Import byacc from invisible island, it brings us lots of compatibilities with

bison, keeping full compatibility with our previous yacc implementation.

Also bring the ability to create reentrant parser

This fix bin/140309 [1]

PR:		bin/140309 [1]
Submitted by:	Philippe Pepiot <ksh@philpep.org> [1]
Approved by:	des (mentor)
MFC after:	1 month

1 files changed, 117 insertions, 0 deletions

diff --git a/contrib/byacc/symtab.c b/contrib/byacc/symtab.c
new file mode 100644
index 0000000..1327eaf
--- /dev/null
+++ b/contrib/byacc/symtab.c
@@ -0,0 +1,117 @@
+/* $Id: symtab.c,v 1.9 2010/11/24 15:12:29 tom Exp $ */
+
+#include "defs.h"
+
+/* TABLE_SIZE is the number of entries in the symbol table. */
+/* TABLE_SIZE must be a power of two.			    */
+
+#define	TABLE_SIZE 1024
+
+static bucket **symbol_table = 0;
+bucket *first_symbol;
+bucket *last_symbol;
+
+static int
+hash(const char *name)
+{
+    const char *s;
+    int c, k;
+
+    assert(name && *name);
+    s = name;
+    k = *s;
+    while ((c = *++s) != 0)
+	k = (31 * k + c) & (TABLE_SIZE - 1);
+
+    return (k);
+}
+
+bucket *
+make_bucket(const char *name)
+{
+    bucket *bp;
+
+    assert(name != 0);
+
+    bp = (bucket *)MALLOC(sizeof(bucket));
+    NO_SPACE(bp);
+
+    bp->link = 0;
+    bp->next = 0;
+
+    bp->name = MALLOC(strlen(name) + 1);
+    NO_SPACE(bp->name);
+
+    bp->tag = 0;
+    bp->value = UNDEFINED;
+    bp->index = 0;
+    bp->prec = 0;
+    bp->class = UNKNOWN;
+    bp->assoc = TOKEN;
+    strcpy(bp->name, name);
+
+    return (bp);
+}
+
+bucket *
+lookup(const char *name)
+{
+    bucket *bp, **bpp;
+
+    bpp = symbol_table + hash(name);
+    bp = *bpp;
+
+    while (bp)
+    {
+	if (strcmp(name, bp->name) == 0)
+	    return (bp);
+	bpp = &bp->link;
+	bp = *bpp;
+    }
+
+    *bpp = bp = make_bucket(name);
+    last_symbol->next = bp;
+    last_symbol = bp;
+
+    return (bp);
+}
+
+void
+create_symbol_table(void)
+{
+    int i;
+    bucket *bp;
+
+    symbol_table = (bucket **)MALLOC(TABLE_SIZE * sizeof(bucket *));
+    NO_SPACE(symbol_table);
+
+    for (i = 0; i < TABLE_SIZE; i++)
+	symbol_table[i] = 0;
+
+    bp = make_bucket("error");
+    bp->index = 1;
+    bp->class = TERM;
+
+    first_symbol = bp;
+    last_symbol = bp;
+    symbol_table[hash("error")] = bp;
+}
+
+void
+free_symbol_table(void)
+{
+    FREE(symbol_table);
+    symbol_table = 0;
+}
+
+void
+free_symbols(void)
+{
+    bucket *p, *q;
+
+    for (p = first_symbol; p; p = q)
+    {
+	q = p->next;
+	FREE(p);
+    }
+}