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The C Users' Group Library 1994 August
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vol_300
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357_01
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cstar1.exe
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MST.C
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1991-06-18
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/*
C* -- macro symbol table routines.
source: mst.c
started: September 22, 1985
version:
January 7, 1987
March 7, 1989
PUBLIC DOMAIN SOFTWARE
The CSTAR program was placed in the public domain on June 15, 1991,
by its author and sole owner,
Edward K. Ream
1617 Monroe Street
Madison, WI 53711
(608) 257-0802
CSTAR may be used for any commercial or non-commercial purpose.
See cstar.h or cstar.c for a DISCLAIMER OF WARRANTIES.
*/
#include "cstar.h"
/*
Externally visible routines:
*/
void mst_delete (char * symbol);
struct mst_node * mst_enter (char * symbol, char * txt, int nargs);
void mst_init (void);
void mst2_init (void);
struct mst_node * mst_lookup (char * symbol);
/*
Internal routines:
*/
static int mst_hash (unsigned char * symbol);
/*
Define the hash table used to access macro table nodes.
*/
#define MAC_PRIME 101
struct mst_node * mst_ht [MAC_PRIME];
#ifdef TESTING
/*
Dump all symbols of a symbol table.
This function is used for debugging only.
*/
void
mst_dump (void)
{
register int i;
register struct mst_node * bp;
/* Dump hash table. */
printf("The hash table is:\n");
for (i = 0; i < MAC_PRIME; i++) {
if (bp = mst_ht [i]) {
printf("mst_ht [%3d] = %p\n", i, bp);
do {
mst_1dump(bp);
} while (bp = bp -> mst_next);
}
}
}
void
mst_1dump(register struct mst_node * bp)
{
printf("bp= %4lx, next= %4lx, ", bp, bp -> mst_next);
printf("hash= %d, ", mst_hash(bp -> mst_name);
printf("name= <%s> ", bp -> mst_name);
printf("nargs= %d, ", bp -> mst_nargs);
printf("text= <%s>\n", bp -> mst_text);
}
#endif /* TESTING */
/*
Remove ALL instances of a symbol from the symbol table.
This ensures that an #undef will expose any non-macro version
of a routine.
*/
void
mst_delete(register char * symbol)
{
register struct mst_node **bp0, *bp1, *bp2;
TRACEPB("mst_delete", printf("(%s)\n", symbol));
/* Point bp0 into hash table. */
bp0 = &mst_ht[0];
bp0 += mst_hash(symbol);
/* bp2 is current node pointer. */
bp2 = *bp0;
/* Special case: delete the first node. */
while (bp2 != NULL) {
if(str_eq(symbol, bp2 -> mst_name)) {
*bp0 = bp2 -> mst_next;
mg_free( (char *) bp2);
bp2 = *bp0;
}
else {
bp2 = bp2 -> mst_next;
bp1 = *bp0;
break;
}
}
/* bp1 is undefined here only if bp2 == NULL */
/* General case */
while (bp2 != NULL) {
if(str_eq(symbol, bp2 -> mst_name)) {
bp1 -> mst_next = bp2 -> mst_next;
mg_free( (char *) bp2);
bp2 = bp1 -> mst_next;
}
else {
bp1 = bp2;
bp2 = bp2 -> mst_next;
}
}
TICKX("mst_delete");
}
/*
Place a macro in the symbol table along with the number of arguments
to the macro and a pointer to the macro's replacement text.
Multiple entries for a symbol can exist in which case the last entry
defined is active.
Return a pointer to the allocated node or NULL.
This code conforms to the new standard. It rejects duplicate
definitions of a macro unless the new definition is exactly the
same as the old.
This code also checks the "initial undef list" to see if the first
definition of a macro should be ignored. If the macro name is
found on the list, it is removed from the list and no entry is made
in the macro symbol table.
*/
struct mst_node *
mst_enter(register char * symbol, register char * txt, register int nargs)
{
register struct mst_node **bp0, *bp1;
int hash;
struct mst_node * bp;
struct u_node *up1, *up2;
char msg [100];
extern struct u_node undef_list;
/*
Search the global "initial undef list" (created by command line
-u arguments) to see if the initial definition of name should
be rejected. If the name appears on the list, remove it from
the list and do not enter the name in the macro table.
