summaryrefslogtreecommitdiffstats
path: root/generic/tclCompExpr.c
diff options
context:
space:
mode:
Diffstat (limited to 'generic/tclCompExpr.c')
-rw-r--r--generic/tclCompExpr.c33
1 files changed, 27 insertions, 6 deletions
diff --git a/generic/tclCompExpr.c b/generic/tclCompExpr.c
index da9007f..bab56f5 100644
--- a/generic/tclCompExpr.c
+++ b/generic/tclCompExpr.c
@@ -12,7 +12,7 @@
* See the file "license.terms" for information on usage and redistribution of
* this file, and for a DISCLAIMER OF ALL WARRANTIES.
*
- * RCS: @(#) $Id: tclCompExpr.c,v 1.68 2007/07/12 22:13:12 dgp Exp $
+ * RCS: @(#) $Id: tclCompExpr.c,v 1.69 2007/07/16 19:50:46 dgp Exp $
*/
#include "tclInt.h"
@@ -514,6 +514,7 @@ ParseExpr(
nodes->precedence = prec[lexeme];
nodes->left = OT_NONE;
nodes->right = OT_NONE;
+ /* TODO: explain. */
nodes->parent = -1;
nodesUsed++;
}
@@ -849,19 +850,32 @@ ParseExpr(
} /* case LEAF */
case UNARY:
+ /*
+ * A unary operator appearing just after something that's not an
+ * operator is a syntax error -- something trying to be the left
+ * operand of an operator that doesn't take one.
+ */
if (NotOperator(lastParsed)) {
msg = Tcl_ObjPrintf("missing operator at %s", mark);
scanned = 0;
insertMark = 1;
code = TCL_ERROR;
+ /* Escape the parse loop to report the syntax error. */
continue;
}
- lastParsed = nodesUsed;
- nodePtr->lexeme = lexeme;
- nodePtr->precedence = prec[lexeme];
- nodePtr->left = OT_NONE;
- nodePtr->right = OT_NONE;
+ /* Create an OpNode for the unary operator */
+ nodePtr->lexeme = lexeme; /* Remember the operator... */
+ nodePtr->precedence = prec[lexeme]; /* ... and its precedence. */
+ nodePtr->left = OT_NONE; /* No left operand */
+ nodePtr->right = OT_NONE; /* Right operand not
+ * yet known. */
+ /* TODO: explain */
nodePtr->parent = nodePtr - nodes - 1;
+ /*
+ * Remember this unary operator as the last thing parsed for
+ * the next pass through the loop.
+ */
+ lastParsed = nodesUsed;
nodesUsed++;
break;
@@ -869,6 +883,11 @@ ParseExpr(
OpNode *otherPtr = NULL;
unsigned char precedence = prec[lexeme];
+ /*
+ * A binary operand appearing just after another operator is a
+ * syntax error -- one of the two operators is missing an operand.
+ */
+
if (IsOperator(lastParsed)) {
if ((lexeme == CLOSE_PAREN)
&& (nodePtr[-1].lexeme == OPEN_PAREN)) {
@@ -879,6 +898,7 @@ ParseExpr(
*/
scanned = 0;
+ /* TODO: explain */
lastParsed = OT_EMPTY;
nodePtr[-1].left--;
break;
@@ -923,6 +943,7 @@ ParseExpr(
continue;
}
+ /* TODO: explain */
if (lastParsed == OT_NONE) {
otherPtr = nodes + lastOpen - 1;
lastParsed = lastOpen;