[features] Feature array, a special case of contiguous string array for adding namespaced features in CRF-like sequence models

src/features.c

@@ -0,0 +1,22 @@
+#include "features.h"
+
+void feature_array_add(char_array *features, int num_args, ...) {
+    if (num_args <= 0) {
+        return;        
+    }
+
+    va_list args;
+    va_start(args, num_args);
+
+    for (int i = 0; i < num_args - 1; i++) {
+        char *arg = va_arg(args, char *);
+        contiguous_string_array_add_string_unterminated(features, arg);
+        contiguous_string_array_add_string_unterminated(features, FEATURE_SEPARATOR_CHAR);
+    }
+
+    char *arg = va_arg(args, char *);
+    contiguous_string_array_add_string(features, arg);
+
+    va_end(args);
+
+}

src/features.h

@@ -0,0 +1,22 @@
+#ifndef FEATURES_H
+#define FEATURES_H
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#include <stdio.h>
+#include <stdarg.h>
+#include "string_utils.h"
+
+#define FEATURE_SEPARATOR_CHAR "|"
+
+void feature_array_add(char_array *features, int num_args, ...);
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif