Struct Planner 

pub struct Planner<'a, C: Catalog> { /* private fields */ }

The SQL query planner.

The planner converts AST statements into logical plans. It performs:

• Name resolution: Validates table and column references
• Type checking: Infers and validates expression types
• Plan construction: Builds the logical plan tree

Design Notes

• The planner uses an immutable reference to the catalog (&C)
• DDL statements produce plans but don’t modify the catalog
• The executor is responsible for applying catalog changes

Examples

use alopex_sql::catalog::MemoryCatalog;
use alopex_sql::planner::Planner;

let catalog = MemoryCatalog::new();
let planner = Planner::new(&catalog);

// Parse and plan a statement
// let stmt = parser.parse("SELECT * FROM users")?;
// let plan = planner.plan(&stmt)?;

Implementations

impl<'a, C: Catalog> Planner<'a, C>

pub fn new(catalog: &'a C) -> Self

Create a new planner with the given catalog.

pub fn plan(&self, stmt: &Statement) -> Result<LogicalPlan, PlannerError>

Plan a SQL statement.

This is the main entry point for converting an AST statement into a logical plan.

Errors

Returns a PlannerError if:

• Referenced tables or columns don’t exist
• Type checking fails
• DDL validation fails (e.g., table already exists for CREATE TABLE)