8 releases
0.4.2 | Sep 13, 2024 |
---|---|
0.4.1 | Jul 22, 2024 |
0.4.0 | Aug 29, 2023 |
0.3.2 | Feb 23, 2023 |
0.1.1 | Apr 29, 2022 |
#636 in Database interfaces
943 downloads per month
Used in shotover
230KB
5K
SLoC
CQL3 Parser
This is a full implementation of an Apache Cassandra CQL3 query language parser. The goal of this package is to parse CQL3 statements into a structure that can be used in a multi-threaded envrionment. It uses the tree-sitter-cql3 parser to parse the original query and then constructs an editable thread safe representation of the query.
Common usage
use crate::cassandra_ast::CassandraAST;
use crate::cassandra_statement::CassandraStatement;
use crate::select::{Named, SelectElement};
let ast = CassandraAST::new("select foo from myTable" );
// verify that there was no error
assert!( !ast.has_error() );
// get the parsed statement
let stmt : CassandraStatement = ast.statement;
match stmt {
CassandraStatement::Select(select) => {
select.columns.push( SelectElement::Column( Named {
name : "bar".as_string(),
alias : Some( "baz".as_string() ),
}));
select.order_clause = Some( OrderClause { name : "baz".as_string() } );
},
_ => {}
}
let edited_stmt = stmt.to_string();
The above code changes SELECT foo FROM myTable
to Select foo, bar AS baz FROM myTable ORDER BY baz ASC
.
NOTE: It is possible to create invalid statements. If in doubt reparse the new statement to verify that it is syntactically correct.
Package Structure
- The parser is in the
cassandra_ast
module. - The Statements are in the
cassandra_statements
module. - The data for the statements are found in various modules named for the statement (e.g.
create_table
has the Create Table specific structs). - Structures that are common to several packages are found in the
common
module. - Many of the
Drop
statements have the same structure, it is incommon_drop
. - The statements dealing with Roles (e.g.
Create Role
) utilize therole_common
module.
A Note on Errors
When a statement is absolutely unparsable the parser will return a CassandraStatement::Unknown
object. For example CassandraAST::new("This is an invalid statement");
yields
CassandraStatement::Unknown("This is an invalid statement")
. However, if a statement is
partially parsable multiple results are returned. For example CassandraAST::new("SELECT * FROM foo WHERE some invalid part");
yields
CassandraStatement::Select( select )
where the select is the result of parsing "SELECT * FROM foo
followed by
CassandraStatement::Unknown("SELECT * FROM foo WHERE some invalid part")
.
Dependencies
~5.5–7.5MB
~161K SLoC