cli: --color/--colour option; smart emacs, windows autodetection (#1296)

hledger-lib/Hledger/Reports/ReportOptions.hs

@@ -4,7 +4,10 @@ Options common to most hledger reports.
 
 -}
 
-{-# LANGUAGE OverloadedStrings, RecordWildCards, LambdaCase, DeriveDataTypeable #-}
+{-# LANGUAGE DeriveDataTypeable #-}
+{-# LANGUAGE LambdaCase #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE RecordWildCards #-}
 
 module Hledger.Reports.ReportOptions (
   ReportOpts(..),
@@ -54,7 +57,9 @@ import Data.Typeable (Typeable)
 import Data.Time.Calendar
 import Data.Default
 import Safe
-import System.Console.ANSI (hSupportsANSI)
+
+import System.Console.ANSI (hSupportsANSIColor)
+import System.Environment (lookupEnv)
 import System.IO (stdout)
 import Text.Megaparsec.Custom
 
@@ -129,6 +134,10 @@ data ReportOpts = ReportOpts {
       --   sign normalisation, converting normally negative subreports to
       --   normally positive for a more conventional display.
     ,color_          :: Bool
+      -- ^ Whether to use ANSI color codes in text output.
+      --   Influenced by the --color/colour flag (cf CliOptions),
+      --   whether stdout is an interactive terminal, and the value of
+      --   TERM and existence of NO_COLOR environment variables.
     ,forecast_       :: Maybe DateSpan
     ,transpose_      :: Bool
  } deriving (Show, Data, Typeable)
@@ -172,7 +181,9 @@ rawOptsToReportOpts :: RawOpts -> IO ReportOpts
 rawOptsToReportOpts rawopts = checkReportOpts <$> do
   let rawopts' = checkRawOpts rawopts
   d <- getCurrentDay
-  color <- hSupportsANSI stdout
+  no_color <- isJust <$> lookupEnv "NO_COLOR"
+  supports_color <- hSupportsANSIColor stdout
+  let colorflag = stringopt "color" rawopts
   return defreportopts{
      today_       = Just d
     ,period_      = periodFromRawOpts d rawopts'
@@ -200,7 +211,10 @@ rawOptsToReportOpts rawopts = checkReportOpts <$> do
     ,percent_     = boolopt "percent" rawopts'
     ,invert_      = boolopt "invert" rawopts'
     ,pretty_tables_ = boolopt "pretty-tables" rawopts'
-    ,color_       = color
+    ,color_       = and [not no_color
+                        ,not $ colorflag `elem` ["never","no"]
+                        ,colorflag `elem` ["always","yes"] || supports_color
+                        ]
     ,forecast_    = forecastPeriodFromRawOpts d rawopts'
     ,transpose_   = boolopt "transpose" rawopts'
     }

hledger-lib/package.yaml

@@ -48,7 +48,7 @@ dependencies:
 - base-compat-batteries >=0.10.1 && <0.12
 - aeson >=1
 - aeson-pretty
-- ansi-terminal >=0.6.2.3
+- ansi-terminal >=0.9
 - array
 - blaze-markup >=0.5.1
 - bytestring

hledger-ui/package.yaml

@@ -43,7 +43,7 @@ cpp-options: -DVERSION="1.18.99"
 dependencies:
 - hledger-lib >=1.18.99 && <1.19
 - hledger >=1.18.99 && <1.19
-- ansi-terminal >=0.6.2.3
+- ansi-terminal >=0.9
 - async
 - base >=4.9 && <4.15
 - base-compat-batteries >=0.10.1 && <0.12

hledger/Hledger/Cli/CliOptions.hs

@@ -188,6 +188,17 @@ reportflags = [
    , "Also, in hledger-ui, make future transactions visible."
    , "Note that = (and not a space) is required before PERIODEXP if you wish to supply it."
    ])
+
+  -- general output-related
+
+ ,flagReq  ["color","colour"] (\s opts -> Right $ setopt "color" s opts) "always|never|auto"
+   (unwords
+     ["When to use color (or colour) in terminal output."
+     ,"'auto' is the default; it tries to enable color when the terminal is color-supporting and interactive."
+     ,"'always' or 'yes' forces color on, useful eg when piping output into 'less -R'."
+     ,"'never' or 'no' forces color off."
+     ,"A NO_COLOR environment variable will also force color off, overriding this option."
+     ])
  ]
 
 -- | Flags for selecting flat/tree mode, used in accounts/balance reports.

hledger/Hledger/Cli/Commands/Balance.md

@@ -124,10 +124,8 @@ Some example formats:
 
 ### Colour support
 
-The balance command shows negative amounts in red, if:
-
-- the `TERM` environment variable is not set to `dumb`
-- the output is not being redirected or piped anywhere
+In terminal output, when colour is enabled, 
+the balance command shows negative amounts in red.
 
 ### Flat mode
 
@@ -320,7 +318,7 @@ the width of multicommodity reports.
 
 When the report is still too wide, a good workaround is to pipe it
 into `less -RS` (-R for colour, -S to chop long lines). 
-Eg: `hledger bal -D | less -RS`.
+Eg: `hledger bal -D --color=yes | less -RS`.
 
 
 ### Budget report

hledger/hledger.m4.md

@@ -1723,12 +1723,17 @@ directory. These are typically prototypes and not guaranteed to work.
 
 # ENVIRONMENT
 
+m4_dnl Standard LEDGER_FILE description:
+_LEDGER_FILE_
+
 **COLUMNS**
 The screen width used by the register command.
 Default: the full terminal width.
 
-m4_dnl Standard LEDGER_FILE description:
-_LEDGER_FILE_
+**NO_COLOR**
+If this variable exists with any value, 
+hledger will not use ANSI color codes in terminal output.
+This overrides the --color/--colour option.
 
 # FILES
 

hledger/package.yaml

@@ -110,7 +110,7 @@ ghc-options:
 dependencies:
 - hledger-lib >=1.18.99 && <1.19
 - aeson >=1
-- ansi-terminal >=0.6.2.3
+- ansi-terminal >=0.9
 - base >=4.9 && <4.15
 - base-compat-batteries >=0.10.1 && <0.12
 - bytestring

stack8.2.yaml

@@ -16,6 +16,7 @@ packages:
 extra-deps:
 # use the latest base-compat with all ghc versions
 - aeson-1.3.1.1
+- ansi-terminal-0.10.3
 - base-compat-0.10.1
 - base-compat-batteries-0.10.1
 - cassava-megaparsec-2.0.0

stack8.4.yaml

@@ -13,6 +13,7 @@ packages:
 - hledger-web
 
 extra-deps:
+- ansi-terminal-0.10.3
 - cassava-megaparsec-2.0.0
 - config-ini-0.2.3.0
 - doctest-0.16.3