jshost - jslibs - jshost executable - Project Hosting on Google Code

Updated May 31, 2009 by soubok
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jshost

jshost executable

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Description

jshost ( javascript host ) is a small executable file that run javascript programs. The main features are:

Lightweight

The binary executable file is less than 60KB

Minimalist internal API

LoadModule is enough, everything else can be added using dynamic loadable modules.

Command line options

-c <0 or 1> (default = 0)

Compile-only. The script is compiled but not executed. This is useful to detect syntax errors.

-u (disabled by default)

Run in unsafe-mode that is a kind of 'release mode'. In unsafe-mode, any runtime checks is avoid and warnings are not reported. This mode allow a better execution speed.

-m <size> (default: no limit)

Specifies the maximum memory usage of the script in megabytes.

-n <size> (default: no limit)

Specifies the number of allocated megabytes after which garbage collection is run.

-g <time> (default = 60)

This is the frequency (in seconds) at witch the GarbageCollector may be launched (0 for disabled).

-l <case> (default = 0)

This is a temporary option that allow to select function name naming. 0:default, 1:lowerCamelCase, 2:UpperCamelCase
node:

Default is UpperCamelCase for jslibs version < 1.0 and lowerCamelCase for jslibs version >= 1.0
example:

loadModule('jsio'); loadModule('jsstd'); var f = new File( arguments[0] ); f.open('r'); print( f.read(100) );

Exit code

The exit code of jshost is 1 on error. On success, exit code is the last evaluated expression of the script.

If this last expression is a positive integer, its value is returned, in any other case, 0 is returned.

If there is a pending uncatched exception and if this exception can be converted into a number (see valueOf), this numeric value is used as exit code.

example:

 function Exit(code) {
  throw code;
 }

 Exit(2);

Global functions

status LoadModule( moduleFileName )

Loads and initialize the specified module. Do not provide the file extension in moduleFileName.
exemple:

LoadModule('jsstd'); Print( 'Unsafe mode: '+configuration.unsafeMode, '\n' );
note:
You can avoid LoadModule to use the global object and load the module in your own namespace:
var std = {}; LoadModule.call( std, 'jsstd' ); std.Print( std.IdOf(1234), '\n' ); std.Print( std.IdOf(1234), '\n' );

Global properties

arguments

The command-line arguments (given after command line options).

example:

  for ( var i in arguments ) {

   Print( 'argument['+i+'] = '+arguments[i] ,'\n' );
  }

 
  ...
   c:\>jshost -g 600 -u foo.js bar
   argument0 = foo.js
   argument1 = bar

endSignal

Is true if a break signal (ctrl-c, ...) has been sent to jshost. This event can be reset.

Configuration object

jshost create a global _configuration object to provide other modules some useful informations like stdout access and unsafeMode flag.

Remarks

Modules entry points signature are

`"ModuleInit"`	`JSBool (ModuleInitFunction)(JSContext , JSObject *)`	Called when the module is being load
`"ModuleRelease"`	`void (ModuleReleaseFunction)(JSContext cx)`	Called when the module is not more needed
`"ModuleFree"`	`void (*ModuleFreeFunction)(void)`	Called to let the module moke some cleanup tasks

Exemple (win32)

extern "C" __declspec(dllexport) JSBool ModuleInit(JSContext *cx, JSObject *obj) {

 InitFileClass(cx, obj);
 InitDirectoryClass(cx, obj);
 InitSocketClass(cx, obj);
 InitErrorClass(cx, obj);
 InitGlobal(cx, obj);

 return JS_TRUE;
}

== Embedding JS scripts in your jshost binary ==
 This can only be done at jshost compilation time.
 # Checkout [http://code.google.com/p/jslibs/source/checkout jslibs sources]
 # Save your embbeded script in the file _jslibs/src/jshost/embeddedBootstrapScript.js_
 # [jslibsBuild Compile jslibs] (or only jshost if jslibs has already been compiled once)

Comment by dusel...@hotmail.ru, Sep 29, 2009

Print( 'Unsafe mode: '+(underscore)configuration.unsafeMode, '\n' ); P.S. Submit eliminates real undescores(?)

Comment by soubok, Sep 29, 2009

I think undescores are used in wiki markups for italic. You can escape them using the back quote: `_`configuration