the Python binding is in pure C again

1 files changed, 1247 insertions, 0 deletions

diff --git a/src/runtime/python/pypgf.c b/src/runtime/python/pypgf.c
new file mode 100644
index 000000000..98ca25e3a
--- /dev/null
+++ b/src/runtime/python/pypgf.c
@@ -0,0 +1,1247 @@
+#include <Python.h>
+#include "structmember.h"
+
+#include <gu/mem.h>
+#include <gu/map.h>
+#include <gu/file.h>
+#include <pgf/pgf.h>
+
+static PyObject* PGFError;
+
+static PyObject* ParseError;
+
+static PyObject*
+gu2py_string(GuString s) {
+	GuWord w = s.w_;
+	uint8_t buf[sizeof(GuWord)];
+
+	char* src;
+	size_t len;
+	if (w & 1) {
+		len = (w & 0xff) >> 1;
+		gu_assert(len <= sizeof(GuWord));
+		size_t i = len;
+		while (i > 0) {
+			w >>= 8;
+			buf[--i] = w & 0xff;
+		}
+		src = (char*) buf;
+	} else {
+		uint8_t* p = (void*) w;
+		len = (p[0] == 0) ? ((size_t*) p)[-1] : p[0];
+		src = (char*) &p[1];
+	}
+
+	return PyString_FromStringAndSize(src, len);
+}
+
+typedef struct {
+	PyObject_HEAD
+	PyObject* master;
+	GuPool* pool;
+    PgfExpr expr;
+} ExprObject;
+
+static ExprObject*
+Expr_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    ExprObject* self = (ExprObject *)type->tp_alloc(type, 0);
+    if (self != NULL) {
+		self->master = NULL;
+		self->pool   = NULL;
+		self->expr   = gu_null_variant;
+    }
+
+    return self;
+}
+
+static void
+Expr_dealloc(ExprObject* self)
+{
+	if (self->master != NULL) {
+		Py_DECREF(self->master);
+	}
+	if (self->pool != NULL) {
+		gu_pool_free(self->pool);
+	}
+
+    self->ob_type->tp_free((PyObject*)self);
+}
+
+static PyObject*
+Expr_getattro(ExprObject *self, PyObject *attr_name);
+
+static int
+Expr_initMeta(ExprObject *self);
+
+static int
+Expr_initLiteral(ExprObject *self, PyObject *lit);
+
+static int
+Expr_initApp(ExprObject *self, const char* fname, PyObject *args);
+
+static PyObject*
+Expr_unpack(ExprObject* self, PyObject *args);
+
+static int
+Expr_init(ExprObject *self, PyObject *args, PyObject *kwds)
+{
+	Py_ssize_t tuple_size = PyTuple_Size(args);
+
+	if (tuple_size == 0) {
+		return Expr_initMeta(self);
+	} else if (tuple_size == 1) {
+		PyObject* lit = NULL;
+		if (!PyArg_ParseTuple(args, "O", &lit))
+			return -1;
+		return Expr_initLiteral(self, lit);
+	} else if (tuple_size == 2) {
+		const char* fname;
+		PyObject* list = NULL;
+		if (!PyArg_ParseTuple(args, "sO!", &fname, &PyList_Type, &list))
+			return -1;
+		return Expr_initApp(self, fname, list);
+	} else {
+		PyErr_Format(PyExc_TypeError, "function takes 0, 1 or 2 arguments (%d given)", tuple_size);
+		return -1;
+	}
+	
+	return 0;
+}
+
+static PyObject *
+Expr_repr(ExprObject *self)
+{
+	GuPool* tmp_pool = gu_local_pool();
+
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+	GuStringBuf* sbuf = gu_string_buf(tmp_pool);
+	GuWriter* wtr = gu_string_buf_writer(sbuf);
+
+	pgf_print_expr(self->expr, 0, wtr, err);
+
+	GuString str = gu_string_buf_freeze(sbuf, tmp_pool);
+	PyObject* pystr = gu2py_string(str);
+	
+	gu_pool_free(tmp_pool);
+	return pystr;
+}
+
+static PyMethodDef Expr_methods[] = {
+    {"unpack", (PyCFunction)Expr_unpack, METH_VARARGS,
+     "Decomposes an expression into its components"
+    },
+    {NULL}  /* Sentinel */
+};
+
+static PyTypeObject pgf_ExprType = {
+    PyObject_HEAD_INIT(NULL)
+    0,                         /*ob_size*/
+    "pgf.Expr",                /*tp_name*/
+    sizeof(ExprObject),        /*tp_basicsize*/
+    0,                         /*tp_itemsize*/
+    (destructor)Expr_dealloc,  /*tp_dealloc*/
+    0,                         /*tp_print*/
+    0,                         /*tp_getattr*/
+    0,                         /*tp_setattr*/
+    0,                         /*tp_compare*/
+    0,                         /*tp_repr*/
+    0,                         /*tp_as_number*/
+    0,                         /*tp_as_sequence*/
+    0,                         /*tp_as_mapping*/
+    0,                         /*tp_hash */
+    0,                         /*tp_call*/
+    (reprfunc) Expr_repr,      /*tp_str*/
+    (getattrofunc) Expr_getattro,/*tp_getattro*/
+    0,                         /*tp_setattro*/
+    0,                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    "abstract syntax tree",    /*tp_doc*/
