JSIL front-end: make parser and lexer reentrant

This avoids hand-crafted init functions with possibly insufficient
guards against reentrant use and also removes (file-local) global
variables.

Author: tautschnig

src/jsil/jsil_parser.cpp

@@ -10,3 +10,16 @@ Author: Michael Tautschnig, [email protected]
 /// Jsil Language
 
 #include "jsil_parser.h"
+
+int yyjsillex_init_extra(jsil_parsert *, void **);
+int yyjsillex_destroy(void *);
+int yyjsilparse(jsil_parsert &, void *);
+
+bool jsil_parsert::parse()
+{
+  void *scanner;
+  yyjsillex_init_extra(this, &scanner);
+  bool parse_fail = yyjsilparse(*this, scanner) != 0;
+  yyjsillex_destroy(scanner);
+  return parse_fail;
+}

src/jsil/jsil_parser.h

@@ -16,10 +16,6 @@ Author: Michael Tautschnig, [email protected]
 
 #include "jsil_parse_tree.h"
 
-class jsil_parsert;
-int yyjsilparse(jsil_parsert &);
-void jsil_scanner_init(jsil_parsert &);
-
 class jsil_parsert:public parsert
 {
 public:
@@ -30,13 +26,9 @@ class jsil_parsert:public parsert
 
   jsil_parse_treet parse_tree;
 
-  virtual bool parse() override
-  {
-    jsil_scanner_init(*this);
-    return yyjsilparse(*this) != 0;
-  }
+  bool parse() override;
 
-  virtual void clear() override
+  void clear() override
   {
     parsert::clear();
     parse_tree.clear();

src/jsil/parser.y

@@ -1,24 +1,19 @@
 %{
 
 // #define YYDEBUG 1
-#define PARSER (*jsil_parser)
+#define PARSER jsil_parser
 
 #include "jsil_parser.h"
 
-int yyjsillex();
-extern char *yyjsiltext;
+int yyjsillex(unsigned *, void *);
+char *yyjsilget_text(void *);
 
-static jsil_parsert *jsil_parser;
-int yyjsilparse(void);
-int yyjsilparse(jsil_parsert &_jsil_parser)
+int yyjsilerror(
+  jsil_parsert &jsil_parser,
+  void *scanner,
+  const std::string &error)
 {
-  jsil_parser = &_jsil_parser;
-  return yyjsilparse();
-}
-
-int yyjsilerror(const std::string &error)
-{
-  jsil_parser->parse_error(error, yyjsiltext);
+  jsil_parser.parse_error(error, yyjsilget_text(scanner));
   return 0;
 }
 
@@ -44,9 +39,23 @@ int yyjsilerror(const std::string &error)
 #pragma warning(disable:4702)
 #endif
 
-/*** token declaration **************************************************/
+// yynerrs may never be used. Will be fixed when bison > 3.8.2 is released (see
+// http://git.savannah.gnu.org/cgit/bison.git/commit/?id=a166d5450e3f47587b98f6005f9f5627dbe21a5b)
+#ifdef __clang__
+#  pragma clang diagnostic ignored "-Wunused-but-set-variable"
+#endif
 %}
 
+// Should be "%define api.pure full" instead of "%pure-parser", but macOS ships
+// bison 2.3, which doesn't yet support this. We have to invoke bison with
+// -Wno-deprecated on all platforms other than macOS.
+%pure-parser
+%parse-param {jsil_parsert &jsil_parser}
+%parse-param {void *scanner}
+%lex-param {void *scanner}
+
+/*** token declaration **************************************************/
+
 /*** special scanner reports ***/
 
 %token TOK_SCANNER_ERROR /* used by scanner to report errors */