add essential file drop from last 3 commits

explain_output_difference.py

@@ -0,0 +1,206 @@
+import os, re
+
+# Expected output has been supplied as an environment variable
+# and the program has been stoped because the output was incorrect
+
+def explain_output_difference(loc, output_stream, color):
+	# autotest may try to print all errors in red, so disable this
+	print(color('', 'black'), end='', file=output_stream)
+	explain_output_difference1(loc, output_stream, color)
+	print(file=output_stream)
+
+def explain_output_difference1(loc, output_stream, color):
+
+	# values supplied for expected output for this execution  
+	expected_stdout = os.environb.get(b'DCC_EXPECTED_STDOUT', '')
+#	ignore_case = getenv_boolean('DCC_IGNORE_CASE')
+#	ignore_empty_lines = getenv_boolean('DCC_IGNORE_EMPTY_LINES')
+	ignore_trailing_white_space = getenv_boolean('DCC_IGNORE_TRAILING_WHITE_SPACE', default=True)
+#	compare_only_characters = os.environ.get('DCC_COMPARE_ONLY_CHARACTERS')
+
+	# value describing discrepency between actual and expected output
+	reason = os.environ.get('DCC_OUTPUT_ERROR', '')
+	line_number = getenv_int('DCC_ACTUAL_LINE_NUMBER')
+
+	# these values do not include current line
+	n_expected_bytes_seen = getenv_int('DCC_N_EXPECTED_BYTES_SEEN')
+	n_actual_bytes_seen = getenv_int('DCC_N_ACTUAL_BYTES_SEEN')
+
+	expected_line = os.environb.get(b'DCC_EXPECTED_LINE', '')
+	actual_line = os.environb.get(b'DCC_ACTUAL_LINE', '')
+	expected_column = getenv_int('DCC_EXPECTED_COLUMN')
+	actual_column = getenv_int('DCC_ACTUAL_COLUMN')
+
+	if 0 <= actual_column < len(actual_line):
+		actual_char = actual_line[actual_column]
+	else:
+		actual_char = None
+
+	if ignore_trailing_white_space and expected_stdout[-1:] == b'\n':
+		expected_stdout = expected_stdout.rstrip() + b'\n'
+
+	n_expected_lines = len(expected_stdout.splitlines())
+	is_last_expected_line = n_expected_bytes_seen + len(expected_line) >= len(expected_stdout)	
+
+	if 0 <= expected_column < len(expected_line):
+		expected_byte = expected_line[expected_column:expected_column+1]
+	else:
+		expected_byte = None
+
+#	primary = lambda text, **kwargs: color(text, style='bold', **kwargs)
+	danger = lambda text, **kwargs: color(text, fg='red', style='bold', **kwargs)
+	success = lambda text, **kwargs: color(text, fg='green', style='bold', **kwargs)
+#	info = lambda text, **kwargs: color(text, fg='cyan', style='bold', **kwargs)
+
+	if not actual_line.endswith(b"\n"):	
+		print("Execution failed because ", end='', file=output_stream)
+	else:
+		print("Execution stopped because ", end='', file=output_stream)
+
+	if reason == "expected line too long":
+		print("internal error: expected line too long", file=output_stream)
+		return
+
+	if reason == "line too long":
+		print("program wrote", danger("a line containing over " + str(actual_column) + " bytes."), file=output_stream)
+		print("Do you have an infinite loop?", file=output_stream)
+		print_line(actual_line, "start of the", danger, output_stream)
+		return
+
+	if reason == "too much output":
+		print("program produced", danger("too much output."), file=output_stream)
+		print("Your program printed", actual_column, "bytes.")
