Difference between revisions of "Conversion Module"
Jump to navigation
Jump to search
(9 intermediate revisions by the same user not shown) | |||
Line 76: | Line 76: | ||
* Only the first 8 bits of the supplied integers will be considered. | * 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. | * Conversion of byte sequences is very efficient, as items of binary type are internally represented as byte arrays. | ||
+ | |- | ||
+ | | '''Examples''' | ||
+ | | | ||
+ | * <code>convert:integers-to-base64(Q{java:java.lang.String}get-bytes('abc'))</code> converts a byte sequence to a {{Code|xs:base64Binary}} item. | ||
|} | |} | ||
Line 230: | Line 234: | ||
=Keys= | =Keys= | ||
− | ==convert: | + | ==convert:encode-key== |
{{Mark|Introduced with Version 9.4:}} | {{Mark|Introduced with Version 9.4:}} | ||
Line 237: | Line 241: | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|convert: | + | |{{Func|convert:encode-key|$key as xs:string|xs:string}}<br />{{Func|convert:encode-key|$key as xs:string, $lax as xs:boolean|xs:string}}<br /> |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | | + | |Encodes the specified {{Code|$key}} (with the optional {{Code|$lax}} conversion method) to a valid NCName representation, which can be used to create an element node: |
+ | * An empty string is converted to a single underscore ({{Code|_}}). | ||
+ | * Existing underscores are rewritten to two underscores ({{Code|__}}). | ||
+ | * Characters that are no valid NCName characters are rewritten to an underscore and the character’s four-digit Unicode. For example, the exclamation mark {{Code|?}} is transformed to {{Code|_003f}}. | ||
+ | * If lax conversion is chosen, invalid characters are replaced with underscores or (when invalid as first character of an element name) prefixed with an underscore. The resulting string may be better readable, but it cannot necessarily be converted back to the original form. | ||
+ | This encoding is employed by the {{Code|direct}} conversion format in the [[JSON Module]] and the [[CSV Module]]. | ||
|- | |- | ||
| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * <code>convert: | + | * <code>element { convert:encode-key("!") } { }</code> creates a new element with an encoded name: <code><_0021/></code>. |
− | |||
|} | |} | ||
− | ==convert: | + | ==convert:decode-key== |
{{Mark|Introduced with Version 9.4:}} | {{Mark|Introduced with Version 9.4:}} | ||
Line 255: | Line 263: | ||
|- | |- | ||
| width='120' | '''Signatures''' | | width='120' | '''Signatures''' | ||
− | |{{Func|convert: | + | |{{Func|convert:decode-key|$key as xs:string|xs:string}}<br />{{Func|convert:decode-key|$key as xs:string, $lax as xs:boolean|xs:string}}<br /> |
|- | |- | ||
| '''Summary''' | | '''Summary''' | ||
− | | | + | |Decodes the specified {{Code|$key}} (with the optional {{Code|$lax}} conversion method) to the original string representation.<br />Keys supplied to this function are usually element names from documents that have been created with the [[JSON Module]] or [[CSV Module]]. |
|- | |- | ||
| '''Examples''' | | '''Examples''' | ||
| | | | ||
− | * <code> | + | * <code>convert:decode-key(name(<_0021/>))</code> yields <code>!</code>. |
+ | * <code>json:doc("doc.json")//* ! convert:decode-key(name())</code> yields the original string representation of all names of a JSON document. | ||
+ | |- | ||
+ | | '''Errors''' | ||
+ | |{{Error|key|#Errors}} The specified key cannot be decoded to its original representation. | ||
|} | |} | ||
Line 282: | Line 294: | ||
|{{Code|integer}} | |{{Code|integer}} | ||
|The specified digit is not valid for the given range. | |The specified digit is not valid for the given range. | ||
+ | |- | ||
+ | |{{Code|key}} | ||
+ | |The specified key cannot be decoded to its original representation. | ||
|- | |- | ||
|{{Code|string}} | |{{Code|string}} | ||
Line 291: | Line 306: | ||
;Version 9.4 | ;Version 9.4 | ||
− | * Added: [[#convert: | + | * Added: [[#convert:encode-key|convert:encode-key]], [[#convert:decode-key|convert:decode-key]]. |
;Version 9.0 | ;Version 9.0 |
Revision as of 09:51, 25 June 2020
This XQuery Module contains functions to convert data between different formats.
Contents
Conventions
All functions and errors in this module are assigned to the http://basex.org/modules/convert
namespace, which is statically bound to the convert
prefix.
