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rcomp.r
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1996-03-22
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421 lines
/*
* File: rcomp.r
* Contents: anycmp, equiv, lexcmp
*/
/*
* anycmp - compare any two objects.
*/
int anycmp(dp1,dp2)
dptr dp1, dp2;
{
register int o1, o2;
register long v1, v2, lresult;
int iresult;
double rres1, rres2, rresult;
/*
* Get a collating number for dp1 and dp2.
*/
o1 = order(dp1);
o2 = order(dp2);
/*
* If dp1 and dp2 aren't of the same type, compare their collating numbers.
*/
if (o1 != o2)
return (o1 > o2 ? Greater : Less);
if (o1 == 3)
/*
* dp1 and dp2 are strings, use lexcmp to compare them.
*/
return lexcmp(dp1,dp2);
switch (Type(*dp1)) {
#ifdef LargeInts
case T_Integer:
if (Type(*dp2) != T_Lrgint) {
v1 = IntVal(*dp1);
v2 = IntVal(*dp2);
if (v1 < v2)
return Less;
else if (v1 == v2)
return Equal;
else
return Greater;
}
/* if dp2 is a Lrgint, flow into next case */
case T_Lrgint:
lresult = bigcmp(dp1, dp2);
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
#else /* LargeInts */
case T_Integer:
v1 = IntVal(*dp1);
v2 = IntVal(*dp2);
if (v1 < v2)
return Less;
else if (v1 == v2)
return Equal;
else
return Greater;
#endif /* LargeInts */
case T_Coexpr:
/*
* Collate on co-expression id.
*/
lresult = (BlkLoc(*dp1)->coexpr.id - BlkLoc(*dp2)->coexpr.id);
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
case T_Cset:
return csetcmp((unsigned int *)((struct b_cset *)BlkLoc(*dp1))->bits,
(unsigned int *)((struct b_cset *)BlkLoc(*dp2))->bits);
case T_File:
/*
* Collate on file name.
*/
return lexcmp(&(BlkLoc(*dp1)->file.fname),
&(BlkLoc(*dp2)->file.fname));
case T_List:
/*
* Collate on list id.
*/
lresult = (BlkLoc(*dp1)->list.id - BlkLoc(*dp2)->list.id);
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
case T_Null:
return Equal;
case T_Proc:
/*
* Collate on procedure name.
*/
return lexcmp(&(BlkLoc(*dp1)->proc.pname),
&(BlkLoc(*dp2)->proc.pname));
case T_Real:
GetReal(dp1,rres1);
GetReal(dp2,rres2);
rresult = rres1 - rres2;
if (rresult == 0.0)
return Equal;
return ((rresult > 0.0) ? Greater : Less);
case T_Record:
/*
* Collate on record id within record name.
*/
iresult = lexcmp(&(BlkLoc(*dp1)->record.recdesc->proc.pname),
&(BlkLoc(*dp2)->record.recdesc->proc.pname));
if (iresult == Equal) {
lresult = (BlkLoc(*dp1)->record.id - BlkLoc(*dp2)->record.id);
if (lresult > 0) /* coded this way because of code-generation */
return Greater; /* bug in MSC++ 7.0A; do not change. */
else if (lresult < 0)
return Less;
else
return Equal;
}
return iresult;
case T_Set:
/*
* Collate on set id.
*/
lresult = (BlkLoc(*dp1)->set.id - BlkLoc(*dp2)->set.id);
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
case T_Table:
/*
* Collate on table id.
*/
lresult = (BlkLoc(*dp1)->table.id - BlkLoc(*dp2)->table.id);
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
case T_External:
/*
* Collate these values according to the relative positions of
* their blocks in the heap.
*/
lresult = ((long)BlkLoc(*dp1) - (long)BlkLoc(*dp2));
if (lresult == 0)
return Equal;
return ((lresult > 0) ? Greater : Less);
default:
syserr("anycmp: unknown datatype.");
}
}
/*
* order(x) - return collating number for object x.
*/
int order(dp)
dptr dp;
{
if (Qual(*dp))
return 3; /* string */
switch (Type(*dp)) {
case T_Null:
return 0;
case T_Integer:
return 1;
#ifdef LargeInts
case T_Lrgint:
return 1;
#endif /* LargeInts */
case T_Real:
return 2;
case T_Cset:
return 4;
case T_Coexpr:
return 5;
case T_File:
return 6;
case T_Proc:
return 7;
case T_List:
return 8;
case T_Table:
return 9;
case T_Set:
return 10;
case T_Record:
return 11;
case T_External:
return 12;
default:
syserr("order: unknown datatype.");
}
}
/*
* equiv - test equivalence of two objects.
*/
int equiv(dp1, dp2)
dptr dp1, dp2;
{
register int result;
register word i;
register char *s1, *s2;
double rres1, rres2;
result = 0;
/*
* If the descriptors are identical, the objects are equivalent.
*/
if (EqlDesc(*dp1,*dp2))
result = 1;
else if (Qual(*dp1) && Qual(*dp2)) {
/*
* If both are strings of equal length, compare their characters.
*/
if ((i = StrLen(*dp1)) == StrLen(*dp2)) {
s1 = StrLoc(*dp1);
s2 = StrLoc(*dp2);
result = 1;
while (i--)
if (*s1++ != *s2++) {
result = 0;
break;
}
}
}
else if (dp1->dword == dp2->dword)
switch (Type(*dp1)) {
/*
* For integers and reals, just compare the values.
*/
case T_Integer:
result = (IntVal(*dp1) == IntVal(*dp2));
break;
#ifdef LargeInts
case T_Lrgint:
result = (bigcmp(dp1, dp2) == 0);
break;
#endif /* LargeInts */
case T_Real:
GetReal(dp1, rres1);
GetReal(dp2, rres2);
result = (rres1 == rres2);
break;
case T_Cset:
/*
* Compare the bit arrays of the csets.
*/
result = 1;
for (i = 0; i < CsetSize; i++)
if (BlkLoc(*dp1)->cset.bits[i] != BlkLoc(*dp2)->cset.bits[i]) {
result = 0;
break;
}
}
else
/*
* dp1 and dp2 are of different types, so they can't be
* equivalent.
*/
result = 0;
return result;
}
/*
* lexcmp - lexically compare two strings.
*/
int lexcmp(dp1, dp2)
dptr dp1, dp2;
{
register char *s1, *s2;
register word minlen;
word l1, l2;
/*
* Get length and starting address of both strings.
*/
l1 = StrLen(*dp1);
s1 = StrLoc(*dp1);
l2 = StrLen(*dp2);
s2 = StrLoc(*dp2);
/*
* Set minlen to length of the shorter string.
*/
minlen = Min(l1, l2);
/*
* Compare as many bytes as are in the smaller string. If an
* inequality is found, compare the differing bytes.
*/
while (minlen--)
if (*s1++ != *s2++)
return (ToAscii(*--s1 & 0377) > ToAscii(*--s2 & 0377) ?
Greater : Less);
/*
* The strings compared equal for the length of the shorter.
*/
if (l1 == l2)
return Equal;
else if (l1 > l2)
return Greater;
else
return Less;
}
/*
* csetcmp - compare two cset bit arrays.
* The order defined by this function is identical to the lexical order of
* the two strings that the csets would be converted into.
*/
int csetcmp(cs1, cs2)
unsigned int *cs1, *cs2;
{
unsigned int nbit, mask, *cs_end;
if (cs1 == cs2) return Equal;
/*
* The longest common prefix of the two bit arrays converts to some
* common prefix string. The first bit on which the csets disagree is
* the first character of the conversion strings that disagree, and so this
* is the character on which the order is determined. The cset that has
* this first non-common bit = one, has in that position the lowest
* character, so this cset is lexically least iff the other cset has some
* following bit set. If the other cset has no bits set after the first
* point of disagreement, then it is a prefix of the other, and is therefor
* lexically less.
*
* Find the first word where cs1 and cs2 are different.
*/
for (cs_end = cs1 + CsetSize; cs1 < cs_end; cs1++, cs2++)
if (*cs1 != *cs2) {
/*
* Let n be the position at which the bits first differ within
* the word. Set nbit to some integer for which the nth bit
* is the first bit in the word that is one. Note here and in the
* following, that bits go from right to left within a word, so
* the _first_ bit is the _rightmost_ bit.
*/
nbit = *cs1 ^ *cs2;
/* Set mask to an integer that has all zeros in bit positions
* upto and including position n, and all ones in bit positions
* _after_ bit position n.
*/
for (mask = (unsigned)MaxLong << 1; !(~mask & nbit); mask <<= 1);
/*
* nbit & ~mask contains zeros everywhere except position n, which
* is a one, so *cs2 & (nbit & ~mask) is non-zero iff the nth bit
* of *cs2 is one.
*/
if (*cs2 & (nbit & ~mask)) {
/*
* If there are bits set in cs1 after bit position n in the
* current word, then cs1 is lexically greater than cs2.
*/
if (*cs1 & mask) return Greater;
while (++cs1 < cs_end)
if (*cs1) return Greater;
/*
* Otherwise cs1 is a proper prefix of cs2 and is therefore
* lexically less.
*/
return Less;
}
/*
* If the nth bit of *cs2 isn't one, then the nth bit of cs1
* must be one. Just reverse the logic for the previous
* case.
*/
if (*cs2 & mask) return Less;
cs_end = cs2 + (cs_end - cs1);
while (++cs2 < cs_end)
if (*cs2) return Less;
return Greater;
}
return Equal;
}