lib: begin supporting colour

Add some basic helpers for working with ANSI colour codes,
and make strWidth and the various string layout functions aware of them.

hledger-lib/Hledger/Utils.hs

@@ -24,6 +24,7 @@ module Hledger.Utils (---- provide these frequently used modules - or not, for c
                           module Hledger.Utils.String,
                           module Hledger.Utils.Text,
                           module Hledger.Utils.Test,
+                          module Hledger.Utils.Color,
                           module Hledger.Utils.Tree,
                           -- Debug.Trace.trace,
                           -- module Data.PPrint,
@@ -55,6 +56,7 @@ import Hledger.Utils.Regex
 import Hledger.Utils.String
 import Hledger.Utils.Text
 import Hledger.Utils.Test
+import Hledger.Utils.Color
 import Hledger.Utils.Tree
 -- import Prelude hiding (readFile,writeFile,appendFile,getContents,putStr,putStrLn)
 -- import Hledger.Utils.UTF8IOCompat   (readFile,writeFile,appendFile,getContents,putStr,putStrLn)

hledger-lib/Hledger/Utils/Color.hs

@@ -0,0 +1,23 @@
+-- | Basic color helpers for prettifying console output.
+
+{-# LANGUAGE OverloadedStrings #-}
+
+module Hledger.Utils.Color 
+(
+  color,
+  bgColor,
+  Color(..),
+  ColorIntensity(..)
+)
+where
+
+import System.Console.ANSI
+
+
+-- | Wrap a string in ANSI codes to set and reset foreground colour.
+color :: ColorIntensity -> Color -> String -> String
+color int col s = setSGRCode [SetColor Foreground int col] ++ s ++ setSGRCode []
+
+-- | Wrap a string in ANSI codes to set and reset background colour.
+bgColor :: ColorIntensity -> Color -> String -> String
+bgColor int col s = setSGRCode [SetColor Background int col] ++ s ++ setSGRCode []

hledger-lib/Hledger/Utils/String.hs

@@ -15,6 +15,7 @@ module Hledger.Utils.String (
  escapeQuotes,
  words',
  unwords',
+ stripAnsi,
  -- * single-line layout
  strip,
  lstrip,
@@ -319,12 +320,17 @@ takeWidth w (c:cs) | cw <= w   = c:takeWidth (w-cw) cs
 -- from Pandoc (copyright John MacFarlane, GPL)
 -- see also http://unicode.org/reports/tr11/#Description
 
--- | Calculate the designated render width of a string, taking into
--- account wide characters and line breaks (the longest line within a
--- multi-line string determines the width ).
+-- | Calculate the render width of a string, considering
+-- wide characters (counted as double width), ANSI escape codes 
+-- (not counted), and line breaks (in a multi-line string, the longest
+-- line determines the width). 
 strWidth :: String -> Int
 strWidth "" = 0
-strWidth s = maximum $ map (foldr (\a b -> charWidth a + b) 0) $ lines s
+strWidth s = maximum $ map (foldr (\a b -> charWidth a + b) 0) $ lines s'
+  where s' = stripAnsi s
+
+stripAnsi :: String -> String
+stripAnsi = regexReplace "\ESC\\[([0-9]+;)*([0-9]+)?[ABCDHJKfmsu]" ""
 
 -- | Get the designated render width of a character: 0 for a combining
 -- character, 1 for a regular character, 2 for a wide character.

hledger-lib/hledger-lib.cabal

@@ -59,6 +59,7 @@ library
   build-depends:
       base >=4.8 && <5
     , base-compat >=0.8.1
+    , ansi-terminal >= 0.6.2.3 && < 0.7
     , array
     , blaze-markup >=0.5.1
     , bytestring
@@ -131,6 +132,7 @@ library
       Hledger.Reports.PostingsReport
       Hledger.Reports.TransactionsReports
       Hledger.Utils
+      Hledger.Utils.Color
       Hledger.Utils.Debug
       Hledger.Utils.Parse
       Hledger.Utils.Regex
@@ -153,6 +155,7 @@ test-suite doctests
   build-depends:
       base >=4.8 && <5
     , base-compat >=0.8.1
+    , ansi-terminal >= 0.6.2.3 && < 0.7
     , array
     , blaze-markup >=0.5.1
     , bytestring
@@ -218,6 +221,7 @@ test-suite doctests
       Hledger.Reports.ReportOptions
       Hledger.Reports.TransactionsReports
       Hledger.Utils
+      Hledger.Utils.Color
       Hledger.Utils.Debug
       Hledger.Utils.Parse
       Hledger.Utils.Regex
@@ -238,6 +242,7 @@ test-suite hunittests
   build-depends:
       base >=4.8 && <5
     , base-compat >=0.8.1
+    , ansi-terminal >= 0.6.2.3 && < 0.7
     , array
     , blaze-markup >=0.5.1
     , bytestring
@@ -312,6 +317,7 @@ test-suite hunittests
       Hledger.Reports.ReportOptions
       Hledger.Reports.TransactionsReports
       Hledger.Utils
+      Hledger.Utils.Color
       Hledger.Utils.Debug
       Hledger.Utils.Parse
       Hledger.Utils.Regex

hledger-lib/package.yaml

@@ -41,6 +41,7 @@ flags:
 dependencies:
 - base >=4.8 && <5
 - base-compat >=0.8.1
+- ansi-terminal >= 0.6.2.3 && < 0.7
 - array
 - blaze-markup >=0.5.1
 - bytestring
@@ -117,6 +118,7 @@ library:
   - Hledger.Reports.PostingsReport
   - Hledger.Reports.TransactionsReports
   - Hledger.Utils
+  - Hledger.Utils.Color
   - Hledger.Utils.Debug
   - Hledger.Utils.Parse
   - Hledger.Utils.Regex

hledger-ui/Hledger/UI/UIUtils.hs

@@ -17,7 +17,7 @@ import Graphics.Vty (Event(..),Key(..),Color,Attr,currentAttr)
 import Lens.Micro.Platform
 import System.Process
 
-import Hledger
+import Hledger hiding (Color)
 import Hledger.UI.UITypes
 import Hledger.UI.UIState