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use crate::ast::{
ddl::{
ColumnAttribute,
ColumnDef,
TableDef,
},
BinaryOperation,
Column,
Expr,
Operator,
};
use sql_ast::ast as sql;
use std::collections::BTreeMap;
use thiserror::Error;
#[derive(Error, Debug)]
pub enum TableError {
#[error("Table join is specified, but no table lookup is supplied")]
NoSuppliedTableLookup,
#[error("Table: `{0}` not found in the supplied TableLookup")]
TableNotFound(String),
}
#[derive(Debug, PartialEq, Default, Clone)]
pub struct FromTable {
pub from: Table,
pub join: Option<(JoinType, Box<FromTable>)>,
}
#[derive(Debug, PartialEq, Default, Clone)]
pub struct Table {
pub name: String,
}
#[derive(Debug, PartialEq, Clone)]
pub enum JoinType {
InnerJoin,
LeftJoin,
RightJoin,
FullJoin,
}
impl Into<sql::TableFactor> for &Table {
fn into(self) -> sql::TableFactor {
sql::TableFactor::Table {
name: Into::into(self),
alias: None,
args: vec![],
with_hints: vec![],
}
}
}
impl Into<sql::ObjectName> for &Table {
fn into(self) -> sql::ObjectName {
sql::ObjectName(vec![sql::Ident::new(&self.name)])
}
}
impl JoinType {
fn into_sql_join_operator(&self, constraint: Expr) -> sql::JoinOperator {
let on_constraint = sql::JoinConstraint::On(Into::into(&constraint));
match self {
JoinType::InnerJoin => sql::JoinOperator::Inner(on_constraint),
JoinType::LeftJoin => sql::JoinOperator::LeftOuter(on_constraint),
JoinType::RightJoin => sql::JoinOperator::RightOuter(on_constraint),
JoinType::FullJoin => sql::JoinOperator::FullOuter(on_constraint),
}
}
}
pub struct TableLookup(BTreeMap<String, TableDef>);
impl TableLookup {
pub fn new() -> Self {
TableLookup(BTreeMap::new())
}
pub fn add_table(&mut self, table_def: TableDef) -> Option<TableDef> {
self.0.insert(table_def.table.name.to_string(), table_def)
}
pub fn get_table_def(&self, name: &str) -> Option<&TableDef> {
self.0.get(name)
}
}
impl TableDef {
pub(crate) fn get_local_columns_to_foreign_table(
&self,
table_name: &str,
) -> Vec<&ColumnDef> {
self.columns
.iter()
.filter(|column| {
match &column.foreign {
Some(foreign) => foreign.name == table_name,
None => false,
}
})
.collect()
}
pub(crate) fn get_primary_columns(&self) -> Vec<&ColumnDef> {
self.columns
.iter()
.filter(|column| {
match &column.attributes {
Some(attributes) => {
attributes
.iter()
.any(|att| *att == ColumnAttribute::Primary)
}
None => false,
}
})
.collect()
}
}
impl FromTable {
pub(crate) fn into_table_with_joins(
&self,
table_lookup: Option<&TableLookup>,
) -> Result<sql::TableWithJoins, TableError> {
Ok(sql::TableWithJoins {
relation: Into::into(&self.from),
joins: self.maybe_extract_join(table_lookup)?,
})
}
fn maybe_extract_join(
&self,
table_lookup: Option<&TableLookup>,
) -> Result<Vec<sql::Join>, TableError> {
match table_lookup {
Some(table_lookup) => self.extract_join(table_lookup),
None => {
match self.join {
Some(_) => Err(TableError::NoSuppliedTableLookup),
None => Ok(vec![]),
}
}
}
}
fn extract_join(
&self,
table_lookup: &TableLookup,
) -> Result<Vec<sql::Join>, TableError> {
match &self.join {
Some((join_type, joined_table)) => {
let joined_table_def =
table_lookup.get_table_def(&joined_table.from.name);
let this_table_def =
table_lookup.get_table_def(&self.from.name);
match (this_table_def, joined_table_def) {
(None, _) => {
Err(TableError::TableNotFound(
self.from.name.to_string(),
))
}
(_, None) => {
Err(TableError::TableNotFound(
joined_table.from.name.to_string(),
))
}
(Some(this_table_def), Some(joined_table_def)) => {
let this_primary_keys =
this_table_def.get_primary_columns();
let joined_local_columns = joined_table_def
.get_local_columns_to_foreign_table(
&this_table_def.table.name,
);
assert_eq!(joined_local_columns.len(), 1);
assert_eq!(this_primary_keys.len(), 1);
let constraint =
Expr::BinaryOperation(Box::new(BinaryOperation {
left: Expr::Column(Column {
name: format!(
"{}.{}",
joined_table_def.table.name,
joined_local_columns[0].column.name
),
}),
operator: Operator::Eq,
right: Expr::Column(Column {
name: format!(
"{}.{}",
this_table_def.table.name,
this_primary_keys[0].column.name
),
}),
}));
let mut ret = vec![sql::Join {
relation: Into::into(&joined_table.from),
join_operator: join_type
.into_sql_join_operator(constraint),
}];
ret.extend(joined_table.extract_join(table_lookup)?);
Ok(ret)
}
}
}
None => Ok(vec![]),
}
}
}