% Specific Features
Npt documentation.
Reference: ANSI Common Lisp npt
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This chapter introduces some of the features specific to npt.
The functions and variables used by npt are available in the npt-system package.
This section describes the following.
ed functionrequire functionload-logical-pathname-translationspathnamerandom-stateload functionThe arguments of the npt command are stored in the following variable.
npt-system::*arguments*
The value is an array, where the first element is the command npt
and the second and subsequent arguments are the arguments of the command.
As an example, suppose you execute the following command.
$ npt -- 10 20 30
*
The argument -- specifies that the following arguments are
to be used in the npt command.
The values are as follows
* npt-system::*arguments*
#("npt" "10" "20" "30")
Environment variables are stored in the following variable.
npt-system::*environment*
The value is a hash table.
For example, the following command is
used to get the value of a home directory $HOME.
$ npt
* (gethash "HOME" npt-system::*environment*)
"/home/username"
T
*
Use the following command to start the garbage collector.
(npt-system:gc)
The garbage collector is automatically run if the heap area is overwhelmed,
but depending on the timing, it may not be judged in time and you may run out of memory.
If there is an out-of-memory situation, a LISP ABORT is triggered.
Here is the function specification.
Lisp Function: System Function
The following command will create the core file.
(npt-system:savecore file)
This instruction executes the savecore condition of the serious-condition
to terminate the npt.
When it finishes with the correct savecore condition,
it starts to save the core file.
To read the core file you created, use the --core argument of the npt command.
Here is the function specification.
Lisp Function: System Function
Exit npt with the following command
(npt-system:exit code)
(npt-system:quit code)
The above two functions are exactly the same.
They are imported into the common-lisp-user package by default so that you can run (exit) and (quit) at the npt prompt.
This instruction executes the exit condition of the serious-condition
to terminate the npt.
When it finishes with the correct exit condition,
the argument is set to the exit code to finish the process.
Here is the function specification.
Lisp Function: System Function
ed functionThe Common Lisp function ed invokes an editor.
This feature is supported by FreeBSD, Linux and Windows.
It is configurable to get the command names of the editors in the following order.
npt-system::*ed-program*.EDITOR environment variableThe standard editor is vi for FreeBSD/Linux,
notepad.exe for Windows, or ed for others.
require functionThe function require in Common Lisp can read a module from its name.
The implementation in npt is almost the same as in sbcl.
When the require is executed, the variable
npt-system::*module-provider-functions* is read as a list of functions,
and the functions are executed with the require arguments in order from the first one.
If any function returns a value other than NIL,
it considers the loading to be successful and exits.
Here is the function specification.
Lisp Function: System Function
(defun require-tmp (var)
(load (merge-pathnames
(format nil "~(~A~).lisp" var)
#p"/tmp/")))
(push #'require-tmp npt-system::*module-provider-functions*)
(require 'aaa)
The following are the results of the execution. (but a failure example)
ERROR: NPT-SYSTEM::SIMPLE-FILE-ERROR
Cannot open file #P"/tmp/aaa.lisp".
0. ABORT Return to eval-loop.
[1]* 0
It shows that require tried to read the file /tmp/aaa.lisp and failed.
EastAsianWidth is a representation of Unicode character width.
For example, in the case of Japanese, the width of a character may be treated as two letters of the alphabet.
The width of a character is used to format the output of format or Pretty Printing.
The following three functions are related to EastAsianWidth.
(defun eastasian-width (var) ...)
(defun eastasian-get (var) ...)
(defun eastasian-set (var size &optional errorp) ...)
Here is the function specification.
Lisp Function: System Function
eastasian-widthReturns the size of EastAsianWidth from an object.
If the argument var is an integer, its size is returned as a Unicode character.
If the argument var is a character, the size of the character is returned.
If the argument var is a string, the total size of all characters in the string is returned.
The first returned value is the size of EastAsianWidth.
The second return value is a boolean value to show whether the size is correct or not.
eastasian-getEastAsianWidth categorizes characters into
6 categories: N, A, H, W, F, and NA.
This function gets the number of characters in each category.
The argument var is a string-designator and represents the name of the category.
The first returned value is the size of EastAsianWidth.
The second return value is a symbol for the category, and the error is NIL.
Example.
* (npt-system:eastasian-get :na)
1
NPT-SYSTEM::NA
* (npt-system:eastasian-get :hello)
0
NIL
*
eastasian-setSet the size of a category of EastAsianWidth.
The argument var is a symbol for the category.
The argument size is the size of the category.
The argument &optional errorp is whether the error condition occurs or not.
load-logical-pathname-translationsThe function load-logical-pathname-translations is a feature to load the settings of a logical pathname from a file.
The location of the file is implementation-dependent.
npt searches for files based on the following special variables.
npt-system::*load-logical-pathname-translations*
The function load-logical-pathname-translations takes
a string as an argument and loads the corresponding configuration file.
For example, suppose that the following is executed
(load-logical-pathname-translations "hello")
Suppose the configuration files are located in
/tmp/host/hello.txt
In this case, the value of the special variable should be set as follows
(setq npt-system::*load-logical-pathname-translations* #p"/tmp/host/*.txt")
Let’s check the operation.
First, create a configuration file.
Here are the contents of the file.
("*.*" "/home/lisp/")
("path;to;*.*" "/home/path/")
Create a configuration file.
