string: Added const replace and replaceAll

which return the replaced string rather than modify the string the function is
called for.

src/OpenFOAM/primitives/strings/string/string.C

@@ -78,6 +78,17 @@ Foam::string& Foam::string::replace
 }
 
 
+Foam::string Foam::string::replace
+(
+    const string& oldStr,
+    const string& newStr,
+    size_type start
+) const
+{
+    return string(*this).replace(oldStr, newStr, start);
+}
+
+
 Foam::string& Foam::string::replaceAll
 (
     const string& oldStr,
@@ -100,6 +111,17 @@ Foam::string& Foam::string::replaceAll
 }
 
 
+Foam::string Foam::string::replaceAll
+(
+    const string& oldStr,
+    const string& newStr,
+    size_type start
+) const
+{
+    return string(*this).replaceAll(oldStr, newStr, start);
+}
+
+
 Foam::string& Foam::string::expand(const bool allowEmpty)
 {
     stringOps::inplaceExpand(*this, allowEmpty);

src/OpenFOAM/primitives/strings/string/string.H

@@ -165,9 +165,27 @@ public:
         //- Avoid masking the normal std::string replace
         using std::string::replace;
 
+        //- In this string replace first occurrence of sub-string oldStr
+        //  with newStr starting at start
+        string& replace
+        (
+            const string& oldStr,
+            const string& newStr,
+            size_type start = 0
+        );
+
         //- Replace first occurrence of sub-string oldStr with newStr
         //  starting at start
-        string& replace
+        string replace
+        (
+            const string& oldStr,
+            const string& newStr,
+            size_type start = 0
+        ) const;
+
+        //- In this string replace all occurrences of sub-string oldStr
+        //  with newStr starting at start
+        string& replaceAll
         (
             const string& oldStr,
             const string& newStr,
@@ -176,12 +194,12 @@ public:
 
         //- Replace all occurrences of sub-string oldStr with newStr
         //  starting at start
-        string& replaceAll
+        string replaceAll
         (
             const string& oldStr,
             const string& newStr,
             size_type start = 0
-        );
+        ) const;
 
         //- Expand initial tildes and all occurrences of environment variables
         //  Expansion includes: