examples: don't use yysyntax_error_arguments

Suggested by Adrian Vogelsgesang.
https://lists.gnu.org/archive/html/bison-patches/2020-02/msg00069.html

* data/skeletons/lalr1.java (Context.EMPTY, Context.getToken): New.
(Context.yyntokens): Rename as...
(Context.NTOKENS): this.
Because (i) all the Java coding styles recommend upper case for
constants, and (ii) the Java Skeleton exposes Lexer.EOF, not
Lexer.YYEOF.
* data/skeletons/yacc.c (yyparse_context_token): New.
* examples/c/bistromathic/parse.y (yyreport_syntax_error): Don't use
yysyntax_error_arguments.
* examples/java/calc/Calc.y (yyreportSyntaxError): Likewise.

2 files changed, 29 insertions, 21 deletions

diff --git a/examples/c/bistromathic/parse.y b/examples/c/bistromathic/parse.y
index 190b1cd0..819313c9 100644
--- a/examples/c/bistromathic/parse.y
+++ b/examples/c/bistromathic/parse.y
@@ -284,23 +284,26 @@ yylex (const char **line, YYSTYPE *yylval, YYLTYPE *yylloc)
 int
 yyreport_syntax_error (const yyparse_context_t *ctx)
 {
-  enum { ARGMAX = 10 };
   int res = 0;
-  int arg[ARGMAX];
-  int n = yysyntax_error_arguments (ctx, arg, ARGMAX);
-  if (n < 0)
-    // Forward errors to yyparse.
-    res = n;
   YY_LOCATION_PRINT (stderr, *yyparse_context_location (ctx));
   fprintf (stderr, ": syntax error");
-  if (n >= 0)
-    {
-      for (int i = 1; i < n; ++i)
+  {
+    enum { TOKENMAX = 10 };
+    int expected[TOKENMAX];
+    int n = yyexpected_tokens (ctx, expected, TOKENMAX);
+    if (n < 0)
+      // Forward errors to yyparse.
+      res = n;
+    else
+      for (int i = 0; i < n; ++i)
         fprintf (stderr, "%s %s",
-                 i == 1 ? ": expected" : " or", yysymbol_name (arg[i]));
-      if (n)
-        fprintf (stderr, " before %s", yysymbol_name (arg[0]));
-    }
+                 i == 0 ? ": expected" : " or", yysymbol_name (expected[i]));
+  }
+  {
+    int lookahead = yyparse_context_token (ctx);
+    if (lookahead != YYEMPTY)
+      fprintf (stderr, " before %s", yysymbol_name (lookahead));
+  }
   fprintf (stderr, "\n");
   return res;
 }
diff --git a/examples/java/calc/Calc.y b/examples/java/calc/Calc.y
index f634937d..4bb01c72 100644
--- a/examples/java/calc/Calc.y
+++ b/examples/java/calc/Calc.y
@@ -108,15 +108,20 @@ class CalcLexer implements Calc.Lexer {
 
   public void yyreportSyntaxError (Calc.Context ctx)
   {
-    final int ARGMAX = 10;
-    int[] arg = new int[ARGMAX];
-    int n = ctx.yysyntaxErrorArguments (arg, ARGMAX);
     System.err.print (ctx.getLocation () + ": syntax error");
-    for (int i = 1; i < n; ++i)
-      System.err.print ((i == 1 ? ": expected " : " or ")
-                        + ctx.yysymbolName (arg[i]));
-    if (n != 0)
-      System.err.print (" before " + ctx.yysymbolName (arg[0]));
+    {
+      final int TOKENMAX = 10;
+      int[] arg = new int[TOKENMAX];
+      int n = ctx.yyexpectedTokens (arg, TOKENMAX);
+      for (int i = 0; i < n; ++i)
+        System.err.print ((i == 0 ? ": expected " : " or ")
+                          + ctx.yysymbolName (arg[i]));
+    }
+    {
+      int lookahead = ctx.getToken ();
+      if (lookahead != ctx.EMPTY)
+        System.err.print (" before " + ctx.yysymbolName (lookahead));
+    }
     System.err.println ("");
   }