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.

5 files changed, 103 insertions, 18 deletions

diff --git a/api_test/main.c b/api_test/main.c
index af40a9f..d341246 100644
--- a/api_test/main.c
+++ b/api_test/main.c
@@ -53,6 +53,14 @@ static void
 test_continuation_byte(test_batch_runner *runner, const char *utf8);
 
 static void
+version(test_batch_runner *runner)
+{
+	INT_EQ(runner, cmark_version, CMARK_VERSION, "cmark_version");
+	STR_EQ(runner, cmark_version_string, CMARK_VERSION_STRING,
+	       "cmark_version_string");
+}
+
+static void
 constructor(test_batch_runner *runner)
 {
 	for (int i = 0; i < num_node_types; ++i) {
@@ -666,6 +674,7 @@ int main() {
 	int retval;
 	test_batch_runner *runner = test_batch_runner_new();
 
+	version(runner);
 	constructor(runner);
 	accessors(runner);
 	node_check(runner);
diff --git a/man/man3/cmark.3 b/man/man3/cmark.3
index f889521..f03a3ae 100644
--- a/man/man3/cmark.3
+++ b/man/man3/cmark.3
@@ -1,4 +1,4 @@
-.TH cmark 3 "January 20, 2015" "LOCAL" "Library Functions Manual"
+.TH cmark 3 "January 23, 2015" "LOCAL" "Library Functions Manual"
 .SH
 NAME
 .PP
@@ -10,18 +10,6 @@ DESCRIPTION
 Simple Interface
 
 .PP
-.nf
-\fC
-.RS 0n
-#define CMARK_VERSION "0.1"
-.RE
-\f[]
-.fi
-
-.PP
-Current version of library.
-
-.PP
 \fIchar *\f[] \fBcmark_markdown_to_html\f[](\fIconst char *text\f[], \fIint len\f[])
 
 .PP
@@ -532,6 +520,66 @@ Render \f[C]softbreak\f[] elements as hard line breaks.
 .PP
 Normalize tree by consolidating adjacent text nodes.
 
+.SS
+Version information
+
+.PP
+.nf
+\fC
+.RS 0n
+#define CMARK_VERSION 0x000100
+.RE
+\f[]
+.fi
+
+.PP
+Macro containing the library version as integer for compile time
+checks.
+.IP \[bu] 2
+Bits 16\-23 contain the major version.
+.IP \[bu] 2
+Bits 8\-15 contain the minor version.
+.IP \[bu] 2
+Bits 0\-7 contain the patchlevel.
+.PP
+In hexadecimal format, the number 0x010203 represents version 1.2.3.
+
+.PP
+.nf
+\fC
+.RS 0n
+#define CMARK_VERSION_STRING "0.1.0"
+.RE
+\f[]
+.fi
+
+.PP
+Macro containing the library version string for compile time checks.
+
+.PP
+.nf
+\fC
+.RS 0n
+extern const int cmark_version;
+.RE
+\f[]
+.fi
+
+.PP
+The library version as integer for runtime checks.
+
+.PP
+.nf
+\fC
+.RS 0n
+extern const char cmark_version_string[];
+.RE
+\f[]
+.fi
+
+.PP
+The library version string for runtime checks.
+
 .SH
 AUTHORS
 .PP
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;
diff --git a/src/cmark.h b/src/cmark.h
index 8177fa8..faa5150 100644
--- a/src/cmark.h
+++ b/src/cmark.h
@@ -18,10 +18,6 @@ extern "C" {
  * ## Simple Interface
  */
 
-/** Current version of library.
- */
-#define CMARK_VERSION "0.1"
-
 /** Convert 'text' (assumed to be a UTF-8 encoded string with length
  * 'len' from CommonMark Markdown to HTML, returning a null-terminated,
  * UTF-8-encoded string.
@@ -499,6 +495,35 @@ char *cmark_render_man(cmark_node *root, long options);
  */
 #define CMARK_OPT_NORMALIZE 4
 
+/**
+ * ## Version information
+ */
+
+/** Macro containing the library version as integer for compile time
+ * checks.
+ *
+ * * Bits 16-23 contain the major version.
+ * * Bits 8-15 contain the minor version.
+ * * Bits 0-7 contain the patchlevel.
+ *
+ * In hexadecimal format, the number 0x010203 represents version 1.2.3.
+ */
+#define CMARK_VERSION 0x000100
+
+/** Macro containing the library version string for compile time checks.
+ */
+#define CMARK_VERSION_STRING "0.1.0"
+
+/** The library version as integer for runtime checks.
+ */
+CMARK_EXPORT
+extern const int cmark_version;
+
+/** The library version string for runtime checks.
+ */
+CMARK_EXPORT
+extern const char cmark_version_string[];
+
 /** # AUTHORS
  *
  * John MacFarlane, Vicent Marti,  Kārlis Gaņģis, Nick Wellnhofer.
diff --git a/src/main.c b/src/main.c
index 5855868..ef40a88 100644
--- a/src/main.c
+++ b/src/main.c
@@ -73,7 +73,7 @@ int main(int argc, char *argv[])
 
 	for (i = 1; i < argc; i++) {
 		if (strcmp(argv[i], "--version") == 0) {
-			printf("cmark %s", CMARK_VERSION);
+			printf("cmark %s", CMARK_VERSION_STRING);
 			printf(" - CommonMark converter (c) 2014 John MacFarlane\n");
 			exit(0);
 		} else if (strcmp(argv[i], "--sourcepos") == 0) {