libgm 0.5.1

A tool for modding, unpacking and decompiling GameMaker games
Documentation 
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use std::borrow::Cow;

use crate::gml::Instruction;
use crate::gml::instruction::CodeVariable;
use crate::gml::instruction::DataType;
use crate::prelude::GMRef;
use crate::wad::elements::function::GMFunction;

/// A value to push to the stack.
/// Used in [`Push`] instructions.
///
/// [`Push`]: Instruction::Push
#[derive(Debug, Clone, PartialEq)]
pub enum PushValue {
    Int16(i16),
    Int32(i32),
    Int64(i64),
    Double(f64),
    Boolean(bool),
    String(String),
    Function(GMRef<GMFunction>),
    Variable(CodeVariable),
}

impl PushValue {
    /// This value's [`DataType`].
    ///
    /// Note that functions are represented as `Int32`.
    /// Some variables are also represented as `Int32` (idk when tho).
    #[must_use]
    pub const fn data_type(&self) -> DataType {
        match self {
            Self::Int16(_) => DataType::Int16,
            Self::Int32(_) | Self::Function(_) => DataType::Int32,
            Self::Variable(var) if var.is_int32 => DataType::Int32,
            Self::Int64(_) => DataType::Int64,
            Self::Double(_) => DataType::Double,
            Self::Boolean(_) => DataType::Boolean,
            Self::String(_) => DataType::String,
            Self::Variable(_) => DataType::Variable,
        }
    }

    /// An approximate boolean representation for this [`PushValue`].
    ///
    /// Warning: This function does not fully conform with the GameMaker
    /// standards (yet).
    #[must_use]
    pub const fn as_bool(&self) -> Option<bool> {
        match self {
            &Self::Int16(int) => Some(int > 0),
            &Self::Int32(int) => Some(int > 0),
            &Self::Int64(int) => Some(int > 0),
            &Self::Double(float) => Some(float > 0.5),
            &Self::Boolean(bool) => Some(bool),
            Self::String(_) | Self::Function(_) | Self::Variable(_) => None,
        }
    }
}

impl Instruction {
    /// Attempts to extract a [`PushValue`] from this instruction.
    ///
    /// TODO(weak): This function sucks ass.
    #[must_use]
    pub(crate) fn push_value(&'_ self) -> Option<Cow<'_, PushValue>> {
        Some(match self {
            Self::Push { value } => Cow::Borrowed(value),
            Self::PushLocal { variable }
            | Self::PushGlobal { variable }
            | Self::PushBuiltin { variable } => Cow::Owned(PushValue::Variable(variable.clone())),
            &Self::PushImmediate { integer } => Cow::Owned(PushValue::Int16(integer)),
            _ => return None,
        })
    }
}