use crate::parser::ast::*;
use crate::parser::error::{Expected, ParseResult};
use crate::parser::state::Parser;
use crate::parser::token::Keyword;
pub fn parse_alter(parser: &mut Parser) -> ParseResult<Statement> {
if parser.at_keyword(Keyword::Table) {
let _ = parser.next();
let table = super::parse_multipart_name(parser)?;
if parser.at_keyword(Keyword::Add) {
let _ = parser.next();
if parser.at_keyword(Keyword::Constraint) {
let _ = parser.next();
let constraint = super::ddl::parse_alter_table_add_constraint(parser)?;
Ok(Statement::Ddl(DdlStatement::AlterTable {
table,
action: AlterTableAction::AddConstraint(constraint),
}))
} else {
let col = super::ddl::parse_column_def(parser)?;
Ok(Statement::Ddl(DdlStatement::AlterTable {
table,
action: AlterTableAction::AddColumn(col),
}))
}
} else if parser.at_keyword(Keyword::Drop) {
let _ = parser.next();
if parser.at_keyword(Keyword::Column) {
let _ = parser.next();
let col_name = match parser.next() {
Some(Token::Identifier(id)) => id.clone(),
Some(Token::Keyword(k)) => k.as_ref().to_string(),
_ => return parser.backtrack(Expected::Description("column name")),
};
Ok(Statement::Ddl(DdlStatement::AlterTable {
table,
action: AlterTableAction::DropColumn(col_name),
}))
} else if parser.at_keyword(Keyword::Constraint) {
let _ = parser.next();
let constraint_name = match parser.next() {
Some(Token::Identifier(id)) => id.clone(),
Some(Token::Keyword(k)) => k.as_ref().to_string(),
_ => return parser.backtrack(Expected::Description("constraint name")),
};
Ok(Statement::Ddl(DdlStatement::AlterTable {
table,
action: AlterTableAction::DropConstraint(constraint_name),
}))
} else {
parser.backtrack(Expected::Description("column or constraint"))
}
} else {
parser.backtrack(Expected::Description("add or drop"))
}
} else {
parser.backtrack(Expected::Description("table"))
}
}