On 03/29/2008 06:13 PM, [EMAIL PROTECTED] wrote:
Author: niq
Date: Sat Mar 29 10:13:28 2008
New Revision: 642558
URL: http://svn.apache.org/viewvc?rev=642558&view=rev
Log:
Introduce ap_expr expression parser API
Added:
httpd/httpd/trunk/include/ap_expr.h
httpd/httpd/trunk/server/util_expr.c
Modified:
httpd/httpd/trunk/CHANGES
httpd/httpd/trunk/NWGNUmakefile
httpd/httpd/trunk/build/nw_export.inc
httpd/httpd/trunk/include/ap_mmn.h
httpd/httpd/trunk/libhttpd.dsp
httpd/httpd/trunk/server/Makefile.in
Added: httpd/httpd/trunk/server/util_expr.c
URL:
http://svn.apache.org/viewvc/httpd/httpd/trunk/server/util_expr.c?rev=642558&view=auto
==============================================================================
--- httpd/httpd/trunk/server/util_expr.c (added)
+++ httpd/httpd/trunk/server/util_expr.c Sat Mar 29 10:13:28 2008
+#define PARSE_STRING(r,s) (string_func ? string_func((r),(s)) : (s))
+AP_DECLARE(int) ap_expr_eval(request_rec *r, parse_node_t *root,
+ int *was_error, backref_t **reptr,
+ string_func_t string_func, opt_func_t eval_func)
+{
+ parse_node_t *current = root;
+ const char *error = NULL;
+ unsigned int regex = 0;
+
+ /* Evaluate Parse Tree */
+ while (current) {
+ switch (current->token.type) {
+ case TOKEN_STRING:
+ current->token.value = PARSE_STRING(r, current->token.value);
+ current->value = !!*current->token.value;
+ break;
+
+ case TOKEN_AND:
+ case TOKEN_OR:
+ if (!current->left || !current->right) {
+ ap_log_rerror(APLOG_MARK, APLOG_ERR, 0, r,
+ "Invalid expression in file %s", r->filename);
+ *was_error = 1;
+ return 0;
+ }
+
+ if (!current->left->done) {
+ switch (current->left->token.type) {
+ case TOKEN_STRING:
+ current->left->token.value =
+ PARSE_STRING(r, current->left->token.value);
+ current->left->value = !!*current->left->token.value;
Why do we use !! here? Isn't this the same as !! not being there?
+ DEBUG_DUMP_EVAL(ctx, current->left);
+ current->left->done = 1;
+ break;
+
+ default:
+ current = current->left;
+ continue;
+ }
+ }
+
+ /* short circuit evaluation */
+ if (!current->right->done && !regex &&
I don't get the purpose of regex here. Why can't we short circuit if regex !=0?
+ ((current->token.type == TOKEN_AND && !current->left->value) ||
+ (current->token.type == TOKEN_OR && current->left->value))) {
+ current->value = current->left->value;
+ }
+ else {
+ if (!current->right->done) {
+ switch (current->right->token.type) {
+ case TOKEN_STRING:
+ current->right->token.value =
+ PARSE_STRING(r,current->right->token.value);
+ current->right->value = !!*current->right->token.value;
same as above.
General question: I know that this parser was taken from mod_include and I
haven't
really dived into its details, but wouldn't it be better and faster for
evaluation
to build UPN stack from the expression instead of the parser tree?
Regards
Rüdiger
