Add C backend - close #4

spec/test_lexer_unknown_character.c

@@ -0,0 +1,18 @@
+#include "testparser.h"
+#include <assert.h>
+#include <string.h>
+
+int main()
+{
+    char const * input = "x";
+    p_context_t context;
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_UNEXPECTED_INPUT);
+
+    input = "123";
+    p_context_init(&context, (uint8_t const *)input, strlen(input));
+    assert(p_parse(&context) == P_SUCCESS);
+    assert(p_result(&context) == 123u);
+
+    return 0;
+}