annotate PyPlugScanner.cpp @ 24:7d28bed0864e

* Rearrange Python plugin construction.

  Formerly, the PyPluginAdapter has retained a single plugin instance pointer
  for each plugin found, and its createPlugin method has simply returned a new
  PyPlugin object wrapping the same instance pointer.  This has a couple of
  negative consequences:
   - Because construction of the actual Python instance occurred before the
     wrapper was constructed, it was not possible to pass arguments (i.e.
     the sample rate) from the wrapper constructor to the Python plugin
     instance constructor -- they had to be passed later, to initialise,
     disadvantaging those plugins that would like to use the sample rate
     for parameter & step/block size calculations etc
   - Because there was only a single Python plugin instance, it was not
     possible to run more than one instance at once with any isolation

  This rework instead stores the Python class pointer (rather than instance
  pointer) in the PyPluginAdapter, and each PyPlugin wrapper instance creates
  its own Python plugin instance.  What could possibly go wrong?

/**
 * This Vamp plugin is a wrapper for Python Scripts. (VamPy)
 * Centre for Digital Music, Queen Mary, University of London.
 * Copyright 2008, George Fazekas.

*/


#include "PyPlugScanner.h"

//#include <fstream>
//#include <cctype>

#ifdef _WIN32
#include <windows.h>
#include <tchar.h>
#define pathsep ("\\")
#else 
#include <dirent.h>
#include <dlfcn.h>
#define pathsep ("/")
#endif 
#define joinPath(a,b) ( (a)+pathsep+(b) )

using std::string;
using std::vector;
using std::cerr;
using std::endl;

PyPlugScanner::PyPlugScanner()
{

} 

PyPlugScanner *PyPlugScanner::m_instance = NULL;
bool PyPlugScanner::m_hasInstance = false;

PyPlugScanner*
PyPlugScanner::getInstance()
{
	if (!m_hasInstance) {
		m_instance = new PyPlugScanner();
		m_hasInstance = true;
	}
	return m_instance;
}

void
PyPlugScanner::setPath(vector<string> path)
{
	m_path=path;
}

// TODO: This should return all scripts for all valid paths
// Validate python classes here?
// For now, we assume that each script on the path has one valid class
vector<string> 
PyPlugScanner::getPyPlugs()
{
	//foreach m_path listFiles then return vector<pyPlugs>
	//format: FullPathString/FileName.py:ClassName
	
	vector<string> pyPlugs;
	string pluginKey;
	PyObject *pyClass;
	
    for (size_t i = 0; i < m_path.size(); ++i) {
        
        vector<string> files = listFiles(m_path[i],"py");

        for (vector<string>::iterator fi = files.begin();
             fi != files.end(); ++fi) {
				string script = *fi;
				if (!script.empty()) {					
					string classname=script.substr(0,script.rfind('.'));
					pluginKey=joinPath(m_path[i],script)+":"+classname;
					pyClass = getScriptClass(m_path[i],classname);
					if (pyClass == NULL) 
					cerr << "Warning: Syntax error in VamPy plugin:  " 
					     << classname << ". Avoiding plugin." << endl;
					else { 
							pyPlugs.push_back(pluginKey);
							m_pyClasses.push_back(pyClass);
						}
					//pyPlugs.push_back(pluginKey);
				}
		}		
	}
		
return pyPlugs;	

}


//For now return one class object found in each script
vector<PyObject*> 
PyPlugScanner::getPyClasses()
{
return m_pyClasses;	

}


//Validate
//This should not be called more than once!
PyObject* 
PyPlugScanner::getScriptClass(string path, string classname)
{

	//Add plugin path to active Python Path 
	string pyCmd = "import sys\nsys.path.append('" + path + "')\n";
	PyRun_SimpleString(pyCmd.c_str());				

	//Assign an object to the source code
	PyObject *pySource = PyString_FromString(classname.c_str());

	//Import it as a module into the py interpreter
	PyObject *pyModule = PyImport_Import(pySource);
	PyObject* pyError = PyErr_Occurred();
	if (! pyError == 0) { 
		cerr << "ERROR: error importing source: " << classname << endl; 
		PyErr_Print(); 
		Py_DECREF(pySource); 
		Py_CLEAR(pyModule);  // safer if pyModule==NULL
		return NULL; 
	}
	Py_DECREF(pySource);

