mentat/query-sql/src/lib.rs

891 lines
28 KiB
Rust

// Copyright 2016 Mozilla
//
// Licensed under the Apache License, Version 2.0 (the "License"); you may not use
// this file except in compliance with the License. You may obtain a copy of the
// License at http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software distributed
// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
// CONDITIONS OF ANY KIND, either express or implied. See the License for the
// specific language governing permissions and limitations under the License.
#[macro_use]
extern crate mentat_core;
extern crate core_traits;
extern crate edn;
extern crate mentat_query_algebrizer;
extern crate mentat_sql;
extern crate sql_traits;
use std::boxed::Box;
use core_traits::{Entid, TypedValue, ValueType};
use mentat_core::SQLTypeAffinity;
use edn::query::{Direction, Limit, Variable};
use mentat_query_algebrizer::{
Column, OrderBy, QualifiedAlias, QueryValue, SourceAlias, TableAlias, VariableColumn,
};
use sql_traits::errors::{BuildQueryResult, SQLError};
use mentat_sql::{QueryBuilder, QueryFragment, SQLQuery, SQLiteQueryBuilder};
//---------------------------------------------------------
// A Mentat-focused representation of a SQL query.
/// One of the things that can appear in a projection or a constraint. Note that we use
/// `TypedValue` here; it's not pure SQL, but it avoids us having to concern ourselves at this
/// point with the translation between a `TypedValue` and the storage-layer representation.
///
/// Eventually we might allow different translations by providing a different `QueryBuilder`
/// implementation for each storage backend. Passing `TypedValue`s here allows for that.
pub enum ColumnOrExpression {
Column(QualifiedAlias),
ExistingColumn(Name),
Entid(Entid), // Because it's so common.
Integer(i32), // We use these for type codes etc.
Long(i64),
Value(TypedValue),
// Some aggregates (`min`, `max`, `avg`) can be over 0 rows, and therefore can be `NULL`; that
// needs special treatment.
NullableAggregate(Box<Expression>, ValueType), // Track the return type.
Expression(Box<Expression>, ValueType), // Track the return type.
}
pub enum Expression {
Unary {
sql_op: &'static str,
arg: ColumnOrExpression,
},
}
/// `QueryValue` and `ColumnOrExpression` are almost identical… merge somehow?
impl From<QueryValue> for ColumnOrExpression {
fn from(v: QueryValue) -> Self {
match v {
QueryValue::Column(c) => ColumnOrExpression::Column(c),
QueryValue::Entid(e) => ColumnOrExpression::Entid(e),
QueryValue::PrimitiveLong(v) => ColumnOrExpression::Long(v),
QueryValue::TypedValue(v) => ColumnOrExpression::Value(v),
}
}
}
pub type Name = String;
pub struct ProjectedColumn(pub ColumnOrExpression, pub Name);
pub enum Projection {
Columns(Vec<ProjectedColumn>),
Star,
One,
}
#[derive(Debug, PartialEq, Eq)]
pub enum GroupBy {
ProjectedColumn(Name),
QueryColumn(QualifiedAlias),
// TODO: non-projected expressions, etc.
}
impl QueryFragment for GroupBy {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
match self {
GroupBy::ProjectedColumn(ref name) => out.push_identifier(name.as_str()),
GroupBy::QueryColumn(ref qa) => qualified_alias_push_sql(out, qa),
}
}
}
#[derive(Copy, Clone)]
pub struct Op(pub &'static str); // TODO: we can do better than this!
pub enum Constraint {
Infix {
op: Op,
left: ColumnOrExpression,
right: ColumnOrExpression,
},
Or {
constraints: Vec<Constraint>,
},
And {
constraints: Vec<Constraint>,
},
In {
left: ColumnOrExpression,
list: Vec<ColumnOrExpression>,
},
IsNull {
value: ColumnOrExpression,
},
IsNotNull {
value: ColumnOrExpression,
},
NotExists {
subquery: TableOrSubquery,
},
TypeCheck {
value: ColumnOrExpression,
affinity: SQLTypeAffinity,
},
}
impl Constraint {
pub fn not_equal(left: ColumnOrExpression, right: ColumnOrExpression) -> Constraint {
Constraint::Infix {
op: Op("<>"), // ANSI SQL for future-proofing!
