correctly represent trailing spaces and newlines

library/lua/dfhack.lua

@@ -618,6 +618,15 @@ function string:trim()
     return self:match('^%s*(.-)%s*$')
 end
 
+local function insert_wrapped_line(wrapped_text, words, opts)
+    local wrapped_line = table.concat(words, '')
+    if not opts.keep_trailing_spaces then
+        local content, eol = wrapped_line:match('(.-)%s*(\n?)$')
+        wrapped_line = content .. eol
+    end
+    table.insert(wrapped_text, wrapped_line)
+end
+
 local function wrap_word(word, width, wrapped_text, words, cur_line_len, opts)
     local word_len = #word
     -- word fits within the current line
@@ -632,21 +641,21 @@ local function wrap_word(word, width, wrapped_text, words, cur_line_len, opts)
         -- trimmed word fits on the current line and ends it
         if cur_line_len + #trimmed_word <= width then
             table.insert(words, trimmed_word)
-            table.insert(wrapped_text, table.concat(words, ''))
+            insert_wrapped_line(wrapped_text, words, opts)
             return {}, 0
         end
     end
     -- word needs to go on the next line, but is not itself longer
     -- than the specified width
     if word_len <= width then
-        table.insert(wrapped_text, table.concat(words, ''))
+        insert_wrapped_line(wrapped_text, words, opts)
         return {word}, word_len
     end
     -- word is too long to fit on one line and needs to be split up
     local emitted_chars, trimmed_word_len = 0, #trimmed_word
     repeat
         if #words > 0 then
-            table.insert(wrapped_text, table.concat(words, ''))
+            insert_wrapped_line(wrapped_text, words, opts)
         end
         local word_frag = word:sub(emitted_chars + 1, emitted_chars + width)
         words, cur_line_len = {word_frag}, #word_frag
@@ -674,7 +683,10 @@ function string:wrap(width, opts)
         for word in line:gmatch('%S+%s*') do
             words, cur_line_len = wrap_word(word, width, wrapped_text, words, cur_line_len, opts)
         end
-        table.insert(wrapped_text, table.concat(words, ''))
+        insert_wrapped_line(wrapped_text, words, opts)
+    end
+    if self:sub(#self) == '\n' then
+        table.insert(wrapped_text, '')
     end
     return opts.return_as_table and wrapped_text or table.concat(wrapped_text, '\n')
 end

test/library/string.lua

@@ -61,7 +61,7 @@ end
 
 function test.wrap()
     expect.eq('', (''):wrap())
-    expect.eq('  ', ('  '):wrap())
+    expect.eq('', ('  '):wrap())
     expect.eq('\n', ('    '):wrap(3))
     expect.eq('\n', ('       '):wrap(3))
 
@@ -72,19 +72,20 @@ function test.wrap()
 
     expect.eq('hello world', ('hello world'):wrap(20))
     expect.eq('hello   world', ('hello   world'):wrap(20))
-    expect.eq('  hello world  ', ('  hello world  '):wrap(20))
-    expect.eq('  hello   world  ', ('  hello   world  '):wrap(20))
-    expect.eq('hello world \nhow are you?',('hello world how are you?'):wrap(12))
+    expect.eq('  hello world', ('  hello world  '):wrap(20))
+    expect.eq('  hello   world', ('  hello   world  '):wrap(20))
+    expect.eq('hello world\nhow are you?',('hello world how are you?'):wrap(12))
     expect.eq('hello\nworld', ('hello world'):wrap(5))
+    expect.eq('hello\nworld\n\n', ('hello world\n'):wrap(5))
     expect.eq('hello\nworld', ('hello        world'):wrap(5))
-    expect.eq('  \nhello\nworld', ('  hello  world  '):wrap(5))
-    expect.eq('hello \nworld', ('hello world'):wrap(8))
-    expect.eq('hel\nlo \nwor\nld', ('hello world'):wrap(3))
+    expect.eq('\nhello\nworld', ('  hello  world  '):wrap(5))
+    expect.eq('hello\nworld', ('hello world'):wrap(8))
+    expect.eq('hel\nlo\nwor\nld', ('hello world'):wrap(3))
     expect.eq('hel\nloo\nwor\nldo', ('helloo  worldo'):wrap(3))
 
     expect.eq('hel\nloo\n  \nwor\nldo', ('helloo  worldo'):wrap(3, {keep_trailing_spaces=true}))
 
-    expect.table_eq({'hel', 'lo ', 'wor', 'ld'}, ('hello world'):wrap(3, {return_as_table=true}))
+    expect.table_eq({'hel', 'lo', 'wor', 'ld'}, ('hello world'):wrap(3, {return_as_table=true}))
 
     expect.error_match('expected width > 0', function() ('somestr'):wrap(0) end)
 
@@ -134,8 +135,9 @@ function test.wrap()
         'is a ',
         'sim\n',
         'ple ',
-        'text'
-    }, ('this is a sim\nple text'):wrap(7, journal_opts),
+        'text\n',
+        ''
+    }, ('this is a sim\nple text\n'):wrap(7, journal_opts),
     'take into account existing new line')
 
     expect.table_eq({