4 files changed, 31 insertions, 2 deletions
diff --git a/tablib/formats/__init__.py b/tablib/formats/__init__.py
index b22a959..69eada7 100644
--- a/tablib/formats/__init__.py
+++ b/tablib/formats/__init__.py
@@ -8,4 +8,4 @@ import _json as json
 import _xls as xls
 import _yaml as yaml
 
-FORMATS = (csv, json, xls, yaml)
+FORMATS = (json, xls, yaml, csv)
diff --git a/tablib/formats/_csv.py b/tablib/formats/_csv.py
index 8b19da7..27d2e0d 100644
--- a/tablib/formats/_csv.py
+++ b/tablib/formats/_csv.py
@@ -40,3 +40,12 @@ def import_set(dset, in_stream, headers=True):
 			dset.headers = row
 		else:
 			dset.append(row)
+
+
+def detect(stream):
+	"""Returns True if given stream is valid CSV."""
+	try:
+		rows = dialect = csv.Sniffer().sniff(stream)
+		return True
+	except csv.Error:
+		return False
+\ No newline at end of file
diff --git a/tablib/formats/_json.py b/tablib/formats/_json.py
index 1f92b58..f7c88ee 100644
--- a/tablib/formats/_json.py
+++ b/tablib/formats/_json.py
@@ -36,3 +36,12 @@ def import_book(dbook, in_stream):
 		data.title = sheet['title']
 		data.dict = sheet['data']
 		dbook.add_sheet(data)
+
+
+def detect(stream):
+	"""Returns True if given stream is valid JSON."""
+	try:
+		json.loads(stream)
+		return True
+	except json.decoder.JSONDecodeError:
+		return False
+\ No newline at end of file
diff --git a/tablib/formats/_yaml.py b/tablib/formats/_yaml.py
index 4cac8aa..57d63d7 100644
--- a/tablib/formats/_yaml.py
+++ b/tablib/formats/_yaml.py
@@ -39,4 +39,15 @@ def import_book(dbook, in_stream):
 		data = tablib.core.Dataset()
 		data.title = sheet['title']
 		data.dict = sheet['data']
-		dbook.add_sheet(data)
-\ No newline at end of file
+		dbook.add_sheet(data)
+		
+def detect(stream):
+	"""Returns True if given stream is valid YAML."""
+	try:
+		_yaml = yaml.load(stream)
+		if isinstance(_yaml, (list, tuple, dict)):
+			return True
+		else:
+			return False
+	except yaml.parser.ParserError:
+		return False
+\ No newline at end of file