Add the "set width" command

This is mostly needed for embedding, since there doesn't seem to be
any practical (let alone portable) standard way to notify pancake of
emacs window size changes.

In pancake.el, width adjustment is now getting done automatically
whenever any other command gets issued.

5 files changed, 30 insertions, 4 deletions

diff --git a/Pancake.hs b/Pancake.hs
index 129585d..5d49b1a 100644
--- a/Pancake.hs
+++ b/Pancake.hs
@@ -74,6 +74,7 @@ data LoopState = LS { history :: Sliding (URI, P.Pandoc)
                     , embedded :: Bool
                     , interrupted :: Bool
                     , unclutterRegexps :: [(Regex, String)]
+                    , columns :: Maybe Int
                     }
 
 -- | Renders a parsed document.
@@ -81,7 +82,7 @@ printDoc :: MonadIO m => URI -> P.Pandoc -> StateT LoopState m ()
 printDoc uri doc = do
   term <- liftIO setupTermFromEnv
   st <- get
-  let cols = fromMaybe 80 $ getCapability term termColumns
+  let cols = fromMaybe 80 $ columns st <|> getCapability term termColumns
       l = renderDoc cols (conf st) doc
       textLines = rLines l
   modify (\s -> s { rendered = l })
@@ -315,6 +316,7 @@ command Quit = liftIO $ do
   when exists $ removeDirectoryRecursive dir
 command Interrupt =
   putErrLn "Received SIGINT. Interrupt twice in a row to quit."
+command (SetWidth w) = modify $ \s -> s { columns = w }
 
 -- | Reads commands, runs them.
 eventLoop :: MonadIO m => StateT LoopState m ()
@@ -353,7 +355,7 @@ main = do
   tid <- myThreadId
   _ <- installHandler sigINT (Catch (throwTo tid UserInterrupt)) Nothing
   let run e = runStateT (updateConfig >> eventLoop)
-              (LS ([],[]) 0 [] def e False [])
+              (LS ([],[]) 0 [] def e False [] Nothing)
               >> pure ()
   case getOpt Permute options args of
     ([], [], []) -> run False
diff --git a/Pancake/Command.hs b/Pancake/Command.hs
index c385dc2..5126146 100644
--- a/Pancake/Command.hs
+++ b/Pancake/Command.hs
@@ -60,6 +60,7 @@ data Command = Quit
              | ShowCurrent
              | Shortcut String String
              | ReloadConfig
+             | SetWidth (Maybe Int)
              deriving (Show, Eq)
 
 -- | Parses a user command.
@@ -141,6 +142,16 @@ shortcut m = do
       q <- manyTill anyChar eof
       pure $ Shortcut u q
 
+-- | A natural numbers parser.
+pNat :: Read i => Parser i
+pNat = read <$> many1 digit
+
+-- | 'SetWidth' command parser.
+setWidth :: Parser Command
+setWidth = string "set width"
+           *> (SetWidth <$> optionMaybe (spaces *> pNat))
+           <* eof
+
 -- | Command parser.
 command :: Config -> Parser Command
 command c =
@@ -152,5 +163,6 @@ command c =
           , saveRef (referenceDigits c) <?> "save ref"
           , saveCurrent <?> "save current"
           , save <?> "save"
+          , setWidth <?> "set width"
           , goTo <?> "follow uri"
           ])
diff --git a/README b/README
index 92d7240..7cabedf 100644
--- a/README
+++ b/README
@@ -73,6 +73,7 @@ Commands
 :save ,[ <path>]: save current document
 :<shortcut> <query>: run a query using a shortcut defined in the
                      configuration (e.g., search)
+:set width[ <columns>]: set terminal/window width manually
 
 pancake-mode provides additional aliases and commands, see built-in
 emacs documentation (``C-h m``) for those.
diff --git a/pancake.1 b/pancake.1
index 66b038f..f5daeaf 100644
--- a/pancake.1
+++ b/pancake.1
@@ -57,6 +57,8 @@ save current document
 .IP "\fIshortcut\fR \fIquery\fR"
 run a query using a shortcut defined in the configuration (e.g.,
 search)
+.IP "\fBset width\fR[ \fIcolumns\fR]"
+set terminal/window width manually
 
 .SH DEFAULT SHORTCUTS
 .IP "\fBg\fR"
diff --git a/pancake.el b/pancake.el
index 98aab6d..6429f67 100644
--- a/pancake.el
+++ b/pancake.el
@@ -174,8 +174,7 @@ if no URL is provided."
                     (current-buffer)
                   (car pancake-buffers))))
     (with-current-buffer buffer
-      (when url
-        (process-send-string pancake-process (concat url "\n")))
+      (when url (pancake-process-send url))
       (display-buffer (current-buffer)))))
 
 (defun pancake-translate-color (name attr)
@@ -356,8 +355,18 @@ property. Returns a list of collected values."
   (interactive)
   (funcall (pancake-input (gui-get-primary-selection))))
 
+(defun pancake-width-adjust (&optional width)
+  "Sets the width (in columns) that the pancake process should
+use. Current window width is used if none is provided."
+  (interactive)
+  ;; Not using `pancake-process-send' here, since it itself would call
+  ;; this function.
+  (process-send-string pancake-process
+                       (format "set width %d\n" (or width (window-width)))))
+
 (defun pancake-process-send (line)
   "Send LINE to the pancake process."
+  (pancake-width-adjust)
   (process-send-string pancake-process (concat line "\n")))
 
 (defun pancake-go-backward ()