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String Parsing Functions

XML often arrives escaped inside something else: a JSON field, a database column, a CSV cell. parse-xml() turns the string into a document, parse-xml-fragment() accepts content without a single root, and serialize() goes the other way, with an optional map of output parameters:

Parsing XML held in strings and serializing nodes
xp 'parse-xml("<a>Hello <b>World</b></a>")//b/string()' \
   'count(parse-xml-fragment("I say<a>Hello</a> twice")/node())' 'parse-xml("<a>")' \
   'serialize(//book[1]/title)'
Output
parse-xml("<a>Hello <b>World</b></a>")//b/string() => "World"
count(parse-xml-fragment("I say<a>Hello</a> twice")/node()) => 3
parse-xml("<a>")                       => error FODC0006
serialize(//book[1]/title)             => "<title>The Quiet Harbor</title>"

The fragment holds three nodes (text, element, text). parse-xml() fails with FODC0006 on malformed input, so wrap it in try (Error Functions) when a feed may be dirty.

String Parsing Functions

String parsing functions convert between XML text and nodes, and serialize sequences back to text.
parse-xml("<a>Hello <b>World</b></a>")Creates an XML document from an XML string and returns its root node.
parse-xml-fragment("I say<a>Hello <b>World</b></a>")Creates an XML fragment from a string and returns its root node. Unlike parse-xml(), this does not raise an error even though the input is not well-formed XML on its own (it has no single root element).
serialize(1 to 3)Returns a serialized string representation of the sequence, with items separated by a single space.
ch03-string-parsing-functions.xpath.txt
merged-01-01-ch03-string-parsing-functions.xpath.txt
serialize(1 to 3)
Output
1 2 3