X-Git-Url: https://www.ginac.de/ginac.git//ginac.git?p=ginac.git;a=blobdiff_plain;f=ginac%2Fbasic.cpp;h=e8c893ba26dd59a963e00fd1056daf34f4f47bf8;hp=a3de04aab9cd306eda820e8d7b50dadc492f3164;hb=e9b5729311fcd5572d806f5df2e645e1845603e5;hpb=83a7ee99a947cbbf331018b803ad6be43a9ccd45

diff --git a/ginac/basic.cpp b/ginac/basic.cpp
index a3de04aa..e8c893ba 100644
--- a/ginac/basic.cpp
+++ b/ginac/basic.cpp
@@ -290,7 +290,7 @@ ex & basic::operator[](size_t i)
  *  but e.has(x+y) is false. */
 bool basic::has(const ex & pattern, unsigned options) const
 {
-	lst repl_lst;
+	exmap repl_lst;
 	if (match(pattern, repl_lst))
 		return true;
 	for (size_t i=0; i<nops(); i++)
@@ -534,9 +534,9 @@ bool basic::contract_with(exvector::iterator self, exvector::iterator other, exv
 }
 
 /** Check whether the expression matches a given pattern. For every wildcard
- *  object in the pattern, an expression of the form "wildcard == matching_expression"
- *  is added to repl_lst. */
-bool basic::match(const ex & pattern, lst & repl_lst) const
+ *  object in the pattern, a pair with the wildcard as a key and matching 
+ *  expression as a value is added to repl_lst. */
+bool basic::match(const ex & pattern, exmap& repl_lst) const
 {
 /*
 	Sweet sweet shapes, sweet sweet shapes,
@@ -559,11 +559,11 @@ bool basic::match(const ex & pattern, lst & repl_lst) const
 		// Wildcard matches anything, but check whether we already have found
 		// a match for that wildcard first (if so, the earlier match must be
 		// the same expression)
-		for (lst::const_iterator it = repl_lst.begin(); it != repl_lst.end(); ++it) {
-			if (it->op(0).is_equal(pattern))
-				return is_equal(ex_to<basic>(it->op(1)));
+		for (exmap::const_iterator it = repl_lst.begin(); it != repl_lst.end(); ++it) {
+			if (it->first.is_equal(pattern))
+				return is_equal(ex_to<basic>(it->second));
 		}
-		repl_lst.append(pattern == *this);
+		repl_lst[pattern] = *this;
 		return true;
 
 	} else {
@@ -585,12 +585,18 @@ bool basic::match(const ex & pattern, lst & repl_lst) const
 		if (!match_same_type(ex_to<basic>(pattern)))
 			return false;
 
+		// Even if the expression does not match the pattern, some of
+		// its subexpressions could match it. For example, x^5*y^(-1)
+		// does not match the pattern $0^5, but its subexpression x^5
+		// does. So, save repl_lst in order to not add bogus entries.
+		exmap tmp_repl = repl_lst;
 		// Otherwise the subexpressions must match one-to-one
 		for (size_t i=0; i<nops(); i++)
-			if (!op(i).match(pattern.op(i), repl_lst))
+			if (!op(i).match(pattern.op(i), tmp_repl))
 				return false;
 
 		// Looks similar enough, match found
+		repl_lst = tmp_repl;
 		return true;
 	}
 }
@@ -608,9 +614,10 @@ ex basic::subs_one_level(const exmap & m, unsigned options) const
 		return thisex;
 	} else {
 		for (it = m.begin(); it != m.end(); ++it) {
-			lst repl_lst;
+			exmap repl_lst;
 			if (match(ex_to<basic>(it->first), repl_lst))
-				return it->second.subs(repl_lst, options | subs_options::no_pattern); // avoid infinite recursion when re-substituting the wildcards
+				return it->second.subs(repl_lst, options | subs_options::no_pattern);
+			// avoid infinite recursion when re-substituting the wildcards
 		}
 	}