kataru 0.1.14

Kataru - the YAML-based dialogue engine for game development.
Documentation 
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use super::{AssignOperator, Map};
use crate::{
    error::{Error, Result},
    traits::FromStr,
    Value,
};

/// Typedef for state, which is a mapping of values.
pub type State = Map<String, Value>;

#[derive(Debug)]
pub struct StateMod<'a> {
    pub var: &'a str,
    pub op: AssignOperator,
}

impl<'a> FromStr<'a> for StateMod<'a> {
    fn from_str(text: &'a str) -> Result<Self> {
        let split: Vec<&str> = text.split(' ').collect();
        if split.len() == 1 {
            return Ok(Self {
                var: &split[0][1..],
                op: AssignOperator::None,
            });
        } else if split.len() == 2 {
            return Ok(Self {
                var: &split[0][1..],
                op: AssignOperator::from_str(split[1])?,
            });
        }
        Err(error!(
            "State modification must be of the form 'VAR [+-]:'."
        ))
    }
}

impl StateMod<'_> {
    pub fn apply(&self, lhs: &mut Value, rhs: Value) -> Result<()> {
        match self.op {
            AssignOperator::None => *lhs = rhs.clone(),
            AssignOperator::Add => *lhs += rhs,
            AssignOperator::Sub => *lhs -= rhs,
        };
        Ok(())
    }
}