Struct Env 

pub struct Env { /* private fields */ }

An instance of the interpreter, the “Tcl machine.”

To run a program, you need one of these. You can create one containing the standard set of commands using Env::default(), and then call eval as many times as required.

Dropping it will deallocate all associated state.

Implementations

impl Env

pub fn empty() -> Self

Creates an environment with no commands registered.

You can load commands by calling register.

pub fn register( &mut self, name: &Value, arity: usize, function: impl Fn(&mut Env, &mut [OwnedValue]) -> Result<OwnedValue, FlowChange> + 'static, )

Adds a command to self, under the name name, expecting arity arguments (including its own name!), and implemented by the Rust function function.

If a command can handle various numbers of arguments, the arity here should be 0, and the command is responsible for checking argument count itself.

pub fn eval(&mut self, s: &Value) -> Result<OwnedValue, FlowChange>

Evaluates the source code s in terms of this interpreter.

On normal completion, returns the result. Otherwise, returns the change in flow control.

pub fn set_or_create_var(&mut self, name: OwnedValue, value: OwnedValue)

Sets a variable named name to value in the current innermost scope, creating it if it doesn’t exist.

If the variable exists, name winds up being freed. This might seem like a good reason for it to be borrowed (&Value) instead. But in practice, the only case where it would be borrowed from a long-lived allocation is also the only case where we always create new bindings: in cmd_proc. So this keeps the code simpler at no performance cost.

pub fn get_existing_var(&mut self, name: &Value) -> Option<OwnedValue>

Gets a copy of the contents of an existing variable, or returns None if it doesn’t exist.

Trait Implementations

impl Default for Env

fn default() -> Self

Creates a new Env environment and initializes it with the standard bundled command set before returning it.