cargo-kconfig 0.0.1

/*
 Cargo KConfig - KConfig parser
 Copyright (C) 2022  Sjoerd van Leent

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THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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*/

use proc_macro::Punct;

use super::eval::{Value, ValueRef};

#[derive(Clone, Copy, Debug)]
pub(crate) enum Comparison {
    Lt,
    Gt,
    Lte,
    Gte,
    Eq,
    Ne,
    And,
    Or,
    None,
}

impl Comparison {
    pub(crate) fn compare(&self, lhs: ValueRef, rhs: ValueRef) -> ValueRef {
        let lhs = lhs.as_value();
        let rhs = rhs.as_value();

        ValueRef::Boolean(match self {
            // Note that comparing a < b should be the same as comparing b > a,
            // so in stead of creating a specific function for "<" comparison,
            // reuse the existing ">" function.
            Comparison::Lt => Self::gt(rhs, lhs),
            Comparison::Gt => Self::gt(lhs, rhs),
            Comparison::Lte => Self::eq(lhs.clone(), rhs.clone()) || (!Self::gt(lhs, rhs)),
            Comparison::Gte => Self::eq(lhs.clone(), rhs.clone()) || Self::gt(lhs, rhs),
            Comparison::Eq => Self::eq(lhs, rhs),
            Comparison::Ne => !Self::eq(lhs, rhs),
            Comparison::And => Self::and(lhs, rhs),
            Comparison::Or => Self::or(lhs, rhs),
            Comparison::None => false,
        })
    }

    fn eq(lhs: Value, rhs: Value) -> bool {
        let lhs_clone = lhs.clone();
        let rhs_clone = rhs.clone();
        match (lhs, rhs) {
            (Value::String(s1), Value::String(s2)) => s1 == s2,
            (Value::String(_), Value::Boolean(b)) => lhs_clone.as_bool() == b,
            (Value::String(_), Value::Int(i)) => match lhs_clone.as_int() {
                Some(i_lhs) => i_lhs == i,
                None => false,
            },
            (Value::Boolean(b), Value::String(_)) => b == rhs_clone.as_bool(),
            (Value::Boolean(b1), Value::Boolean(b2)) => b1 == b2,
            (Value::Boolean(_), Value::Int(i)) => match lhs_clone.as_int() {
                Some(i_lhs) => i_lhs == i,
                None => false,
            },
            (Value::Int(i), Value::String(_)) => match rhs_clone.as_int() {
                Some(i_rhs) => i == i_rhs,
                None => false,
            },
            (Value::Int(i), Value::Boolean(_)) => match rhs_clone.as_int() {
                Some(i_rhs) => i == i_rhs,
                None => false,
            },
            (Value::Int(i1), Value::Int(i2)) => i1 == i2,
        }
    }

    fn gt(lhs: Value, rhs: Value) -> bool {
        let lhs_clone = lhs.clone();
        let rhs_clone = rhs.clone();
        match (lhs, rhs) {
            (Value::String(s1), Value::String(s2)) => s1 > s2,
            (Value::String(_), Value::Boolean(b)) => lhs_clone.as_bool() > b,
            (Value::String(_), Value::Int(i)) => match lhs_clone.as_int() {
                Some(i_lhs) => i_lhs > i,
                None => false,
            },
            (Value::Boolean(b), Value::String(_)) => b > rhs_clone.as_bool(),
            (Value::Boolean(b1), Value::Boolean(b2)) => b1 > b2,
            (Value::Boolean(_), Value::Int(i)) => match lhs_clone.as_int() {
                Some(i_lhs) => i_lhs > i,
                None => false,
            },
            (Value::Int(i), Value::String(_)) => match rhs_clone.as_int() {
                Some(i_rhs) => i > i_rhs,
                None => false,
            },
            (Value::Int(i), Value::Boolean(_)) => match rhs_clone.as_int() {
                Some(i_rhs) => i > i_rhs,
                None => false,
            },
            (Value::Int(i1), Value::Int(i2)) => i1 > i2,
        }
    }

    fn and(lhs: Value, rhs: Value) -> bool {
        lhs.as_bool() && rhs.as_bool()
    }

    fn or(lhs: Value, rhs: Value) -> bool {
        lhs.as_bool() || rhs.as_bool()
    }

    pub(crate) fn single(p: &Punct) -> Self {
        match p.as_char() {
            '<' => Self::Lt,
            '>' => Self::Gt,
            _ => panic!("Operator {} invalid", p.as_char()),
        }
    }

    pub(crate) fn dual(p1: &Punct, p2: &Punct) -> Self {
        match (p1.as_char(), p2.as_char()) {
            ('<', '=') => Self::Lte,
            ('>', '=') => Self::Gte,
            ('=', '=') => Self::Eq,
            ('!', '=') => Self::Ne,
            ('&', '&') => Self::And,
            ('|', '|') => Self::Or,
            _ => panic!("Operator {}{} invalid", p1.as_char(), p2.as_char()),
        }
    }
}