+    0,		                   /*tp_traverse */
+    0,		                   /*tp_clear */
+    0,		                   /*tp_richcompare */
+    0,		                   /*tp_weaklistoffset */
+    0,		                   /*tp_iter */
+    0,		                   /*tp_iternext */
+    Expr_methods,              /*tp_methods */
+    0,                         /*tp_members */
+    0,                         /*tp_getset */
+    0,                         /*tp_base */
+    0,                         /*tp_dict */
+    0,                         /*tp_descr_get */
+    0,                         /*tp_descr_set */
+    0,                         /*tp_dictoffset */
+    (initproc)Expr_init,       /*tp_init */
+    0,                         /*tp_alloc */
+    (newfunc) Expr_new,        /*tp_new */
+};
+
+static int
+Expr_initMeta(ExprObject *self)
+{
+	self->master = NULL;
+	self->pool = gu_new_pool();
+	PgfExprMeta* e =
+		gu_new_variant(PGF_EXPR_META,
+					   PgfExprMeta,
+					   &self->expr, self->pool);
+	e->id = 0;
+	return 0;
+}
+
+static int
+Expr_initLiteral(ExprObject *self, PyObject *lit)
+{
+	self->master = NULL;
+	self->pool   = gu_new_pool();
+	PgfExprLit* e =
+		gu_new_variant(PGF_EXPR_LIT,
+					   PgfExprLit,
+					   &self->expr, self->pool);
+	e->lit = gu_null_variant;
+
+	if (PyString_Check(lit)) {
+		PgfLiteralStr* slit =
+			gu_new_variant(PGF_LITERAL_STR,
+			               PgfLiteralStr,
+			               &e->lit, self->pool);
+		slit->val = gu_str_string(PyString_AsString(lit), self->pool);
+	} else if (PyInt_Check(lit)) {
+		PgfLiteralInt* ilit =
+			gu_new_variant(PGF_LITERAL_INT,
+			               PgfLiteralInt,
+			               &e->lit, self->pool);
+		ilit->val = PyInt_AsLong(lit);
+	} else if (PyFloat_Check(lit)) {
+		PgfLiteralFlt* flit =
+			gu_new_variant(PGF_LITERAL_FLT,
+			               PgfLiteralFlt,
+			               &e->lit, self->pool);
+		flit->val = PyFloat_AsDouble(lit);
+	} else {
+		PyErr_SetString(PyExc_TypeError, "the literal must be a string, an integer, or a float");
+		return -1;
+	}
+	return 0;
+}
+
+static int
+Expr_initApp(ExprObject *self, const char* fname, PyObject *args)
+{
+	Py_ssize_t n_args = PyList_Size(args);
+
+	self->master = PyTuple_New(n_args);
+	if (self->master == NULL)
+		return -1;
+
+	self->pool = gu_new_pool();
+	PgfExprFun* e =
+		gu_new_variant(PGF_EXPR_FUN,
+					   PgfExprFun,
+					   &self->expr, self->pool);
+	e->fun = gu_str_string(fname, self->pool);
+
+	for (Py_ssize_t i = 0; i < n_args; i++) {
+		PyObject* obj = PyList_GetItem(args, i);
+		if (obj->ob_type != &pgf_ExprType) {
+			PyErr_SetString(PyExc_TypeError, "the arguments in the list must be expressions");
+			return -1;
+		}
+
+		PyTuple_SetItem(self->master, i, obj);
+		Py_INCREF(obj);
+
+		PgfExpr fun = self->expr;
+		PgfExpr arg = ((ExprObject*) obj)->expr;
+
+		PgfExprApp* e =
+			gu_new_variant(PGF_EXPR_APP,
+						   PgfExprApp,
+						   &self->expr, self->pool);
+		e->fun = fun;
+		e->arg = arg;
+	}
+	
+	return 0;
+}
+
+static PyObject*
+Expr_unpack(ExprObject* self, PyObject *fargs)
+{
+	PgfExpr expr = self->expr;
+	PyObject* args = PyList_New(0);
+
+	for (;;) {
+		GuVariantInfo i = gu_variant_open(expr);
+		switch (i.tag) {
+		case PGF_EXPR_APP: {
+			PgfExprApp* eapp = i.data;
+			
+			ExprObject* pyexpr = (ExprObject*) pgf_ExprType.tp_alloc(&pgf_ExprType, 0);
+			if (pyexpr == NULL)
+				return NULL;
+			pyexpr->pool   = NULL;
+			pyexpr->master = (self->master) ? self->master : (PyObject*) self;
+			pyexpr->expr   = eapp->arg;
+			Py_INCREF(pyexpr->master);
+
+			if (PyList_Insert(args, 0, (PyObject*) pyexpr) == -1) {
+				Py_DECREF(args);
+				return NULL;
+			}
+
+			Py_DECREF((PyObject*) pyexpr);
+
+			expr = eapp->fun;
+			break;
+		}
+		case PGF_EXPR_LIT: {
+			PgfExprLit* elit = i.data;
+
+			Py_DECREF(args);
+			
+			GuVariantInfo i = gu_variant_open(elit->lit);
+			switch (i.tag) {
+			case PGF_LITERAL_STR: {
+				PgfLiteralStr* lstr = i.data;
+				return gu2py_string(lstr->val);
+			}
+			case PGF_LITERAL_INT: {
+				PgfLiteralInt* lint = i.data;
+				return PyInt_FromLong(lint->val);
+			}
+			case PGF_LITERAL_FLT: {
