Add support for fixated prices and costs

beancount doesn't have a notion of a fixated price or cost.  However,
you can achieve the same result in beancount.  ledger2beancount will
always convert ledger fixated prices and costs to costs in beancount.
This way, the original cost is always attached to the transaction.
You can then use `SUM(COST(position))` to get the original value.

README.md

@@ -92,6 +92,7 @@ Please refer to [the manual](docs/manual.md#features) for more details.
 * Directives
   * `payee`: skipped (not needed in beancount)
   * `tag`: skipped (not needed in beancount)
+* Fixated prices (`=$10` and the `fixed` directive)
 * Tags and links on posting-level (not supported by beancount)
 * Transaction codes: stored as metadata (no equivalence in beancount)
 * Virtual postings: can be skipped or converted to real postings
@@ -109,7 +110,6 @@ Please refer to [the manual](docs/manual.md#features) for more details.
   * `expr`
   * `N`
   * Timeclock (`I`, `i`, `O`, `o`, `b`, `h`)
-* Fixated prices (`=$10` and the `fixed` directive)
 * Periodic transactions
 
 

bin/ledger2beancount

@@ -768,7 +768,7 @@ sub process_txn(@) {
 
 	    $l = replace_account $l;
 
-	    if ($l =~ /^$posting_RE(\s*(?<curlyopen>\{\{?)\s*(?<lot_cost>$amount_RE)\s*(?<curlyclose>\}\}?))?\s*(\[(?<date>$date_RE)\])?\s*(\((?<lot_note>[^@].*)\))?\s*(\(?(?<at>@@?)\)?\s*(?<lot_price>$amount_RE))?(\s*=\s*(?<assertion>$amount_RE))?(\s*$comment_RE)?/) {
+	    if ($l =~ /^$posting_RE(\s*(?<curlyopen>\{\{?)\s*(?<fixated_cost>=\s*)?(?<lot_cost>$amount_RE)\s*(?<curlyclose>\}\}?))?\s*(\[(?<date>$date_RE)\])?\s*(\((?<lot_note>[^@].*)\))?\s*(\(?(?<at>@@?)\)?\s*?(?<fixated_price>=\s*)?(?<lot_price>$amount_RE))?(\s*=\s*(?<assertion>$amount_RE))?(\s*$comment_RE)?/) {
 		# posting with unit price and optional lot price
 		# XXX refactor/merge with previous regex case
 		my $lot_info = "";
@@ -792,10 +792,10 @@ sub process_txn(@) {
 		    # commodities that should be treated as currencies.
 		    my $commodity1 = map_commodity $+{commodity};
 		    my $commodity2 = map_commodity parse_commodity $+{lot_price};
-		    if ((length $commodity1 == 3 && length $commodity2 == 3 &&
+		    if (!$+{fixated_price} && ((length $commodity1 == 3 && length $commodity2 == 3 &&
 			!($commodity1 ~~ @{$config->{currency_is_commodity}})) ||
 			$commodity1 ~~ @{$config->{commodity_is_currency}} ||
-			$commodity2 ~~ @{$config->{commodity_is_currency}}) {
+			$commodity2 ~~ @{$config->{commodity_is_currency}})) {
 			$l = sprintf "$+{posting} %s %s", "@" x length $+{at}, replace_commodity $+{lot_price};
 		    } else {
 			$l = sprintf "$+{posting} %s%s%s%s", "{" x length $+{at},
@@ -811,6 +811,16 @@ sub process_txn(@) {
 		} else {
 		    $l = $+{posting};
 		}
+		if (!defined $+{lot_cost}) {
+		    # Apply any fixated costs if needed
+		    foreach my $a (reverse @ledger_apply) {
+			if (${$a}[0] eq "fixed") {
+			    my ($commodity, $fixated) = split /\s+/, ${$a}[1], 2;
+			    $fixated = replace_commodity $fixated;
+			    $l =~ s/($+{amount})/$1 {$fixated}/ if $+{commodity} eq $commodity;
+			}
+		    }
+		}
 		if ($+{comment}) {
 		    my $comment = handle_comment $depth, "; $+{comment}", 1;
 		    $l .= " ; $comment" if $comment;
@@ -938,6 +948,8 @@ while (@input) {
 	$ledger_alias{$+{account}} = map_account_apply $+{val};
     } elsif ($l =~ /^[!@]?apply\s+(?<type>account)\s+(?<val>.*)/) {  # apply account
 	push @ledger_apply, [$+{type}, $+{val}];
+    } elsif ($l =~ /^[!@]?apply\s+(?<type>fixed)\s+(?<val>.*)/) {  # apply fixed
+	push @ledger_apply, [$+{type}, $+{val}];
     } elsif ($l =~ /^[!@]?apply\s+(?<type>tag)\s+(?<val>.*)/) {  # apply tag
 	# `apply tag` can be converted to beancount in three ways:
 	# * using pushtag/poptag for tags

docs/changelog.md

@@ -2,6 +2,7 @@
 
 ## 1.6 (unreleased)
 
+* Add support for fixated prices and costs
 * Handle account names that contain brackets
 * Don't parse trailing tabs as part of the account name
 * Escape backslashes in the narration

docs/manual.md

@@ -659,6 +659,20 @@ postings in a transaction (the most common case).  More complex
 implicit conversations are not supported.
 
 
+### Fixated prices and costs
+
+ledger allows you to ["fix" the cost or price](https://www.ledger-cli.org/3.0/doc/ledger3.html#Fixated-prices-and-costs)
+at the time of a transaction, which means the amount will not be revalued
+subsequently when the price of the commodity changes in the `pricedb`.
+beancount doesn't have a notion of a fixated price or cost.
+
+However, you can achieve the same result in beancount.  ledger2beancount
+will always convert ledger fixated prices and costs to costs in
+beancount.  This way, the original cost is always attached to the
+transaction.  You can then use `SUM(COST(position))` to get the original
+value.
+
+
 ### hledger syntax
 
 The syntax of [hledger](http://hledger.org/) is largely compatible with
@@ -746,7 +760,6 @@ Unsupported features in ledger2beancount
 The following ledger features are currently not supported by
 ledger2beancount:
 
-* Fixated prices (`=$10` syntax and the `fixed` directive)
 * The `define` directive
 
 Contributions [are welcome!](CONTRIBUTING.md)