use anyhow::{Result, anyhow, bail, ensure};
use ordered_float::OrderedFloat;
use sqlparser::ast::{
BinaryOperator, Expr, FunctionArg, FunctionArgExpr, FunctionArguments, Ident, OrderByExpr,
Query, Select, SelectItem, SetExpr, Statement, TableFactor, Value as SqlValue,
};
use sqlparser::dialect::SQLiteDialect;
use sqlparser::parser::Parser;
use crate::types::{DataType, Schema, Value};
#[derive(Debug)]
pub enum Command {
CreateTable(Schema),
Insert(InsertPlan),
Select(SelectPlan),
}
#[derive(Debug)]
pub struct InsertPlan {
pub table_name: String,
pub rows: Vec<Vec<Value>>,
}
#[derive(Debug, Clone, Copy)]
pub enum CompareOp {
Eq,
NotEq,
Lt,
Lte,
Gt,
Gte,
IsNull,
IsNotNull,
}
#[derive(Debug, Clone)]
pub struct Filter {
pub column: String,
pub op: CompareOp,
pub value: Option<Value>,
}
#[derive(Debug, Clone, Copy)]
pub enum AggregateKind {
Count,
Sum,
Min,
Max,
Avg,
}
#[derive(Debug, Clone)]
pub enum ProjectionExpr {
Column(String),
Aggregate {
kind: AggregateKind,
column: Option<String>,
},
}
#[derive(Debug, Clone)]
pub struct Projection {
pub expr: ProjectionExpr,
pub alias: String,
}
#[derive(Debug, Clone)]
pub struct OrderByPlan {
pub field: String,
pub descending: bool,
}
#[derive(Debug, Clone)]
pub struct SelectPlan {
pub table_name: String,
pub filters: Vec<Filter>,
pub projections: Vec<Projection>,
pub group_by: Vec<String>,
pub order_by: Option<OrderByPlan>,
pub limit: Option<usize>,
}
pub fn parse_sql(sql: &str) -> Result<Vec<Command>> {
let dialect = SQLiteDialect {};
let statements = Parser::parse_sql(&dialect, sql)?;
statements.into_iter().map(parse_statement).collect()
}
fn parse_statement(statement: Statement) -> Result<Command> {
match statement {
Statement::CreateTable(create) => parse_create_table(create),
Statement::Insert(insert) => parse_insert(insert),
Statement::Query(query) => parse_query(*query),
other => bail!("unsupported statement: {other}"),
}
}
fn parse_create_table(statement: sqlparser::ast::CreateTable) -> Result<Command> {
let table_name = object_name_to_string(&statement.name.0)?;
let mut columns = Vec::with_capacity(statement.columns.len());
for column in statement.columns {
columns.push(crate::types::ColumnDef {
name: column.name.value,
data_type: DataType::from_sql_name(&column.data_type.to_string())?,
});
}
Ok(Command::CreateTable(Schema {
table_name,
columns,
}))
}
fn parse_insert(statement: sqlparser::ast::Insert) -> Result<Command> {
ensure!(
statement.columns.is_empty(),
"explicit insert column lists are not supported yet"
);
let table_name = object_name_to_string(&statement.table_name.0)?;
let Some(source) = statement.source else {
bail!("INSERT source is required")
};
let rows = match *source.body {
SetExpr::Values(values) => values
.rows
.into_iter()
.map(|row| row.into_iter().map(parse_sql_value_expr).collect())
.collect::<Result<Vec<Vec<Value>>>>()?,
other => bail!("unsupported INSERT source: {other}"),
