antlr4-cypher 0.1.2

A Python package for parsing Cypher queries using ANTLR4.

antlr4-cypher

antlr4-cypher is a Python package that provides the Lexer and Parser for the Cypher query language, generated using ANTLR with the command java -jar antlr-4.13.2-complete.jar -Dlanguage=Python3 -listener -visitor -o ./antlr4_cypher CypherLexer.g4 CypherParser.g4. The project includes the necessary grammar, lexer, and parser files, as well as empty listener and visitor classes that serve as a reference for implementing custom logic.

Installation

You can install the package using pip:

pip install antlr4-cypher

Grammar Source

The grammar files (CypherLexer.g4 and CypherParser.g4) are sourced from the ANTLR grammars-v4 repository. These files define the syntax and structure of the Cypher query language.

Usage

To use the lexer and parser in your project, you can import them as follows:

from antlr4 import InputStream, CommonTokenStream
from antlr4_cypher import CypherLexer, CypherParser

# Example input
input_query = "MATCH (n) RETURN n"

# Create a lexer and parser
input_stream = InputStream(input_query)
lexer = CypherLexer(input_stream)
token_stream = CommonTokenStream(lexer)
parser = CypherParser(token_stream)

# Parse the input
tree = parser.script()

# Use the tree for further processing

Custom Listeners and Visitors

The package includes empty listener and visitor classes that you can extend to implement custom logic for traversing the parse tree. For example:

from antlr4_cypher import CypherParserListener

class MyCypherListener(CypherParserListener):
    def enterMatchSt(self, ctx):
        print("Entering MATCH clause")

    def exitMatchSt(self, ctx):
        print("Exiting MATCH clause")


from antlr4_cypher import CypherParserVisitor

class CustomCypherParserVisitor(CypherParserVisitor):
    def __init__(self, mapping: dict):
        super().__init__()
        self.mapping = mapping

    def visit(self, tree):
        print("Visiting node:", tree.getText())
        return tree.accept(self)

    # Example of overriding a specific visit method
    def visitMatchSt(self, ctx):
        print("Processing MATCH clause with mapping:", self.mapping)
        return self.visitChildren(ctx)

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This README provides a basic overview of the antlr4-cypher project. For more detailed information, please refer to the source code and the ANTLR documentation.