Trickybrain Creating the LineReader file (#14)

Author: nedtwigg

python/selfie-lib/selfie_lib/LineReader.py

@@ -0,0 +1,35 @@
+import io
+
+
+class LineReader:
+    def __init__(self, content: bytes):
+        self.__buffer = io.BytesIO(content)
+        self.__uses_unix_newlines = self.__detect_newline_type()
+        self.__line_count = 0  # Initialize line count
+
+    @classmethod
+    def for_binary(cls, content: bytes):
+        return cls(content)
+
+    @classmethod
+    def for_string(cls, content: str):
+        return cls(content.encode("utf-8"))
+
+    def __detect_newline_type(self) -> bool:
+        first_line = self.__buffer.readline()
+        self.__buffer.seek(0)  # Reset buffer for actual reading
+        return b"\r\n" not in first_line
+
+    def unix_newlines(self) -> bool:
+        return self.__uses_unix_newlines
+
+    def read_line(self) -> str:
+        line_bytes = self.__buffer.readline()
+        if line_bytes:
+            self.__line_count += 1  # Increment line count for each line read
+        line = line_bytes.decode("utf-8")
+        return line.rstrip("\r\n" if not self.__uses_unix_newlines else "\n")
+
+    # Method to get the current line number
+    def get_line_number(self) -> int:
+        return self.__line_count

python/selfie-lib/selfie_lib/__init__.py

@@ -1 +1,3 @@
+from .LineReader import LineReader as LineReader
 from .Slice import Slice as Slice
+

python/selfie-lib/tests/LineReader_test.py

@@ -0,0 +1,42 @@
+from selfie_lib import LineReader
+
+def test_should_find_unix_separator_from_binary():
+    reader = LineReader.for_binary(b"This is a new line\n")
+    assert reader.unix_newlines() is True
+    assert reader.read_line() == "This is a new line"
+
+def test_should_find_windows_separator_from_binary():
+    reader = LineReader.for_binary(b"This is a new line\r\n")
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "This is a new line"
+
+def test_should_find_unix_separator_from_string():
+    reader = LineReader.for_string("This is a new line\n")
+    assert reader.unix_newlines() is True
+    assert reader.read_line() == "This is a new line"
+
+def test_should_find_windows_separator_from_string():
+    reader = LineReader.for_string("This is a new line\r\n")
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "This is a new line"
+
+def test_should_get_unix_line_separator_when_there_is_none():
+    reader = LineReader.for_binary(b"This is a new line")
+    assert reader.unix_newlines() is True
+    assert reader.read_line() == "This is a new line"
+
+def test_should_read_next_line_without_problem():
+    reader = LineReader.for_binary(b"First\r\nSecond\r\n")
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "First"
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "Second"
+    assert reader.unix_newlines() is False
+
+def test_should_use_first_line_separator_and_ignore_next():
+    reader = LineReader.for_binary(b"First\r\nAnother separator\n")
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "First"
+    assert reader.unix_newlines() is False
+    assert reader.read_line() == "Another separator"
+    assert reader.unix_newlines() is False