Add optimized version of count_words for default whitespace chars

src/utils.cpp

@@ -368,6 +368,35 @@ std::string utils::trim_comment(const std::string & line) {
    Return number of words
 ------------------------------------------------------------------------- */
 
+size_t utils::count_words(const std::string & text) {
+  size_t count = 0;
+  const char * buf = text.c_str();
+  char c = *buf;
+
+  while (c) {
+    if (c == ' ' || c == '\t' || c == '\r' ||  c == '\n' || c == '\f') {
+      c = *++buf;
+      continue;
+    };
+
+    ++count;
+    c = *++buf;
+
+    while (c) {
+      if (c == ' ' || c == '\t' || c == '\r' || c == '\n' || c == '\f') {
+        break;
+      }
+      c = *++buf;
+    }
+  }
+
+  return count;
+}
+
+/* ----------------------------------------------------------------------
+   Return number of words
+------------------------------------------------------------------------- */
+
 size_t utils::count_words(const std::string & text, const std::string & separators) {
   size_t count = 0;
   size_t start = text.find_first_not_of(separators);

src/utils.h

@@ -156,7 +156,15 @@ namespace LAMMPS_NS {
      * \param separators string containing characters that will be treated as whitespace
      * \return number of words found
      */
-    size_t count_words(const std::string & text, const std::string & separators = " \t\r\n\f");
+    size_t count_words(const std::string & text, const std::string & separators);
+
+    /**
+     * \brief Count words in string, ignore any whitespace matching " \t\r\n\f"
+     * \param text string that should be searched
+     * \param separators string containing characters that will be treated as whitespace
+     * \return number of words found
+     */
+    size_t count_words(const std::string & text);
 
     /**
      * \brief Count words in a single line, trim anything from '#' onward

unittest/utils/test_utils.cpp

@@ -28,6 +28,10 @@ TEST(Utils, count_words) {
     ASSERT_EQ(utils::count_words("some text # comment"), 4);
 }
 
+TEST(Utils, count_words_non_default) {
+    ASSERT_EQ(utils::count_words("some text # comment", " #"), 3);
+}
+
 TEST(Utils, trim_and_count_words) {
     ASSERT_EQ(utils::trim_and_count_words("some text # comment"), 2);
 }