Conversion Module

This XQuery Module contains functions to convert data between different formats.

Conventions

All functions and errors in this module are assigned to the http://basex.org/modules/convert namespace, which is statically bound to the convert prefix.

Strings

convert:binary-to-string

Signature	convert:binary-to-string( $bytes as xs:anyAtomicType, $encoding as xs:string := (), $fallback as xs:boolean? := false() ) as xs:string
Summary	Converts the specifed $bytes (xs:base64Binary, xs:hexBinary) to a string: The UTF-8 default encoding can be overwritten with the optional $encoding argument. By default, invalid characters will be rejected. If $fallback is set to true, these characters will be replaced with the Unicode replacement character FFFD (�).
Errors	string: The input is an invalid XML string, or the wrong encoding has been specified. BXCO0002: The specified encoding is invalid or not supported.
Examples	convert:binary-to-string(xs:hexBinary('48656c6c6f576f726c64')) yields HelloWorld.

convert:string-to-base64

Signature	convert:string-to-base64( $string as xs:string, $encoding as xs:string := () ) as xs:base64Binary
Summary	Converts the specified $string to an xs:base64Binary item. If the default encoding is chosen, conversion will be cheap, as strings and binaries are both internally represented as byte arrays. The UTF-8 default encoding can be overwritten with the optional $encoding argument.
Errors	binary: The input cannot be represented in the specified encoding. encoding: The specified encoding is invalid or not supported.
Examples	string(convert:string-to-base64('HelloWorld')) yields SGVsbG9Xb3JsZA==.

convert:string-to-hex

Signature	convert:string-to-hex( $string as xs:string, $encoding as xs:string := () ) as xs:hexBinary
Summary	Converts the specified $string to an xs:hexBinary item. If the default encoding is chosen, conversion will be cheap, as strings and binaries are both internally represented as byte arrays. The UTF-8 default encoding can be overwritten with the optional $encoding argument.
Errors	binary: The input cannot be represented in the specified encoding. encoding: The specified encoding is invalid or not supported.
Examples	string(convert:string-to-hex('HelloWorld')) yields 48656C6C6F576F726C64.

Binary Data

convert:integers-to-base64

Signature	convert:integers-to-base64( $integers as xs:integer* ) as xs:base64Binary
Summary	Converts the specified $integers to an item of type xs:base64Binary: Only the first 8 bits of the supplied integers will be considered. Conversion of byte sequences is very efficient, as items of binary type are internally represented as byte arrays.
Examples	convert:integers-to-base64(Q{java:java.lang.String}get-bytes('abc')) converts a byte sequence to a xs:base64Binary item.

convert:integers-to-hex

Signature	convert:integers-to-hex( $integers as xs:integer* ) as xs:hexBinary
Summary	Converts the specified $integers to an item of type xs:hexBinary: Only the first 8 bits of the supplied integers will be considered. Conversion of byte sequences is very efficient, as items of binary type are internally represented as byte arrays.

convert:binary-to-integers

Signature	convert:binary-to-integers( $binary as xs:anyAtomicType ) as xs:integer*
Summary	Returns the specified $binary (xs:base64Binary, xs:hexBinary) as a sequence of unsigned integers (octets).
Examples	convert:binary-to-integers(xs:hexBinary('FF')) yields 255.

convert:binary-to-bytes

Signature	convert:binary-to-bytes( $binary as xs:anyAtomicType ) as xs:byte*
Summary	Returns the specified $binary (xs:base64Binary, xs:hexBinary) as a sequence of bytes. The conversion is very cheap and takes no additional memory, as items of binary type are internally represented as byte arrays.
Examples	convert:binary-to-bytes(xs:base64Binary('QmFzZVggaXMgY29vbA==')) yields the sequence (66, 97, 115, 101, 88, 32, 105, 115, 32, 99, 111, 111, 108). convert:binary-to-bytes(xs:hexBinary("4261736558")) yields the sequence (66 97 115 101 88).

Numbers

convert:integer-to-base

Signature	convert:integer-to-base( $number as xs:integer, $base as xs:integer ) as xs:string
Summary	Converts $number to a string, using the specified $base, interpreting it as a 64-bit unsigned integer. The first base elements of the sequence '0',..,'9','a',..,'z' are used as digits. Valid bases are 2, .., 36.
Errors	base: The specified base is not in the range 2-36.
Examples	convert:integer-to-base(-1, 16) yields 'ffffffffffffffff'. convert:integer-to-base(22, 5) yields '42'.

convert:integer-from-base

Signature	convert:integer-from-base( $string as xs:string, $base as xs:integer ) as xs:integer
Summary	Decodes an integer from $string, using the specified $base. The first base elements of the sequence '0',..,'9','a',..,'z' are allowed as digits; case does not matter. Valid bases are 2 - 36. If the supplied string contains more than 64 bits of information, the result will be truncated.
Errors	base: The specified base is not in the range 2-36. integer: The specified digit is not valid for the given range.
Examples	convert:integer-from-base('ffffffffffffffff', 16) yields -1. convert:integer-from-base('CAFEBABE', 16) yields 3405691582. convert:integer-from-base('42', 5) yields 22. convert:integer-from-base(convert:integer-to-base(123, 7), 7) yields 123.

Dates and Durations

convert:integer-to-dateTime

Signature	convert:integer-to-dateTime( $milliseconds as xs:integer ) as xs:dateTime
Summary	Converts the specified number of $milliseconds since 1 Jan 1970 to an item of type xs:dateTime.
Examples	convert:integer-to-dateTime(0) yields 1970-01-01T00:00:00Z. convert:integer-to-dateTime(1234567890123) yields 2009-02-13T23:31:30.123Z. convert:integer-to-dateTime(prof:current-ms()) returns the current miliseconds in the xs:dateTime format.

convert:dateTime-to-integer

Signature	convert:dateTime-to-integer( $dateTime as xs:dateTime ) as xs:integer
Summary	Converts the specified $dateTime item to the number of milliseconds since 1 Jan 1970.
Examples	convert:dateTime-to-integer(xs:dateTime('1970-01-01T00:00:00Z')) yields 0.

convert:integer-to-dayTime

Signature	convert:integer-to-dayTime( $milliseconds as xs:integer ) as xs:dayTimeDuration
Summary	Converts the specified number of $milliseconds to an item of type xs:dayTimeDuration.
Examples	convert:integer-to-dayTime(1234) yields PT1.234S.

convert:dayTime-to-integer

Signature	convert:dayTime-to-integer( $dayTime as xs:dayTimeDuration ) as xs:integer
Summary	Converts the specified $dayTime duration to milliseconds represented by an integer.
Examples	convert:dayTime-to-integer(xs:dayTimeDuration('PT1S')) yields 1000.

Keys

convert:encode-key

Signature	convert:encode-key( $key as xs:string, $lax as xs:boolean? := false() ) as xs:string
Summary	Encodes the specified $key (with the optional $lax conversion method) to a valid NCName representation, which can be used to create an element node: An empty string is converted to a single underscore (_). Existing underscores are rewritten to two underscores (__). Characters that are no valid NCName characters are rewritten to an underscore and the character’s four-digit Unicode. For example, the exclamation mark ? is transformed to _003f. If lax conversion is chosen, invalid characters are replaced with underscores or (when invalid as first character of an element name) prefixed with an underscore. The resulting string may be better readable, but it cannot necessarily be converted back to the original form. This encoding is employed by the direct conversion format in the JSON Module and the CSV Module.
Examples	element { convert:encode-key("!") } { } creates a new element with an encoded name: <_0021/>.

convert:decode-key

Signature	convert:decode-key( $key as xs:string, $lax as xs:boolean? := false() ) as xs:string
Summary	Decodes the specified $key (with the optional $lax conversion method) to the original string representation. Keys supplied to this function are usually element names from documents that have been created with the JSON Module or CSV Module.
Examples	convert:decode-key(name(<_0021/>)) yields !. json:doc("doc.json")//* ! convert:decode-key(name()) yields the original string representation of all names of a JSON document.
Errors	key: The specified key cannot be decoded to its original representation.

Errors

Code	Description
base	The specified base is not in the range 2-36.
binary	The input cannot be converted to a binary representation.
encoding	The specified encoding is invalid or not supported.
integer	The specified digit is not valid for the given range.
key	The specified key cannot be decoded to its original representation.
string	The input is an invalid XML string, or the wrong encoding has been specified.

Changelog

Version 9.4

• Added: convert:encode-key, convert:decode-key.

Version 9.0

• Added: convert:binary-to-integers.
• Updated: convert:integers-to-base64, convert:integers-to-hex: Renamed from convert:bytes-to-base64; argument type relaxed from xs:byte to xs:integer.
• Updated: error codes updated; errors now use the module namespace

Version 8.5

• Updated: convert:binary-to-string: $fallback argument added.

Version 7.5

• Added: convert:integer-to-dateTime, convert:dateTime-to-integer, convert:integer-to-dayTime, convert:dayTime-to-integer.

The module was introduced with Version 7.3. Some of the functions have been adopted from the obsolete Utility Module.