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use polars::error::PolarsError;
use polars::prelude::{col, lit, DataType, Expr, LiteralValue, PolarsResult as Result, TimeUnit};
use sqlparser::ast::{
ArrayElemTypeDef, BinaryOperator as SQLBinaryOperator, DataType as SQLDataType,
Expr as SqlExpr, Function as SQLFunction, Value as SqlValue, WindowType,
};
fn map_sql_polars_datatype(data_type: &SQLDataType) -> Result<DataType> {
Ok(match data_type {
SQLDataType::Char(_)
| SQLDataType::Varchar(_)
| SQLDataType::Uuid
| SQLDataType::Clob(_)
| SQLDataType::Text
| SQLDataType::String(_) => DataType::String,
SQLDataType::Float(_) => DataType::Float32,
SQLDataType::Real => DataType::Float32,
SQLDataType::Double => DataType::Float64,
SQLDataType::TinyInt(_) => DataType::Int8,
SQLDataType::UnsignedTinyInt(_) => DataType::UInt8,
SQLDataType::SmallInt(_) => DataType::Int16,
SQLDataType::UnsignedSmallInt(_) => DataType::UInt16,
SQLDataType::Int(_) => DataType::Int32,
SQLDataType::UnsignedInt(_) => DataType::UInt32,
SQLDataType::BigInt(_) => DataType::Int64,
SQLDataType::UnsignedBigInt(_) => DataType::UInt64,
SQLDataType::Boolean => DataType::Boolean,
SQLDataType::Date => DataType::Date,
SQLDataType::Time(_, _) => DataType::Time,
SQLDataType::Timestamp(_, _) => DataType::Datetime(TimeUnit::Microseconds, None),
SQLDataType::Interval => DataType::Duration(TimeUnit::Microseconds),
SQLDataType::Array(array_type_def) => match array_type_def {
ArrayElemTypeDef::AngleBracket(inner_type)
| ArrayElemTypeDef::SquareBracket(inner_type) => {
DataType::List(Box::new(map_sql_polars_datatype(inner_type)?))
}
_ => {
return Err(PolarsError::ComputeError(
"SQL Datatype Array(None) was not supported in polars-sql yet!".into(),
))
}
},
_ => {
return Err(PolarsError::ComputeError(
format!("SQL Datatype {data_type:?} was not supported in polars-sql yet!").into(),
))
}
})
}
fn cast_(expr: Expr, data_type: &SQLDataType) -> Result<Expr> {
let polars_type = map_sql_polars_datatype(data_type)?;
Ok(expr.cast(polars_type))
}
fn binary_op_(left: Expr, right: Expr, op: &SQLBinaryOperator) -> Result<Expr> {
Ok(match op {
SQLBinaryOperator::Plus => left + right,
SQLBinaryOperator::Minus => left - right,
SQLBinaryOperator::Multiply => left * right,
SQLBinaryOperator::Divide => left / right,
SQLBinaryOperator::Modulo => left % right,
SQLBinaryOperator::StringConcat => {
left.cast(DataType::String) + right.cast(DataType::String)
}
SQLBinaryOperator::Gt => left.gt(right),
SQLBinaryOperator::Lt => left.lt(right),
SQLBinaryOperator::GtEq => left.gt_eq(right),
SQLBinaryOperator::LtEq => left.lt_eq(right),
SQLBinaryOperator::Eq => left.eq(right),
SQLBinaryOperator::NotEq => left.eq(right).not(),
SQLBinaryOperator::And => left.and(right),
SQLBinaryOperator::Or => left.or(right),
SQLBinaryOperator::Xor => left.xor(right),
_ => {
return Err(PolarsError::ComputeError(
format!("SQL Operator {op:?} was not supported in polars-sql yet!").into(),
))
}
})
}
fn literal_expr(value: &SqlValue) -> Result<Expr> {
Ok(match value {
SqlValue::Number(s, _) => {
// Check for existence of decimal separator dot
if s.contains('.') {
s.parse::<f64>().map(lit).map_err(|_| {
PolarsError::ComputeError(format!("Can't parse literal {s:?}").into())
})
} else {
s.parse::<i64>().map(lit).map_err(|_| {
PolarsError::ComputeError(format!("Can't parse literal {s:?}").into())
})
}?
