Copyright © 2010-2013 Christian Grün, published by the
This specification was published by the
This proposal provides a file system API for XPath. It defines extension functions to perform file system related operations such as listing, reading, or writing files or directories. It has been designed to be compatible with XQuery 1.0 and XSLT 2.0, as well as any other XPath 2.0 usage.
revisiondesc
This document is in a final draft stage. Comments are welcomed at
The module defined by this document defines functions and errors in the
namespace http://expath.org/ns/file
. In this document, the
file
prefix is bound to this namespace URI.
The output
prefix is bound to the namespace
http://www.w3.org/2010/xslt-xquery-serialization
. It is used
to specify serialization parameters.
All file paths are specified as strings, and are resolved against the current working directory. An implementation must accept absolute and relative UNIX/Linux and Windows paths as well as absolute file URIs. Some examples:
C:\Test Dir\my file.xml
: An absolute path on Windows
platforms.
/Test Dir/my file.xml
: An absolute path on UNIX-based
platforms.
C:\\\Test Dir//\\my file.xml
: An absolute path on Windows
platforms that tolerates an arbitrary number of slashes and backslashes.
my file.xml
: A relative path, pointing to a file in the current
working directory.
file:///C:/Test%20Dir/my%20file.xml
: An absolute file URI on
Windows platforms.
file:///Test%20Dir/my%20file.xml
: An absolute path on UNIX-based
platforms.
Before further processing, all paths are normalized to an implementation-defined representation (which usually is the representation of the underlying operating system).
If a function returns a string that refers to a directory, it will always be suffixed with the system-specific directory separator.
The standard function fn:static-base-uri
can be used to
resolve file operations against the base URI:
Some function are marked as ·nondeterministic·, which means they are not guaranteed to perform the same operations and produce identical results from repeated calls. A query processor must ensure that these functions are not relocated or pre-evaluated and that its results are not cached when compiling and evaluating the query and serializing its results.
Error conditions are identified by a code (a QName
). When such an error
condition is reached during the execution of the function, a dynamic error is thrown,
with the corresponding error code (as if the standard XPath function
fn:error
had been called).
Error codes are defined through the specification. The generic error
For a list of specific errors see the "Summary of Error Conditions" section of this document.
file:exists
Tests if the file or directory pointed by $path
exists.
This function is ·nondeterministic·.
file:is-dir
Tests if $path
points to a directory. On UNIX-based systems the root and
the volume roots are considered directories.
This function is ·nondeterministic·.
file:is-file
Tests if $path
points to a file.
This function is ·nondeterministic·.
file:last-modified
Returns the last modification time of a file or directory.
This function is ·nondeterministic·.
$path
does not
exist.file:size
Returns the byte size of a file, or the value 0
for directories.
This function is ·nondeterministic·.
$path
does not
exist.file:append
Appends a sequence of items to a file. If the file pointed by $file
does
not exist, a new file will be created.
$params
controls the way the $items
items are serialized.
The semantics of $params
is the same as for the
fn:serialize
function in output:serialization-parameters
element whose format is defined in
fn:serialize,
the encoding stage will not be skipped by this function.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.file:append-binary
Appends a Base64 item as binary to a file. If the file pointed by $file
does not exist, a new file will be created.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.file:append-text
Appends a string to a file. If the file pointed by $file
does not exist,
a new file will be created.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.file:append-text-lines
Appends a sequence of strings to a file, each followed by the system-dependent
newline character. If the file pointed by $file
does not exist, a new
file will be created.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.file:copy
Copies a file or a directory given a source and a target path/URI. The following
cases may occur if $source
points to a file:
$target
does not exist, it will be created.$target
is a file, it will be overwritten.$target
is a directory, the file will be created in that
directory with the name of the source file. If a file already exists, it will be
overwritten.The following cases may occur if $source
points to a directory:
$target
does not exist, it will be created as directory, and all
files of the source directory are copied to this directory with their existing
local names.$target
is a directory, the source directory with all its files
will be copied into the target directory. At each level, if a file already exists
in the target with the same name as in the source, it is overwritten. If a directory
already exists in the target with the same name as in the source, it is not removed,
it is recursed in place (if it does not exist, it is created before recursing).Other cases will raise one of the errors listed below.
The function returns the empty sequence if the operation is successful. If an error occurs during the operation, no rollback to the original state will be possible
This function is ·nondeterministic·.
$source
path does not
exist.$source
points to a
directory and $target
points to an existing file.$source
does not exist.$source
points to a file
and $target
points to a directory, in which a subdirectory exists
with the name of the source file.file:create-dir
Creates a directory, or does nothing if the directory already exists. The operation will create all non-existing parent directories.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
file:create-temp-dir
Creates a temporary directory and all non-existing parent directories and returns the full path to the created directory.
The temporary directory will not be automatically deleted after query execution. It is guaranteed to not already exist when the function is called.
If $dir
is not given, the directory will be created inside
the system-dependent default temporary-file directory.
This function is ·nondeterministic·.
file:create-temp-file
Creates a temporary file and all non-existing parent directories and returns the full path to the created file.
The temporary file will not be automatically deleted after query execution. It is guaranteed to not already exist when the function is called.