	//Read the namespace of the module into a dictionary object (borrowed reference)
	PyObject *pyDict = PyModule_GetDict(pyModule);
	Py_DECREF(pyModule);

	//Get the PluginClass from the module (borrowed reference)
	PyObject *pyClass = PyDict_GetItemString(pyDict, classname.c_str());

	//Check if class is present and a callable method is implemented
	if (pyClass && PyCallable_Check(pyClass)) {

	    return pyClass;
	}	
	else {
		cerr << "ERROR: callable plugin class could not be found in source: " << classname << endl 
			<< "Hint: plugin source filename and plugin class name must be the same." << endl;
		PyErr_Print(); 
		return NULL;
	}
}



// Return a list of files in dir with given extension
// Code taken from hostext/PluginLoader.cpp
vector<string>
PyPlugScanner::listFiles(string dir, string extension)
{
    vector<string> files;

#ifdef _WIN32

    string expression = dir + "\\*." + extension;
    WIN32_FIND_DATA data;
    HANDLE fh = FindFirstFile(expression.c_str(), &data);
    if (fh == INVALID_HANDLE_VALUE) return files;

    bool ok = true;
    while (ok) {
        files.push_back(data.cFileName);
        ok = FindNextFile(fh, &data);
    }

    FindClose(fh);

#else

    size_t extlen = extension.length();
    DIR *d = opendir(dir.c_str());
    if (!d) return files;
            
    struct dirent *e = 0;
    while ((e = readdir(d))) {
 
        if (!(e->d_type & DT_REG) && (e->d_type != DT_UNKNOWN)) continue;
        
        if (!e->d_name) continue;
       
        size_t len = strlen(e->d_name);
        if (len < extlen + 2 ||
            e->d_name + len - extlen - 1 != "." + extension) {
            continue;
        }
		//cerr << "pyscripts: " << e->d_name <<  endl;
        files.push_back(e->d_name);
    }

    closedir(d);
#endif

    return files;
}

//Return correct plugin directories as per platform
//Code taken from vamp-sdk/PluginHostAdapter.cpp

//!!! It would probably be better to actually call
// PluginHostAdapter::getPluginPath.  That would mean this "plugin"
// needs to link against vamp-hostsdk, but that's probably acceptable
// as it is sort of a host as well.

std::vector<std::string>
PyPlugScanner::getAllValidPath()
{
    std::vector<std::string> path;
    std::string envPath;

    char *cpath = getenv("VAMP_PATH");
    if (cpath) envPath = cpath;

#ifdef _WIN32
#define PATH_SEPARATOR ';'
#define DEFAULT_VAMP_PATH "%ProgramFiles%\\Vamp Plugins"
#else
#define PATH_SEPARATOR ':'
#ifdef __APPLE__
#define DEFAULT_VAMP_PATH "$HOME/Library/Audio/Plug-Ins/Vamp:/Library/Audio/Plug-Ins/Vamp"
#else
#define DEFAULT_VAMP_PATH "$HOME/vamp:$HOME/.vamp:/usr/local/lib/vamp:/usr/lib/vamp"
#endif
#endif

    if (envPath == "") {
        envPath = DEFAULT_VAMP_PATH;
        char *chome = getenv("HOME");
        if (chome) {
            std::string home(chome);
            std::string::size_type f;
            while ((f = envPath.find("$HOME")) != std::string::npos &&
                    f < envPath.length()) {
                envPath.replace(f, 5, home);
            }
        }
#ifdef _WIN32
        char *cpfiles = getenv("ProgramFiles");
        if (!cpfiles) cpfiles = "C:\\Program Files";
        std::string pfiles(cpfiles);
        std::string::size_type f;
        while ((f = envPath.find("%ProgramFiles%")) != std::string::npos &&
               f < envPath.length()) {
            envPath.replace(f, 14, pfiles);
        }
#endif
    }

    std::string::size_type index = 0, newindex = 0;

    while ((newindex = envPath.find(PATH_SEPARATOR, index)) < envPath.size()) {
	path.push_back(envPath.substr(index, newindex - index));
	index = newindex + 1;
    }
    
    path.push_back(envPath.substr(index));

    return path;
}