c841527f61
Write a function that reads a string of compressed XML and outputs the decompressed version. Note to self: Now that I'm growing more comfortable writing parsers, I'd like to become equally comfortable writing pretty-printers.
98 lines
2.5 KiB
Python
98 lines
2.5 KiB
Python
import string
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from parser import Parser
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mapping = {
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1: "family",
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2: "person",
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3: "firstName",
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4: "lastName",
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5: "state",
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}
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def parse_int(i, xs):
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result = ""
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while i < len(xs) and xs[i] in string.digits:
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result += xs[i]
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i += 1
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return i, int(result)
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def parse_string(i, xs):
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result = ""
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while xs[i+1] not in string.digits:
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result += xs[i]
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i += 1
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return i, result
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def tokenize(xs):
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result = []
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i = 0
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while i < len(xs):
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if xs[i] in string.digits:
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i, n = parse_int(i, xs)
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result.append(n)
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elif xs[i] in string.ascii_letters:
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i, x = parse_string(i, xs)
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result.append(x)
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elif xs[i] == " ":
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i += 1
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continue
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return result
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def parse(xs):
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parser = Parser(tokenize(xs))
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return parse_element(parser)
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# Element -> Tag Attribute* End Element* End ;
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# Tag -> INTEGER ;
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# Value -> STRING End ;
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# Attribute -> Tag Value ;
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# End -> 0 ;
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def parse_element(parser):
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if type(parser.curr()) == str:
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return parser.consume()
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tag_id = parser.expect_predicate(lambda x: type(x) == int)
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tag = mapping[tag_id]
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attrs = parse_attrs(parser)
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parser.expect([0])
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children = []
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while not parser.exhausted() and parser.curr() != 0:
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children.append(parse_element(parser))
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parser.expect([0])
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return [tag, attrs, children]
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def parse_attrs(parser):
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result = []
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while parser.curr() != 0:
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tag_id = parser.expect_predicate(lambda x: type(x) == int)
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tag = mapping[tag_id]
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value = parser.consume()
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result.append((tag, value))
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return result
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def stringify_xml(tree, indent=0):
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if type(tree) == str:
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return tree
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result = ""
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tag, attrs, children = tree
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str_attrs = []
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for k, v in attrs:
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str_attrs.append("{}=\"{}\"".format(k, v))
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str_attrs = (" " if str_attrs else "") + " ".join(str_attrs)
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str_children = []
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for child in children:
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str_children.append(" " * 2 * indent + stringify_xml(child, indent + 1))
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str_children = "\n".join(str_children)
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result += "{}<{}{}>\n{}{}\n{}</{}>".format(
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" " * 2 * indent, tag, str_attrs, " " * 2 * indent, str_children,
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" " * 2 * indent, tag)
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return result
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x = "1 4 McDowell 5 CA 0 2 3 Gayle 0 Some Message 0 0"
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print("Input: {}".format(x))
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print("Tokens: {}".format(tokenize(x)))
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print("Parsed: {}".format(parse(x)))
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print("{}".format(stringify_xml(parse(x))))
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