+				PgfLiteralFlt* lflt = i.data;
+				return PyFloat_FromDouble(lflt->val);
+			}
+			default:
+				gu_impossible();
+				return NULL;
+			}
+		}
+		case PGF_EXPR_META: {
+			Py_DECREF(args);
+			return Py_None;
+		}
+		case PGF_EXPR_FUN: {
+			PgfExprFun* efun = i.data;
+			PyObject* fun = gu2py_string(efun->fun);
+			PyObject* res = Py_BuildValue("OO", fun, args);
+			Py_DECREF(fun);
+			Py_DECREF(args);
+			return res;
+		}
+		default:
+			gu_impossible();
+			return NULL;
+		}
+	}
+	return NULL;
+}
+
+static PyObject*
+Expr_getattro(ExprObject *self, PyObject *attr_name) {
+	const char* name = PyString_AsString(attr_name);
+
+    GuVariantInfo i = gu_variant_open(self->expr);
+    switch (i.tag) {
+	case PGF_EXPR_APP: {
+		PgfExprApp* eapp = i.data;
+		
+		ExprObject* pyexpr = (ExprObject*) pgf_ExprType.tp_alloc(&pgf_ExprType, 0);
+		if (pyexpr == NULL)
+			return NULL;
+		pyexpr->pool   = NULL;
+		pyexpr->master = (self->master) ? self->master : (PyObject*) self;
+		pyexpr->expr   = gu_null_variant;
+		Py_INCREF(pyexpr->master);
+
+		if (strcmp(name, "fun") == 0) {
+			pyexpr->expr = eapp->fun;
+			return ((PyObject*) pyexpr);
+		} else if (strcmp(name, "arg") == 0) {
+			pyexpr->expr = eapp->arg;
+			return ((PyObject*) pyexpr);
+		} else {
+			Py_DECREF(pyexpr);
+		}
+		break;
+	}
+	case PGF_EXPR_LIT: {
+		PgfExprLit* elit = i.data;
+		
+		if (strcmp(name, "val") == 0) {
+			GuVariantInfo i = gu_variant_open(elit->lit);
+			switch (i.tag) {
+			case PGF_LITERAL_INT: {
+				PgfLiteralInt* lint = i.data;
+				return PyInt_FromLong(lint->val);
+			}
+			case PGF_LITERAL_FLT: {
+				PgfLiteralFlt* lflt = i.data;
+				return PyFloat_FromDouble(lflt->val);
+			}
+			case PGF_LITERAL_STR: {
+				PgfLiteralStr* lstr = i.data;
+				return gu2py_string(lstr->val);
+			}
+			}
+		}
+		break;
+	}
+	case PGF_EXPR_META: {
+		PgfExprMeta* emeta = i.data;
+		if (strcmp(name, "id") == 0)
+			return PyInt_FromLong(emeta->id);
+		break;
+	}
+	case PGF_EXPR_FUN: {		
+		PgfExprFun* efun = i.data;
+		if (strcmp(name, "name") == 0) {
+			return gu2py_string(efun->fun);
+		}
+		break;
+	}
+	default:
+		gu_impossible();
+	}
+
+	return PyObject_GenericGetAttr((PyObject*)self, attr_name);
+}
+
+typedef struct {
+    PyObject_HEAD
+    GuPool* pool;
+    int max_count;
+    int counter;
+    GuEnum* res;
+} ExprIterObject;
+
+static ExprIterObject*
+ExprIter_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    ExprIterObject* self = (ExprIterObject *)type->tp_alloc(type, 0);
+    if (self != NULL) {
+		self->pool = NULL;
+		self->max_count = -1;
+		self->counter   = 0;
+		self->res  = NULL;
+    }
+
+    return self;
+}
+
+static void
+ExprIter_dealloc(ExprIterObject* self)
+{
+	if (self->pool != NULL)
+		gu_pool_free(self->pool);
+
+    self->ob_type->tp_free((PyObject*)self);
+}
+
+static int
+ExprIter_init(ExprIterObject *self, PyObject *args, PyObject *kwds)
+{
+    return -1;
+}
+
+static PyObject*
+ExprIter_iter(ExprIterObject *self)
+{
+	Py_INCREF(self);
+	return (PyObject*) self;
+}
+
+static PyObject*
+ExprIter_iternext(ExprIterObject *self)
+{
+	if (self->max_count >= 0 && self->counter >= self->max_count) {
+		return NULL;
+	}
+	self->counter++;
+
+	PgfExprProb* ep = gu_next(self->res, PgfExprProb*, self->pool);
+	if (ep == NULL)
+		return NULL;
+
+	ExprObject* pyexpr = (ExprObject*) pgf_ExprType.tp_alloc(&pgf_ExprType, 0);
+	if (pyexpr == NULL)
+		return NULL;
+	pyexpr->pool   = NULL;
+	pyexpr->expr   = ep->expr;
+	pyexpr->master = (PyObject*) self;
+	Py_INCREF(self);
+
+	PyObject* res = Py_BuildValue("(f,O)", ep->prob, pyexpr);
+	Py_DECREF(pyexpr);
+
+	return res;
+}
+
+static PyMethodDef ExprIter_methods[] = {
+    {NULL}  /* Sentinel */
+};
+
+static PyTypeObject pgf_ExprIterType = {
+    PyObject_HEAD_INIT(NULL)
+    0,                         /*ob_size*/
+    "pgf.ExprIter",            /*tp_name*/
+    sizeof(ExprIterObject),    /*tp_basicsize*/
+    0,                         /*tp_itemsize*/
+    (destructor)ExprIter_dealloc, /*tp_dealloc*/
+    0,                         /*tp_print*/
+    0,                         /*tp_getattr*/
+    0,                         /*tp_setattr*/