}
SqlValue::SingleQuotedString(s) => lit(s.clone()),
SqlValue::NationalStringLiteral(s) => lit(s.clone()),
SqlValue::HexStringLiteral(s) => lit(s.clone()),
SqlValue::DoubleQuotedString(s) => lit(s.clone()),
SqlValue::Boolean(b) => lit(*b),
SqlValue::Null => Expr::Literal(LiteralValue::Null),
_ => {
return Err(PolarsError::ComputeError(
format!("Parsing SQL Value {value:?} was not supported in polars-sql yet!").into(),
))
}
})
}
pub fn parse_sql_expr(expr: &SqlExpr) -> Result<Expr> {
Ok(match expr {
SqlExpr::Identifier(e) => col(&e.value),
SqlExpr::BinaryOp { left, op, right } => {
let left = parse_sql_expr(left)?;
let right = parse_sql_expr(right)?;
binary_op_(left, right, op)?
}
SqlExpr::Function(sql_function) => parse_sql_function(sql_function)?,
SqlExpr::Cast {
expr,
data_type,
format: _,
} => cast_(parse_sql_expr(expr)?, data_type)?,
SqlExpr::Nested(expr) => parse_sql_expr(expr)?,
SqlExpr::Value(value) => literal_expr(value)?,
_ => {
return Err(PolarsError::ComputeError(
format!("Expression: {expr:?} was not supported in polars-sql yet!").into(),
))
}
})
}
fn apply_window_spec(expr: Expr, window_type: Option<&WindowType>) -> Result<Expr> {
Ok(match &window_type {
Some(wtype) => match wtype {
WindowType::WindowSpec(window_spec) => {
// Process for simple window specification, partition by first
let partition_by = window_spec
.partition_by
.iter()
.map(parse_sql_expr)
.collect::<Result<Vec<_>>>()?;
expr.over(partition_by)
// Order by and Row range may not be supported at the moment
}
// TODO: make NamedWindow work
WindowType::NamedWindow(_named) => {
return Err(PolarsError::ComputeError(
format!("Expression: {expr:?} was not supported in polars-sql yet!").into(),
))
}
},
None => expr,
})
}
fn parse_sql_function(sql_function: &SQLFunction) -> Result<Expr> {
use sqlparser::ast::{FunctionArg, FunctionArgExpr};
// Function name mostly do not have name space, so it mostly take the first args
let function_name = sql_function.name.0[0].value.to_ascii_lowercase();
let args = sql_function
.args
.iter()
.map(|arg| match arg {
FunctionArg::Named { arg, .. } => arg,
FunctionArg::Unnamed(arg) => arg,
})
.collect::<Vec<_>>();
Ok(
match (
function_name.as_str(),
args.as_slice(),
sql_function.distinct,
) {
("sum", [FunctionArgExpr::Expr(expr)], false) => {
apply_window_spec(parse_sql_expr(expr)?, sql_function.over.as_ref())?.sum()
}
("count", [FunctionArgExpr::Expr(expr)], false) => {
apply_window_spec(parse_sql_expr(expr)?, sql_function.over.as_ref())?.count()
}
("count", [FunctionArgExpr::Expr(expr)], true) => {
apply_window_spec(parse_sql_expr(expr)?, sql_function.over.as_ref())?.n_unique()
}
// Special case for wildcard args to count function.
("count", [FunctionArgExpr::Wildcard], false) => lit(1i32).count(),
_ => {
return Err(PolarsError::ComputeError(
format!(
"Function {function_name:?} with args {args:?} was not supported in polars-sql yet!"
)
.into(),
))
}
},
)
}
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