Fix GiNaC's internal parsing of expressions.

[ginac.git] / ginac / parser / parse_binop_rhs.cpp

diff --git a/ginac/parser/parse_binop_rhs.cpp b/ginac/parser/parse_binop_rhs.cpp
index 1b3d325484244343f77c7e4b162f529fa969a0d4..a56a485c6e0863027de41a0761e6daec3fe1ba38 100644 (file)
--- a/ginac/parser/parse_binop_rhs.cpp
+++ b/ginac/parser/parse_binop_rhs.cpp
@@ -114,6 +114,18 @@ ex parser::parse_binop_rhs(int expr_prec, ex& lhs)
        }
 }
 
+/// unary_expr: [+-] expression
+ex parser::parse_unary_expr()
+{
+       // Parse a binary expression with the priority of exponentiation
+       // or higher. Ignore the overall sign, because parse_primary()
+       // handles it for us.
+       get_next_tok(); // Skip [+-]
+       ex lhs = parse_primary();
+       ex e = parse_binop_rhs(get_tok_prec('^'), lhs);
+       return e;
+}
+
 extern const numeric* _num_1_p;
 
 static ex make_minus_expr(const exvector& args)
@@ -137,6 +149,16 @@ static ex make_divide_expr(const exvector& args)
        return dynallocate<mul>(args[0], rest);
 }
 
+static ex make_power_expr(const exvector& args)
+{
+       size_t n = args.size();
+       ex p = pow(args[n - 2], args[n - 1]);
+       for (size_t i = n - 2; i > 0; i--) {
+               p = pow(args[i - 1], p);
+       }
+       return p;
+}
+
 static ex make_binop_expr(const int binop, const exvector& args)
 {
        switch (binop) {
@@ -149,11 +171,7 @@ static ex make_binop_expr(const int binop, const exvector& args)
                case '/':
                        return make_divide_expr(args);
                case '^':
-                       if (args.size() != 2)
-                               throw std::invalid_argument(
-                                               std::string(__func__) 
-                                               + ": power should have exactly 2 operands");
-                       return pow(args[0], args[1]);
+                       return make_power_expr(args);
                default:
                        throw std::invalid_argument(
                                        std::string(__func__)