};
Ok(Command::Insert(InsertPlan { table_name, rows }))
}
fn parse_query(query: Query) -> Result<Command> {
let select = match *query.body {
SetExpr::Select(select) => select,
other => bail!("unsupported query body: {other}"),
};
let plan = parse_select(*select, query.order_by, query.limit)?;
Ok(Command::Select(plan))
}
fn parse_select(
select: Select,
order_by: Option<sqlparser::ast::OrderBy>,
limit: Option<Expr>,
) -> Result<SelectPlan> {
ensure!(select.from.len() == 1, "exactly one table is supported");
let table_name = match &select.from[0].relation {
TableFactor::Table { name, .. } => object_name_to_string(&name.0)?,
other => bail!("unsupported table source: {other}"),
};
let filters = match select.selection {
Some(expr) => parse_filters(expr)?,
None => Vec::new(),
};
let group_by = match select.group_by {
sqlparser::ast::GroupByExpr::Expressions(exprs, _) => exprs
.into_iter()
.map(parse_identifier_expr)
.collect::<Result<Vec<String>>>()?,
sqlparser::ast::GroupByExpr::All(_) => bail!("GROUP BY ALL is not supported"),
};
let projections = parse_projections(select.projection, &group_by)?;
let order_by = parse_order_by(order_by)?;
let limit = match limit {
Some(expr) => Some(parse_usize_literal(expr)?),
None => None,
};
Ok(SelectPlan {
table_name,
filters,
projections,
group_by,
order_by,
limit,
})
}
fn parse_filters(expr: Expr) -> Result<Vec<Filter>> {
match expr {
Expr::BinaryOp { left, op: BinaryOperator::And, right } => {
let mut filters = parse_filters(*left)?;
filters.extend(parse_filters(*right)?);
Ok(filters)
}
Expr::BinaryOp { left, op, right } => {
let column = parse_identifier_expr(*left)?;
let value = parse_sql_value_expr(*right)?;
let op = match op {
BinaryOperator::Eq => CompareOp::Eq,
BinaryOperator::NotEq => CompareOp::NotEq,
BinaryOperator::Lt => CompareOp::Lt,
BinaryOperator::LtEq => CompareOp::Lte,
BinaryOperator::Gt => CompareOp::Gt,
BinaryOperator::GtEq => CompareOp::Gte,
other => bail!("unsupported filter operator: {other}"),
};
Ok(vec![Filter { column, op, value: Some(value) }])
}
Expr::IsNull(expr) => {
let column = parse_identifier_expr(*expr)?;
Ok(vec![Filter { column, op: CompareOp::IsNull, value: None }])
}
Expr::IsNotNull(expr) => {
let column = parse_identifier_expr(*expr)?;
Ok(vec![Filter { column, op: CompareOp::IsNotNull, value: None }])
}
other => bail!("unsupported WHERE expression: {other}"),
}
}
fn parse_projections(items: Vec<SelectItem>, group_by: &[String]) -> Result<Vec<Projection>> {
let mut projections = Vec::new();
for item in items {
match item {
SelectItem::Wildcard(_) => projections.push(Projection {
expr: ProjectionExpr::Column("*".to_string()),
alias: "*".to_string(),
}),
SelectItem::UnnamedExpr(expr) => {
projections.push(parse_projection_expr(expr, group_by, None)?)
}
SelectItem::ExprWithAlias { expr, alias } => {
projections.push(parse_projection_expr(expr, group_by, Some(alias.value))?)
}
other => bail!("unsupported SELECT projection: {other}"),
}
}
Ok(projections)
}
fn parse_projection_expr(
expr: Expr,
group_by: &[String],
alias_override: Option<String>,
) -> Result<Projection> {
match expr {
Expr::Identifier(ident) => {
let alias = alias_override.unwrap_or_else(|| ident.value.clone());
if !group_by.is_empty() && !group_by.iter().any(|column| column == &ident.value) {
bail!(
"non-aggregated projection {} must appear in GROUP BY",
ident.value
);
}
Ok(Projection {
expr: ProjectionExpr::Column(ident.value),
alias,
})
}
Expr::CompoundIdentifier(parts) => {
let name = compound_identifier_to_string(&parts)?;
let alias = alias_override.unwrap_or_else(|| name.clone());
if !group_by.is_empty() && !group_by.iter().any(|column| column == &name) {
bail!("non-aggregated projection {name} must appear in GROUP BY");
}
Ok(Projection {
expr: ProjectionExpr::Column(name),
alias,
})
}
Expr::Function(function) => {
let name = function.name.to_string().to_ascii_uppercase();
let kind = match name.as_str() {
"COUNT" => AggregateKind::Count,
"SUM" => AggregateKind::Sum,
"MIN" => AggregateKind::Min,
"MAX" => AggregateKind::Max,
"AVG" => AggregateKind::Avg,
_ => bail!("unsupported aggregate: {name}"),
};
let column = parse_function_column(function.args)?;
let alias = alias_override.unwrap_or_else(|| {
if let Some(column) = &column {
format!("{}_{}", name.to_ascii_lowercase(), column)
} else {
name.to_ascii_lowercase()
}
});
Ok(Projection {
expr: ProjectionExpr::Aggregate { kind, column },
alias,
})
}
other => bail!("unsupported projection expression: {other}"),
}
}
fn parse_function_column(arguments: FunctionArguments) -> Result<Option<String>> {
match arguments {
FunctionArguments::None => Ok(None),
FunctionArguments::Subquery(_) => bail!("subquery function arguments are not supported"),
FunctionArguments::List(list) => {
if list.args.len() == 1 {
match &list.args[0] {
FunctionArg::Unnamed(FunctionArgExpr::Wildcard) => Ok(None),
FunctionArg::Unnamed(FunctionArgExpr::Expr(expr)) => {
Ok(Some(parse_identifier_expr(expr.clone())?))
}
other => bail!("unsupported function argument: {other}"),
}
} else {
bail!("only single-argument aggregates are supported")
}
}
}
}
fn parse_order_by(order_by: Option<sqlparser::ast::OrderBy>) -> Result<Option<OrderByPlan>> {
let Some(order_by) = order_by else {
return Ok(None);
};
ensure!(
order_by.exprs.len() == 1,
"only one ORDER BY expression is supported"
);
let OrderByExpr { expr, asc, .. } = order_by.exprs.into_iter().next().unwrap();
Ok(Some(OrderByPlan {
field: parse_identifier_expr(expr)?,
descending: matches!(asc, Some(false)),
}))
}
fn parse_identifier_expr(expr: Expr) -> Result<String> {
match expr {
Expr::Identifier(ident) => Ok(ident.value),
Expr::CompoundIdentifier(parts) => compound_identifier_to_string(&parts),
other => bail!("expected column identifier, got {other}"),
}
}
fn compound_identifier_to_string(parts: &[Ident]) -> Result<String> {
let Some(last) = parts.last() else {
bail!("empty identifier")
};
Ok(last.value.clone())
}
fn parse_usize_literal(expr: Expr) -> Result<usize> {
match parse_sql_value_expr(expr)? {
Value::Int64(value) => Ok(value as usize),
other => bail!("expected integer literal, got {other:?}"),
}
}
fn parse_sql_value_expr(expr: Expr) -> Result<Value> {
match expr {
Expr::Value(value) => parse_sql_value(value),
Expr::UnaryOp { op, expr } if op.to_string() == "-" => match parse_sql_value_expr(*expr)? {
Value::Int64(value) => Ok(Value::Int64(-value)),
Value::Float64(value) => Ok(Value::Float64(OrderedFloat(-value.into_inner()))),
other => bail!("unsupported unary negation for {other:?}"),
},
Expr::IsNull(_) => {
bail!("IS NULL expressions must appear in WHERE clauses")
}
other => bail!("expected literal value, got {other}"),
}
}
fn parse_sql_value(value: sqlparser::ast::Value) -> Result<Value> {
match value {
SqlValue::Number(number, _) => {
if number.contains('.') {
Ok(Value::Float64(OrderedFloat(number.parse::<f64>()?)))
} else {
Ok(Value::Int64(number.parse::<i64>()?))
}
}
SqlValue::SingleQuotedString(value) | SqlValue::DoubleQuotedString(value) => {
Ok(Value::String(value))
}
SqlValue::Boolean(value) => Ok(Value::Bool(value)),
SqlValue::Null => Ok(Value::Null),
other => Err(anyhow!("unsupported literal value: {other}")),
}
}
fn object_name_to_string(parts: &[Ident]) -> Result<String> {
let Some(last) = parts.last() else {
bail!("empty object name")
};
Ok(last.value.clone())
}