Parse multiline text using the Parsimonious Python library

Question

I am trying to parse multiline text with the python parsimonious library. I've been playing with it for a while and can't figure out how to deal effectively with newlines. One example is below. The behavior below makes sense. I saw this comment from Erik Rose in the parsimonious issues, but I could not figure out how to implement it without errors. Thanks for any tips here...

singleline_text = '''\
FIRST   something cool'''

multiline_text = '''\
FIRST   something very
        cool
SECOND  more awesomeness        
'''

grammar = Grammar(
    """
    bin           = ORDER spaces description
    ORDER         = 'FIRST' / 'SECOND'
    spaces        = ~'\s*'
    description   = ~'[A-z0-9 ]*'
    """)

Works ok for single line output, print(grammar.parse(singleline_text)) gives:

<Node called "bin" matching "FIRST   something cool">
    <Node called "ORDER" matching "FIRST">
        <Node matching "FIRST">
    <RegexNode called "spaces" matching "   ">
    <RegexNode called "description" matching "something cool">

But multiline gives problems, and I was unable to resolve based on the link above, print(grammar.parse(multiline_text)) gives:

---------------------------------------------------------------------------
IncompleteParseError                      Traceback (most recent call last)
<ipython-input-123-c346891dc883> in <module>()
----> 1 print(grammar.parse(multiline_text))

/Users/me/anaconda3/lib/python3.6/site-packages/parsimonious/grammar.py in parse(self, text, pos)
    121         """
    122         self._check_default_rule()
--> 123         return self.default_rule.parse(text, pos=pos)
    124 
    125     def match(self, text, pos=0):

/Users/me/anaconda3/lib/python3.6/site-packages/parsimonious/expressions.py in parse(self, text, pos)
    110         node = self.match(text, pos=pos)
    111         if node.end < len(text):
--> 112             raise IncompleteParseError(text, node.end, self)
    113         return node
    114 

IncompleteParseError: Rule 'bin' matched in its entirety, but it didn't consume all the text. The non-matching portion of the text begins with '
        cool
SECOND' (line 1, column 23).

Here is one thing I tried that did not work:

grammar2 = Grammar(
    """
    bin           = ORDER spaces description newline
    ORDER         = 'FIRST' / 'SECOND'
    spaces        = ~'\s*'
    description   = ~'[A-z0-9 \n]*'
    newline       = ~r'#[^\r\n]*'
    """)

print(grammar2.parse(multiline_text))

(truncated from the 211-line stack trace):

ERROR:root:An unexpected error occurred while tokenizing input
The following traceback may be corrupted or invalid
The error message is: ('EOF in multi-line string', (1, 4))

---------------------------------------------------------------------------
SyntaxError                               Traceback (most recent call last)

...


VisitationError: SyntaxError: EOL while scanning string literal (<unknown>, line 1)

Parse tree:
<Node called "spaceless_literal" matching "'[A-z0-9 
]*'">  <-- *** We were here. ***
    <RegexNode matching "'[A-z0-9 
    ]*'">

Tomasz Swider · Accepted Answer · 2017-02-08 08:39:09Z

3

It looks like you need to repeat the bin element in your grammar:

grammar = Grammar(
    r"""
    one           = bin +
    bin           = ORDER spaces description newline 
    ORDER         = 'FIRST' / 'SECOND'
    newline       = ~"\n*"
    spaces        = ~"\s*"
    description   = ~"[A-z0-9 ]*"i
    """)

with that you can parse things like:

multiline_text = '''\
FIRST   something very cool
SECOND  more awesomeness      
SECOND  even better
'''

answered Feb 8, 2017 at 8:39

Tomasz Swider

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1 Comment

Mark Over a year ago

This works well to deal with the issue of one entry on each line...Thank you. I am trying to use your tips to address the wrapping issue, where a description may span multiple lines.

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