simplemarkup.py

"""simplemarkup, version 2.1, https://github.com/chingc/simplemarkup

Copyright (c) 2012, Ching Chow
All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright notice,
      this list of conditions and the following disclaimer.

    * Redistributions in binary form must reproduce the above copyright notice,
      this list of conditions and the following disclaimer in the documentation
      and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

"""

class SimpleMarkup():
    """A simple pretty print markup generator."""
    def __init__(self, width=4):
        self._output = []
        self._open_tags = []
        self._width = " " * width
        self._depth = 0

    def _check(self, value):
        """Raises ValueError if given is not a string."""
        if not isinstance(value, str):
            raise ValueError("must be of type string")
        return value

    def _check_attr(self, attr):
        """Raises ValueError if given is not a list of 2-tuple strings."""
        if not isinstance(attr, list):
            raise ValueError("must be of type list")
        for element in attr:
            if not isinstance(element, tuple) or len(element) != 2:
                raise ValueError("list elements must be a tuple of length 2")
        for name, value in attr:
            if not isinstance(name, str) or not isinstance(value, str):
                raise ValueError("tuple values must be of type string")
        return attr

    def _untrim(self, string, newline):
        """Inserts indentation and newline to a string."""
        lead = "" if not self._output or self._output[-1][-1] != "\n" else self._depth * self._width
        trail = "" if not newline else "\n"
        return lead + string + trail

    def _attr_str(self, attr):
        """Turns a list of attribute tuples into a string."""
        attribute = []
        for name, value in attr:
            attribute.append('{}="{}"'.format(name, value))
        return " " + " ".join(attribute) if len(attribute) > 0 else ""

    def _raw(self, string, newline):
        """Add a string exactly as given."""
        self._output.append(self._untrim(string, newline))
        return self

    def _empty(self, tag, attr, newline):
        """Add an empty element."""
        self._output.append(self._untrim("<{}{} />".format(tag, self._attr_str(attr)), newline))
        return self

    def _begin(self, tag, attr, value, newline):
        """Begin and add a new element."""
        self._open_tags.append(tag)
        self._output.append(self._untrim("<{}{}>".format(tag, self._attr_str(attr)), newline))
        self._depth += 1
        if len(value) > 0:
            self._output.append(self._untrim(value, newline))
        return self

    def _end(self, newline):
        """End an element."""
        self._depth -= 1
        self._output.append(self._untrim("</{}>".format(self._open_tags.pop()), newline))
        return self

    # # # # #

    def output(self):
        """Returns the output in pretty print."""
        return "".join(self._output)

    def raw(self, string):
        """Add a string exactly as given."""
        return self._raw(self._check(string), False)

    def rawln(self, string):
        """Add a string exactly as given and start a newline."""
        return self._raw(self._check(string), True)

    def empty(self, tag, attr=[]):
        """Add an empty element."""
        return self._empty(self._check(tag), self._check_attr(attr), False)

    def emptyln(self, tag, attr=[]):
        """Add an empty element and start a newline."""
        return self._empty(self._check(tag), self._check_attr(attr), True)

    def begin(self, tag, attr=[], value=""):
        """Add the opening tag of an element."""
        return self._begin(self._check(tag), self._check_attr(attr), self._check(value), False)

    def beginln(self, tag, attr=[], value=""):
        """Add the opening tag of an element and start a newline."""
        return self._begin(self._check(tag), self._check_attr(attr), self._check(value), True)

    def end(self):
        """Add the closing tag of an element."""
        if self._depth == 0:
            raise IndexError("already ended")
        return self._end(False)

    def endln(self):
        """Add the closing tag of an element and start a newline."""
        if self._depth == 0:
            raise IndexError("already ended")
        return self._end(True)