*/
TRACEPB("mst_enter", printf("(%s, %s, %d)\n", symbol, txt, nargs));
if (undef_list . u_next != NULL) {
up1 = &undef_list;
up2 = up1 -> u_next;
while (up2 != NULL) {
if (str_eq(symbol, up2 -> u_name)) {
up1 -> u_next = up2 -> u_next;
RETURN_PTR("mst_enter", NULL);
}
else {
up1 = up2;
up2 = up2 -> u_next;
}
}
}
/* Search down the list of mst_nodes. */
hash = mst_hash(symbol);
for (bp = mst_ht [hash]; bp; bp = bp -> mst_next) {
/* Reject redefinitions of a macro unless identical. */
if (str_eq (symbol, bp -> mst_name)) {
if (nargs == bp -> mst_nargs) {
if (str_eq(txt, bp -> mst_text)) {
/* Benign redefinition. */
strcpy(msg, "(Warning) ");
strcat(msg, "Duplicate definition of ");
strcat(msg, symbol);
strcat(msg, ".");
t_error(msg);
RETURN_PTR("mst_enter", bp);
}
}
strcpy(msg, "Non-identical redefinition of ");
strcat(msg, symbol);
strcat(msg, " ignored.");
t_error(msg);
RETURN_PTR("mst_enter", NULL);
}
}
/* Dynamically allocate space for node. */
bp1 = CAST(struct mst_node *) mg_alloc(sizeof(struct mst_node));
/* Hang node from hash table. */
bp0 = &mst_ht[0];
bp0 += mst_hash(symbol);
bp1 -> mst_next = *bp0;
*bp0 = bp1;
/* Fill in the name and text fields. */
bp1 -> mst_name = str_galloc(symbol);
bp1 -> mst_text = str_galloc(txt);
bp1 -> mst_nargs = nargs;
RETURN_PTR("mst_enter", bp1);
}
/*
Return the hash value for symbol.
*/
static int
mst_hash (register unsigned char * symbol)
{
register int hash;
SL_DISABLE();
for (hash = 0; *symbol; ) {
hash *= 3;
hash += (int) *symbol++;
hash %= MAC_PRIME;
}
return hash;
}
/*
Initialize the macro module.
*/
void
mst_init(void)
{
register int i;
register struct mst_node ** bp0;
TICK("mst_init");
/* Clear the hash table. */
for (i = 0, bp0 = &mst_ht[0]; i < MAC_PRIME; i++) {
*bp0++ = NULL;
}
/* Clear the "initial undef list." */
undef_list . u_next = NULL;
}
/*
Enter the predefined macros into the table.
Do nothing if the initial definitions have been
suppressed with -u options.
*/
void
mst2_init(void)
{
struct mst_node * bp;
struct mst_node * mst_enter();
/*
Define the __line__ macro and allocate enough space for
all line numbers.
*/
TICKB("mst2_init");
bp = mst_enter("__line__", "", -3);
if (bp != NULL) {
bp -> mst_text = mg_alloc(10);
}
/*
Define the __file__ macro and allocate enough space
for the largest possible file name.
*/
bp = mst_enter("__file__", "", -3);
if (bp != NULL) {
bp -> mst_text = mg_alloc(MAX_FILE_NAME);
}
TICKX("mst2_init");
}
/*
Look up a symbol in the macro table.
Return a pointer to the node or NULL.
*/
struct mst_node *
mst_lookup (register char * symbol)
{
register struct mst_node ** bp0, *bp1;
char buffer [100];
/* Calculate the hash value of the symbol. */
TRACEPB("mst_lookup", printf("(%s)\n", symbol));
bp0 = &mst_ht[0];
bp0 += mst_hash(symbol);
/* Search down the list of mst_nodes. */
for (bp1 = *bp0; bp1; bp1 = bp1 -> mst_next) {
if (str_eq(symbol, bp1 -> mst_name)) {
/* Special case for __line__ and __file__. */
if (bp1 -> mst_nargs == -3) {
if (str_eq(bp1 -> mst_name, "__line__")) {
/* Set current line number. */
conv2s(t_line, buffer);
str_cpy(bp1 -> mst_text, buffer);
}
if (str_eq(bp1 -> mst_name, "__file__")) {
/* Set current file name. */
str_cpy(bp1 -> mst_text, t_file);
}
}
/* Return success. */
RETURN_PTR("mst_lookup", bp1);
}
}
/* Return failure. */
RETURN_PTR("mst_lookup", NULL);
}