left,
right,
}
}
pub fn equal(left: ColumnOrExpression, right: ColumnOrExpression) -> Constraint {
Constraint::Infix {
op: Op("="),
left,
right,
}
}
pub fn fulltext_match(left: ColumnOrExpression, right: ColumnOrExpression) -> Constraint {
Constraint::Infix {
op: Op("MATCH"), // SQLite specific!
left,
right,
}
}
}
#[allow(dead_code)]
enum JoinOp {
Inner,
}
// Short-hand for a list of tables all inner-joined.
pub struct TableList(pub Vec<TableOrSubquery>);
impl TableList {
fn is_empty(&self) -> bool {
self.0.is_empty()
}
}
pub struct Join {
left: TableOrSubquery,
op: JoinOp,
right: TableOrSubquery,
// TODO: constraints (ON, USING).
}
#[allow(dead_code)]
pub enum TableOrSubquery {
Table(SourceAlias),
Union(Vec<SelectQuery>, TableAlias),
Subquery(Box<SelectQuery>),
Values(Values, TableAlias),
}
pub enum Values {
/// Like "VALUES (0, 1), (2, 3), ...".
/// The vector must be of a length that is a multiple of the given size.
Unnamed(usize, Vec<TypedValue>),
/// Like "SELECT 0 AS x, SELECT 0 AS y WHERE 0 UNION ALL VALUES (0, 1), (2, 3), ...".
/// The vector of values must be of a length that is a multiple of the length
/// of the vector of names.
Named(Vec<Variable>, Vec<TypedValue>),
}
pub enum FromClause {
TableList(TableList), // Short-hand for a pile of inner joins.
Join(Join),
Nothing,
}
pub struct SelectQuery {
pub distinct: bool,
pub projection: Projection,
pub from: FromClause,
pub constraints: Vec<Constraint>,
pub group_by: Vec<GroupBy>,
pub order: Vec<OrderBy>,
pub limit: Limit,
}
fn push_variable_column(qb: &mut dyn QueryBuilder, vc: &VariableColumn) -> BuildQueryResult {
match vc {
VariableColumn::Variable(ref v) => qb.push_identifier(v.as_str()),
VariableColumn::VariableTypeTag(ref v) => {
qb.push_identifier(format!("{}_value_type_tag", v.name()).as_str())
}
}
}
fn push_column(qb: &mut dyn QueryBuilder, col: &Column) -> BuildQueryResult {
match col {
Column::Fixed(ref d) => {
qb.push_sql(d.as_str());
Ok(())
}
Column::Fulltext(ref d) => {
qb.push_sql(d.as_str());
Ok(())
}
Column::Variable(ref vc) => push_variable_column(qb, vc),
Column::Transactions(ref d) => {
qb.push_sql(d.as_str());
Ok(())
}
}
}
//---------------------------------------------------------
// Turn that representation into SQL.
impl QueryFragment for ColumnOrExpression {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
use self::ColumnOrExpression::*;
match self {
Column(ref qa) => qualified_alias_push_sql(out, qa),
ExistingColumn(ref alias) => out.push_identifier(alias.as_str()),
Entid(entid) => {
out.push_sql(entid.to_string().as_str());
Ok(())
}
Integer(integer) => {
out.push_sql(integer.to_string().as_str());
Ok(())
}
Long(long) => {
out.push_sql(long.to_string().as_str());
Ok(())
}
Value(ref v) => out.push_typed_value(v),
NullableAggregate(ref e, _) | &Expression(ref e, _) => e.push_sql(out),
}
}
}
impl QueryFragment for Expression {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
match self {
Expression::Unary {
ref sql_op,
ref arg,
} => {
out.push_sql(sql_op); // No need to escape built-ins.
