moose@edgar:~/public_html/tmpl2$ ./expr_test.pl
{expr}:1:1: Warning: parse: (1+2) * (2+1) at Tmpl/Template/Expression/Parser.pm line 47.
{expr}:1:2: Warning: level1: ( at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:3: Warning: level1: 1 at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:3: Warning: level1: Tree::Binary=HASH(0x816a8a4) at Tmpl/Template/Expression/Parser.pm line 159.
{expr}:1:4: Warning: level2: + at Tmpl/Template/Expression/Parser.pm line 186.
{expr}:1:4: Warning: level3: + at Tmpl/Template/Expression/Parser.pm line 222.
{expr}:1:5: Warning: level1: 2 at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:5: Warning: level1: + 2 at Tmpl/Template/Expression/Parser.pm line 158.
{expr}:1:5: Warning: level1: Tree::Binary=HASH(0x822f118) Tree::Binary=HASH(0x816a940) at Tmpl/Template/Expression/Parser.pm line 159.
{expr}:1:6: Warning: level3: 1 + 2 at Tmpl/Template/Expression/Parser.pm line 232.
{expr}:1:6: Warning: level1 tok: ) at Tmpl/Template/Expression/Parser.pm line 167.
{expr}:1:8: Warning: level2: * at Tmpl/Template/Expression/Parser.pm line 186.
{expr}:1:10: Warning: level1: ( at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:11: Warning: level1: 2 at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:11: Warning: level1: * 2 at Tmpl/Template/Expression/Parser.pm line 158.
{expr}:1:11: Warning: level1: Tree::Binary=HASH(0x816aa3c) Tree::Binary=HASH(0x816adfc) at Tmpl/Template/Expression/Parser.pm line 159.
{expr}:1:12: Warning: level2: + at Tmpl/Template/Expression/Parser.pm line 186.
{expr}:1:12: Warning: level3: + at Tmpl/Template/Expression/Parser.pm line 222.
{expr}:1:13: Warning: level1: 1 at Tmpl/Template/Expression/Parser.pm line 132.
{expr}:1:13: Warning: level1: + 1 at Tmpl/Template/Expression/Parser.pm line 158.
{expr}:1:13: Warning: level1: Tree::Binary=HASH(0x816aa6c) Tree::Binary=HASH(0x816ae98) at Tmpl/Template/Expression/Parser.pm line 159.
{expr}:1:14: Warning: level3: 2 + 1 at Tmpl/Template/Expression/Parser.pm line 232.
{expr}:1:14: Warning: level1 tok: ) at Tmpl/Template/Expression/Parser.pm line 167.
SCALAR(0x819cbc8):1:14: Warning: eof? at Tmpl/Tokenizer.pm line 290.
{expr}:1:14: Warning: level2: at Tmpl/Template/Expression/Parser.pm line 186.
{expr}:1:14: Warning: level3: at Tmpl/Template/Expression/Parser.pm line 222.
{expr}:1:14: Warning: level2: 'Tree::Binary=HASH(0x822f118)' 'Tree::Binary=HASH(0x816aa3c)' 'Tree::Binary=HASH(0x816aa6c)' at Tmpl/Template/Expression/Parser.pm line 198.
{expr}:1:14: Warning: level2: + * + at Tmpl/Template/Expression/Parser.pm line 199.
{expr}:1:14: Warning: level3: at Tmpl/Template/Expression/Parser.pm line 222.
+---+
+--------| * |-------+
| +---+ |
+---+ +---+
+--| + |--+ +--| + |--+
| +---+ | | +---+ |
+---+ +---+ +---+ +---+
| 1 | | 2 | | 2 | | 1 |
+---+ +---+ +---+ +---+