From 737acae240f8de8b21c9ed3a9db71709c64c1013 Mon Sep 17 00:00:00 2001
From: Alexander Klauer <Alexander.Klauer@googlemail.com>
Date: Sun, 11 Nov 2018 18:05:42 +0100
Subject: [PATCH] Provide grammar to read_terminal() and read_rule()

Hack for #12 while using the current API.
---
 src/yaep.c | 26 ++++++++++++++------------
 src/yaep.h | 25 +++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 12 deletions(-)

diff --git a/src/yaep.c b/src/yaep.c
index a77a382..cd1f2b0 100644
--- a/src/yaep.c
+++ b/src/yaep.c
@@ -3359,34 +3359,36 @@ yaep_read_grammar (struct grammar *g, int strict_p,
   const char *name, *lhs, **rhs, *anode;
   struct symb *symb, *start;
   struct rule *rule;
-  int anode_cost;
   int *transl;
-  int i, el, code;
+  int i, el;
+  struct _yaep_reentrant_hack anode_cost, code;
 
   assert (g != NULL);
+  anode_cost.grammar = g;
+  code.grammar = g;
   grammar = g;
   symbs_ptr = g->symbs_ptr;
   term_sets_ptr = g->term_sets_ptr;
   rules_ptr = g->rules_ptr;
-  if ((code = setjmp (error_longjump_buff)) != 0)
+  if ((code.value = setjmp (error_longjump_buff)) != 0)
     {
-      return code;
+      return code.value;
     }
   if (!grammar->undefined_p)
     yaep_empty_grammar ();
-  while ((name = (*read_terminal) (&code)) != NULL)
+  while ((name = (*read_terminal) (&code.value)) != NULL)
     {
-      if (code < 0)
+      if (code.value < 0)
 	yaep_error (YAEP_NEGATIVE_TERM_CODE,
 		    "term `%s' has negative code", name);
       symb = symb_find_by_repr (name);
       if (symb != NULL)
 	yaep_error (YAEP_REPEATED_TERM_DECL,
 		    "repeated declaration of term `%s'", name);
-      if (symb_find_by_code (code) != NULL)
+      if (symb_find_by_code (code.value) != NULL)
 	yaep_error (YAEP_REPEATED_TERM_CODE,
-		    "repeated code %d in term `%s'", code, name);
-      symb_add_term (name, code);
+		    "repeated code %d in term `%s'", code.value, name);
+      symb_add_term (name, code.value);
     }
 
   /* Adding error symbol. */
@@ -3398,7 +3400,7 @@ yaep_read_grammar (struct grammar *g, int strict_p,
   grammar->term_error = symb_add_term (TERM_ERROR_NAME, TERM_ERROR_CODE);
   grammar->term_error_num = grammar->term_error->u.term.term_num;
   grammar->axiom = grammar->end_marker = NULL;
-  while ((lhs = (*read_rule) (&rhs, &anode, &anode_cost, &transl)) != NULL)
+  while ((lhs = (*read_rule) (&rhs, &anode, &anode_cost.value, &transl)) != NULL)
     {
       symb = symb_find_by_repr (lhs);
       if (symb == NULL)
@@ -3409,7 +3411,7 @@ yaep_read_grammar (struct grammar *g, int strict_p,
       if (anode == NULL && transl != NULL && *transl >= 0 && transl[1] >= 0)
 	yaep_error (YAEP_INCORRECT_TRANSLATION,
 		    "rule for `%s' has incorrect translation", lhs);
-      if (anode != NULL && anode_cost < 0)
+      if (anode != NULL && anode_cost.value < 0)
 	yaep_error (YAEP_NEGATIVE_COST,
 		    "translation for `%s' has negative cost", lhs);
       if (grammar->axiom == NULL)
@@ -3439,7 +3441,7 @@ yaep_read_grammar (struct grammar *g, int strict_p,
 	  rule->order[0] = 0;
 	  rule->trans_len = 1;
 	}
-      rule = rule_new_start (symb, anode, (anode != NULL ? anode_cost : 0));
+      rule = rule_new_start (symb, anode, (anode != NULL ? anode_cost.value : 0));
       while (*rhs != NULL)
 	{
 	  symb = symb_find_by_repr (*rhs);
diff --git a/src/yaep.h b/src/yaep.h
index 6c89c9a..3bb9a64 100644
--- a/src/yaep.h
+++ b/src/yaep.h
@@ -33,6 +33,7 @@
 #define __YAEP__
 
 #include <limits.h>
+#include<stddef.h>
 
 /* The following is a forward declaration of grammar formed by function
    yaep_read_grammar. */
@@ -148,6 +149,30 @@ struct yaep_tree_node
   } val;
 };
 
+/* The following structure is used to work around a limitation of
+   yaep_read_grammar(). The read_terminal() and read_rule() functions
+   passed to yaep_read_grammar() cannot take a user-defined argument,
+   but this is required for reentrant operation.
+   The long-term solution would be to expand the API of yaep (FIXME).
+   When sticking to the old API, however, we hijack the pointer-to-int
+   parameters to slip through the grammar as additional information.
+   This structure is for internal use only.
+   Use the yaep_reentrant_hack_grammar() macro to retrieve the grammar. */
+struct _yaep_reentrant_hack
+{
+  int value;
+  struct grammar *grammar;
+};
+
+/* The following macro retrieves the grammar from a pointer-to-int argument.
+   It can only be applied to arguments to the code parameter of the
+   read_terminal() parameter, and to the anode_cost parameter of the
+   read_rule() parameter of yaep_read_grammar(). */
+#define yaep_reentrant_hack_grammar(x) \
+  (((struct _yaep_reentrant_hack *) \
+    (((char *) (x)) - offsetof (struct _yaep_reentrant_hack, value))) \
+   ->grammar)
+
 #ifndef __cplusplus
 
 /* The following function creates undefined grammar.  The function