Fix for ALEs with too few or too many blank lines between sections

src/otio_ale_adapter/ale.py

@@ -9,6 +9,7 @@
 
 DEFAULT_VIDEO_FORMAT = '1080'
 ASC_SOP_REGEX = re.compile(r'(-*\d+\.\d+)')
+ALE_SECTION_DESIGNATORS = {"Heading", "Column", "Data"}
 
 
 def AVID_VIDEO_FORMAT_FROM_WIDTH_HEIGHT(width, height):
@@ -182,6 +183,70 @@ def _video_format_from_metadata(clips):
         return AVID_VIDEO_FORMAT_FROM_WIDTH_HEIGHT(max_width, max_height)
 
 
+def _read_heading_lines(lines):
+    """
+    Consumes all the Header information from lines returning a dictionary
+    mapping header keys to header values.
+    """
+    header = {}
+    # read until we run out of lines or the next section starts, not consuming
+    # the next section designator
+    while len(lines) and lines[0] not in ALE_SECTION_DESIGNATORS:
+        line = lines.pop(0)
+        if line.strip() == "":
+            continue
+
+        if "\t" not in line:
+            raise ALEParseError("Invalid Heading line: " + line)
+
+        segments = line.split("\t")
+        while len(segments) >= 2:
+            key, val = segments.pop(0), segments.pop(0)
+            header[key] = val
+        if len(segments) != 0:
+            raise ALEParseError("Invalid Heading line: " + line)
+
+    return header
+
+
+def _pop_columns(lines):
+    """
+    Consumes the Column information from the ALE and returns the list of
+    columns.
+    """
+    try:
+        line = lines.pop(0)
+        # skip blank lines
+        while not line.strip():
+            line = lines.pop(0)
+    except IndexError:
+        raise ALEParseError("Unexpected end of file after 'Column'")
+
+    columns = line.split("\t")
+
+    return columns
+
+
+def _read_data(lines, columns, fps, ale_name_column_key):
+    """
+    Generator consuming the Data section of the ALE yielding Clips.
+    """
+    while len(lines):
+        line = lines.pop(0)
+
+        if line.strip() == "":
+            continue
+
+        clip = _parse_data_line(
+            line,
+            columns,
+            fps,
+            ale_name_column_key=ale_name_column_key
+        )
+
+        yield clip
+
+
 def read_from_string(input_str, fps=24, **adapter_argument_map):
     ale_name_column_key = adapter_argument_map.get(
         "ale_name_column_key", "Name"
@@ -203,21 +268,7 @@ def nextline(lines):
             continue
 
         if line.strip() == "Heading":
-            while len(lines):
-                line = nextline(lines)
-
-                if line.strip() == "":
-                    break
-
-                if "\t" not in line:
-                    raise ALEParseError("Invalid Heading line: " + line)
-
-                segments = line.split("\t")
-                while len(segments) >= 2:
-                    key, val = segments.pop(0), segments.pop(0)
-                    header[key] = val
-                if len(segments) != 0:
-                    raise ALEParseError("Invalid Heading line: " + line)
+            header.update(_read_heading_lines(lines))
 
         if "FPS" in header:
             read_fps = float(header["FPS"])
@@ -234,24 +285,13 @@ def nextline(lines):
             if len(lines) == 0:
                 raise ALEParseError("Unexpected end of file after: " + line)
 
-            line = nextline(lines)
-            columns = line.split("\t")
+            columns = _pop_columns(lines)
 
         if line.strip() == "Data":
-            while len(lines):
-                line = nextline(lines)
-
-                if line.strip() == "":
-                    continue
-
-                clip = _parse_data_line(
-                    line,
-                    columns,
-                    fps,
-                    ale_name_column_key=ale_name_column_key
-                )
-
-                collection.append(clip)
+            clip_generator = _read_data(
+                lines, columns, fps, ale_name_column_key
+            )
+            collection.extend(clip_generator)
 
     collection.metadata["ALE"] = {
         "header": header,

tests/sample_data/sample_blanks.ale

@@ -0,0 +1,22 @@
+Heading
+
+FIELD_DELIM	TABS
+
+VIDEO_FORMAT	1080
+
+AUDIO_FORMAT	48khz
+
+FPS	25
+
+
+
+Column
+
+Name	Tracks	Start	End	Take	Tape	UNC	FPS	Reel	Scene	Shoot date	Manufacturer	Source Resolution	Source Bit Depth	DESCRIPT	Comments	Audio SR	Audio Bit Depth	Auxiliary TC1	KN Start	Source File Path	Filter	Camera ID	ISO	Lens Number	Camera Serial #	Camera Type	White Point (Kelvin)	Angle	Camera	Clip Number	Stereoscopic Eye	Gamma Space	LUT 1	ASC_SOP	ASC_SAT	RESOLVE_SIZING	
+
+
+
+Data
+
+A020C003_150905_E2XZ.mov	V	05:42:12:20	05:42:30:12		A020E2XZ	Y:\Pennrand_CompWorkflow_XXXXXX\04_Compositing\11_Render_Compositing\PennComp_Za250\PennComp_Za250_Raw\A020C003_150905_E2XZ.mov	25	A020E2XZ		20150905	DaVinci Resolve	2048x1152	16							Y:\Pennrand_CompWorkflow_XXXXXX\04_Compositing\11_Render_Compositing\PennComp_Za250\PennComp_Za250_Raw\A020C003_150905_E2XZ.mov	0	E2XZ	800	0	3120	Alexa Plus	4700	1800	A	A020C003_150905_E2XZ	SINGLE	LOG-C	None	(1.1822 1.2183 1.2284)(-0.2429 -0.2823 -0.2849)(0.7283 0.7096 0.7054)	1.0680	(0.0000 0.0000 1.0000 0.0000 0.0000 0 0)	
+