marpa 0.3.0

Safe bindings to the libmarpa parsing engine
Documentation 
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use crate::thin::bocage as b;
use crate::thin::bocage::Bocage;
use crate::thin::grammar::Grammar;
use libmarpa_sys::*;

use crate::result::*;

pub struct Order {
    internal: Marpa_Order,
    // we need to keep a reference to this accessible
    // in order to read error codes.
    grammar: Grammar,
}

result_from!(Order, Bocage);

pub fn internal(order: &Order) -> Marpa_Order {
    order.internal
}

pub fn grammar(order: &Order) -> Grammar {
    order.grammar.clone()
}

impl Clone for Order {
    fn clone(&self) -> Order {
        unsafe { marpa_o_ref(self.internal) };
        Order {
            internal: self.internal,
            grammar: self.grammar.clone(),
        }
    }
}

impl Drop for Order {
    fn drop(&mut self) {
        unsafe {
            marpa_o_unref(self.internal);
        }
    }
}

impl Order {
    pub fn new(b: Bocage) -> Result<Order> {
        let b_internal = b::internal(&b);
        let grammar = b::grammar(&b);
        match unsafe { marpa_o_new(b_internal) } {
            n if n.is_null() => grammar.error_or("error creating order"),
            o => Ok(Order { internal: o, grammar }),
        }
    }

    pub fn ambiguity_metric(&self) -> Result<i32> {
        match unsafe { marpa_o_ambiguity_metric(self.internal) } {
            -2 => self.grammar.error_or("error getting order ambiguity metric"),
            m if m >= 1 => Ok(m),
            e => panic!("unexpected error code: {}", e),
        }
    }

    pub fn is_null(&self) -> Result<bool> {
        match unsafe { marpa_o_is_null(self.internal) } {
            -2 => self.grammar.error_or("error getting order is_null"),
            0 => Ok(false),
            1 => Ok(true),
            e => panic!("unexpected error code: {}", e),
        }
    }

    pub fn high_rank_only_set(&mut self, high_only: bool) -> Result<()> {
        match unsafe { marpa_o_high_rank_only_set(self.internal, high_only as i32) } {
            -2 => self.grammar.error_or("error setting high rank only"),
            0 | 1 => Ok(()),
            e => panic!("unexpected error code: {}", e),
        }
    }

    pub fn high_rank_only(&self) -> Result<bool> {
        match unsafe { marpa_o_high_rank_only(self.internal) } {
            -2 => self.grammar.error_or("error getting high rank only"),
            0 => Ok(false),
            1 => Ok(true),
            e => panic!("unexpected error code: {}", e),
        }
    }

    pub fn rank(&mut self) -> Result<()> {
        match unsafe { marpa_o_rank(self.internal) } {
            -2 => self.grammar.error_or("error ranking order"),
            i if i >= 0 => Ok(()),
            e => panic!("unexpected error code: {}", e),
        }
    }
}