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//! Relational Query AST
//!
//! Strictly typed AST for describing relational queries.

mod expr;
mod fold;
mod ids;
mod transform;

pub use expr::{Expr, ExprKind, UnOp};
pub use fold::*;
pub use ids::*;
pub use transform::*;

use enum_as_inner::EnumAsInner;
use serde::{Deserialize, Serialize};

use super::pl::InterpolateItem;
use super::pl::{ColumnSort, QueryDef, Range, RelationLiteral, WindowFrame};

#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
pub struct Query {
    pub def: QueryDef,

    pub tables: Vec<TableDecl>,
    pub relation: Relation,
}

#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
pub struct Relation {
    pub kind: RelationKind,

    /// Column definitions.
    /// This is the interface of the table that can be referenced from other tables.
    pub columns: Vec<RelationColumn>,
}

#[derive(Debug, PartialEq, Clone, Serialize, Deserialize, EnumAsInner)]
pub enum RelationKind {
    ExternRef(String),
    Pipeline(Vec<Transform>),
    Literal(RelationLiteral),
    SString(Vec<InterpolateItem<Expr>>),
}

#[derive(Debug, PartialEq, Clone, Eq, Hash, Serialize, Deserialize, EnumAsInner)]
pub enum RelationColumn {
    /// Description of a single column that may have a name.
    /// Unnamed columns cannot be referenced.
    Single(Option<String>),

    /// Means "and other unmentioned columns". Does not mean "all columns".
    Wildcard,
}

#[derive(Debug, PartialEq, Clone, Serialize, Deserialize)]
pub struct TableDecl {
    /// An id for this table, unique within all tables in this query.
    pub id: TId,

    /// Name hint for this declaration (name of the CTE)
    pub name: Option<String>,

    /// Table's contents.
    pub relation: Relation,
}

#[derive(Debug, PartialEq, Eq, Clone, Serialize, Deserialize)]
pub struct TableRef {
    // Referenced table
    pub source: TId,

    // New column definitions are required because there may be multiple instances
    // of this table in the same query
    pub columns: Vec<(RelationColumn, CId)>,

    /// Name hint for relation within this pipeline (table alias)
    pub name: Option<String>,
}