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arangodb/js/actions/api-traversal.js

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JavaScript

/*jshint strict: false */
////////////////////////////////////////////////////////////////////////////////
/// @brief traversal actions
///
/// @file
///
/// DISCLAIMER
///
/// Copyright 2014 ArangoDB GmbH, Cologne, Germany
///
/// Licensed under the Apache License, Version 2.0 (the "License");
/// you may not use this file except in compliance with the License.
/// You may obtain a copy of the License at
///
/// http://www.apache.org/licenses/LICENSE-2.0
///
/// Unless required by applicable law or agreed to in writing, software
/// distributed under the License is distributed on an "AS IS" BASIS,
/// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
/// See the License for the specific language governing permissions and
/// limitations under the License.
///
/// Copyright holder is ArangoDB GmbH, Cologne, Germany
///
/// @author Jan Steemann
/// @author Copyright 2014, ArangoDB GmbH, Cologne, Germany
/// @author Copyright 2013, triAGENS GmbH, Cologne, Germany
////////////////////////////////////////////////////////////////////////////////
var arangodb = require("org/arangodb");
var actions = require("org/arangodb/actions");
var db = require("internal").db;
var traversal = require("org/arangodb/graph/traversal");
var Traverser = traversal.Traverser;
var graph = require("org/arangodb/general-graph");
// -----------------------------------------------------------------------------
// --SECTION-- private functions
// -----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////
/// @brief create a "bad parameter" error
////////////////////////////////////////////////////////////////////////////////
function badParam (req, res, message) {
actions.resultBad(req,
res,
arangodb.ERROR_HTTP_BAD_PARAMETER,
message);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief create a "not found" error
////////////////////////////////////////////////////////////////////////////////
function notFound (req, res, code, message) {
actions.resultNotFound(req,
res,
code,
message);
}
////////////////////////////////////////////////////////////////////////////////
/// @brief execute a server-side traversal
/// @startDocuBlock JSF_HTTP_API_TRAVERSAL
///
/// @RESTHEADER{POST /_api/traversal,executes a traversal}
///
/// @RESTBODYPARAM{body,string,required}
///
/// @RESTDESCRIPTION
/// Starts a traversal starting from a given vertex and following.
/// edges contained in a given edgeCollection. The request must
/// contain the following attributes.
///
/// - *startVertex*: id of the startVertex, e.g. *"users/foo"*.
///
/// - *edgeCollection*: (optional) name of the collection that contains the edges.
///
/// - *graphName*: (optional) name of the graph that contains the edges.
/// Either *edgeCollection* or *graphName* has to be given.
/// In case both values are set the *graphName* is prefered.
///
/// - *filter* (optional, default is to include all nodes):
/// body (JavaScript code) of custom filter function
/// function signature: (config, vertex, path) -> mixed
/// can return four different string values:
/// - *"exclude"* -> this vertex will not be visited.
/// - *"prune"* -> the edges of this vertex will not be followed.
/// - *""* or *undefined* -> visit the vertex and follow it's edges.
/// - *Array* -> containing any combination of the above.
/// If there is at least one *"exclude"* or *"prune"* respectivly
/// is contained, it's effect will occur.
///
/// - *minDepth* (optional, ANDed with any existing filters):
/// visits only nodes in at least the given depth
///
/// - *maxDepth* (optional, ANDed with any existing filters):
/// visits only nodes in at most the given depth
///
/// - *visitor* (optional): body (JavaScript) code of custom visitor function
/// function signature: (config, result, vertex, path) -> void
/// visitor function can do anything, but its return value is ignored. To
/// populate a result, use the *result* variable by reference
///
/// - *direction* (optional): direction for traversal
/// - *if set*, must be either *"outbound"*, *"inbound"*, or *"any"*
/// - *if not set*, the *expander* attribute must be specified
///
/// - *init* (optional): body (JavaScript) code of custom result initialisation function
/// function signature: (config, result) -> void
/// initialise any values in result with what is required
///
/// - *expander* (optional): body (JavaScript) code of custom expander function
/// *must* be set if *direction* attribute is **not** set
/// function signature: (config, vertex, path) -> array
/// expander must return an array of the connections for *vertex*
/// each connection is an object with the attributes *edge* and *vertex*
/// - *sort* (optional): body (JavaScript) code of a custom comparison function
/// for the edges. The signature of this function is
/// (l, r) -> integer (where l and r are edges) and must
/// return -1 if l is smaller than, +1 if l is greater than,
/// and 0 if l and r are equal. The reason for this is the
/// following: The order of edges returned for a certain
/// vertex is undefined. This is because there is no natural
/// order of edges for a vertex with multiple connected edges.
