Improve currency regex for lexer to avoid stealing numbers

beancount-parser-lima/examples/data/full.beancount

@@ -45,6 +45,10 @@ pushmeta price: "expensive"
 
 2012-01-09 * "VISA DDA PUR 444500     WHOLEFDS -- VISA DDA PUR 444500     WHOLEFDS HOU 10236          NEW YORK      * NY"
 
+; Martin
+2013-01-01 * "Buy CRA shares" ^old-transactions-008
+  Assets:CA:RBC-Investing:Taxable-CAD:Cash                          -1395.43 CAD @ 1/1.4576 USD
+
 2023-05-29 * "New World Gardens North East Va ;" ^newworld.co.nz
   Assets:Bank:Current                        -30 -9.65 NZD
   ofxid: "0.12-3456-1234567-01.29May2023.1"  ; from ledger-autosync

beancount-parser-lima/src/lexer.rs

@@ -13,7 +13,7 @@ use time::{Date, Month, Time};
 #[logos(error = LexerError, skip r"[ \t]+")]
 #[logos(subpattern ignored_whole_line= r"([*:!&#?%][^\n]*\n)")] // rolled into end-of-line handling below
 #[logos(subpattern comment_to_eol= r"(;[^\n]*)")] // rolled into end-of-line handling below
-#[logos(subpattern currency = r"[A-Z][A-Z0-9'\._-]*|/[A-Z0-9'\._-]+")] // not all matches are valid so we lean on the validation provided by try_from
+#[logos(subpattern currency = r"[A-Z][A-Z0-9'\._-]*|/[0-9'\._-]*[A-Z][A-Z0-9'\._-]*")]
 #[logos(subpattern date = r"\d{4}[\-/]\d{2}[\-/]\d{2}")]
 #[logos(subpattern time = r"\d{1,2}:\d{2}(:\d{2})?")]
 #[logos(subpattern account_type = r"[\p{Lu}\p{Lo}][\p{L}\p{N}\-]*")]