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import sys
import traceback
def add_error_marker(text, position, start_line=1):
"""Add a caret marking a given position in a string of input.
Returns (new_text, caret_line).
"""
indent = " "
lines = []
caret_line = start_line
for line in text.split("\n"):
lines.append(indent + line)
if 0 <= position <= len(line):
lines.append(indent + (" " * position) + "^")
caret_line = start_line
position -= len(line)
position -= 1 # for the newline
start_line += 1
return "\n".join(lines), caret_line
class SassError(Exception):
"""Error class that wraps another exception and attempts to bolt on some
useful context.
"""
def __init__(self, exc, rule=None, expression=None, expression_pos=None):
self.exc = exc
self.rule_stack = []
if rule:
self.rule_stack.append(rule)
self.expression = expression
self.expression_pos = expression_pos
_, _, self.original_traceback = sys.exc_info()
def add_rule(self, rule):
"""Add a new rule to the "stack" of rules -- this is used to track,
e.g., how a file was ultimately imported.
"""
self.rule_stack.append(rule)
def format_prefix(self):
# TODO this contains NULs and line numbers; could be much prettier
if self.rule_stack:
return "Error parsing block:\n" + " " + self.rule_stack[0].unparsed_contents
else:
return "Unknown error"
def __str__(self):
prefix = self.format_prefix()
ret = [prefix, "\n\n"]
if self.rule_stack:
# TODO this looks very neat-o but doesn't actually work because
# manage_children doesn't recurse for imports :)
ret.extend(("From ", self.rule_stack[0].file_and_line, "\n"))
last_file = self.rule_stack[0].source_file
for rule in self.rule_stack[1:]:
if rule.source_file is not last_file:
ret.extend(("...imported from ", rule.file_and_line, "\n"))
last_file = rule.source_file
ret.append("\n")
ret.append("Traceback:\n")
ret.extend(traceback.format_tb(self.original_traceback))
ret.extend((type(self.exc).__name__, ": ", str(self.exc), "\n"))
return ''.join(ret)
class SassParseError(SassError):
"""Error raised when parsing a Sass expression fails."""
def format_prefix(self):
decorated_expr, line = add_error_marker(self.expression, self.expression_pos or -1)
return """Error parsing expression:\n""" + decorated_expr
class SassEvaluationError(SassError):
"""Error raised when evaluating a parsed expression fails."""
def format_prefix(self):
# TODO would be nice for the AST to have position information
# TODO might be nice to print the AST and indicate where the failure
# was?
decorated_expr, line = add_error_marker(self.expression, self.expression_pos or -1)
return """Error evaluating expression:\n""" + decorated_expr
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