def analyze_scalar()

in lib/python3/yaml/emitter.py [0:0]

• 111 lines of code
• 30 McCabe index (conditional complexity)

    def analyze_scalar(self, scalar):

        # Empty scalar is a special case.
        if not scalar:
            return ScalarAnalysis(scalar=scalar, empty=True, multiline=False,
                    allow_flow_plain=False, allow_block_plain=True,
                    allow_single_quoted=True, allow_double_quoted=True,
                    allow_block=False)

        # Indicators and special characters.
        block_indicators = False
        flow_indicators = False
        line_breaks = False
        special_characters = False

        # Important whitespace combinations.
        leading_space = False
        leading_break = False
        trailing_space = False
        trailing_break = False
        break_space = False
        space_break = False

        # Check document indicators.
        if scalar.startswith('---') or scalar.startswith('...'):
            block_indicators = True
            flow_indicators = True

        # First character or preceded by a whitespace.
        preceeded_by_whitespace = True

        # Last character or followed by a whitespace.
        followed_by_whitespace = (len(scalar) == 1 or
                scalar[1] in '\0 \t\r\n\x85\u2028\u2029')

        # The previous character is a space.
        previous_space = False

        # The previous character is a break.
        previous_break = False

        index = 0
        while index < len(scalar):
            ch = scalar[index]

            # Check for indicators.
            if index == 0:
                # Leading indicators are special characters.
                if ch in '#,[]{}&*!|>\'\"%@`': 
                    flow_indicators = True
                    block_indicators = True
                if ch in '?:':
                    flow_indicators = True
                    if followed_by_whitespace:
                        block_indicators = True
                if ch == '-' and followed_by_whitespace:
                    flow_indicators = True
                    block_indicators = True
            else:
                # Some indicators cannot appear within a scalar as well.
                if ch in ',?[]{}':
                    flow_indicators = True
                if ch == ':':
                    flow_indicators = True
                    if followed_by_whitespace:
                        block_indicators = True
                if ch == '#' and preceeded_by_whitespace:
                    flow_indicators = True
                    block_indicators = True

            # Check for line breaks, special, and unicode characters.
            if ch in '\n\x85\u2028\u2029':
                line_breaks = True
            if not (ch == '\n' or '\x20' <= ch <= '\x7E'):
                if (ch == '\x85' or '\xA0' <= ch <= '\uD7FF'
                        or '\uE000' <= ch <= '\uFFFD') and ch != '\uFEFF':
                    unicode_characters = True
                    if not self.allow_unicode:
                        special_characters = True
                else:
                    special_characters = True

            # Detect important whitespace combinations.
            if ch == ' ':
                if index == 0:
                    leading_space = True
                if index == len(scalar)-1:
                    trailing_space = True
                if previous_break:
                    break_space = True
                previous_space = True
                previous_break = False
            elif ch in '\n\x85\u2028\u2029':
                if index == 0:
                    leading_break = True
                if index == len(scalar)-1:
                    trailing_break = True
                if previous_space:
                    space_break = True
                previous_space = False
                previous_break = True
            else:
                previous_space = False
                previous_break = False

            # Prepare for the next character.
            index += 1
            preceeded_by_whitespace = (ch in '\0 \t\r\n\x85\u2028\u2029')
            followed_by_whitespace = (index+1 >= len(scalar) or
                    scalar[index+1] in '\0 \t\r\n\x85\u2028\u2029')

        # Let's decide what styles are allowed.
        allow_flow_plain = True
        allow_block_plain = True
        allow_single_quoted = True
        allow_double_quoted = True
        allow_block = True

        # Leading and trailing whitespaces are bad for plain scalars.
        if (leading_space or leading_break
                or trailing_space or trailing_break):
            allow_flow_plain = allow_block_plain = False

        # We do not permit trailing spaces for block scalars.
        if trailing_space:
            allow_block = False

        # Spaces at the beginning of a new line are only acceptable for block
        # scalars.
        if break_space:
            allow_flow_plain = allow_block_plain = allow_single_quoted = False

        # Spaces followed by breaks, as well as special character are only
        # allowed for double quoted scalars.
        if space_break or special_characters:
            allow_flow_plain = allow_block_plain =  \
            allow_single_quoted = allow_block = False

        # Although the plain scalar writer supports breaks, we never emit
        # multiline plain scalars.
        if line_breaks:
            allow_flow_plain = allow_block_plain = False

        # Flow indicators are forbidden for flow plain scalars.
        if flow_indicators:
            allow_flow_plain = False

        # Block indicators are forbidden for block plain scalars.
        if block_indicators:
            allow_block_plain = False

        return ScalarAnalysis(scalar=scalar,
                empty=False, multiline=line_breaks,
                allow_flow_plain=allow_flow_plain,
                allow_block_plain=allow_block_plain,
                allow_single_quoted=allow_single_quoted,
                allow_double_quoted=allow_double_quoted,
                allow_block=allow_block)