From 4275211e4fab824f459f47761276bf4f9b83851c Mon Sep 17 00:00:00 2001
From: jbarbero <jbarbero@gmail.com>
Date: Tue, 26 Apr 2016 16:10:48 -0700
Subject: suppress ANSI color codes if stdout or stderr is not a terminal

---
 graph.lua |  9 +++++----
 init.lua  |  2 +-
 usage.lua | 20 ++++++++++++--------
 3 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/graph.lua b/graph.lua
index 32e3a0c..7d839fb 100644
--- a/graph.lua
+++ b/graph.lua
@@ -351,20 +351,21 @@ function ACN:usage(...)
       function(self)
          if self.rules and not history[self.rules] then
             history[self.rules] = true
-            table.insert(txt, usage(true, self.rules))
+            table.insert(txt, usage.usage(true, self.rules))
          end
       end
    )
    return string.format(
       "%s\n%s\n",
       table.concat(txt, '\n\nor\n\n'),
-      usage(false, self, ...)
+      usage.usage(false, self, ...)
    )
 end
 
 function ACN:generate(upvalues)
    assert(upvalues, 'upvalues table missing')
    local code = {}
+   table.insert(code, 'local usage = require "argcheck.usage"')
    table.insert(code, 'return function(...)')
    table.insert(code, '  local narg = select("#", ...)')
    self:generate_ordered_or_named(code, upvalues, 'O')
@@ -421,9 +422,9 @@ function ACN:generate(upvalues)
       end
    )
    if quiet then
-      table.insert(code, '  return false, graph:usage(...)')
+      table.insert(code, '  return false, usage.render(graph:usage(...))')
    else
-      table.insert(code, '  error(string.format("%s\\ninvalid arguments!", graph:usage(...)))')
+      table.insert(code, '  error(string.format("%s\\ninvalid arguments!", usage.render(graph:usage(...))))')
    end
    table.insert(code, 'end')
    return table.concat(code, '\n')
diff --git a/init.lua b/init.lua
index 0461de3..8e67716 100644
--- a/init.lua
+++ b/init.lua
@@ -99,7 +99,7 @@ local function argcheck(rules)
 
    -- dump doc if any
    if rules.doc or rules.help then
-      doc(usage(true, rules, true))
+      doc(usage.render(usage.usage(true, rules, true)))
    end
 
    local code, upvalues = generaterules(rules)
diff --git a/usage.lua b/usage.lua
index 3eed346..fe6165b 100644
--- a/usage.lua
+++ b/usage.lua
@@ -4,6 +4,8 @@ pcall(function()
          sdascii = require 'sundown.ascii'
       end)
 
+local usage = {}
+
 local function generateargp(rules)
    local txt = {}
    for idx, rule in ipairs(rules) do
@@ -76,7 +78,16 @@ local function generateargt(rules)
    return txt
 end
 
-local function usage(truth, rules, ...)
+function usage.render(doc)
+   -- We render any markdown in the input into ANSI color codes using sundown, but only if stdout and stderr are terminals
+   if sdascii and pcall(require, 'torch') and torch.isatty(io.stderr) and torch.isatty(io.stdout) then
+      doc = sdascii.render(doc)
+   end
+
+   return doc
+end
+
+function usage.usage(truth, rules, ...)
    if truth then
       local norender = select(1, ...)
       local doc = rules.help or rules.doc
@@ -97,10 +108,6 @@ local function usage(truth, rules, ...)
          doc = '\n*Arguments:*\n' .. generateargt(rules)
       end
 
-      if sdascii and not norender then
-         doc = sdascii.render(doc)
-      end
-
       return doc
    else
       local self = rules
@@ -137,9 +144,6 @@ local function usage(truth, rules, ...)
          args[argtblidx] = string.format("**table**={ %s }", table.concat(argtbl, ', '))
       end
       local doc = string.format("*Got:* %s", table.concat(args, ', '))
-      if sdascii then
-         doc = sdascii.render(doc)
-      end
       return doc
    end
 end
-- 
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