+		print("Do you have an infinite loop?", file=output_stream)
+		print_line(actual_line, "last", danger, output_stream)
+		return
+
+	if reason == "zero byte":	
+		print("a", danger("zero byte ('\\0')"), "was printed.", file=output_stream)
+		print("Byte", actual_column, "of line", line_number, "of program's output was a zero byte ('\\0')", file=output_stream)
+		if len(expected_line):
+			print("Here are the characters on the line before the zero byte:", file=output_stream)
+			print(sanitize(actual_line), file=output_stream)
+		print("\nFor more information go to:", explanation_url("zero_byte"), file=output_stream)
+		return
+
+	if n_actual_bytes_seen == 0 and len(actual_line) == 0:
+		print("program produced", danger("no output."), file=output_stream)
+		print(n_expected_lines, "lines of output were expected", file=output_stream)
+		print_line(expected_line, "first expected", success, output_stream)
+		return
+
+	if len(actual_line) == 0:
+		print("of", danger("missing output lines."), file=output_stream)
+		print("Your program printed", line_number, "lines of correct output but stopped before printing all the expected output.", file=output_stream)
+		print_line(expected_line, "next expected", success, output_stream)
+		return
+
+	if n_expected_bytes_seen == 0 and len(expected_line) == 0:
+		print("program produced", danger("output when no output was expected."), file=output_stream)
+		print_line(actual_line, "unexpected", danger, output_stream)
+		return
+
+	if len(expected_line) == 0:
+		print("of", danger("unexpected extra output."), file=output_stream)
+		print("The program produced all the expected output and then produced extra output.", file=output_stream)
+		print_line(actual_line, "extra", danger, output_stream)
+		return
+
+	if is_last_expected_line and expected_byte == b'\n' and actual_char is None:
+		print('the last', danger("newline was missing."), file=output_stream)
+		print("Your program produced all the expected output, except the last newline ('\\n') was missing.", file=output_stream)
+		print("\nFor more information go to", explanation_url("missing_newline"), file=output_stream)
+		return
+
+	show_line_length = max(len(expected_line) + 8, 80)
+
+
+	bad_characters_explanation = check_bad_characters(actual_line, line_number, danger, expected_line)
+	if bad_characters_explanation:
+		print(bad_characters_explanation, end='', file=output_stream)
+		return
+
+	print("of an", danger('incorrect output line.'), file=output_stream)
+	print('Byte', actual_column + 1, 'of line', line_number, "of program output was incorrect.", file=output_stream)
+
+	if not actual_line[actual_column+1:]:
+		if actual_line.rstrip(b'\n') + expected_byte == expected_line.rstrip(b'\n'):
+			print("A", "'" + danger(sanitize(expected_byte)) + "'", "was missing from the end of the output line.", file=output_stream)
+		else:
+			print("The characters you printed were correct, but more characters were expected.", file=output_stream)
+
+	print("The correct output line was:", file=output_stream)
+	print(success(sanitize(expected_line, max_line_length_shown=show_line_length)), file=output_stream)
+
+	print("Your program printed this line:", file=output_stream)
+
+	correct_prefix = success(sanitize(actual_line[0:actual_column]))
+	print(correct_prefix, end='', file=output_stream)
+
+	incorrect_byte = actual_line[actual_column:actual_column + 1]
+	if incorrect_byte == ' ':
+		print(danger(sanitize(incorrect_byte), bg='red'), end='', file=output_stream)
+	else:
+		print(danger(sanitize(incorrect_byte)), end='', file=output_stream)
+
+	print(sanitize(actual_line[actual_column+1:], max_line_length_shown=show_line_length - actual_column), file=output_stream)
+
+def print_line(line, description, line_color, output_stream):
+	if line == b'\n':
+		print("The", description, "line was an empty line (a '\\n').", file=output_stream)
+	else:
+		print("The", description, "line was:", file=output_stream)
+		print(line_color(sanitize(line)), file=output_stream)
+
+
+def sanitize(line, max_line_length_shown=256):
+	if len(line) > max_line_length_shown:
+		line = line[0:max_line_length_shown] + b' ...'
+	return repr(line.rstrip(b'\n'))[2:-1]
+
+
+def check_bad_characters(line, line_number, danger, expected):
+	if re.search(rb'[\x00-\x08\x14-\x1f\x7f-\xff]', expected):
+		return None
+	m = re.search(rb'^(.*?)([\x00-\x08\x14-\x1f\x7f-\xff])', line)
+	if not m:
+		return None
+	(prefix, offending_char) = m.groups()
+	offending_value = ord(offending_char)
+	if offending_value == 0:
+		description = "zero byte ('" + danger('\\0') + "')"
+	elif offending_value > 127:
+		description = "non-ascii byte " + danger("\\x%02x" % (offending_value))
+	else:
+		description = "non-printable character " + danger("\\x%02x" % (offending_value))
+	column = len(prefix)
+	explanation =  "a " + danger("non-ASCII byte") + " was printed.\n"
+	explanation +=  "Byte %d of line %d of program output was a %s\n" % (column + 1, line_number, description)
+
+	explanation += "Here is line %d with non-printable characters replaced with backslash-escaped equivalents:\n" % (line_number)
+	line = repr(line)[2:-1] + '\n'
+	line = re.sub(r'(\\x[0-9a-f][0-9a-f])', danger(r'\1'), line)
+	explanation += line
+	if offending_value == 255:
+		explanation += "\nHave you accidentally printed the special EOF value getchar returns?\n"
+		explanation += 	"For more information go to: " + explanation_url("eof_byte") + "\n"
+	return explanation
+
+def getenv_boolean(name, default=False):
+	if name in os.environ:
+		value = os.environ[name]
+		return value and value[0] not in "0fFnN"
+	else:
+		return default
+
+
+def getenv_int(name):
+	try:
+		return int(os.environ.get(name, 0))
+	except ValueError:
+		return 0
+
+EXPLANATION_BASE_URL = "https://comp1511unsw.github.io/dcc/"
+
+def explanation_url(page):
+	return 	EXPLANATION_BASE_URL + page + ".html"