Questions about the Lark parser project
Use this tag when asking questions about the Lark parser project (https://github.com/lark-parser/lark)
Questions tagged [lark-parser]
97 questions
1
vote
1 answer
LARK: All occurrences but the last one?
Let say I have the following :
items : (item separator)+
this would work for :
i1, i2, i3,
but not for :
i1, i2, i3
how to make it so it does not require end-separator ?
sten
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1
vote
3 answers
LARK: Parsing : Implementing import file?
How would you implement a grammar that can import a file and still parsing it using LARK ?
f.e.:
@import file.txt
.....
sten
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1
vote
1 answer
Node depth encoded as number of stars
Documents in this language look like
* A top-level Headline
Some text about that headline.
** Sub-Topic 1
Text about the sub-topic 1.
*** Sub-sub-topic
More text here about the sub-sub-topic
** Sub-Topic 2
Extra text here about…
Hatshepsut
- 5,962
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1
vote
1 answer
Lark parser grammar works with Earley but not LALR
Consider this simple test of the Python Lark parser:
GRAMMAR = '''
start: container*
container: string ":" "{" (container | attribute | attribute_value)* "}"
attribute: attribute_name "=" (attribute_value | container)
attribute_value: string ":"…
C. E.
- 10,297
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1
vote
2 answers
How to exclude certain possibilities from a regular expression?
For a parser I am creating, I use this regular expression as the definition of an ID:
ID: /[a-z_][a-z0-9]*/i
(For anyone who is not familiar with the syntax of the particular parser I'm using, the "i" flag simply means case-insensitive.)
I also…
Elektito
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1
vote
2 answers
Collision in between "END" and "END IF" in BASIC grammar, using Lark
I'm trying to create an LALR parser for BASIC using Lark, and I'm having a hard time fixing a collision between the "END" statement and statements like "END IF". Here's a simplified version of the grammar:
%ignore /[ \t\f]+/
program: _nlopt…
Elektito
- 3,863
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1
vote
0 answers
difference between earley and lalr parser in lark?
I have a simple grammar, which parse key-value pairs section by section.
k1:1
k2:x
k3:3
k4:4
The grammar I have for it is:
start: section (_sep section)*
_sep: _NEWLINE _NEWLINE+
section: item (_NEWLINE item)*
item: NAME ":" VALUE
_NEWLINE:…
echo
- 2,666
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1
vote
1 answer
How to parse invalid JSON using Lark?
Let's start by considering a simple json parser using lark:
import sys
from lark import Lark, Transformer, v_args
json_grammar = r"""
?start: value
?value: object
| array
| string
| SIGNED_NUMBER ->…
BPL
- 9,632
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1
vote
2 answers
RecursionError: maximum recursion depth exceeded while using lark in python
I've written the decaf grammar specified in cs143 course.
Here is my code.
import sys
from lark import Lark, Transformer, v_args
decaf_grammar = r"""
start : PROGRAM
PROGRAM : DECL+
DECL : VARIABLEDECL | FUNCTIONDECL | CLASSDECL |…
Umair Javaid
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- 2
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1
vote
1 answer
How to get a control flow graph of a program?
I want to get a control flow graph of a code/program (be it any programming language and given its grammar).
I have tried using lark library in python to parse a basic C sample program [I provided the grammar for basic c syntax to lark]. As a…
Ben Claude
- 11
- 2
1
vote
0 answers
Understanding what constitutes an ambiguity in a lark grammar
I was trying to simplifying the case presented in another question and got to the following parsing attempt using lark:
from lark.lark import Lark
text = """
start_thing {
loc int {
from 0,
to 1093,
strand plus,
id gi 384632836
…
bli
- 7,549
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1
vote
1 answer
Correctly set priorities between rules and terminals in a grammar for lark
This is my first time writing a parser using a grammar and a parser generator. I want to parse some kind of asn.1 format using the lark python module.
Here is an example of the data I'm trying to parse:
text = """
start_thing {
literal {
…
bli
- 7,549
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1
vote
1 answer
LARK parsing error for hex number
I try to parse hex number with:
hex_number : "0x" HEXDIGIT+ and with 0xA as input, and it always throws me an error, A is unexpected token.
Djordje Zivanovic
- 185
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1
vote
0 answers
Python: create grammar and realize operators
I try to describe grammar and operators.
I use next code
from lark import Lark
json_parser = Lark(r""" ?start: value
?value: dict
| array
| operator
|…
Petr Petrov
- 4,090
- 10
- 31
- 68
1
vote
0 answers
Python: creating DSL
I need to solve some specialized task, connecting with creating a DSL to specific purposes.
But I have no experience with it and after some research I choose python Lark.
I need to realize some like
age1 = 20, age2 = 35; If age1 more than age2,…
Petr Petrov
- 4,090
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