From b251c5f2e20ef1b635c925c749292148251dac29 Mon Sep 17 00:00:00 2001
From: Hatter Jiang <jht5945@gmail.com>
Date: Mon, 18 Nov 2019 00:05:02 +0800
Subject: [PATCH] add read from stdin

---
 prettyjson.dart | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/prettyjson.dart b/prettyjson.dart
index b063714..b026bf2 100644
--- a/prettyjson.dart
+++ b/prettyjson.dart
@@ -1,13 +1,26 @@
 import 'dart:convert';
 import 'dart:io';
 
-main(List<String> args) async {
-  if (args.length == 0) {
-    print('File name is not assigned\nUsage: prettyjson.dart <file.json>');
-    return;
-  }
-  final jsonContent = await new File(args[0]).readAsString();
+main(List<String> args) async {  
+  final jsonContent = await readContent(args);
   final jsonDecoded = json.decode(jsonContent);
   JsonEncoder encoder = new JsonEncoder.withIndent('    ');
   print(encoder.convert(jsonDecoded));
 }
+
+Future<String> readContent(List<String> args) async {
+  if (args.length == 0) {
+    return readFromStdin();
+  } else {
+    return new File(args[0]).readAsString();
+  }
+}
+
+Future<String> readFromStdin() async {
+    final stdinContentLines = stdin.transform(utf8.decoder);
+    final stdinContentArray = new List<String>();
+    await for (var line in stdinContentLines) {
+      stdinContentArray.add(line);
+    }
+    return Future<String>.value(stdinContentArray.join('\n'));
+}