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* Copyright (c) 2010-2011 Luaj.org. All rights reserved.
*
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*
* The above copyright notice and this permission notice shall be included in
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package org.luaj.vm2.lib;
import java.io.InputStream;
import org.luaj.vm2.Globals;
import org.luaj.vm2.LuaFunction;
import org.luaj.vm2.LuaString;
import org.luaj.vm2.LuaTable;
import org.luaj.vm2.LuaValue;
import org.luaj.vm2.Varargs;
/**
* Subclass of {@link LibFunction} which implements the lua standard package and module
* library functions.
*
* Lua Environment Variables
* The following variables are available to lua scrips when this library has been loaded:
*
* "package.loaded" Lua table of loaded modules.
* "package.path" Search path for lua scripts.
* "package.preload" Lua table of uninitialized preload functions.
* "package.searchers" Lua table of functions that search for object to load.
*
*
* Java Environment Variables
* These Java environment variables affect the library behavior:
*
* "luaj.package.path" Initial value for "package.path". Default value is "?.lua"
*
*
* Loading
* Typically, this library is included as part of a call to either
* {@link JsePlatform#standardGlobals()} or {@link JmePlatform#standardGlobals()}
* {@code
* Globals globals = JsePlatform.standardGlobals();
* System.out.println( globals.get("require").call"foo") );
* }
*
* To instantiate and use it directly,
* link it into your globals table via {@link LuaValue#load(LuaValue)} using code such as:
*
{@code
* Globals globals = new Globals();
* globals.load(new JseBaseLib());
* globals.load(new PackageLib());
* System.out.println( globals.get("require").call("foo") );
* }
* Limitations
* This library has been implemented to match as closely as possible the behavior in the corresponding library in C.
* However, the default filesystem search semantics are different and delegated to the bas library
* as outlined in the {@link BaseLib} and {@link JseBaseLib} documentation.
*
* @see LibFunction
* @see BaseLib
* @see JseBaseLib
* @see JsePlatform
* @see JmePlatform
* @see Lua 5.2 Package Lib Reference
*/
public class PackageLib extends TwoArgFunction {
/** The default value to use for package.path. This can be set with the system property
* "luaj.package.path", and is "?.lua" by default. */
public static String DEFAULT_LUA_PATH = System.getProperty("luaj.package.path");
static {
if (DEFAULT_LUA_PATH == null)
DEFAULT_LUA_PATH = "?.lua";
}
private static final LuaString _LOADED = valueOf("loaded");
private static final LuaString _LOADLIB = valueOf("loadlib");
private static final LuaString _PRELOAD = valueOf("preload");
private static final LuaString _PATH = valueOf("path");
private static final LuaString _SEARCHPATH = valueOf("searchpath");
private static final LuaString _SEARCHERS = valueOf("searchers");
/** The globals that were used to load this library. */
Globals globals;
/** The table for this package. */
LuaTable package_;
/** Loader that loads from {@link preload} table if found there */
public preload_searcher preload_searcher;
/** Loader that loads as a lua script using the lua path currently in {@link path} */
public lua_searcher lua_searcher;
/** Loader that loads as a Java class. Class must have public constructor and be a LuaValue. */
public java_searcher java_searcher;
private static final LuaString _SENTINEL = valueOf("\u0001");
private static final String FILE_SEP = System.getProperty("file.separator");
public PackageLib() {}
public LuaValue call(LuaValue modname, LuaValue env) {
globals = env.checkglobals();
globals.set("require", new require());
package_ = new LuaTable();
package_.set(_LOADED, new LuaTable());
package_.set(_PRELOAD, new LuaTable());
package_.set(_PATH, LuaValue.valueOf(DEFAULT_LUA_PATH));
package_.set(_LOADLIB, new loadlib());
package_.set(_SEARCHPATH, new searchpath());
LuaTable searchers = new LuaTable();
searchers.set(1, preload_searcher = new preload_searcher());
searchers.set(2, lua_searcher = new lua_searcher());
searchers.set(3, java_searcher = new java_searcher());
package_.set(_SEARCHERS, searchers);
package_.get(_LOADED).set("package", package_);
env.set("package", package_);
globals.package_ = this;
return env;
}
/** Allow packages to mark themselves as loaded */
public void setIsLoaded(String name, LuaTable value) {
package_.get(_LOADED).set(name, value);
}
/** Set the lua path used by this library instance to a new value.
* Merely sets the value of {@link path} to be used in subsequent searches. */
public void setLuaPath( String newLuaPath ) {
package_.set(_PATH, LuaValue.valueOf(newLuaPath));
}
public String tojstring() {
return "package";
}
// ======================== Package loading =============================
/**
* require (modname)
*
* Loads the given module. The function starts by looking into the package.loaded table
* to determine whether modname is already loaded. If it is, then require returns the value
* stored at package.loaded[modname]. Otherwise, it tries to find a loader for the module.
*
* To find a loader, require is guided by the package.searchers sequence.
* By changing this sequence, we can change how require looks for a module.
* The following explanation is based on the default configuration for package.searchers.
*
* First require queries package.preload[modname]. If it has a value, this value
* (which should be a function) is the loader. Otherwise require searches for a Lua loader using
* the path stored in package.path. If that also fails, it searches for a Java loader using
* the classpath, using the public default constructor, and casting the instance to LuaFunction.