+    0,                         /*tp_compare*/
+    0,                         /*tp_repr*/
+    0,                         /*tp_as_number*/
+    0,                         /*tp_as_sequence*/
+    0,                         /*tp_as_mapping*/
+    0,                         /*tp_hash */
+    0,                         /*tp_call*/
+    0,                         /*tp_str*/
+    0,                         /*tp_getattro*/
+    0,                         /*tp_setattro*/
+    0,                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    "an iterator over a sequence of expressions",/*tp_doc*/
+    0,		                   /*tp_traverse */
+    0,		                   /*tp_clear */
+    0,		                   /*tp_richcompare */
+    0,		                   /*tp_weaklistoffset */
+    (getiterfunc) ExprIter_iter, /*tp_iter */
+    (iternextfunc) ExprIter_iternext, /*tp_iternext */
+    ExprIter_methods,          /*tp_methods */
+    0,                         /*tp_members */
+    0,                         /*tp_getset */
+    0,                         /*tp_base */
+    0,                         /*tp_dict */
+    0,                         /*tp_descr_get */
+    0,                         /*tp_descr_set */
+    0,                         /*tp_dictoffset */
+    (initproc)ExprIter_init,   /*tp_init */
+    0,                         /*tp_alloc */
+    (newfunc) ExprIter_new,    /*tp_new */
+};
+
+typedef struct {
+    PyObject_HEAD
+    GuPool* pool;
+    PgfPGF* pgf;
+} PGFObject;
+
+typedef struct {
+    PyObject_HEAD
+    PGFObject* grammar;
+    PgfConcr* concr;
+} ConcrObject;
+
+static ConcrObject*
+Concr_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    ConcrObject* self = (ConcrObject *)type->tp_alloc(type, 0);
+    if (self != NULL) {
+		self->grammar = NULL;
+		self->concr   = NULL;
+    }
+
+    return self;
+}
+
+static void
+Concr_dealloc(ConcrObject* self)
+{
+	Py_XDECREF(self->grammar);
+    self->ob_type->tp_free((PyObject*)self);
+}
+
+static int
+Concr_init(ConcrObject *self, PyObject *args, PyObject *kwds)
+{
+    return -1;
+}
+
+static PyObject*
+Concr_printName(ConcrObject* self, PyObject *args)
+{
+	const char *name_s;
+    if (!PyArg_ParseTuple(args, "s", &name_s))
+        return NULL;
+
+	GuPool *tmp_pool = gu_local_pool();
+    GuString name = gu_str_string(name_s, tmp_pool);
+    PyObject* pyname = gu2py_string(pgf_print_name(self->concr, name));
+	gu_pool_free(tmp_pool);
+
+	return pyname;
+}
+
+static ExprIterObject*
+Concr_parse(ConcrObject* self, PyObject *args, PyObject *keywds)
+{
+	static char *kwlist[] = {"sentence", "cat", "n", NULL};
+
+	size_t len;
+	const uint8_t *buf;
+	const char *catname_s = NULL;
+	int max_count = -1;
+    if (!PyArg_ParseTupleAndKeywords(args, keywds, "s#|si", kwlist,
+                                     &buf, &len, &catname_s, &max_count))
+        return NULL;
+
+	ExprIterObject* pyres = (ExprIterObject*) 
+		pgf_ExprIterType.tp_alloc(&pgf_ExprIterType, 0);
+	if (pyres == NULL) {
+		return NULL;
+	}
+
+	pyres->pool = gu_new_pool();
+	pyres->max_count = max_count;
+	pyres->counter   = 0;
+
+	GuPool *tmp_pool = gu_local_pool();
+    GuString catname = 
+		(catname_s == NULL) ? pgf_start_cat(self->grammar->pgf, tmp_pool)
+		                    : gu_str_string(catname_s, tmp_pool);
+	GuIn* in = gu_data_in(buf, len, tmp_pool);
+	GuReader* rdr = gu_new_utf8_reader(in, tmp_pool);
+	PgfLexer *lexer =
+		pgf_new_lexer(rdr, tmp_pool);
+
+	pyres->res =
+		pgf_parse(self->concr, catname, lexer, pyres->pool);
+	if (pyres->res == NULL) {
+		Py_DECREF(pyres);
+
+		PgfToken tok =
+			pgf_lexer_current_token(lexer);
+
+		if (gu_string_eq(tok, gu_empty_string))
+			PyErr_SetString(PGFError, "The sentence cannot be parsed");
+		else {
+			PyObject* py_tok = gu2py_string(tok);
+			PyObject_SetAttrString(ParseError, "token", py_tok);
+			PyErr_Format(ParseError, "Unexpected token: \"%s\"", 
+										PyString_AsString(py_tok));
+			Py_DECREF(py_tok);
+		}
+
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+
+	return pyres;
+}
+
+// Concr_parse_tokens is the same as the above function but
+// instead of a string it expect a sequence of tokens as argument.