out.push_sql("(");
arg.push_sql(out)?;
out.push_sql(")");
Ok(())
}
}
}
}
impl QueryFragment for Projection {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
use self::Projection::*;
match self {
One => out.push_sql("1"),
Star => out.push_sql("*"),
Columns(ref cols) => {
let &ProjectedColumn(ref col, ref alias) = &cols[0];
col.push_sql(out)?;
out.push_sql(" AS ");
out.push_identifier(alias.as_str())?;
for &ProjectedColumn(ref col, ref alias) in &cols[1..] {
out.push_sql(", ");
col.push_sql(out)?;
out.push_sql(" AS ");
out.push_identifier(alias.as_str())?;
}
}
};
Ok(())
}
}
impl QueryFragment for Op {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
// No escaping needed.
out.push_sql(self.0);
Ok(())
}
}
impl QueryFragment for Constraint {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
use self::Constraint::*;
match self {
Infix {
ref op,
ref left,
ref right,
} => {
left.push_sql(out)?;
out.push_sql(" ");
op.push_sql(out)?;
out.push_sql(" ");
right.push_sql(out)
}
IsNull { ref value } => {
value.push_sql(out)?;
out.push_sql(" IS NULL");
Ok(())
}
IsNotNull { ref value } => {
value.push_sql(out)?;
out.push_sql(" IS NOT NULL");
Ok(())
}
And { ref constraints } => {
// An empty intersection is true.
if constraints.is_empty() {
out.push_sql("1");
return Ok(());
}
out.push_sql("(");
interpose!(constraint, constraints, { constraint.push_sql(out)? }, {
out.push_sql(" AND ")
});
out.push_sql(")");
Ok(())
}
Or { ref constraints } => {
// An empty alternation is false.
if constraints.is_empty() {
out.push_sql("0");
return Ok(());
}
out.push_sql("(");
interpose!(constraint, constraints, { constraint.push_sql(out)? }, {
out.push_sql(" OR ")
});
out.push_sql(")");
Ok(())
}
In { ref left, ref list } => {
left.push_sql(out)?;
out.push_sql(" IN (");
interpose!(item, list, { item.push_sql(out)? }, { out.push_sql(", ") });
out.push_sql(")");
Ok(())
}
NotExists { ref subquery } => {
out.push_sql("NOT EXISTS ");
subquery.push_sql(out)
}
TypeCheck {
ref value,
ref affinity,
} => {
out.push_sql("typeof(");
value.push_sql(out)?;
out.push_sql(") = ");
out.push_sql(match *affinity {
SQLTypeAffinity::Null => "'null'",
SQLTypeAffinity::Integer => "'integer'",
SQLTypeAffinity::Real => "'real'",
SQLTypeAffinity::Text => "'text'",
SQLTypeAffinity::Blob => "'blob'",
});
Ok(())
}
}
}
}
impl QueryFragment for JoinOp {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
out.push_sql(" JOIN ");
Ok(())
}
}
// We don't own QualifiedAlias or QueryFragment, so we can't implement the trait.
fn qualified_alias_push_sql(out: &mut dyn QueryBuilder, qa: &QualifiedAlias) -> BuildQueryResult {
out.push_identifier(qa.0.as_str())?;
out.push_sql(".");
push_column(out, &qa.1)
}
// We don't own SourceAlias or QueryFragment, so we can't implement the trait.
fn source_alias_push_sql(out: &mut dyn QueryBuilder, sa: &SourceAlias) -> BuildQueryResult {
let &SourceAlias(ref table, ref alias) = sa;
out.push_identifier(table.name())?;
out.push_sql(" AS ");
out.push_identifier(alias.as_str())
}
impl QueryFragment for TableList {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
if self.0.is_empty() {
return Ok(());
}
interpose!(t, self.0, { t.push_sql(out)? }, { out.push_sql(", ") });
Ok(())
}
}
impl QueryFragment for Join {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
self.left.push_sql(out)?;
self.op.push_sql(out)?;
self.right.push_sql(out)
}
}
impl QueryFragment for TableOrSubquery {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
use self::TableOrSubquery::*;
match *self {
Table(ref sa) => source_alias_push_sql(out, sa),
Union(ref subqueries, ref table_alias) => {
out.push_sql("(");
interpose!(subquery, subqueries, { subquery.push_sql(out)? }, {
out.push_sql(" UNION ")
});
out.push_sql(") AS ");
out.push_identifier(table_alias.as_str())
}
Subquery(ref subquery) => {
out.push_sql("(");
subquery.push_sql(out)?;
out.push_sql(")");
Ok(())
}
Values(ref values, ref table_alias) => {
// XXX: does this work for Values::Unnamed?
out.push_sql("(");
values.push_sql(out)?;
out.push_sql(") AS ");
out.push_identifier(table_alias.as_str())
}
}
}
}
impl QueryFragment for Values {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
// There are at least 3 ways to name the columns of a VALUES table:
// 1) the columns are named "", ":1", ":2", ... -- but this is undocumented. See
// http://stackoverflow.com/a/40921724.
// 2) A CTE ("WITH" statement) can declare the shape of the table, like "WITH
// table_name(column_name, ...) AS (VALUES ...)".
// 3) We can "UNION ALL" a dummy "SELECT" statement in place.
//
// We don't want to use an undocumented SQLite quirk, and we're a little concerned that some
// SQL systems will not optimize WITH statements well. It's also convenient to have an in
// place table to query, so for now we implement option 3.
if let Values::Named(ref names, _) = *self {
out.push_sql("SELECT ");
interpose!(
alias,
names,
{
out.push_sql("0 AS ");
out.push_identifier(alias.as_str())?
},
{ out.push_sql(", ") }
);
out.push_sql(" WHERE 0 UNION ALL ");
}
let values = match *self {
Values::Named(ref names, ref values) => values.chunks(names.len()),
Values::Unnamed(ref size, ref values) => values.chunks(*size),
};
out.push_sql("VALUES ");
interpose_iter!(
outer,
values,
{
out.push_sql("(");
interpose!(inner, outer, { out.push_typed_value(inner)? }, {
out.push_sql(", ")
});
out.push_sql(")");
},
{ out.push_sql(", ") }
);
Ok(())
}
}
impl QueryFragment for FromClause {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
use self::FromClause::*;
match *self {
TableList(ref table_list) => {
if table_list.is_empty() {
Ok(())
} else {
out.push_sql(" FROM ");
table_list.push_sql(out)
}
}
Join(ref join) => {
out.push_sql(" FROM ");
join.push_sql(out)
}
Nothing => Ok(()),
}
}
}
/// `var` is something like `?foo99-people`.
/// Trim the `?` and escape the rest. Prepend `i` to distinguish from
/// the inline value space `v`.
fn format_select_var(var: &str) -> String {
use std::iter::once;
let without_question = var.split_at(1).1;
let replaced_iter =
without_question
.chars()
.map(|c| if c.is_ascii_alphanumeric() { c } else { '_' });
// Prefix with `i` (Avoiding this copy is probably not worth the trouble but whatever).
once('i').chain(replaced_iter).collect()
}
impl SelectQuery {
fn push_variable_param(&self, var: &Variable, out: &mut dyn QueryBuilder) -> BuildQueryResult {
let bind_param = format_select_var(var.as_str());
out.push_bind_param(bind_param.as_str())
}
}
impl QueryFragment for SelectQuery {
fn push_sql(&self, out: &mut dyn QueryBuilder) -> BuildQueryResult {
if self.distinct {
out.push_sql("SELECT DISTINCT ");
} else {
out.push_sql("SELECT ");
}
self.projection.push_sql(out)?;
self.from.push_sql(out)?;
if !self.constraints.is_empty() {
out.push_sql(" WHERE ");
interpose!(
constraint,
self.constraints,
{ constraint.push_sql(out)? },
{ out.push_sql(" AND ") }
);
}
match &self.group_by {
group_by if !group_by.is_empty() => {
out.push_sql(" GROUP BY ");
interpose!(group, group_by, { group.push_sql(out)? }, {
out.push_sql(", ")
});
}
_ => {}
}
if !self.order.is_empty() {
out.push_sql(" ORDER BY ");
interpose!(
&OrderBy(ref dir, ref var),
self.order,
{
push_variable_column(out, var)?;
match *dir {
Direction::Ascending => {
out.push_sql(" ASC");
}
Direction::Descending => {
out.push_sql(" DESC");
}
};
},
{ out.push_sql(", ") }
);
}
match self.limit {
Limit::None => (),
Limit::Fixed(limit) => {
// Guaranteed to be non-negative: u64.
