add support for stream input

deepmatcher/data/dataset.py

@@ -69,6 +69,16 @@ def split(table,
         tables[i].to_csv(os.path.join(path, prefixes[i]), index=False)
 
 
+class CountingWrapper(object):
+    def __init__(self, stream):
+        self.line_count = 0
+        self.f = stream
+
+    def read(self, *args, **kwargs):
+        self.line_count += 1
+        return self.f.read(*args, **kwargs)
+
+
 class MatchingDataset(data.Dataset):
     r"""Represents dataset with associated metadata.
 
@@ -101,7 +111,7 @@ class CacheStaleException(Exception):
     def __init__(self,
                  fields,
                  column_naming,
-                 path=None,
+                 stream=None,
                  format='csv',
                  examples=None,
                  metadata=None,
@@ -141,26 +151,29 @@ def __init__(self,
         """
         if examples is None:
             make_example = {
-                'json': Example.fromJSON, 'dict': Example.fromdict,
-                'tsv': Example.fromCSV, 'csv': Example.fromCSV}[format.lower()]
+                'json': Example.fromJSON,
+                'dict': Example.fromdict,
+                'tsv': Example.fromCSV,
+                'csv': Example.fromCSV
+            }[format.lower()]
 
+            f = CountingWrapper(stream)
             lines = 0
-            with open(os.path.expanduser(path), encoding="utf8") as f:
-                for line in f:
-                    lines += 1
-
-            with open(os.path.expanduser(path), encoding="utf8") as f:
-                if format == 'csv':
-                    reader = unicode_csv_reader(f)
-                elif format == 'tsv':
-                    reader = unicode_csv_reader(f, delimiter='\t')
-                else:
-                    reader = f
-
-                next(reader)
-                examples = [make_example(line, fields) for line in
-                    pyprind.prog_bar(reader, iterations=lines,
-                        title='\nReading and processing data from "' + path + '"')]
+            if format == 'csv':
+                reader = unicode_csv_reader(f)
+            elif format == 'tsv':
+                reader = unicode_csv_reader(f, delimiter='\t')
+            else:
+                reader = f
+            lines = f.line_count
+
+            next(reader)
+            examples = [
+                make_example(line, fields) for line in pyprind.prog_bar(
+                    reader,
+                    iterations=lines,
+                    title='\nReading and processing data from "' + path + '"')
+            ]
 
             super(MatchingDataset, self).__init__(examples, fields, **kwargs)
         else: