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1.1 root 1: # include <ingres.h>
2: # include <tree.h>
3: # include <symbol.h>
4: # include <sccs.h>
5:
6: SCCSID(@(#)tempvar.c 8.1 12/31/84)
7:
8:
9: /*
10: ** TEMPVAR
11: **
12: ** This file contains routines associated with redefining
13: ** attribute numbers. This is needed when one variable sub queries
14: ** or reduction change the positions of attributes in a relation.
15: ** This file includes:
16: **
17: ** Tempvar -- Change the attribute numbers to new ones.
18: **
19: ** Origvar -- Restore attribute numbers back to their previous values.
20: **
21: ** Ckvar -- Return the currently active VAR node
22: **
23: ** Trace Flags:
24: ** 51
25: */
26: /*
27: ** Tempvar -- Replace a VAR attribute number with its new number.
28: **
29: ** Tempvar is given a list of subqueries which will potentially
30: ** alter the attribute numbers of VARs they reference. An attno
31: ** is changed by making the current VAR point to a new VAR node
32: ** which has the updated attno.
33: **
34: ** The new attno is determined from the target list of the subquery
35: ** for that VAR. The RESDOM number is the new attno and the VAR it
36: ** points to is the old attno. For example:
37: ** RESDOM/2 -> right = VAR 1/3
38: ** The right subtree of result domain 2 is domain 3 of variable 1.
39: ** Thus domain 3 should be renumbered to be domain 2.
40: */
41:
42: tempvar(node, sqlist, buf)
43: register QTREE *node;
44: QTREE *sqlist[];
45: char *buf;
46: {
47: register QTREE *v, *sq;
48: QTREE *ckvar();
49: extern char *need(), *rangename();
50:
51:
52: if (node == NULL)
53: return;
54:
55: if (node->sym.type == VAR )
56: {
57: node = ckvar(node);
58: if (sq = sqlist[node->sym.value.sym_var.varno])
59: {
60: /* This var has a subquery on it */
61:
62: /* allocate a new VAR node */
63: if (buf)
64: {
65: node->sym.value.sym_var.valptr = (ANYTYPE *) need(buf, QT_HDR_SIZ + sizeof(struct varnode));
66: v = (QTREE *) node->sym.value.sym_var.valptr;
67: bmove(&node->sym, &v->sym, SYM_HDR_SIZ + sizeof(struct varnode) - sizeof v);
68: v->left = v->right = NULL;
69: v->sym.value.sym_var.valptr = NULL;
70: node->sym.value.sym_var.varno = -1;
71: }
72: else
73: v = node;
74:
75: /* search for the new attno */
76: for (sq = sq->left; sq->sym.type != TREE; sq = sq->left)
77: {
78: if (ckvar(sq->right)->sym.value.sym_var.attno == node->sym.value.sym_var.attno)
79: {
80:
81: v->sym.value.sym_var.attno = sq->sym.value.sym_resdom.resno;
82: # ifdef xDTR1
83: if (tTf(51, 3))
84: {
85: printf("Tempvar:");
86: nodepr(node);
87: }
88: # endif
89:
90: return;
91: }
92: }
93: syserr("tempvar:dom %d of %s missing", node->sym.value.sym_var.attno, rangename(node->sym.value.sym_var.varno));
94: }
95: return;
96: }
97:
98: tempvar(node->left, sqlist, buf);
99: tempvar(node->right, sqlist, buf);
100: }
101: /*
102: ** Origvar -- Restore VAR node to previous state.
103: **
104: ** Origvar undoes the effect of tempvar. All vars listed
105: ** in the sqlist will have their most recent tempvar removed.
106: */
107:
108: origvar(t, sqlist)
109: register QTREE *t;
110: QTREE *sqlist[];
111: {
112: register char v;
113: register QTREE *q;
114:
115: if (t == NULL)
116: return;
117: if (t->sym.type == VAR && t->sym.value.sym_var.varno < 0)
118: {
119: while ((v = (q = (QTREE *) (t->sym.value.sym_var.valptr))->sym.value.sym_var.varno) < 0)
120: t = q;
121:
122: if (sqlist[v])
123: {
124: t->sym.value.sym_var.varno = v;
125: t->sym.value.sym_var.valptr = NULL;
126: }
127: return;
128: }
129: origvar(t->left, sqlist);
130: origvar(t->right, sqlist);
131: }
132: /*
133: ** Ckvar -- Return pointer to currently "active" VAR.
134: **
135: ** This routine guarantees that "t" will point to
136: ** the most current definition of the VAR.
137: */
138:
139: QTREE *
140: ckvar(t)
141: register QTREE *t;
142: {
143: if (t->sym.type != VAR)
144: {
145: syserr("ckvar: not a VAR %d", t->sym.type);
146: }
147: # ifdef xDTR1
148: if (tTf(51, 2))
149: {
150: printf("ckvar: var %d.%d, type ",
151: t->sym.value.sym_var.varno, t->sym.value.sym_var.attno);
152: xputchar(t->sym.value.sym_var.varfrmt);
153: printf("%3d\n", t->sym.value.sym_var.varfrml);
154: }
155: # endif
156: while (t != NULL && t->sym.value.sym_var.varno < 0)
157: t = (QTREE *) t->sym.value.sym_var.valptr;
158:
159: if (t == NULL)
160: syserr("ckvar null valptr");
161: return (t);
162: }
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