrayify($ctx);
// remove empty contexts
$tmp = $ctx;
$ctx = array();
foreach($tmp as $v) {
if(!is_object($v) || count(array_keys((array)$v)) > 0) {
$ctx[] = $v;
}
}
// remove array if only one context
$ctx_length = count($ctx);
$has_context = ($ctx_length > 0);
if($ctx_length === 1) {
$ctx = $ctx[0];
}
// add context and/or @graph
if(is_array($compacted)) {
// use '@graph' keyword
$kwgraph = $this->_compactIri($active_ctx, '@graph');
$graph = $compacted;
$compacted = new stdClass();
if($has_context) {
$compacted->{'@context'} = $ctx;
}
$compacted->{$kwgraph} = $graph;
} else if(is_object($compacted) && $has_context) {
// reorder keys so @context is first
$graph = $compacted;
$compacted = new stdClass();
$compacted->{'@context'} = $ctx;
foreach($graph as $k => $v) {
$compacted->{$k} = $v;
}
}
if($options['activeCtx']) {
return array('compacted' => $compacted, 'activeCtx' => $active_ctx);
}
return $compacted;
}
/**
* Performs JSON-LD expansion.
*
* @param mixed $input the JSON-LD object to expand.
* @param assoc $options the options to use:
* [base] the base IRI to use.
* [expandContext] a context to expand with.
* [keepFreeFloatingNodes] true to keep free-floating nodes,
* false not to, defaults to false.
* [documentLoader(url)] the document loader.
*
* @return array the expanded JSON-LD output.
*/
public function expand($input, $options) {
global $jsonld_default_load_document;
self::setdefaults($options, array(
'keepFreeFloatingNodes' => false,
'documentLoader' => $jsonld_default_load_document));
// if input is a string, attempt to dereference remote document
if(is_string($input)) {
$remote_doc = call_user_func($options['documentLoader'], $input);
} else {
$remote_doc = (object)array(
'contextUrl' => null,
'documentUrl' => null,
'document' => $input);
}
try {
if($remote_doc->document === null) {
throw new JsonLdException(
'No remote document found at the given URL.',
'jsonld.NullRemoteDocument');
}
if(is_string($remote_doc->document)) {
$remote_doc->document = self::_parse_json($remote_doc->document);
}
} catch(Exception $e) {
throw new JsonLdException(
'Could not retrieve a JSON-LD document from the URL.',
'jsonld.LoadDocumentError', 'loading document failed',
array('remoteDoc' => $remote_doc), $e);