Add json output for show command

src/Composer/Command/ShowCommand.php

@@ -14,6 +14,7 @@ namespace Composer\Command;
 
 use Composer\DependencyResolver\Pool;
 use Composer\DependencyResolver\DefaultPolicy;
+use Composer\Json\JsonFile;
 use Composer\Package\CompletePackageInterface;
 use Composer\Package\Version\VersionParser;
 use Composer\Package\BasePackage;
@@ -74,6 +75,7 @@ class ShowCommand extends BaseCommand
                 new InputOption('minor-only', 'm', InputOption::VALUE_NONE, 'Show only packages that have minor SemVer-compatible updates. Use with the --outdated option.'),
                 new InputOption('direct', 'D', InputOption::VALUE_NONE, 'Shows only packages that are directly required by the root package'),
                 new InputOption('strict', null, InputOption::VALUE_NONE, 'Return a non-zero exit code when there are outdated packages'),
+                new InputOption('format', 'f', InputOption::VALUE_REQUIRED, 'Format of the output: text or json', 'text'),
             ))
             ->setHelp(<<<EOT
 The show command displays detailed information about a package, or
@@ -114,6 +116,13 @@ EOT
             return 1;
         }
 
+        $format = $input->getOption('format');
+        if (!in_array($format, array('text', 'json'))) {
+            $io->writeError(sprintf('Unsupported format "%s". See help for supported formats.', $format));
+
+            return 1;
+        }
+
         // init repos
         $platformOverrides = array();
         if ($composer) {
@@ -378,6 +387,9 @@ EOT
             }
         }
 
+        if ('json' === $format) {
+            $io->write(JsonFile::encode($viewData));
+        } else {
             foreach ($viewData as $type => $packages) {
                 $nameLength = $viewMetaData[$type]['nameLength'];
                 $versionLength = $viewMetaData[$type]['versionLength'];
@@ -437,6 +449,7 @@ EOT
                     $io->write('');
                 }
             }
+        }
 
         return $exitCode;
     }