Enum ControlFlow 

#[non_exhaustive]
pub enum ControlFlow {
    Normal(ExecResult),
    Break {
        levels: usize,
        result: ExecResult,
    },
    Continue {
        levels: usize,
        result: ExecResult,
    },
    Return {
        value: ExecResult,
    },
    Exit {
        code: i64,
        result: ExecResult,
    },
}

Control flow signal from statement execution.

Normal execution returns Normal(result). Loop control uses Break and Continue. Function returns use Return, and script exits use Exit.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

Normal(ExecResult)

Normal completion with a result.

Break

Break out of loop(s). levels indicates how many loops to break out of.

Fields

levels: usize

result: ExecResult

Continue

Continue to next iteration of loop(s). levels indicates how many loops to skip.

Fields

levels: usize

result: ExecResult

Return

Return from a function with a result.

Fields

value: ExecResult

Exit

Exit the entire script with an exit code.

result carries the output produced before the exit. An immediate exit stops the script; it does not discard the iterations that already ran. code stays authoritative for the script’s status — result.code is never read.

Fields

code: i64

result: ExecResult

Implementations

impl ControlFlow

pub fn ok(result: ExecResult) -> Self

Create a normal control flow with a successful result.

pub fn break_one() -> Self

Create a break with 1 level.

pub fn break_n(n: usize) -> Self

Create a break with n levels.

pub fn continue_one() -> Self

Create a continue with 1 level.

pub fn continue_n(n: usize) -> Self

Create a continue with n levels.

pub fn return_value(value: ExecResult) -> Self

Create a return with a value.

pub fn exit_code(code: i64) -> Self

Create an exit with a code, carrying no output yet.

Each loop the exit passes through folds its own accumulated output in, so the output arrives with the signal rather than being left behind.

pub fn is_normal(&self) -> bool

Check if this is normal flow.

pub fn into_result(self) -> Option<ExecResult>

Get the result if this is normal flow.

pub fn decrement_level(&mut self) -> bool

Decrement break/continue levels by 1 and return whether we should stop here.

Returns true if the break/continue should be handled at this level, false if it should propagate further.

Trait Implementations

impl Clone for ControlFlow

fn clone(&self) -> ControlFlow

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for ControlFlow

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for ControlFlow

fn default() -> Self

Returns the “default value” for a type.

impl From<ExecResult> for ControlFlow

fn from(result: ExecResult) -> Self

Converts to this type from the input type.