Split plpython.c into smaller pieces

This moves the code around from one huge file into hopefully logical
and more manageable modules.  For the most part, the code itself was
not touched, except: PLy_function_handler and PLy_trigger_handler were
renamed to PLy_exec_function and PLy_exec_trigger, because they were
not actually handlers in the PL handler sense, and it makes the naming
more similar to the way PL/pgSQL is organized.  The initialization of
the procedure caches was separated into a new function
init_procedure_caches to keep the hash tables private to
plpy_procedures.c.

Jan Urbański and Peter Eisentraut

src/pl/plpython/plpy_util.c

@@ -0,0 +1,125 @@
+/*
+ * utility functions
+ *
+ * src/pl/plpython/plpy_util.c
+ */
+
+#include "postgres.h"
+
+#include "mb/pg_wchar.h"
+#include "utils/memutils.h"
+#include "utils/palloc.h"
+
+#include "plpython.h"
+
+#include "plpy_util.h"
+
+#include "plpy_elog.h"
+
+
+void *
+PLy_malloc(size_t bytes)
+{
+	/* We need our allocations to be long-lived, so use TopMemoryContext */
+	return MemoryContextAlloc(TopMemoryContext, bytes);
+}
+
+void *
+PLy_malloc0(size_t bytes)
+{
+	void	   *ptr = PLy_malloc(bytes);
+
+	MemSet(ptr, 0, bytes);
+	return ptr;
+}
+
+char *
+PLy_strdup(const char *str)
+{
+	char	   *result;
+	size_t		len;
+
+	len = strlen(str) + 1;
+	result = PLy_malloc(len);
+	memcpy(result, str, len);
+
+	return result;
+}
+
+/* define this away */
+void
+PLy_free(void *ptr)
+{
+	pfree(ptr);
+}
+
+/*
+ * Convert a Python unicode object to a Python string/bytes object in
+ * PostgreSQL server encoding.	Reference ownership is passed to the
+ * caller.
+ */
+PyObject *
+PLyUnicode_Bytes(PyObject *unicode)
+{
+	PyObject   *rv;
+	const char *serverenc;
+
+	/*
+	 * Python understands almost all PostgreSQL encoding names, but it doesn't
+	 * know SQL_ASCII.
+	 */
+	if (GetDatabaseEncoding() == PG_SQL_ASCII)
+		serverenc = "ascii";
+	else
+		serverenc = GetDatabaseEncodingName();
+	rv = PyUnicode_AsEncodedString(unicode, serverenc, "strict");
+	if (rv == NULL)
+		PLy_elog(ERROR, "could not convert Python Unicode object to PostgreSQL server encoding");
+	return rv;
+}
+
+/*
+ * Convert a Python unicode object to a C string in PostgreSQL server
+ * encoding.  No Python object reference is passed out of this
+ * function.  The result is palloc'ed.
+ *
+ * Note that this function is disguised as PyString_AsString() when
+ * using Python 3.	That function retuns a pointer into the internal
+ * memory of the argument, which isn't exactly the interface of this
+ * function.  But in either case you get a rather short-lived
+ * reference that you ought to better leave alone.
+ */
+char *
+PLyUnicode_AsString(PyObject *unicode)
+{
+	PyObject   *o = PLyUnicode_Bytes(unicode);
+	char	   *rv = pstrdup(PyBytes_AsString(o));
+
+	Py_XDECREF(o);
+	return rv;
+}
+
+#if PY_MAJOR_VERSION >= 3
+/*
+ * Convert a C string in the PostgreSQL server encoding to a Python
+ * unicode object.	Reference ownership is passed to the caller.
+ */
+PyObject *
+PLyUnicode_FromString(const char *s)
+{
+	char	   *utf8string;
+	PyObject   *o;
+
+	utf8string = (char *) pg_do_encoding_conversion((unsigned char *) s,
+													strlen(s),
+													GetDatabaseEncoding(),
+													PG_UTF8);
+
+	o = PyUnicode_FromString(utf8string);
+
+	if (utf8string != s)
+		pfree(utf8string);
+
+	return o;
+}
+#endif   /* PY_MAJOR_VERSION >= 3 */