Add some string utils; rework Benchmark

include/ABACUS.h

@@ -22,6 +22,7 @@ const char ABACUS_VERSION[20] = "ABACUS_0a";
 // Standard includes
 #include <cmath>
 #include <complex>  // for complex number algebra
+#include <algorithm>  // for count
 #include <string>
 
 #include <iostream>

include/ABACUS_Utils.h

@@ -37,8 +37,38 @@ const DP MACHINE_EPS_SQ = pow(MACHINE_EPS, 2.0);
 
 namespace ABACUS {
 
+  // Inexplicably missing string functions in standard library:
+
+  std::string replace(const std::string& str, const std::string& from, const std::string& to) {
+    std::string repl = str;
+    size_t start_pos = repl.find(from);
+    if(start_pos < std::string::npos)
+      repl.replace(start_pos, from.length(), to);
+    return repl;
+  }
+
+  std::string replace_all(const std::string& str, const std::string& from, const std::string& to) {
+    std::string repl = str;
+    if(from.empty())
+      return repl;
+    size_t start_pos = 0;
+    while((start_pos = repl.find(from, start_pos)) != std::string::npos) {
+      repl.replace(start_pos, from.length(), to);
+      start_pos += to.length();
+    }
+    return repl;
+  }
+
+
   // File checks:
 
+  inline unsigned int count_lines(std::string filename)
+  {
+    std::ifstream infile(filename);
+    return(std::count(std::istreambuf_iterator<char>(infile),
+		      std::istreambuf_iterator<char>(), '\n'));
+  }
+
   inline bool file_exists (const char* filename)
   {
     std::fstream file;