feat: add support for truncate statement

[pert5432]

What kind of change does this PR introduce?

Progress on #51

What is the current behavior?

TRUNCATE statements don't get parsed

What is the new behavior?

TRUNCATE statements get parsed

pg_query output:

TruncateStmt(
            TruncateStmt {
                relations: [
                    Node {
                        node: Some(
                            RangeVar(
                                RangeVar {
                                    catalogname: "",
                                    schemaname: "",
                                    relname: "users",
                                    inh: true,
                                    relpersistence: "p",
                                    alias: None,
                                    location: 15,
                                },
                            ),
                        ),
                    },
                ],
                restart_seqs: false,
                behavior: DropRestrict,
            },
        )

Additional context

1. I am not sure if the name of the table to be truncated should be a part of the result token stream. For example in test_create_type the name of the type is not a part of the token stream but in test_create_database the name of the database is.

[psteinroe]

Thanks! Can you add a truncate statement to the integration tests too?

[pert5432]

I added a snapshot test but it only works with TRUNCATE table_name and not TRUNCATE TABLE table_name syntax.
It fails with:

---- valid_statements stdout ----
thread 'valid_statements' panicked at crates/parser/src/parse/libpg_query_node.rs:147:17:
could not find node for token Token { kind: Table, text: "TABLE", span: 9..14, token_type: ReservedKeyword } at depth 2

My guess is that its because I don't emit a token for the TABLE keyword in the custom handler for TruncateStmt but I don't know how to determine whether I should emit that token based on the output of libpg_query which looks like this:

pub struct TruncateStmt {
    #[prost(message, repeated, tag="1")]
    pub relations: ::prost::alloc::vec::Vec<Node>,
    #[prost(bool, tag="2")]
    pub restart_seqs: bool,
    #[prost(enumeration="DropBehavior", tag="3")]
    pub behavior: i32,
}

I would greatly appreciate help resolving this.

[psteinroe]

Thanks for looking into this! It seems like Table is an optional token. So just pass it. The parser is designed so that it can handle optional tokens.

[pert5432]

Thanks for the clarification! Fixed it and added more tests.