/// To explicitly define the order in which edges on the
/// vertex are followed, you can specify an edge comparator
/// function with this attribute. Note that the value here has
/// to be a string to conform to the JSON standard, which in
/// turn is parsed as function body on the server side. Furthermore
/// note that this attribute is only used for the standard
/// expanders. If you use your custom expander you have to
/// do the sorting yourself within the expander code.
///
/// - *strategy* (optional): traversal strategy
/// can be *"depthfirst"* or *"breadthfirst"*
///
/// - *order* (optional): traversal order
/// can be *"preorder"* or *"postorder"*
///
/// - *itemOrder* (optional): item iteration order
/// can be *"forward"* or *"backward"*
///
/// - *uniqueness* (optional): specifies uniqueness for vertices and edges visited
/// if set, must be an object like this:
/// *"uniqueness": {"vertices": "none"|"global"|path", "edges": "none"|"global"|"path"}*
///
/// - *maxIterations* (optional): Maximum number of iterations in each traversal. This number can be
/// set to prevent endless loops in traversal of cyclic graphs. When a traversal performs
/// as many iterations as the *maxIterations* value, the traversal will abort with an
/// error. If *maxIterations* is not set, a server-defined value may be used.
///
///
/// If the Traversal is successfully executed *HTTP 200* will be returned.
/// Additionally the *result* object will be returned by the traversal.
///
/// For successful traversals, the returned JSON object has the
/// following properties:
///
/// - *error*: boolean flag to indicate if an error occurred (*false*
/// in this case)
///
/// - *code*: the HTTP status code
///
/// - *result*: the return value of the traversal
///
/// If the traversal specification is either missing or malformed, the server
/// will respond with *HTTP 400*.
///
/// The body of the response will then contain a JSON object with additional error
/// details. The object has the following attributes:
///
/// - *error*: boolean flag to indicate that an error occurred (*true* in this case)
///
/// - *code*: the HTTP status code
///
/// - *errorNum*: the server error number
///
/// - *errorMessage*: a descriptive error message
///
/// @RESTRETURNCODES
///
/// @RESTRETURNCODE{200}
/// If the traversal is fully executed
/// *HTTP 200* will be returned.
///
/// @RESTRETURNCODE{400}
/// If the traversal specification is either missing or malformed, the server
/// will respond with *HTTP 400*.
///
/// @RESTRETURNCODE{404}
/// The server will responded with *HTTP 404* if the specified edge collection
/// does not exist, or the specified start vertex cannot be found.
///
/// @RESTRETURNCODE{500}
/// The server will responded with *HTTP 500* when an error occurs inside the
/// traversal or if a traversal performs more than *maxIterations* iterations.
///
/// *Examples*
///
/// In the following examples the underlying graph will contain five persons
/// *Alice*, *Bob*, *Charlie*, *Dave* and *Eve*.
/// We will have the following directed relations:
/// - *Alice* knows *Bob*
/// - *Bob* knows *Charlie*
/// - *Bob* knows *Dave*
/// - *Eve* knows *Alice*
/// - *Eve* knows *Bob*
///
/// The starting vertex will always be Alice.
