This refactoring fixes an O(n^2) slowdown in the balance command with
large numbers of accounts. It's now speedy, and the implementation is
clearer. To facilitate this, the Account type now represents a tree of
accounts which can easily be traversed up or down (and/or flattened
into a list).
Benchmark on a 2010 macbook:
+-------------------------------------------++--------------+------------+--------+
| || before: | after: | |
| || hledger-0.18 | hledgeropt | ledger |
+===========================================++==============+============+========+
| -f data/100x100x10.journal balance || 0.21 | 0.07 | 0.09 |
| -f data/1000x1000x10.journal balance || 10.13 | 0.47 | 0.62 |
| -f data/1000x10000x10.journal balance || 40.67 | 0.67 | 1.01 |
| -f data/10000x1000x10.journal balance || 15.01 | 3.22 | 2.36 |
| -f data/10000x1000x10.journal balance aa || 4.77 | 4.40 | 2.33 |
+-------------------------------------------++--------------+------------+--------+
- use new query system for command line too, filterspec is no more
- move unit tests near the code they test, run them in bottom up order, add more
- more precise Show instances, used for debugging not ui