*
* Once a loader is found, require calls the loader with two arguments: modname and an extra value
* dependent on how it got the loader. If the loader came from a file, this extra value is the file name.
* If the loader is a Java instance of LuaFunction, this extra value is the environment.
* If the loader returns any non-nil value, require assigns the returned value to package.loaded[modname].
* If the loader does not return a non-nil value and has not assigned any value to package.loaded[modname],
* then require assigns true to this entry.
* In any case, require returns the final value of package.loaded[modname].
*
* If there is any error loading or running the module, or if it cannot find any loader for the module,
* then require raises an error.
*/
public class require extends OneArgFunction {
public LuaValue call( LuaValue arg ) {
LuaString name = arg.checkstring();
LuaValue loaded = package_.get(_LOADED);
LuaValue result = loaded.get(name);
if ( result.toboolean() ) {
if ( result == _SENTINEL )
error("loop or previous error loading module '"+name+"'");
return result;
}
/* else must load it; iterate over available loaders */
LuaTable tbl = package_.get(_SEARCHERS).checktable();
StringBuffer sb = new StringBuffer();
Varargs loader = null;
for ( int i=1; true; i++ ) {
LuaValue searcher = tbl.get(i);
if ( searcher.isnil() ) {
error( "module '"+name+"' not found: "+name+sb );
}
/* call loader with module name as argument */
loader = searcher.invoke(name);
if ( loader.isfunction(1) )
break;
if ( loader.isstring(1) )
sb.append( loader.tojstring(1) );
}
// load the module using the loader
loaded.set(name, _SENTINEL);
result = loader.arg1().call(name, loader.arg(2));
if ( ! result.isnil() )
loaded.set( name, result );
else if ( (result = loaded.get(name)) == _SENTINEL )
loaded.set( name, result = LuaValue.TRUE );
return result;
}
}
public static class loadlib extends VarArgFunction {
public Varargs loadlib( Varargs args ) {
args.checkstring(1);
return varargsOf(NIL, valueOf("dynamic libraries not enabled"), valueOf("absent"));
}
}
public class preload_searcher extends VarArgFunction {
public Varargs invoke(Varargs args) {
LuaString name = args.checkstring(1);
LuaValue val = package_.get(_PRELOAD).get(name);
return val.isnil()?
valueOf("\n\tno field package.preload['"+name+"']"):
val;
}
}
public class lua_searcher extends VarArgFunction {
public Varargs invoke(Varargs args) {
LuaString name = args.checkstring(1);
InputStream is = null;
// get package path
LuaValue path = package_.get(_PATH);
if ( ! path.isstring() )
return valueOf("package.path is not a string");
// get the searchpath function.
Varargs v = package_.get(_SEARCHPATH).invoke(varargsOf(name, path));
// Did we get a result?
if (!v.isstring(1))
return v.arg(2).tostring();
LuaString filename = v.arg1().strvalue();
// Try to load the file.
v = globals.loadfile(filename.tojstring());
if ( v.arg1().isfunction() )
return LuaValue.varargsOf(v.arg1(), filename);
// report error
return varargsOf(NIL, valueOf("'"+filename+"': "+v.arg(2).tojstring()));
}
}
public class searchpath extends VarArgFunction {
public Varargs invoke(Varargs args) {
String name = args.checkjstring(1);
String path = args.checkjstring(2);
String sep = args.optjstring(3, ".");
String rep = args.optjstring(4, FILE_SEP);
// check the path elements
int e = -1;
int n = path.length();
StringBuffer sb = null;
name = name.replace(sep.charAt(0), rep.charAt(0));
while ( e < n ) {
// find next template
int b = e+1;
e = path.indexOf(';',b);
if ( e < 0 )
e = path.length();
String template = path.substring(b,e);
// create filename
int q = template.indexOf('?');
String filename = template;
if ( q >= 0 ) {
filename = template.substring(0,q) + name + template.substring(q+1);
}
// try opening the file
InputStream is = globals.FINDER.findResource(filename);
if (is != null) {
try { is.close(); } catch ( java.io.IOException ioe ) {}
return valueOf(filename);
}
// report error
if ( sb == null )
sb = new StringBuffer();
sb.append( "\n\t"+filename );
}
return varargsOf(NIL, valueOf(sb.toString()));
}
}
public class java_searcher extends VarArgFunction {
public Varargs invoke(Varargs args) {
String name = args.checkjstring(1);
String classname = toClassname( name );
Class c = null;
LuaValue v = null;
try {
c = Class.forName(classname);
v = (LuaValue) c.newInstance();
if (v.isfunction())
((LuaFunction)v).initupvalue1(globals);
return varargsOf(v, globals);
} catch ( ClassNotFoundException cnfe ) {
return valueOf("\n\tno class '"+classname+"'" );
} catch ( Exception e ) {
return valueOf("\n\tjava load failed on '"+classname+"', "+e );
}
}
}
/** Convert lua filename to valid class name */
public static final String toClassname( String filename ) {
int n=filename.length();
int j=n;
if ( filename.endsWith(".lua") )
j -= 4;
for ( int k=0; k='a'&&c<='z') || (c>='A'&&c<='Z') || (c>='0'&&c<='9') )
return true;
switch ( c ) {
case '.':
case '$':
case '_':
return true;
default:
return false;
}
}
}