blvm-consensus 0.1.45

Bitcoin Commons BLVM: Direct mathematical implementation of Bitcoin consensus rules from the Orange Paper
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//! Control flow structures for script execution (OP_IF, OP_NOTIF, OP_ENDIF).

use blvm_spec_lock::spec_locked;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub(crate) enum ControlBlock {
    If { executing: bool },
    NotIf { executing: bool },
}

/// True if we're in a non-executing branch (IF/NOTIF with executing=false). Used by both paths.
#[inline(always)]
pub(crate) fn in_false_branch(control_stack: &[ControlBlock]) -> bool {
    control_stack.iter().any(|b| {
        !matches!(
            b,
            ControlBlock::If { executing: true } | ControlBlock::NotIf { executing: true }
        )
    })
}

/// Minimal IF/NOTIF argument. Core accepts only the empty vector or exactly `[0x01]`.
#[spec_locked("5.2.4", "IsMinimalIfCondition")]
#[blvm_spec_lock::ensures(result == false || bytes.len() <= 1)]
pub(crate) fn is_minimal_if_condition(bytes: &[u8]) -> bool {
    match bytes.len() {
        0 => true,
        1 => bytes[0] == 0x01,
        _ => false,
    }
}