implement folding of trailing newlines

Fixes #20.

Author: kljohann

README.mkd

@@ -56,22 +56,25 @@ behaviour of the ledger filetype.
 
         let g:ledger_fillstring = '    -'
 
-  My special tip is to use so-called digraphs: Press <C-K> followed by the
-  two-characters key sequence below. (in insert-mode)
-
-        '. = ˙ or ': = ¨ --> ˙˙˙˙˙˙ or ¨¨¨¨¨¨
-        ', = ¸           --> ¸¸¸¸¸¸
-        .M = ·           --> ······
-        >> = »           --> »»»»»»
-
-  All those look rather unobtrusive and provide a good visual aid to find the
-  correct amount.
-
 * If you want the account completion to be sorted by level of detail/depth
   instead of alphabetical, include the following line:
 
         let g:ledger_detailed_first = 1
 
+* By default vim will fold ledger transactions, leaving surrounding blank lines
+  unfolded. You can use `g:ledger_fold_blanks` to hide blank lines following a
+  transaction.
+
+        let g:ledger_fold_blanks = 0
+
+  A value of 0 will disable folding of blank lines, 1 will allow folding of a
+  single blank line between transactions; any larger value will enable folding
+  undconditionally.
+
+  Note that only lines containing no trailing spaces are considered for
+  folding. You can take advantage of this to disable this feature on a
+  case-by-case basis.
+
 Completion
 ----------
 

doc/ledger.txt

@@ -71,22 +71,25 @@ behaviour of the ledger filetype.
 
         let g:ledger_fillstring = '    -'
 
-  My special tip is to use so-called digraphs: Press <C-K> followed by the
-  two-characters key sequence below. (in insert-mode)
-
-        '. = ˙ or ': = ¨ --> ˙˙˙˙˙˙ or ¨¨¨¨¨¨
-        ', = ¸           --> ¸¸¸¸¸¸
-        .M = ·           --> ······
-        >> = »           --> »»»»»»
-
-  All those look rather unobtrusive and provide a good visual aid to find the
-  correct amount.
-
 * If you want the account completion to be sorted by level of detail/depth
   instead of alphabetical, include the following line:
 
         let g:ledger_detailed_first = 1
 
+* By default vim will fold ledger transactions, leaving surrounding blank lines
+  unfolded. You can use 'g:ledger_fold_blanks' to hide blank lines following a
+  transaction.
+
+        let g:ledger_fold_blanks = 0
+
+  A value of 0 will disable folding of blank lines, 1 will allow folding of a
+  single blank line between transactions; any larger value will enable folding
+  undconditionally.
+
+  Note that only lines containing no trailing spaces are considered for
+  folding. You can take advantage of this to disable this feature on a
+  case-by-case basis.
+
 ==============================================================================
 COMPLETION                                                 *ledger-completion*
 

syntax/ledger.vim

@@ -15,15 +15,21 @@ endif
 let s:oe = v:version < 704 ? '' : '\%#=1'
 let s:lb1 = v:version < 704 ? '\@<=' : '\@1<='
 
+let s:fb = get(g:, 'ledger_fold_blanks', 0)
+let s:skip = s:fb > 0 ? '\|^\n' : ''
+if s:fb == 1
+  let s:skip .= '\n\@!'
+endif
+
 " for debugging
 syntax clear
 
 " DATE[=EDATE] [*|!] [(CODE)] DESC <-- first line of transaction
 "   ACCOUNT AMOUNT [; NOTE]  <-- posting
 
-syn region ledgerTransaction start=/^[[:digit:]~=]/ skip=/^\s/ end=/^/
-    \ fold keepend transparent
-    \ contains=ledgerTransactionDate,ledgerMetadata,ledgerPosting,ledgerTransactionExpression
+exe 'syn region ledgerTransaction start=/^[[:digit:]~=]/ '.
+  \ 'skip=/^\s'. s:skip . '/ end=/^/ fold keepend transparent '.
+  \ 'contains=ledgerTransactionDate,ledgerMetadata,ledgerPosting,ledgerTransactionExpression'
 syn match ledgerTransactionDate /^\d\S\+/ contained
 syn match ledgerTransactionExpression /^[=~]\s\+\zs.*/ contained
 syn match ledgerPosting /^\s\+[^[:blank:];][^;]*\ze\%($\|;\)/