Struct rustdb::exec::EvalEnv

#[non_exhaustive]
pub struct EvalEnv<'r> {
    pub stack: Vec<Value>,
    pub bp: usize,
    pub db: DB,
    pub tr: &'r mut dyn Transaction,
    pub call_depth: usize,
}

Evaluation environment - stack of Values, references to DB and Transaction.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

stack: Vec<Value>

Stack of values, holds function parameters and local variables.

bp: usize

“Base Pointer” - stack index of current parameters and local variables.

db: DB

Pointer to Database.

tr: &'r mut dyn Transaction

Pointer to Transaction.

call_depth: usize

Function call depth, prevents stack overflow.

Implementations

impl<'r> EvalEnv<'r>

pub fn new(db: DB, tr: &'r mut dyn Transaction) -> Self

Construct a new EvalEnv.

pub fn alloc_locals(&mut self, dt: &[DataType], param_count: usize)

Allocate and initialise local variables.

pub fn go(&mut self, ilist: &[Instruction])

Execute list of instructions.

pub fn call(&mut self, r: &Function)

Call a function.