icydb-core 0.73.2

//! Module: query::plan::expr::ast
//! Responsibility: planner expression AST domain types and field/operator identifiers.
//! Does not own: expression type inference policy or runtime expression evaluation.
//! Boundary: defines canonical expression tree structures consumed by planner validation/lowering.

use crate::{db::query::builder::aggregate::AggregateExpr, value::Value};

///
/// FieldId
///
/// Canonical planner-owned field identity token for expression trees.
/// This wrapper carries the declared field name and avoids ad-hoc string use.
///

#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub(crate) struct FieldId(String);

impl FieldId {
    /// Build one field-id token from a field name.
    #[must_use]
    pub(crate) fn new(field: impl Into<String>) -> Self {
        Self(field.into())
    }

    /// Borrow the canonical field name.
    #[must_use]
    pub(crate) const fn as_str(&self) -> &str {
        self.0.as_str()
    }
}

impl From<&str> for FieldId {
    fn from(value: &str) -> Self {
        Self::new(value)
    }
}

impl From<String> for FieldId {
    fn from(value: String) -> Self {
        Self::new(value)
    }
}

///
/// Alias
///
/// Canonical planner-owned alias token attached to expression projections.
/// Alias remains presentation metadata and does not affect semantic identity.
///

#[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
pub(crate) struct Alias(String);

impl Alias {
    /// Build one alias token from owned/borrowed text.
    #[must_use]
    pub(crate) fn new(name: impl Into<String>) -> Self {
        Self(name.into())
    }

    /// Borrow the alias as text.
    #[must_use]
    pub(crate) const fn as_str(&self) -> &str {
        self.0.as_str()
    }
}

impl From<&str> for Alias {
    fn from(value: &str) -> Self {
        Self::new(value)
    }
}

impl From<String> for Alias {
    fn from(value: String) -> Self {
        Self::new(value)
    }
}

///
/// UnaryOp
///
/// Canonical unary expression operator taxonomy.
///

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub(crate) enum UnaryOp {
    Neg,
    Not,
}

///
/// BinaryOp
///
/// Canonical binary expression operator taxonomy.
///

#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub(crate) enum BinaryOp {
    Add,
    Sub,
    Mul,
    Div,
    And,
    Or,
    Eq,
    Ne,
    Lt,
    Lte,
    Gt,
    Gte,
}

///
/// Expr
///
/// Canonical planner-owned expression tree for projection semantics.
/// This model is semantic-only and intentionally excludes execution logic.
///

#[derive(Clone, Debug, Eq, PartialEq)]
pub(crate) enum Expr {
    Field(FieldId),
    Literal(Value),
    Unary {
        op: UnaryOp,
        expr: Box<Self>,
    },
    Binary {
        op: BinaryOp,
        left: Box<Self>,
        right: Box<Self>,
    },
    Aggregate(AggregateExpr),
    Alias {
        expr: Box<Self>,
        name: Alias,
    },
}