Improve version information

Add version number and string as macros and symbols. Version numbers can
be easily compared, for example in the C preprocessor:

    #include <cmark.h>

    #if CMARK_VERSION < 0x020200
    #error Requires libcmark 2.2.0 or higher
    #endif

Storing the version in a global variable allows to check the library
version at runtime. For example:

    if (CMARK_VERSION != cmark_version) {
        warn("Compiled against libcmark %s, but using %s",
             CMARK_VERSION_STRING, cmark_version_string);
    }

The version should be updated whenever the public API is changed.

1 files changed, 3 insertions, 0 deletions

diff --git a/src/cmark.c b/src/cmark.c
index 1d7a500..2ec9be9 100644
--- a/src/cmark.c
+++ b/src/cmark.c
@@ -6,6 +6,9 @@
 #include "cmark.h"
 #include "buffer.h"
 
+const int cmark_version = CMARK_VERSION;
+const char cmark_version_string[] = CMARK_VERSION_STRING;
+
 char *cmark_markdown_to_html(const char *text, int len)
 {
 	cmark_node *doc;