add --installed to json info

Closes Homebrew/homebrew#29315.

2 files changed, 9 insertions, 2 deletions

diff --git a/Library/Homebrew/cmd/info.rb b/Library/Homebrew/cmd/info.rb
index 9deda9dfb..ef8e2ac52 100644
--- a/Library/Homebrew/cmd/info.rb
+++ b/Library/Homebrew/cmd/info.rb
@@ -41,8 +41,14 @@ module Homebrew extend self
   end
 
   def print_json
-    formulae = ARGV.include?("--all") ? Formula : ARGV.formulae
-    json = formulae.map {|f| f.to_hash}
+    ff = if ARGV.include? "--all"
+           Formula
+         elsif ARGV.include? "--installed"
+           Formula.installed
+         else
+           ARGV.formulae
+         end
+    json = ff.map {|f| f.to_hash}
     if json.size == 1
       puts Utils::JSON.dump(json.pop)
     else
diff --git a/Library/Homebrew/formula.rb b/Library/Homebrew/formula.rb
index d6a6f60e1..f0217bb74 100644
--- a/Library/Homebrew/formula.rb
+++ b/Library/Homebrew/formula.rb
@@ -369,6 +369,7 @@ class Formula
     include Enumerable
   end
 
+  # An array of all installed formulae
   def self.installed
     return [] unless HOMEBREW_CELLAR.directory?