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restore Expr_visit

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krangelov
2021-09-27 06:12:14 +02:00
parent b12e8a6969
commit fbd0be2c3e
1 changed files with 75 additions and 0 deletions
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75
src/runtime/python/expr.c
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@@ -239,6 +239,74 @@ Expr_call(ExprObject* self, PyObject* args, PyObject* kw)
return res;
}
static PyObject*
Expr_visit(ExprObject* self, PyObject *args)
{
PyObject* py_visitor = NULL;
if (!PyArg_ParseTuple(args, "O", &py_visitor))
return NULL;
if (PyObject_TypeCheck(self, &pgf_ExprTypedType)) {
self = ((ExprTypedObject *) self)->expr;
}
ExprObject *o = (ExprObject *) self;
size_t arity = 0;
while (PyObject_TypeCheck(o, &pgf_ExprAppType)) {
arity++;
o = ((ExprAppObject *) o)->fun;
if (PyObject_TypeCheck(o, &pgf_ExprTypedType)) {
o = ((ExprTypedObject *) o)->expr;
}
}
if (PyObject_TypeCheck(o, &pgf_ExprFunType)) {
Py_ssize_t len;
const char *text = PyUnicode_AsUTF8AndSize(((ExprFunObject *) o)->name, &len);
if (text == NULL)
return NULL;
char* method_name = alloca(len+4);
strcpy(method_name, "on_");
memcpy(method_name+3, text, len+1);
if (PyObject_HasAttrString(py_visitor, method_name)) {
PyObject* method_args = PyTuple_New(arity);
if (method_args == NULL) {
return NULL;
}
o = (ExprObject *) self;
for (size_t i = 0; i < arity; i++) {
ExprObject *arg = ((ExprAppObject *) o)->arg;
if (PyObject_TypeCheck(arg, &pgf_ExprImplArgType)) {
arg = ((ExprImplArgObject *) arg)->expr;
}
Py_INCREF(arg);
if (PyTuple_SetItem(method_args, i, (PyObject *) arg) == -1) {
Py_DECREF(method_args);
return NULL;
}
o = ((ExprAppObject *) o)->fun;
if (PyObject_TypeCheck(o, &pgf_ExprTypedType)) {
o = ((ExprTypedObject *) o)->expr;
}
}
PyObject* method =
PyObject_GetAttrString(py_visitor, method_name);
if (method == NULL) {
Py_DECREF(method_args);
return NULL;
}
return PyObject_CallObject(method, method_args);
}
}
return PyObject_CallMethod(py_visitor, "default", "O", self);
}
static PyObject*
Expr_reduce_ex(ExprObject* self, PyObject *args)
{
@@ -270,6 +338,13 @@ Expr_reduce_ex(ExprObject* self, PyObject *args)
}
static PyMethodDef Expr_methods[] = {
{"visit", (PyCFunction)Expr_visit, METH_VARARGS,
"Implementation of the visitor pattern for abstract syntax trees. "
"If e is an expression equal to f a1 .. an then "
"e.visit(self) calls method self.on_f(a1,..an). "
"If the method doesn't exist then the method self.default(e) "
"is called."
},
{"__reduce_ex__", (PyCFunction)Expr_reduce_ex, METH_VARARGS,
"This method allows for transparent pickling/unpickling of expressions."
},