xml_parsert: construct with message handler

src/xmllang/parser.y

@@ -3,12 +3,12 @@
 
 #include "xml_parser.h"
 
-int yyxmllex();
-extern char *yyxmltext;
+int yyxmllex(void *);
+char *yyxmlget_text(void *);
 
-int yyxmlerror(const std::string &error)
+int yyxmlerror(xml_parsert &xml_parser, void *scanner, const std::string &error)
 {
-  xml_parser.parse_error(error, yyxmltext);
+  xml_parser.parse_error(error, yyxmlget_text(scanner));
   return 0;
 }
 
@@ -26,6 +26,10 @@
 #endif
 %}
 
+%parse-param {xml_parsert &xml_parser}
+%parse-param {void *scanner}
+%lex-param {void *scanner}
+
 %union {char *s;}
 
 %token STARTXMLDECL

src/xmllang/scanner.l

@@ -3,6 +3,9 @@
 %option noinput
 %option nounistd
 %option never-interactive
+%option noyywrap
+%option reentrant
+%option extra-type="xml_parsert *"
 
 %{
 
@@ -19,7 +22,7 @@
 #include "xml_parser.h"
 #include "xml_y.tab.h"
 
-#define PARSER xml_parser
+#define PARSER (*yyextra)
 
 //static int keep;  /* To store start condition */
 
@@ -87,9 +90,5 @@
 <DTD>.            {/* skip */}
 <DTD>\]{close}    {BEGIN(INITIAL); /* skip */}
 
-.                 { yyxmlerror("unexpected character"); }
+.                 { yyxmlerror(*yyextra, yyscanner, "unexpected character"); }
 {nl}              {/* skip, must be an extra one at EOF */;}
-
-%%
-
-int yywrap() { return 1; }

src/xmllang/xml_parser.cpp

@@ -10,7 +10,20 @@ Author: Daniel Kroening, kroening@kroening.com
 
 #include <fstream>
 
-xml_parsert xml_parser;
+int xml_parsert::instance_count = 0;
+
+int yyxmllex_init_extra(xml_parsert *, void **);
+int yyxmllex_destroy(void *);
+int yyxmlparse(xml_parsert &, void *);
+
+bool xml_parsert::parse()
+{
+  void *scanner;
+  yyxmllex_init_extra(this, &scanner);
+  bool parse_fail = yyxmlparse(*this, scanner) != 0;
+  yyxmllex_destroy(scanner);
+  return parse_fail;
+}
 
 // 'do it all' function
 bool parse_xml(
@@ -19,19 +32,16 @@ bool parse_xml(
   message_handlert &message_handler,
   xmlt &dest)
 {
-  xml_parser.clear();
+  xml_parsert xml_parser{message_handler};
+
   xml_parser.set_file(filename);
   xml_parser.in=&in;
-  xml_parser.log.set_message_handler(message_handler);
 
-  bool result=yyxmlparse()!=0;
+  bool result = xml_parser.parse();
 
   // save result
   xml_parser.parse_tree.element.swap(dest);
 
-  // save some memory
-  xml_parser.clear();
-
   return result;
 }
 

src/xmllang/xml_parser.h

@@ -14,11 +14,25 @@
 
 #include "xml_parse_tree.h"
 
-int yyxmlparse();
-
 class xml_parsert:public parsert
 {
 public:
+  explicit xml_parsert(message_handlert &message_handler)
+    : parsert(message_handler)
+  {
+    // Simplistic check that we don't attempt to do reentrant parsing as the
+    // Bison-generated parser has global state.
+    PRECONDITION(++instance_count == 1);
+    stack.push_back(&parse_tree.element);
+  }
+
+  xml_parsert(const xml_parsert &) = delete;
+
+  ~xml_parsert() override
+  {
+    --instance_count;
+  }
+
   xml_parse_treet parse_tree;
 
   std::list<xmlt *> stack;
@@ -28,29 +42,30 @@
     return *stack.back();
   }
 
-  virtual bool parse()
-  {
-    return yyxmlparse()!=0;
-  }
+  bool parse() override;
 
   void new_level()
   {
     current().elements.push_back(xmlt());
     stack.push_back(&current().elements.back());
   }
 
-  virtual void clear()
+  /// Clears the parser state. May be removed in future as there should not be a
+  /// need to re-use an existing parser object.
+  void clear() override
   {
     parse_tree.clear();
     // set up stack
     stack.clear();
     stack.push_back(&parse_tree.element);
+    parsert::clear();
   }
-};
 
-extern xml_parsert xml_parser;
+protected:
+  static int instance_count;
+};
 
-int yyxmlerror(const std::string &error);
+int yyxmlerror(xml_parsert &, void *, const std::string &);
 
 // 'do it all' functions
 bool parse_xml(