out.push_sql(" LIMIT ");
out.push_sql(limit.to_string().as_str());
}
Limit::Variable(ref var) => {
// Guess this wasn't bound yet. Produce an argument.
out.push_sql(" LIMIT ");
self.push_variable_param(var, out)?;
}
}
Ok(())
}
}
impl SelectQuery {
pub fn to_sql_query(&self) -> Result<SQLQuery, SQLError> {
let mut builder = SQLiteQueryBuilder::new();
self.push_sql(&mut builder).map(|_| builder.finish())
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::rc::Rc;
use mentat_query_algebrizer::{Column, DatomsColumn, DatomsTable, FulltextColumn};
fn build_query(c: &dyn QueryFragment) -> SQLQuery {
let mut builder = SQLiteQueryBuilder::new();
c.push_sql(&mut builder)
.map(|_| builder.finish())
.expect("to produce a query for the given constraint")
}
fn build(c: &dyn QueryFragment) -> String {
build_query(c).sql
}
#[test]
fn test_in_constraint() {
let none = Constraint::In {
left: ColumnOrExpression::Column(QualifiedAlias::new(
"datoms01".to_string(),
Column::Fixed(DatomsColumn::Value),
)),
list: vec![],
};
let one = Constraint::In {
left: ColumnOrExpression::Column(QualifiedAlias::new(
"datoms01".to_string(),
DatomsColumn::Value,
)),
list: vec![ColumnOrExpression::Entid(123)],
};
let three = Constraint::In {
left: ColumnOrExpression::Column(QualifiedAlias::new(
"datoms01".to_string(),
DatomsColumn::Value,
)),
list: vec![
ColumnOrExpression::Entid(123),
ColumnOrExpression::Entid(456),
ColumnOrExpression::Entid(789),
],
};
assert_eq!("`datoms01`.v IN ()", build(&none));
assert_eq!("`datoms01`.v IN (123)", build(&one));
assert_eq!("`datoms01`.v IN (123, 456, 789)", build(&three));
}
#[test]
fn test_and_constraint() {
let c = Constraint::And {
constraints: vec![Constraint::And {
constraints: vec![
Constraint::Infix {
op: Op("="),
left: ColumnOrExpression::Entid(123),
right: ColumnOrExpression::Entid(456),
},
Constraint::Infix {
op: Op("="),
left: ColumnOrExpression::Entid(789),
right: ColumnOrExpression::Entid(246),
},
],
}],
};
// Two sets of parens: the outermost AND only has one child,
// but still contributes parens.
assert_eq!("((123 = 456 AND 789 = 246))", build(&c));
}
#[test]
fn test_unnamed_values() {
let build = |len, values| build(&Values::Unnamed(len, values));
assert_eq!(build(1, vec![TypedValue::Long(1)]), "VALUES (1)");
assert_eq!(
build(2, vec![TypedValue::Boolean(false), TypedValue::Long(1)]),
"VALUES (0, 1)"
);
assert_eq!(
build(
2,
vec![
TypedValue::Boolean(false),
TypedValue::Long(1),
TypedValue::Boolean(true),
TypedValue::Long(2)
]
),
"VALUES (0, 1), (1, 2)"
);
}
#[test]
fn test_named_values() {
let build = |names: Vec<_>, values| {
build(&Values::Named(
names.into_iter().map(Variable::from_valid_name).collect(),
values,
))
};
assert_eq!(
build(vec!["?a"], vec![TypedValue::Long(1)]),
"SELECT 0 AS `?a` WHERE 0 UNION ALL VALUES (1)"
);
assert_eq!(
build(
vec!["?a", "?b"],
vec![TypedValue::Boolean(false), TypedValue::Long(1)]
),
"SELECT 0 AS `?a`, 0 AS `?b` WHERE 0 UNION ALL VALUES (0, 1)"
);
assert_eq!(
build(
vec!["?a", "?b"],
vec![
TypedValue::Boolean(false),
TypedValue::Long(1),
