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/// For tracking bytecode offsets in jumps
#[derive(Clone, Copy, PartialEq, Debug)]
#[must_use]
pub struct BytecodeOffset {
pub offset: usize,
}
impl BytecodeOffset {
fn new(offset: usize) -> Self {
Self { offset }
}
/// diff_from is useful for finding the offset between two bytecodes. This is usually
/// used for jumps and jump_targets.
///
/// For a forward jump, self will be a larger number, and start will be smaller
/// the output will be a positive number. for a backward jump, the reverse
/// will be true, and the number will be negative. So it is important to use this api
/// consistently in both cases.
///
/// Examples:
/// let offset_diff: BytecodeOffsetDiff = forward_jump_target_offset.diff_from(jump)
/// let offset_diff: BytecodeOffsetDiff = backward_jump_target_offset.diff_from(jump)
pub fn diff_from(self, start: BytecodeOffset) -> BytecodeOffsetDiff {
BytecodeOffsetDiff::new(self, start)
}
}
impl From<BytecodeOffset> for usize {
fn from(offset: BytecodeOffset) -> usize {
offset.offset
}
}
impl From<usize> for BytecodeOffset {
fn from(offset: usize) -> BytecodeOffset {
BytecodeOffset::new(offset)
}
}
pub struct BytecodeOffsetDiff {
diff: i32,
}
impl BytecodeOffsetDiff {
fn new(end: BytecodeOffset, start: BytecodeOffset) -> Self {
let diff = (end.offset as i128 - start.offset as i128) as i32;
Self { diff }
}
pub fn uninitialized() -> Self {
Self { diff: 0i32 }
}
}
impl From<BytecodeOffsetDiff> for i32 {
fn from(offset: BytecodeOffsetDiff) -> i32 {
offset.diff
}
}