Strings
convert:binary-to-string
Signatures | convert:binary-to-string($bytes as xs:anyAtomicType) as xs:string convert:binary-to-string($bytes as xs:anyAtomicType, $encoding as xs:string) as xs:string convert:binary-to-string($bytes as xs:anyAtomicType, $encoding as xs:string, $fallback as xs:boolean) as xs:string
|
Summary | Converts the specifed $bytes (xs:base64Binary , xs:hexBinary ) to a string:
|
Errors | string : The input is an invalid XML string, or the wrong encoding has been specified.BXCO0002 : The specified encoding is invalid or not supported.
|
Examples |
|
convert:string-to-base64
Signatures | convert:string-to-base64($string as xs:string) as xs:base64Binary 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 $encoding argument.
|
Errors | binary : The input cannot be represented in the specified encoding.encoding : The specified encoding is invalid or not supported.
|
Examples |
|
convert:string-to-hex
Signatures | convert:string-to-hex($string as xs:string) as xs:hexBinary 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 $encoding argument.
|
Errors | binary : The input cannot be represented in the specified encoding.encoding : The specified encoding is invalid or not supported.
|
Examples |
|
Binary Data
convert:integers-to-base64
Signatures | convert:integers-to-base64($integers as xs:integer*) as xs:base64Binary
|
Summary | Converts the specified $integers to an item of type xs:base64Binary :
|
Examples |
|
convert:integers-to-hex
Signatures | convert:integers-to-hex($integers as xs:integer*) as xs:hexBinary
|
Summary | Converts the specified $integers to an item of type xs:hexBinary :
|
convert:binary-to-integers
Signatures | convert:binary-to-integers($binary as xs:anyAtomicType) as xs:integer*
|
Summary | Returns the specified $binary (xs:base64Binary , xs:hexBinary ) as a sequence of unsigned integers (octets).
|
Examples |
|
convert:binary-to-bytes
Signatures | convert:binary-to-bytes($binary as xs:anyAtomicType) as xs:byte*
|
Summary | Returns the specified $binary (xs:base64Binary , xs:hexBinary ) as a sequence of bytes. The conversion is very cheap and takes no additional memory, as items of binary type are internally represented as byte arrays.
|
Examples |
|
Numbers
convert:integer-to-base
Signatures | convert:integer-to-base($number as xs:integer, $base as xs:integer) as xs:string |
Summary | Converts $number to a string, using the specified $base , interpreting it as a 64-bit unsigned integer.The first base elements of the sequence '0',..,'9','a',..,'z' are used as digits.Valid bases are 2, .., 36 . |
Errors | base : The specified base is not in the range 2-36.
|
Examples |
|
convert:integer-from-base
Signatures | convert:integer-from-base($string as xs:string, $base as xs:integer) as xs:integer |
Summary | Decodes an integer from $string , using the specified $base .The first base elements of the sequence '0',..,'9','a',..,'z' are allowed as digits; case does not matter. Valid bases are 2 - 36. If the supplied string contains more than 64 bits of information, the result will be truncated. |
Errors | base : The specified base is not in the range 2-36.integer : The specified digit is not valid for the given range.
|
Examples |
|
Dates and Durations
convert:integer-to-dateTime
Signatures | convert:integer-to-dateTime($milliseconds as xs:integer) as xs:dateTime |
Summary | Converts the specified number of $milliseconds since 1 Jan 1970 to an item of type xs:dateTime. |
Examples |
|
convert:dateTime-to-integer
Signatures | convert:dateTime-to-integer($dateTime as xs:dateTime) as xs:integer |
Summary | Converts the specified $dateTime item to the number of milliseconds since 1 Jan 1970. |
Examples |
|
convert:integer-to-dayTime
Signatures | convert:integer-to-dayTime($milliseconds as xs:integer) as xs:dayTimeDuration |
Summary | Converts the specified number of $milliseconds to an item of type xs:dayTimeDuration. |
Examples |
|
convert:dayTime-to-integer
Signatures | convert:dayTime-to-integer($dayTime as xs:dayTimeDuration) as xs:integer |
Summary | Converts the specified $dayTime duration to milliseconds represented by an integer. |
Examples |
|
Keys
convert:encode-key
Signatures | convert:encode-key($key as xs:string) as xs:string convert:encode-key($key as xs:string, $lax as xs:boolean) as xs:string |
Summary | Encodes the specified $key (with the optional $lax conversion method) to a valid NCName representation, which can be used to create an element node:
This encoding is employed by the |
Examples |
|
convert:decode-key
Signatures | convert:decode-key($key as xs:string) as xs:string convert:decode-key($key as xs:string, $lax as xs:boolean) 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 |
|
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 fromxs:byte
toxs: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.