$ cd /tmp
$ mkdir host
$ cd host
$ vi hello.txt
Enter the above information
$
npt to execute the following commands
(load-logical-pathname-translations "hello")
-> t
(translate-logical-pathname "hello:name.txt")
-> #P"/home/lisp/name.txt"
(translate-logical-pathname "hello:path;to;name.txt")
-> #P"/home/path/name.txt"
It is converted correctly.
pathnameThe pathname is an object for the name of a file.
The pathname-host specifies the environment to which the file name belongs.
The following values are used by npt
pathname-host |
Environment |
|---|---|
npt-system::unix |
Unix |
npt-system::windows |
Windows |
| string-tyoe | logical-pathname |
The default is the value of host set to
the pathname object of the *default-pathname-defaults*.
The parse-namestring function determines how to analyze
a string according to the value of host.
Because the behavior is determined by the value of host,
for example, even if the system is running on a Unix system,
you can recognize Windows file names.
For example, the following.
* (parse-namestring "C:\\Windows\\" 'npt-system::windows)
#P"C:\\Windows\\"
11
* (pathname-directory *)
(:ABSOLUTE "Windows")
The function equal allows you to check whether the pathname is the same or not.
If the namestring is the same but the host is different, they are not the same.
* (parse-namestring "notepad.exe" 'npt-system::windows)
#P"notepad.exe"
11
* (parse-namestring "notepad.exe" 'npt-system::unix)
#P"notepad.exe"
11
* (equal ** *)
NIL
The equal function checks the value of host and evaluates the case of a string.
On Unix, the value of host is considered
to be different from the case of the string,
and on Windows, it is considered to be the same.
* (equal
(parse-namestring "Hello.TXT" 'npt-system::unix)
(parse-namestring "hello.txt" 'npt-system::unix))
NIL
* (equal
(parse-namestring "Hello.TXT" 'npt-system::windows)
(parse-namestring "hello.txt" 'npt-system::windows))
T
The pathname-device is ignored for Unix and logical paths.
On Windows, it is set to the type of the file or the drive letter.
* (pathname-device (parse-namestring "C:\\Windows\\" 'npt-system::windows))
"C"
* (pathname-device (parse-namestring "notepad.exe" 'npt-system::windows))
NIL
* (pathname-device (parse-namestring "\\\\.\\COM1" 'npt-system::windows))
NPT-SYSTEM::DEVICE
The pathname-version is ignored on Unix and Windows,
and is used by rules for logical paths.
* (pathname-version (logical-pathname "test:hello.txt"))
:NEWEST
* (pathname-version (logical-pathname "test:hello.txt.999"))
999
random-stateThe random-state is an object used to generate a random number.
npt uses a random number generator called xorshift,
which holds a 128-bit internal state in the random-state.
The initial value can be set to as random as possible
by passing the argument t to the function make-random-state.
For example
* (make-random-state t)
#<RANDOM-STATE #x85A5B416389D9716A81B4F43F76E922A>
* (make-random-state t)
#<RANDOM-STATE #xE51C94EB01856FEAC5B1EC8C90E3107E>
Determining the initial value of a random number is not easy,
so basically the operating system sets the initial value.
This chapter describes how to get the initial value of a random number.
If the compilation mode is FreeBSD or Linux,
get the initial value of the random number from the file /dev/urandom.
Note that the device to be read is not /dev/random.
On FreeBSD, there is no difference between the two,
but on Linux, /dev/random is more secure.
npt has chosen to use /dev/urandom for convenience rather than safety.
Takes 256 bytes of data from /dev/urandom and sends it to MD5 hash
and set the internal state of MD5 to the internal state of xorshift as it is.
If reading /dev/urandom fails, it is an error.
If the compilation mode is on Windows,
get the initial value from the function SystemFunction036,
commonly known as the RtlGenRandom function of Advapi32.dll.
Takes 256 bytes of data from RtlGenRandom and sends it to MD5 hash
and set the internal state of MD5 to the internal state of xorshift as it is.
If reading RtlGenRandom fails, it is an error.
Attempt to read the file /dev/urandom.
If the value is obtained, it is used as the initial value.
If the value can’t be obtained, it is given up and
the time and so on are used as the initial value of the random number.
Unlike FreeBSD, Linux, and Windows, it continues without error even if the device could not be loaded for the initial value.
load functionThe load function can load either a text file containing Lisp expressions
or a binary file generated by the compile-file function
(commonly known as a FASL file).
Which one to load is determined by whether pathname-type is FASL
or not, but the type can also be specified by the
:type argument of the load function.
To load a text file.
(load file :type :lisp)
To load a fasl file.
(load file :type :fasl)
The first argument of the load function is not only pathname,
but can also be memory-stream.
However, since memory-stream does not have a pathname,
you need to specify the :type argument.
Here is an example of execution.
(let ((input (npt-system:make-memory-io-stream))
(output (npt-system:make-memory-io-stream)))
(with-open-file (stream input :direction :output)
(format stream "(format t \"Hello~~%\")"))
(with-open-file (stream input :direction :input)
(compile-file stream :output-file output))
(file-position output :start)
(load output :type :fasl))
Here are the execution results.
Hello
T
In this example, a text file is written to the input variable,
and a fasl file is output to the output variable
by the compile-file function.
After returning the file pointer of the output to the top,
execute the fasl file generated by the load function.