implement utils::is_type() convenience function

doc/src/Developer_utils.rst

@@ -175,6 +175,12 @@ and parsing files or arguments.
 .. doxygenfunction:: is_double
    :project: progguide
 
+.. doxygenfunction:: is_id
+   :project: progguide
+
+.. doxygenfunction:: is_type
+   :project: progguide
+
 Potential file functions
 ^^^^^^^^^^^^^^^^^^^^^^^^
 

src/utils.cpp

@@ -1139,6 +1139,34 @@ bool utils::is_id(const std::string &str)
   return true;
 }
 
+/* ----------------------------------------------------------------------
+   Check whether string is a valid type or type label string
+------------------------------------------------------------------------- */
+
+int utils::is_type(const std::string &str)
+{
+  if (str.empty()) return -1;
+
+  bool numeric = true;
+  int nstar = 0;
+  for (auto c : str) {
+    if (isdigit(c)) continue;
+    if (c == '*') {
+      ++nstar;
+      continue;
+    }
+    numeric = false;
+  }
+  if (numeric && (nstar < 2)) return 0;
+
+  // TODO: the first two checks below are not really needed with this function.
+  // If a type label has at least one character that is not a digit or '*'
+  // it can be identified by this function as type label due to the check above.
+  if (isdigit(str[0]) || (str[0] == '*') || (str[0] == '#')) return -1;
+  if (str.find_first_of(" \t\r\n\f") != std::string::npos) return -1;
+  return 1;
+}
+
 /* ----------------------------------------------------------------------
    try to find potential file as specified by name
    search current directory and the LAMMPS_POTENTIALS directory if

src/utils.h

@@ -544,6 +544,19 @@ namespace utils {
 
   bool is_id(const std::string &str);
 
+  /*! Check if string is a valid type label, or numeric type, or numeric type range.
+   * Numeric type or type range may only contain digits or the '*' character.
+   * Type label strings may not contain a digit, or a '*', or a '#' character as the
+   * first character to distinguish them from comments and numeric types or type ranges.
+   * They also may not contain any whitespace. If the string is a valid numeric type
+   * or type range the function returns 0, if it is a valid type label the function
+   * returns 1, otherwise it returns -1.
+   *
+   * \param str string that should be checked
+   * \return 0, 1, or -1, depending on whether the string is valid numeric type, valid type label or neither, respectively */
+
+  int is_type(const std::string &str);
+
   /*! Determine full path of potential file. If file is not found in current directory,
    *  search directories listed in LAMMPS_POTENTIALS environment variable
    *

unittest/utils/test_utils.cpp

@@ -440,6 +440,51 @@ TEST(Utils, invalid_id4)
     ASSERT_FALSE(utils::is_id("a$12"));
 }
 
+TEST(Utils, valid_numeric)
+{
+    ASSERT_EQ(utils::is_type("1"), 0);
+    ASSERT_EQ(utils::is_type("21"), 0);
+    ASSERT_EQ(utils::is_type("05"), 0);
+    ASSERT_EQ(utils::is_type("1*"), 0);
+    ASSERT_EQ(utils::is_type("*2"), 0);
+    ASSERT_EQ(utils::is_type("1*4"), 0);
+}
+
+TEST(Utils, invalid_numeric)
+{
+    ASSERT_EQ(utils::is_type("1*2*"), -1);
+    ASSERT_EQ(utils::is_type("**2"), -1);
+    ASSERT_EQ(utils::is_type("*4*"), -1);
+    ASSERT_EQ(utils::is_type("30**"), -1);
+}
+
+TEST(Utils, valid_label)
+{
+    ASSERT_EQ(utils::is_type("A"), 1);
+    ASSERT_EQ(utils::is_type("c1"), 1);
+    ASSERT_EQ(utils::is_type("o1_"), 1);
+    ASSERT_EQ(utils::is_type("C1'"), 1);
+    ASSERT_EQ(utils::is_type("N2\"-C1'"), 1);
+    ASSERT_EQ(utils::is_type("[N2\"][C1']"), 1);
+    ASSERT_EQ(utils::is_type("@X2=&X1"), 1);
+    ASSERT_EQ(utils::is_type("|Na|Cl|H2O|"), 1);
+    ASSERT_EQ(utils::is_type("CA(1)/CB(1)"), 1);
+}
+
+TEST(Utils, invalid_label)
+{
+    ASSERT_EQ(utils::is_type("1A"), -1);
+    ASSERT_EQ(utils::is_type("#c"), -1);
+    ASSERT_EQ(utils::is_type("*B"), -1);
+    ASSERT_EQ(utils::is_type(" B"), -1);
+    ASSERT_EQ(utils::is_type("A "), -1);
+    ASSERT_EQ(utils::is_type("A B"), -1);
+    ASSERT_EQ(utils::is_type("\tB"), -1);
+    ASSERT_EQ(utils::is_type("C\n"), -1);
+    ASSERT_EQ(utils::is_type("d\r"), -1);
+    ASSERT_EQ(utils::is_type(""), -1);
+}
+
 TEST(Utils, strmatch_beg)
 {
     ASSERT_TRUE(utils::strmatch("rigid/small/omp", "^rigid"));