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cts.walk

cts.walk(
   $node as Node,
   $query as cts.query,
   $callback as function(xs.string, text(), cts.query*, xs.integer) as xs.string?
) as null

Summary

Walks a node, evaluating a callback function for any text matching a query. It returns the empty-sequence(). This is similar to cts.highlight in how it evaluates its expression, but it is different in what it returns.

Parameters
$node A node to walk. The node must be either a document node or an element node; it cannot be a text node.
$query A query specifying the text on which to evaluate the expression. If a string is entered, the string is treated as a cts:word-query of the specified string.
$callback A function to call with matching text.

Usage Notes

The arguments to the callback function provide context for the match.

text as xs:string

The matched text.

node as text()

The node containing the matched text.

queries as cts:query*

The matching queries.

start as xs:integer

The string-length position of the first character of text in node. Therefore, the following always returns true:

fn.substring(node, start,
             fn.stringLength(text)) eq text 

The return from the callback function is an action that specifies what happens next in the walk:

"continue"
(default) Walk the next match. If there are no more matches, return.
"skip"
Skip walking any more matches and return.
"break"
Stop walking matches and return.
null
Continue with the previous action.

You cannot use cts.walk to walk results matching cts:similar-query and cts:element-attribute-*-query items.

The callback function can use variables in scope to accumulate results.

Unfiltered queries, including registered queries, do not match in cts.walk or cts.highlight.

Example

//
//   Return all text nodes containing matches to the query "the".
//
var doc = new NodeBuilder();
doc.startElement("p");
doc.addText("the quick brown fox ");
doc.startElement("b"); doc.addText("jumped"); doc.endElement();
doc.addText(" over the lazy dog's back");
doc.endElement();

var results = [];
function callback(text, node, queries, start) {
  results.push(node);
  return "continue";
};

cts.walk(doc.toNode(), "the", callback);
results;
=>
  ["the quick brown fox ", " over the lazy dog's back"]

Example

//
//  Do not show any more matches that occur after
//  $threshold characters.
//
var doc = new NodeBuilder();
doc.startElement("p");
doc.addText("This is 1, this is 2, this is 3, this is 4, this is 5.");
doc.endElement();
var pos = 1;
var threshold = 20;
var results = [];

function callback(text, node, queries, start) {
  if (pos > threshold )
     return "break";
  else {
    results.push(text);
    pos = start;
    return "continue";
  }
}

cts.walk(doc.toNode(), "this is", callback);
results;

=>
["This is", "this is", "this is"]

Example

//
//   Show the first two matches.
//
var doc = new NodeBuilder();
doc.startElement("p");
doc.addText("This is 1, this is 2, this is 3, this is 4, this is 5.");
doc.endElement();
var match = 0;
var threshold = 2;
var results = [];

function callback(text, node, queries, start) {
  if (match >= threshold )
     return "break";
  else {
    results.push(text);
    match = match + 1;
    return "continue";
  }
}

cts.walk(doc.toNode(), "this is", callback);
results;

=>
["This is", "this is"]

Example

//
//  Similar to the example above but on JSON nodes.
//
var x = ["This is 1, this is 2, this is 3, this is 4, this is 5."];
var match = 0;
var threshold = 2;
var results = [];

function callback(text, node, queries, start) {
  if (match >= threshold )
     return "break";
  else {
    results.push(text);
    match = match + 1;
    return "continue";
  }
}

cts.walk(x, "this is", callback);
results;
=>
["This is", "this is"]

Example

//
//  It works on JSON number, boolean and null nodes as well.
//
var x = { "p1" : "There are ", "p2" : 10,  "p3" : " books here."};
var results = [];
function callback (text, node, queries, start) {
  results.push(node);
  return "continue";
}
cts.walk(x, cts.jsonPropertyValueQuery("p2",10), callback);
results;
=>
[10]

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