modernize musrfit function handling using spirit x3 instead of spirit classic now.

src/classes/PFunctionHandler.cpp

@@ -30,8 +30,12 @@
 #include <string>
 #include <cassert>
 
+#include <boost/spirit/home/x3.hpp>
+
 #include "PFunctionHandler.h"
 
+namespace x3 = boost::spirit::x3;
+
 //-------------------------------------------------------------
 // Constructor
 //-------------------------------------------------------------
@@ -67,7 +71,6 @@ PFunctionHandler::~PFunctionHandler()
 Bool_t PFunctionHandler::DoParse()
 {
   Bool_t success = true;
-  PFunctionGrammar function;
   TString line;
 
   // feed the function block into the parser. Start with i=1, since i=0 is FUNCTIONS
@@ -89,14 +92,32 @@ Bool_t PFunctionHandler::DoParse()
     }
     line.ToUpper();
 
-    // do parsing
-    tree_parse_info<> info = ast_parse(line.Data(), function, space_p);
+    // do parsing with X3
+    musrfit::ast::assignment assignment;
+    std::string str(line.Data());
+    auto iter = str.begin();
+    auto end = str.end();
 
-    if (info.full) { // parsing successful
-      PFunction func(info); // generate an evaluation function object based on the AST tree
-      fFuncs.push_back(func); // feeds it to the functions vector
-    } else {
+    // Get the X3 grammar
+    auto const& grammar = musrfit::function_grammar();
+
+    try {
+      bool parseSuccess = x3::phrase_parse(iter, end, grammar, x3::space, assignment);
+
+      if (parseSuccess && iter == end) { // parsing successful
+        PFunction func(assignment); // generate an evaluation function object based on the AST
+        fFuncs.push_back(func); // feeds it to the functions vector
+      } else {
+        std::cerr << std::endl << "**ERROR**: FUNCTIONS parse failed in line " << fLines[i].fLineNo << std::endl;
+        if (iter != end) {
+          std::cerr << "**ERROR**: Stopped at: " << std::string(iter, end) << std::endl;
+        }
+        success = false;
+        break;
+      }
+    } catch (x3::expectation_failure<std::string::iterator> const& e) {
       std::cerr << std::endl << "**ERROR**: FUNCTIONS parse failed in line " << fLines[i].fLineNo << std::endl;
+      std::cerr << "**ERROR**: Expected: " << e.which() << std::endl;
       success = false;
       break;
     }