If $dir
is not given, the directory will be created inside
the system-dependent default temporary-file directory.
This function is ·nondeterministic·.
file:delete
Deletes a file or a directory from the file system.
If the optional parameter $recursive
is set to true()
,
sub-directories will be deleted as well.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$path
does not
exist.$file
points to a
non-empty directory.file:list
Lists all files and directories in a given directory. The order of the items in the
resulting sequence is not defined. The "." and ".." items are never returned. The
returned paths are relative to the provided directory $dir
.
If the optional parameter $recursive
is set to true()
, all
directories and files will be returned that are found while recursively traversing
the given directory.
The optional $pattern
parameter defines a name pattern in the glob
syntax. If this is provided, only the paths of the files and directories whose names
are matching the pattern will be returned.
An implementation must support at least the following glob syntax for the pattern:
*
for matching any number of unknown characters and?
for matching one unknown character.This function is ·nondeterministic·.
$dir
does not point to an
existing directory.file:move
Moves a file or a directory given a source and a target path/URI. The following cases
may occur if $source
points to a file:
$target
does not exist, it will be created.$target
is a file, it will be overwritten.$target
is a directory, the file will be created in that
directory with the name of the source file. If a file already exists, it will be
overwritten.The following cases may occur if $source
points to a directory:
$target
does not exist, it will be created as directory, and all
files of the source directory are moved to this directory with their existing
local names.$target
is a directory, the source directory with all its files
will be moved into the target directory. If the target directory contains a
directory with the same name as the source, the error Other cases will raise one of the errors listed below.
The function returns the empty sequence if the operation is successful. If an error occurs during the operation, no rollback to the original state will be possible
This function is ·nondeterministic·.
$source
path does not
exist.$source
points to a
directory and $target
points to an existing file.$source
does not exist.$target
points to a directory,
in which a subdirectory exists with the name of the source.file:read-binary
Returns the content of a file in its Base64 representation.
The optional parameters $offset
and $length
can be
used to read chunks of a file.
This function is ·nondeterministic·.
$file
does not
exist.$file
points to a
directory.$offset
or
$length
is negative, or if the chosen values would exceed the file bounds.file:read-text
Returns the content of a file in its string representation.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
This function is ·nondeterministic·.
$file
does not
exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.file:read-text-lines
Returns the contents of a file as a sequence of strings, separated at newline boundaries.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
The newline handling is the same as for the fn:unparsed-text-lines
function in
This function is ·nondeterministic·.
$file
does not
exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.file:write
Writes a sequence of items to a file.
If $file
already exists, it will be overwritten; otherwise, it will be created.
$params
controls the way the $items
items are serialized.
The semantics of $params
is the same as for the
fn:serialize
function in output:serialization-parameters
element whose format is defined in
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.file:write-binary
Writes a Base64 item as binary to a file.
If $file
already exists, it will be overwritten; otherwise, it will be created.
If the optional parameter $offset
is specified, data will be written
to this file position. An existing file may be resized by that operation.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.$offset
is negative,
or if it exceeds the current file size.file:write-text
Writes a strings to a file. If $file
already exists, it will be
overwritten.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.file:write-text-lines
Writes a sequence of strings to a file, each followed by the system-dependent newline character.
If $file
already exists, it will be overwritten; otherwise, it will be created.
The optional parameter $encoding
, if not provided, is considered to be
UTF-8
.
The function returns the empty sequence if the operation is successful.
This function is ·nondeterministic·.
$file
does not exist.$file
points to a
directory.$encoding
is invalid or
not supported by the implementation.None of the functions in this section performs any check regarding the existence of the received or returned paths.
file:name
Returns the name of a file or directory.
An empty string is returned if the path points to the root directory, or if it contains no directory separators.
This function is ·deterministic· (no path existence check is made).
file:parent
Transforms the given path into an absolute path, as specified by
An empty sequence is returned if the path points to a root directory.
This function is ·nondeterministic·.
file:path-to-native
Transforms a URI, an absolute path, or relative path to a canonical, system-dependent path representation. A canonical path is both absolute and unique and thus contains no redirections such as references to parent directories or symbolic links.
If the resulting path points to a directory, it will be suffixed with the system-specific directory separator.
This function is ·nondeterministic·.
file:path-to-uri
Transforms a file system path into a URI with the file://
scheme. If the
path is relative, it is first resolved against the current working directory.
This function is ·deterministic· (no path existence check is made).
file:resolve-path
Transforms a relative path into an absolute operating system path by resolving it against the current working directory.
If the resulting path points to a directory, it will be suffixed with the system-specific directory separator.
This function is ·nondeterministic·.
file:dir-separator
Returns the value of the operating system-specific directory separator, which usually
is /
on UNIX-based systems and \
on Windows systems.
This function is ·nondeterministic·.
file:line-separator
Returns the value of the operating system-specific line separator, which usually is
on UNIX-based systems,
on
Windows systems and
on Mac systems.
This function is ·nondeterministic·.
file:path-separator
Returns the value of the operating system-specific path separator, which usually is
:
on UNIX-based systems and ;
on Windows systems.
This function is ·nondeterministic·.
file:temp-dir
Returns the path to the default temporary-file directory of an operating system.
This function is ·nondeterministic·.