+// This is usefull if you want to implement your own tokenizer in
+// python.
+static ExprIterObject*
+Concr_parse_tokens(ConcrObject* self, PyObject *args, PyObject *keywds)
+{
+    static char *kwlist[] = {"tokens", "cat", "n", NULL};
+    // Variable for the input list of tokens
+    PyObject* obj;
+    PyObject* seq;
+    int len;
+    const char *catname_s = NULL;
+    int max_count = -1;
+
+    // Parsing arguments: the tokens is a python object (O),
+    // cat is a string (s) and n an integer (i)
+    if (!PyArg_ParseTupleAndKeywords(args, keywds, "O|si", kwlist,
+                                    &obj, &catname_s, &max_count))
+        return NULL;
+    // The python object should be a sequence
+    seq = PySequence_Fast(obj, "expected a sequence");
+    len = PySequence_Size(obj);
+
+    ExprIterObject* pyres = (ExprIterObject*) 
+        pgf_ExprIterType.tp_alloc(&pgf_ExprIterType, 0);
+    if (pyres == NULL) {
+        return NULL;
+    }
+
+    pyres->pool = gu_new_pool();
+    pyres->max_count = max_count;
+    pyres->counter   = 0;
+
+    GuPool *tmp_pool = gu_local_pool();
+    GuString catname = 
+        (catname_s == NULL) ? pgf_start_cat(self->grammar->pgf, tmp_pool)
+                            : gu_str_string(catname_s, tmp_pool);
+
+    // turn the (python) list of tokens into a string array
+    char* tokens[len];
+    for (int i = 0; i < len; i++) {
+        tokens[i] = PyString_AsString(PySequence_Fast_GET_ITEM(seq, i));
+        if (tokens[i] == NULL) {
+            // Note: if the list item is not a string, 
+            // PyString_AsString raises TypeError itself
+            // so we just have to return
+            gu_pool_free(tmp_pool);
+            return NULL;
+        }
+    }
+    Py_DECREF(seq);
+    
+    pyres->res =
+        pgf_parse_tokens(self->concr, catname, tokens, len, pyres->pool);
+
+    if (pyres->res == NULL) {
+        Py_DECREF(pyres);
+
+        PyErr_SetString(PGFError, "Something went wrong during parsing");
+        gu_pool_free(tmp_pool);
+        return NULL;
+    }
+
+    gu_pool_free(tmp_pool);
+    return pyres;
+}
+
+static PyObject*
+Concr_linearize(ConcrObject* self, PyObject *args)
+{
+	ExprObject* pyexpr;
+	if (!PyArg_ParseTuple(args, "O!", &pgf_ExprType, &pyexpr))
+        return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+	GuStringBuf* sbuf = gu_string_buf(tmp_pool);
+	GuWriter* wtr = gu_string_buf_writer(sbuf);
+	
+	pgf_linearize(self->concr, pyexpr->expr, wtr, err);
+	if (!gu_ok(err)) {
+		PyErr_SetString(PGFError, "The abstract tree cannot be linearized");
+		return NULL;
+	}
+
+	GuString str = gu_string_buf_freeze(sbuf, tmp_pool);
+	PyObject* pystr = gu2py_string(str);
+	
+	gu_pool_free(tmp_pool);
+	return pystr;
+}
+
+static PyMethodDef Concr_methods[] = {
+    {"printName", (PyCFunction)Concr_printName, METH_VARARGS,
+     "Returns the print name of a function or category"
+    },
+    {"parse", (PyCFunction)Concr_parse, METH_VARARGS | METH_KEYWORDS,
+     "Parses a string and returns an iterator over the abstract trees for this sentence"
+    },
+    {"parse_tokens", (PyCFunction)Concr_parse_tokens, METH_VARARGS | METH_KEYWORDS,
+     "Parses list of tokens and returns an iterator over the abstract trees for this sentence. Allows you to write your own tokenizer in python."
+    },
+    {"linearize", (PyCFunction)Concr_linearize, METH_VARARGS,
+     "Takes an abstract tree and linearizes it to a sentence"
+    },
+    {NULL}  /* Sentinel */
+};
+
+static PyTypeObject pgf_ConcrType = {
+    PyObject_HEAD_INIT(NULL)
+    0,                         /*ob_size*/
+    "pgf.Concr",               /*tp_name*/
+    sizeof(ConcrObject),       /*tp_basicsize*/
+    0,                         /*tp_itemsize*/
+    (destructor)Concr_dealloc, /*tp_dealloc*/
+    0,                         /*tp_print*/
+    0,                         /*tp_getattr*/
+    0,                         /*tp_setattr*/
+    0,                         /*tp_compare*/
+    0,                         /*tp_repr*/
+    0,                         /*tp_as_number*/
+    0,                         /*tp_as_sequence*/
+    0,                         /*tp_as_mapping*/
+    0,                         /*tp_hash */
+    0,                         /*tp_call*/
+    0,                         /*tp_str*/
+    0,                         /*tp_getattro*/
+    0,                         /*tp_setattro*/
+    0,                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    "concrete syntax",         /*tp_doc*/
+    0,		                   /*tp_traverse */
+    0,		                   /*tp_clear */
+    0,		                   /*tp_richcompare */
+    0,		                   /*tp_weaklistoffset */
+    0,		                   /*tp_iter */
+    0,		                   /*tp_iternext */
+    Concr_methods,             /*tp_methods */
+    0,                         /*tp_members */
+    0,                         /*tp_getset */
+    0,                         /*tp_base */
+    0,                         /*tp_dict */
+    0,                         /*tp_descr_get */
+    0,                         /*tp_descr_set */
+    0,                         /*tp_dictoffset */
+    (initproc)Concr_init,      /*tp_init */
+    0,                         /*tp_alloc */
+    (newfunc)Concr_new,        /*tp_new */
+};
+
+static PGFObject*
+PGF_new(PyTypeObject *type, PyObject *args, PyObject *kwds)
+{
+    PGFObject* self = (PGFObject *)type->tp_alloc(type, 0);
+    if (self != NULL) {
+		self->pool = NULL;
+		self->pgf  = NULL;
+    }
+
+    return self;
+}
+
+static void
+PGF_dealloc(PGFObject* self)
+{
+	if (self->pool != NULL)
+		gu_pool_free(self->pool);
+    self->ob_type->tp_free((PyObject*)self);
+}
+
+static int
+PGF_init(PGFObject *self, PyObject *args, PyObject *kwds)
+{
+    return -1;
+}
+
+static PyObject*
+PGF_getAbstractName(PGFObject *self, void *closure)
+{
+    return gu2py_string(pgf_abstract_name(self->pgf));
+}
+
+typedef struct {
+	GuMapItor fn;
+	PGFObject* grammar;
+	PyObject* object;
+} PyPGFClosure;
+
+static void
+pgf_collect_langs(GuMapItor* fn, const void* key, void* value, GuExn* err)
+{
+	PgfCId name = *((PgfCId*) key);
+    PgfConcr* concr = *((PgfConcr**) value);
+    PyPGFClosure* clo = (PyPGFClosure*) fn;
+    
+    PyObject* py_name = NULL;
+    PyObject* py_lang = NULL;
+    
+	py_name = gu2py_string(name);
+	if (py_name == NULL) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+	py_lang = pgf_ConcrType.tp_alloc(&pgf_ConcrType, 0);
+	if (py_lang == NULL) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+	((ConcrObject *) py_lang)->concr = concr;
+	((ConcrObject *) py_lang)->grammar = clo->grammar;
+	Py_INCREF(clo->grammar);
+
+    if (PyDict_SetItem(clo->object, py_name, py_lang) != 0) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+end:
+    Py_XDECREF(py_lang);
+    Py_XDECREF(py_name);
+}
+
+static PyObject*
+PGF_getLanguages(PGFObject *self, void *closure)
+{
+	PyObject* languages = PyDict_New();
+	if (languages == NULL)
+		return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	PyPGFClosure clo = { { pgf_collect_langs }, self, languages };
+	pgf_iter_languages(self->pgf, &clo.fn, err);
+	if (!gu_ok(err)) {
+		Py_DECREF(languages);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	PyObject* proxy = PyDictProxy_New(languages);
+	
+	Py_DECREF(languages);
+	gu_pool_free(tmp_pool);
+
+    return proxy;
+}
+
+static void
+pgf_collect_cats(GuMapItor* fn, const void* key, void* value, GuExn* err)
+{
+	PgfCId name = *((PgfCId*) key);
+    PyPGFClosure* clo = (PyPGFClosure*) fn;
+    
+    PyObject* py_name = NULL;
+    
+	py_name = gu2py_string(name);
+	if (py_name == NULL) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+    if (PyList_Append(clo->object, py_name) != 0) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+end:
+    Py_XDECREF(py_name);
+}
+
+static PyObject*
+PGF_getCategories(PGFObject *self, void *closure)
+{
+	PyObject* categories = PyList_New(0);
+	if (categories == NULL)
+		return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	PyPGFClosure clo = { { pgf_collect_cats }, self, categories };
+	pgf_iter_categories(self->pgf, &clo.fn, err);
+	if (!gu_ok(err)) {
+		Py_DECREF(categories);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+    return categories;
+}
+
+static PyObject*
+PGF_getStartCat(PGFObject *self, void *closure)
+{
+	GuPool* tmp_pool = gu_local_pool();
+	PyObject* pyname = gu2py_string(pgf_start_cat(self->pgf, tmp_pool));
+	gu_pool_free(tmp_pool);
+    return pyname;
+}
+
+static void
+pgf_collect_funs(GuMapItor* fn, const void* key, void* value, GuExn* err)
+{
+	PgfCId name = *((PgfCId*) key);
+    PyPGFClosure* clo = (PyPGFClosure*) fn;
+    
+    PyObject* py_name = NULL;
+    
+	py_name = gu2py_string(name);
+	if (py_name == NULL) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+    if (PyList_Append(clo->object, py_name) != 0) {
+		gu_raise(err, PgfExn);
+		goto end;
+	}
+
+end:
+    Py_XDECREF(py_name);
+}
+
+static PyObject*
+PGF_getFunctions(PGFObject *self, void *closure)
+{
+	PyObject* functions = PyList_New(0);
+	if (functions == NULL)
+		return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	PyPGFClosure clo = { { pgf_collect_funs }, self, functions };
+	pgf_iter_functions(self->pgf, &clo.fn, err);
+	if (!gu_ok(err)) {
+		Py_DECREF(functions);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+    return functions;
+}
+
+static PyObject*
+PGF_functionsByCat(PGFObject* self, PyObject *args)
+{
+	const char *catname_s;
+    if (!PyArg_ParseTuple(args, "s", &catname_s))
+        return NULL;
+
+	GuPool *tmp_pool = gu_local_pool();
+    GuString catname = gu_str_string(catname_s, tmp_pool);
+
+	PyObject* functions = PyList_New(0);
+	if (functions == NULL) {
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	PyPGFClosure clo = { { pgf_collect_funs }, self, functions };
+	pgf_iter_functions_by_cat(self->pgf, catname, &clo.fn, err);
+	if (!gu_ok(err)) {
+		Py_DECREF(functions);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+    return functions;
+}
+
+static ExprIterObject*
+PGF_generate(PGFObject* self, PyObject *args, PyObject *keywds)
+{
+	static char *kwlist[] = {"cat", "n", NULL};
+
+	const char *catname_s;
+	int max_count = -1;
+    if (!PyArg_ParseTupleAndKeywords(args, keywds, "s|i", kwlist,
+                                     &catname_s, &max_count))
+        return NULL;
+
+	ExprIterObject* pyres = (ExprIterObject*)
+		pgf_ExprIterType.tp_alloc(&pgf_ExprIterType, 0);
+	if (pyres == NULL) {
+		return NULL;
+	}
+
+	pyres->pool = gu_new_pool();
+	pyres->max_count = max_count;
+	pyres->counter   = 0;
+
+	GuPool *tmp_pool = gu_local_pool();
+    GuString catname = gu_str_string(catname_s, tmp_pool);
+
+	pyres->res =
+		pgf_generate(self->pgf, catname, pyres->pool);
+	if (pyres->res == NULL) {
+		Py_DECREF(pyres);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+
+	return pyres;
+}
+
+static PyGetSetDef PGF_getseters[] = {
+    {"abstractName", 
+     (getter)PGF_getAbstractName, NULL,
+     "the abstract syntax name",
+     NULL},
+    {"languages", 
+     (getter)PGF_getLanguages, NULL,
+     "a map containing all concrete languages in the grammar",
+     NULL},
+    {"categories", 
+     (getter)PGF_getCategories, NULL,
+     "a list containing all categories in the grammar",
+     NULL},
+    {"startCat", 
+     (getter)PGF_getStartCat, NULL,
+     "the start category for the grammar",
+     NULL},
+    {"functions", 
+     (getter)PGF_getFunctions, NULL,
+     "a list containing all functions in the grammar",
+     NULL},
+    {NULL}  /* Sentinel */
+};
+
+static PyMemberDef PGF_members[] = {
+    {NULL}  /* Sentinel */
+};
+
+static PyMethodDef PGF_methods[] = {
+    {"functionsByCat", (PyCFunction)PGF_functionsByCat, METH_VARARGS,
+     "Returns the list of functions for a given category"
+    },
+    {"generate", (PyCFunction)PGF_generate, METH_VARARGS | METH_KEYWORDS,
+     "Generates abstract syntax trees of given category in decreasing probability order"
+    },
+    {NULL}  /* Sentinel */
+};
+
+static PyTypeObject pgf_PGFType = {
+    PyObject_HEAD_INIT(NULL)
+    0,                         /*ob_size*/
+    "pgf.PGF",                 /*tp_name*/
+    sizeof(PGFObject),         /*tp_basicsize*/
