cmStringAlgorithms: Add cmIsInternallyOn, cmIsNOTFOUND, cmIsOn, cmIsOff

This adds the following functions to cmStringAlgorithms:

- `cmIsInternallyOn`
- `cmIsNOTFOUND`
- `cmIsOn`
- `cmIsOff`

The implementations were copied from the equivalent functions in cmSystemTools.

Source/cmStringAlgorithms.cxx

@@ -212,6 +212,85 @@ std::string cmCatViews(std::initializer_list<cm::string_view> views)
   return result;
 }
 
+bool cmIsInternallyOn(cm::string_view val)
+{
+  return (val.size() == 4) &&           //
+    (val[0] == 'I' || val[0] == 'i') && //
+    (val[1] == '_') &&                  //
+    (val[2] == 'O' || val[2] == 'o') && //
+    (val[3] == 'N' || val[3] == 'n');
+}
+
+bool cmIsNOTFOUND(cm::string_view val)
+{
+  return (val == "NOTFOUND") || cmHasLiteralSuffix(val, "-NOTFOUND");
+}
+
+bool cmIsOn(cm::string_view val)
+{
+  switch (val.size()) {
+    case 1:
+      return val[0] == '1' || val[0] == 'Y' || val[0] == 'y';
+    case 2:
+      return                                //
+        (val[0] == 'O' || val[0] == 'o') && //
+        (val[1] == 'N' || val[1] == 'n');
+    case 3:
+      return                                //
+        (val[0] == 'Y' || val[0] == 'y') && //
+        (val[1] == 'E' || val[1] == 'e') && //
+        (val[2] == 'S' || val[2] == 's');
+    case 4:
+      return                                //
+        (val[0] == 'T' || val[0] == 't') && //
+        (val[1] == 'R' || val[1] == 'r') && //
+        (val[2] == 'U' || val[2] == 'u') && //
+        (val[3] == 'E' || val[3] == 'e');
+    default:
+      break;
+  }
+
+  return false;
+}
+
+bool cmIsOff(cm::string_view val)
+{
+  switch (val.size()) {
+    case 0:
+      return true;
+    case 1:
+      return val[0] == '0' || val[0] == 'N' || val[0] == 'n';
+    case 2:
+      return                                //
+        (val[0] == 'N' || val[0] == 'n') && //
+        (val[1] == 'O' || val[1] == 'o');
+    case 3:
+      return                                //
+        (val[0] == 'O' || val[0] == 'o') && //
+        (val[1] == 'F' || val[1] == 'f') && //
+        (val[2] == 'F' || val[2] == 'f');
+    case 5:
+      return                                //
+        (val[0] == 'F' || val[0] == 'f') && //
+        (val[1] == 'A' || val[1] == 'a') && //
+        (val[2] == 'L' || val[2] == 'l') && //
+        (val[3] == 'S' || val[3] == 's') && //
+        (val[4] == 'E' || val[4] == 'e');
+    case 6:
+      return                                //
+        (val[0] == 'I' || val[0] == 'i') && //
+        (val[1] == 'G' || val[1] == 'g') && //
+        (val[2] == 'N' || val[2] == 'n') && //
+        (val[3] == 'O' || val[3] == 'o') && //
+        (val[4] == 'R' || val[4] == 'r') && //
+        (val[5] == 'E' || val[5] == 'e');
+    default:
+      break;
+  }
+
+  return cmIsNOTFOUND(val);
+}
+
 bool cmStrToLong(const char* str, long* value)
 {
   errno = 0;

Source/cmStringAlgorithms.h

@@ -180,6 +180,51 @@ std::string cmWrap(char prefix, Range const& rng, char suffix,
                 sep);
 }
 
+/**
+ * Does a string indicates that CMake/CPack/CTest internally
+ * forced this value. This is not the same as On, but this
+ * may be considered as "internally switched on".
+ */
+bool cmIsInternallyOn(cm::string_view val);
+inline bool cmIsInternallyOn(const char* val)
+{
+  if (!val) {
+    return false;
+  }
+  return cmIsInternallyOn(cm::string_view(val));
+}
+
+/** Return true if value is NOTFOUND or ends in -NOTFOUND.  */
+bool cmIsNOTFOUND(cm::string_view val);
+
+/**
+ * Does a string indicate a true or ON value? This is not the same as ifdef.
+ */
+bool cmIsOn(cm::string_view val);
+inline bool cmIsOn(const char* val)
+{
+  if (!val) {
+    return false;
+  }
+  return cmIsOn(cm::string_view(val));
+}
+
+/**
+ * Does a string indicate a false or off value ? Note that this is
+ * not the same as !IsOn(...) because there are a number of
+ * ambiguous values such as "/usr/local/bin" a path will result in
+ * IsON and IsOff both returning false. Note that the special path
+ * NOTFOUND, *-NOTFOUND or IGNORE will cause IsOff to return true.
+ */
+bool cmIsOff(cm::string_view val);
+inline bool cmIsOff(const char* val)
+{
+  if (!val) {
+    return true;
+  }
+  return cmIsOff(cm::string_view(val));
+}
+
 /** Returns true if string @a str starts with the character @a prefix.  */
 inline bool cmHasPrefix(cm::string_view str, char prefix)
 {