///
/// Follow only outbound edges:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalOutbound}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound"}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Follow only inbound edges:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalInbound}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "inbound"}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Follow any direction of edges:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalAny}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// uniqueness: {
/// vertices: "none",
/// edges: "global"
/// }
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Excluding *Charlie* and *Bob*:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalFilterExclude}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound", ';
/// body += '"filter" : "if (vertex.name === \\"Bob\\" || ';
/// body += 'vertex.name === \\"Charlie\\") {';
/// body += 'return \\"exclude\\";'
/// body += '}'
/// body += 'return;"}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Do not follow edges from *Bob*:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalFilterPrune}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound", ';
/// body += '"filter" : "if (vertex.name === \\"Bob\\") {';
/// body += 'return \\"prune\\";'
/// body += '}'
/// body += 'return;"}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Visit only nodes in a depth of at least 2:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalMinDepth}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound", ';
/// body += '"minDepth" : 2}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Visit only nodes in a depth of at most 1:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalMaxDepth}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound", ';
/// body += '"maxDepth" : 1}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Count all visited nodes and return a list of nodes only:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalVisitorCountAndList}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = '{ "startVertex": "' + a + '", ';
/// body += '"graphName" : "' + g.__name + '", ';
/// body += '"direction" : "outbound", ';
/// body += '"init" : "result.visited = 0; result.myVertices = [ ];", ';
/// body += '"visitor" : "result.visited++; result.myVertices.push(vertex);"}';
///
/// var response = logCurlRequest('POST', url, body);
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Expand only inbound edges of *Alice* and outbound edges of *Eve*:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalVisitorExpander}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// expander: "var connections = [ ];" +
/// "if (vertex.name === \"Alice\") {" +
/// "config.datasource.getInEdges(vertex).forEach(function (e) {" +
/// "connections.push({ " +
/// "vertex: require(\"internal\").db._document(e._from), " +
/// "edge: e" +
/// "});" +
/// "});" +
/// "}" +
/// "if (vertex.name === \"Eve\") {" +
/// "config.datasource.getOutEdges(vertex).forEach(function (e) {" +
/// "connections.push({" +
/// "vertex: require(\"internal\").db._document(e._to), " +
/// "edge: e" +
/// "});" +
/// "});" +
/// "}" +
/// "return connections;"
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Follow the *depthfirst* strategy:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalDepthFirst}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// strategy: "depthfirst"
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Using *postorder* ordering:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalPostorder}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// order: "postorder"
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Using *backward* item-ordering:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalBackwardItemOrder}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// itemOrder: "backward"
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// Edges should only be included once globally,
/// but nodes are included every time they are visited:
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalEdgeUniqueness}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// uniqueness: {
/// vertices: "none",
/// edges: "global"
/// }
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 200);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// If the underlying graph is cyclic, *maxIterations* should be set:
///
/// The underlying graph has two vertices *Alice* and *Bob*.
/// With the directed edges:
/// - *Alice* knows *Bob*
/// _ *Bob* knows *Alice*
///
///
/// @EXAMPLE_ARANGOSH_RUN{RestTraversalMaxIterations}
/// var examples = require("org/arangodb/graph-examples/example-graph.js");
/// var g = examples.loadGraph("knows_graph");
/// var a = g.persons.document("alice")._id;
/// var b = g.persons.document("bob")._id;
/// g.knows.truncate();
/// g.knows.save(a, b, {});
/// g.knows.save(b, a, {});
/// var url = "/_api/traversal";
/// var body = {
/// startVertex: a,
/// graphName: g.__name,
/// direction: "any",
/// uniqueness: {
/// vertices: "none",
/// edges: "none"
/// },
/// maxIterations: 5
/// };
///
/// var response = logCurlRequest('POST', url, JSON.stringify(body));
/// assert(response.code === 500);
///
/// logJsonResponse(response);
/// examples.dropGraph("knows_graph");
/// @END_EXAMPLE_ARANGOSH_RUN
///
/// @endDocuBlock
////////////////////////////////////////////////////////////////////////////////
function post_api_traversal(req, res) {
/*jshint evil: true */
var json = actions.getJsonBody(req, res);
if (json === undefined) {
return badParam(req, res);
}
// check start vertex
// -----------------------------------------
if (json.startVertex === undefined ||
typeof json.startVertex !== "string") {
return badParam(req, res, "missing or invalid startVertex");
}
var doc;
try {
doc = db._document(json.startVertex);
}
catch (err) {
return notFound(req, res, arangodb.ERROR_ARANGO_DOCUMENT_NOT_FOUND, "invalid startVertex");
}
var datasource;
var edgeCollection;
if (json.graphName === undefined) {
// check edge collection
// -----------------------------------------
if (json.edgeCollection === undefined) {
return badParam(req, res, arangodb.ERROR_GRAPH_NOT_FOUND,
"missing graphname");
}
if (typeof json.edgeCollection !== "string") {
return notFound(req, res, "invalid edgecollection");
}
try {
edgeCollection = db._collection(json.edgeCollection);
datasource = traversal.collectionDatasourceFactory(edgeCollection);
}
catch (ignore) {
}
if (edgeCollection === undefined ||
edgeCollection === null) {
return notFound(req, res, arangodb.ERROR_ARANGO_COLLECTION_NOT_FOUND,
"invalid edgeCollection");
}
} else {
if (typeof json.graphName !== "string" || !graph._exists(json.graphName)) {
return notFound(req, res, arangodb.ERROR_GRAPH_NOT_FOUND,
"invalid graphname");
}
datasource = traversal.generalGraphDatasourceFactory(json.graphName);
}
// set up filters
// -----------------------------------------
var filters = [ ];
if (json.minDepth !== undefined) {
filters.push(traversal.minDepthFilter);
}
if (json.maxDepth !== undefined) {
filters.push(traversal.maxDepthFilter);
}
if (json.filter) {
try {
filters.push(new Function('config', 'vertex', 'path', json.filter));
}
catch (err3) {
return badParam(req, res, "invalid filter function");
}
}
// if no filter given, use the default filter (does nothing)
if (filters.length === 0) {
filters.push(traversal.visitAllFilter);
}
// set up visitor
// -----------------------------------------
var visitor;
if (json.visitor !== undefined) {
try {
visitor = new Function('config', 'result', 'vertex', 'path', 'connected', json.visitor);
}
catch (err4) {
return badParam(req, res, "invalid visitor function");
}
}
else {
visitor = traversal.trackingVisitor;
}
// set up expander
// -----------------------------------------
var expander;
if (json.direction !== undefined) {
expander = json.direction;
}
else if (json.expander !== undefined) {
try {
expander = new Function('config', 'vertex', 'path', json.expander);
}
catch (err5) {
return badParam(req, res, "invalid expander function");
}
}
if (expander === undefined) {
return badParam(req, res, "missing or invalid expander");
}
// set up sort
// -----------------------------------------
var sort;
if (json.sort !== undefined) {
try {
sort = new Function('l', 'r', json.sort);
}
catch (err6) {
return badParam(req, res, "invalid sort function");
}
}
// assemble config object
// -----------------------------------------
var config = {
params: json,
datasource: datasource,
strategy: json.strategy,
order: json.order,
itemOrder: json.itemOrder,
expander: expander,
sort: sort,
visitor: visitor,
filter: filters,
minDepth: json.minDepth,
maxDepth: json.maxDepth,
maxIterations: json.maxIterations,
uniqueness: json.uniqueness
};
if (edgeCollection !== undefined) {
config.edgeCollection = edgeCollection;
}
// assemble result object
// -----------------------------------------
var result = {
visited: {
vertices: [ ],
paths: [ ]
}
};
if (json.init !== undefined) {
try {
var init = new Function('result', json.init);
init(result);
}
catch (err7) {
return badParam(req, res, "invalid init function");
}
}
// run the traversal
// -----------------------------------------
var traverser;
try {
traverser = new Traverser(config);
traverser.traverse(result, doc);
actions.resultOk(req, res, actions.HTTP_OK, { result : result });
}
catch (err8) {
if (traverser === undefined) {
// error during traversal setup
return badParam(req, res, err8);
}
actions.resultException(req, res, err8, undefined, false);
}
}
// -----------------------------------------------------------------------------
// --SECTION-- initialiser
// -----------------------------------------------------------------------------
////////////////////////////////////////////////////////////////////////////////
/// @brief gateway
////////////////////////////////////////////////////////////////////////////////
actions.defineHttp({
url : "_api/traversal",
callback : function (req, res) {
try {
switch (req.requestType) {
case actions.POST:
post_api_traversal(req, res);
break;
default:
actions.resultUnsupported(req, res);
}
}
catch (err) {
actions.resultException(req, res, err);
}
}
});
// -----------------------------------------------------------------------------
// --SECTION-- END-OF-FILE
// -----------------------------------------------------------------------------
// Local Variables:
// mode: outline-minor
// outline-regexp: "/// @brief\\|/// {@inheritDoc}\\|/// @page\\|// --SECTION--\\|/// @\\}"
// End: