Start work on marshalling in Python bindings

src/runtime/python/marshaller.c

@@ -0,0 +1,103 @@
+// #define PY_SSIZE_T_CLEAN
+// #include <Python.h>
+
+#include <pgf/pgf.h>
+#include "./expr.h"
+
+/* The PgfUnmarshaller structure tells the runtime how to create
+ * abstract syntax expressions and types in the heap of the host language.
+ * In Python the expressions are normal objects.
+ * From the point of view of the runtime, each node is a value of type object.
+ * For Python that would be a PyObject pointer.
+ */
+
+PgfExpr eabs(PgfUnmarshaller *this, PgfBindType btype, PgfText *name, PgfExpr body)
+{
+    return 0;
+}
+
+PgfExpr eapp(PgfUnmarshaller *this, PgfExpr fun, PgfExpr arg)
+{
+    return 0;
+}
+
+PgfExpr elit(PgfUnmarshaller *this, PgfLiteral lit)
+{
+    return 0;
+}
+
+PgfExpr emeta(PgfUnmarshaller *this, PgfMetaId meta)
+{
+    return 0;
+}
+
+PgfExpr efun(PgfUnmarshaller *this, PgfText *name)
+{
+    return 0;
+}
+
+PgfExpr evar(PgfUnmarshaller *this, int index)
+{
+    return 0;
+}
+
+PgfExpr etyped(PgfUnmarshaller *this, PgfExpr expr, PgfType typ)
+{
+    return 0;
+}
+
+PgfExpr eimplarg(PgfUnmarshaller *this, PgfExpr expr)
+{
+    return 0;
+}
+
+PgfLiteral lint(PgfUnmarshaller *this, size_t size, uintmax_t *v)
+{
+    return 0;
+}
+
+PgfLiteral lflt(PgfUnmarshaller *this, double v)
+{
+    return 0;
+}
+
+PgfLiteral lstr(PgfUnmarshaller *this, PgfText *v)
+{
+    return 0;
+}
+
+PgfType dtyp(PgfUnmarshaller *this, int n_hypos, PgfTypeHypo *hypos, PgfText *cat, int n_exprs, PgfExpr *exprs)
+{
+    PgfText* catname = (PgfText*) malloc(sizeof(PgfText)+cat->size+1);
+    memcpy(catname->text, cat->text, cat->size+1);
+    catname->size = cat->size;
+
+    TypeObject* pytype = (TypeObject*) pgf_TypeType.tp_alloc(&pgf_TypeType, 0);
+    pytype->cat = catname;
+    return (PgfType) pytype;
+}
+
+void free_ref(PgfUnmarshaller *this, object x)
+{
+    return;
+}
+
+static PgfUnmarshallerVtbl unmarshallervtbl =
+{
+    eabs,
+    eapp,
+    elit,
+    emeta,
+    efun,
+    evar,
+    etyped,
+    eimplarg,
+    lint,
+    lflt,
+    lstr,
+    dtyp,
+    free_ref
+};
+
+/* static */
+PgfUnmarshaller unmarshaller = { &unmarshallervtbl };