simplify instructions

Author: picnixz

Doc/c-api/expat.rst

@@ -15,20 +15,25 @@ the module state:
 
    struct PyExpat_CAPI *capi = NULL;
    capi = (struct PyExpat_CAPI *)PyCapsule_Import(PyExpat_CAPSULE_NAME, 0);
-   if (capi == NULL) { goto error; }
-
-   /* check if the C API is compatible with the version of Expat version */
-   if (strcmp(capi->magic, PyExpat_CAPI_MAGIC) != 0
-       || (size_t)capi->size < sizeof(struct PyExpat_CAPI)
-       || capi->MAJOR_VERSION != XML_MAJOR_VERSION
-       || capi->MINOR_VERSION != XML_MINOR_VERSION
-       || capi->MICRO_VERSION != XML_MICRO_VERSION
-   ) {
+   if (capi == NULL) {
+       goto error;
+   }
+   if (!PyExpat_CheckCompatibility(capi)) {
        PyErr_SetString(PyExc_ImportError, "pyexpat version is incompatible");
        goto error;
    }
 
 
+.. c:function:: int PyExpat_CheckCompatibility(struct PyExpat_API *api)
+
+   Return ``1`` if *api* is compatible with the linked Expat library,
+   and ``0`` otherwise. This function never sets a Python exception.
+
+   *api* must not be ``NULL``.
+
+   .. versionadded:: next
+
+
 .. c:macro:: PyExpat_CAPI_MAGIC
 
    The Expat C API magic number.

Include/pyexpat.h

@@ -6,9 +6,8 @@
 #define PyExpat_CAPI_MAGIC  "pyexpat.expat_CAPI 1.1"
 #define PyExpat_CAPSULE_NAME "pyexpat.expat_CAPI"
 
-struct PyExpat_CAPI
-{
-    char* magic; /* set to PyExpat_CAPI_MAGIC */
+struct PyExpat_CAPI {
+    char *magic; /* set to PyExpat_CAPI_MAGIC */
     int size; /* set to sizeof(struct PyExpat_CAPI) */
     int MAJOR_VERSION;
     int MINOR_VERSION;
@@ -65,3 +64,15 @@ struct PyExpat_CAPI
     /* always add new stuff to the end! */
 };
 
+static inline int
+PyExpat_CheckCompatibility(struct PyExpat_CAPI *api)
+{
+    return (
+        api != NULL
+        && strcmp(api->magic, PyExpat_CAPI_MAGIC) == 0
+        && (size_t)api->size >= sizeof(struct PyExpat_CAPI)
+        && api->MAJOR_VERSION == XML_MAJOR_VERSION
+        && api->MINOR_VERSION == XML_MINOR_VERSION
+        && api->MICRO_VERSION == XML_MICRO_VERSION
+    );
+}