+    0,                         /*tp_itemsize*/
+    (destructor)PGF_dealloc,   /*tp_dealloc*/
+    0,                         /*tp_print*/
+    0,                         /*tp_getattr*/
+    0,                         /*tp_setattr*/
+    0,                         /*tp_compare*/
+    0,                         /*tp_repr*/
+    0,                         /*tp_as_number*/
+    0,                         /*tp_as_sequence*/
+    0,                         /*tp_as_mapping*/
+    0,                         /*tp_hash */
+    0,                         /*tp_call*/
+    0,                         /*tp_str*/
+    0,                         /*tp_getattro*/
+    0,                         /*tp_setattro*/
+    0,                         /*tp_as_buffer*/
+    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE, /*tp_flags*/
+    "PGF object",              /*tp_doc*/
+    0,		                   /*tp_traverse */
+    0,		                   /*tp_clear */
+    0,		                   /*tp_richcompare */
+    0,		                   /*tp_weaklistoffset */
+    0,		                   /*tp_iter */
+    0,		                   /*tp_iternext */
+    PGF_methods,               /*tp_methods */
+    PGF_members,               /*tp_members */
+    PGF_getseters,             /*tp_getset */
+    0,                         /*tp_base */
+    0,                         /*tp_dict */
+    0,                         /*tp_descr_get */
+    0,                         /*tp_descr_set */
+    0,                         /*tp_dictoffset */
+    (initproc)PGF_init,        /*tp_init */
+    0,                         /*tp_alloc */
+    (newfunc)PGF_new,          /*tp_new */
+};
+
+static PGFObject*
+pgf_readPGF(PyObject *self, PyObject *args)
+{
+    const char *fpath;
+    if (!PyArg_ParseTuple(args, "s", &fpath))
+        return NULL;
+
+	PGFObject* py_pgf = (PGFObject*) pgf_PGFType.tp_alloc(&pgf_PGFType, 0);
+	py_pgf->pool = gu_new_pool();
+
+	GuPool* tmp_pool = gu_local_pool();
+
+	// Create an exception frame that catches all errors.
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	// Read the PGF grammar.
+	py_pgf->pgf = pgf_read(fpath, py_pgf->pool, err);
+	if (!gu_ok(err)) {
+		PyErr_SetString(PGFError, "The grammar cannot be loaded");
+		Py_DECREF(py_pgf);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+	return py_pgf;
+}
+
+static ExprObject*
+pgf_readExpr(PyObject *self, PyObject *args) {
+	size_t len;
+    const uint8_t *buf;
+    if (!PyArg_ParseTuple(args, "s#", &buf, &len))
+        return NULL;
+
+	ExprObject* pyexpr = (ExprObject*) pgf_ExprType.tp_alloc(&pgf_ExprType, 0);
+	if (pyexpr == NULL)
+		return NULL;
+
+	GuPool* tmp_pool = gu_local_pool();
+	GuIn* in = gu_data_in(buf, len, tmp_pool);
+	GuReader* rdr = gu_new_utf8_reader(in, tmp_pool);
+	GuExn* err = gu_new_exn(NULL, gu_kind(type), tmp_pool);
+
+	pyexpr->pool = gu_new_pool();
+	pyexpr->expr = pgf_read_expr(rdr, pyexpr->pool, err);
+	pyexpr->master = NULL;
+	
+	if (!gu_ok(err) || gu_variant_is_null(pyexpr->expr)) {
+		PyErr_SetString(PGFError, "The expression cannot be parsed");
+		Py_DECREF(pyexpr);
+		gu_pool_free(tmp_pool);
+		return NULL;
+	}
+
+	gu_pool_free(tmp_pool);
+    return pyexpr;
+}
+
+static PyMethodDef module_methods[] = {
+    {"readPGF",  (void*)pgf_readPGF,  METH_VARARGS,
+     "Reads a PGF file in the memory"},
+    {"readExpr", (void*)pgf_readExpr, METH_VARARGS,
+     "Parses a string as an abstract tree"},
+    {NULL, NULL, 0, NULL}        /* Sentinel */
+};
+
+PyMODINIT_FUNC
+initpgf(void)
+{
+    PyObject *m;
+
+    if (PyType_Ready(&pgf_PGFType) < 0)
+        return;
+
+    if (PyType_Ready(&pgf_ConcrType) < 0)
+        return;
+
+    if (PyType_Ready(&pgf_ExprType) < 0)
+        return;
+
+	if (PyType_Ready(&pgf_ExprIterType) < 0)
+		return;
+
+    m = Py_InitModule("pgf", module_methods);
+    if (m == NULL)
+        return;
+        
+    PGFError = PyErr_NewException("pgf.PGFError", NULL, NULL);
+    PyModule_AddObject(m, "PGFError", PGFError);
+    Py_INCREF(PGFError);
+    
+    PyObject *dict = PyDict_New();
+    PyDict_SetItemString(dict, "token", PyString_FromString("")); 
+    ParseError = PyErr_NewException("pgf.ParseError", NULL, dict);
+    PyModule_AddObject(m, "ParseError", ParseError);
+    Py_INCREF(ParseError);
+
+    PyModule_AddObject(m, "Expr", (PyObject *) &pgf_ExprType);
+    Py_INCREF(&pgf_ExprType);
+
+    Py_INCREF(&pgf_PGFType);
+    Py_INCREF(&pgf_ConcrType);
+    Py_INCREF(&pgf_ExprIterType);
+}