TypedValue::Boolean(true),
TypedValue::Long(2)
]
),
"SELECT 0 AS `?a`, 0 AS `?b` WHERE 0 UNION ALL VALUES (0, 1), (1, 2)"
);
}
#[test]
fn test_matches_constraint() {
let c = Constraint::Infix {
op: Op("MATCHES"),
left: ColumnOrExpression::Column(QualifiedAlias(
"fulltext01".to_string(),
Column::Fulltext(FulltextColumn::Text),
)),
right: ColumnOrExpression::Value("needle".into()),
};
let q = build_query(&c);
assert_eq!("`fulltext01`.text MATCHES $v0", q.sql);
assert_eq!(
vec![(
"$v0".to_string(),
Rc::new(rusqlite::types::Value::Text("needle".to_string()))
)],
q.args
);
let c = Constraint::Infix {
op: Op("="),
left: ColumnOrExpression::Column(QualifiedAlias(
"fulltext01".to_string(),
Column::Fulltext(FulltextColumn::Rowid),
)),
right: ColumnOrExpression::Column(QualifiedAlias(
"datoms02".to_string(),
Column::Fixed(DatomsColumn::Value),
)),
};
assert_eq!("`fulltext01`.rowid = `datoms02`.v", build(&c));
}
#[test]
fn test_end_to_end() {
// [:find ?x :where [?x 65537 ?v] [?x 65536 ?v]]
let datoms00 = "datoms00".to_string();
let datoms01 = "datoms01".to_string();
let eq = Op("=");
let source_aliases = vec![
TableOrSubquery::Table(SourceAlias(DatomsTable::Datoms, datoms00.clone())),
TableOrSubquery::Table(SourceAlias(DatomsTable::Datoms, datoms01.clone())),
];
let mut query = SelectQuery {
distinct: true,
projection: Projection::Columns(vec![ProjectedColumn(
ColumnOrExpression::Column(QualifiedAlias::new(
datoms00.clone(),
DatomsColumn::Entity,
)),
"x".to_string(),
)]),
from: FromClause::TableList(TableList(source_aliases)),
constraints: vec![
Constraint::Infix {
op: eq,
left: ColumnOrExpression::Column(QualifiedAlias::new(
datoms01.clone(),
DatomsColumn::Value,
)),
right: ColumnOrExpression::Column(QualifiedAlias::new(
datoms00.clone(),
DatomsColumn::Value,
)),
},
Constraint::Infix {
op: eq,
left: ColumnOrExpression::Column(QualifiedAlias::new(
datoms00,
DatomsColumn::Attribute,
)),
right: ColumnOrExpression::Entid(65537),
},
Constraint::Infix {
op: eq,
left: ColumnOrExpression::Column(QualifiedAlias::new(
datoms01,
DatomsColumn::Attribute,
)),
right: ColumnOrExpression::Entid(65536),
},
],
group_by: vec![],
order: vec![],
limit: Limit::None,
};
let SQLQuery { sql, args } = query.to_sql_query().unwrap();
println!("{}", sql);
assert_eq!("SELECT DISTINCT `datoms00`.e AS `x` FROM `datoms` AS `datoms00`, `datoms` AS `datoms01` WHERE `datoms01`.v = `datoms00`.v AND `datoms00`.a = 65537 AND `datoms01`.a = 65536", sql);
assert!(args.is_empty());
// And without distinct…
query.distinct = false;
let SQLQuery { sql, args } = query.to_sql_query().unwrap();
println!("{}", sql);
assert_eq!("SELECT `datoms00`.e AS `x` FROM `datoms` AS `datoms00`, `datoms` AS `datoms01` WHERE `datoms01`.v = `datoms00`.v AND `datoms00`.a = 65537 AND `datoms01`.a = 65536", sql);
assert!(args.is_empty());
}
#[test]
fn test_format_select_var() {
assert_eq!(format_select_var("?foo99-people"), "ifoo99_people");
assert_eq!(format_select_var("?FOO99-pëople.123"), "iFOO99_p_ople_123");
assert_eq!(format_select_var("?foo①bar越"), "ifoo_bar_");
}
}