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    use std::fmt;
    use std::mem;

    use super::{
        FAIL_STATE,
        StateIdx, AcAutomaton, Transitions, Match,
        usize_bytes, vec_bytes,
    };
    use super::autiter::Automaton;

    /// A complete Aho-Corasick automaton.
    ///
    /// This uses a single transition matrix that permits each input character
    /// to move to the next state with a single lookup in the matrix.
    ///
    /// This is as fast as it gets, but it is guaranteed to use a lot of memory.
    /// Namely, it will use at least `4 * 256 * #states`, where the number of
    /// states is capped at length of all patterns concatenated.
    #[derive(Clone)]
    pub struct FullAcAutomaton<P> {
        pats: Vec<P>,
        trans: Vec<StateIdx>,  // row-major, where states are rows
        out: Vec<Vec<usize>>, // indexed by StateIdx
        start_bytes: Vec<u8>,
    }

    impl<P: AsRef<[u8]>> FullAcAutomaton<P> {
        /// Build a new expanded Aho-Corasick automaton from an existing
        /// Aho-Corasick automaton.
        pub fn new<T: Transitions>(ac: AcAutomaton<P, T>) -> FullAcAutomaton<P> {
            let mut fac = FullAcAutomaton {
                pats: vec![],
                trans: vec![FAIL_STATE; 256 * ac.states.len()],
                out: vec![vec![]; ac.states.len()],
                start_bytes: vec![],
            };
            fac.build_matrix(&ac);
            fac.pats = ac.pats;
            fac.start_bytes = ac.start_bytes;
            fac
        }

        #[doc(hidden)]
        pub fn memory_usage(&self) -> usize {
            self.pats.iter()
                .map(|p| vec_bytes() + p.as_ref().len())
                .fold(0, |a, b| a + b)
            + (4 * self.trans.len())
            + self.out.iter()
                  .map(|v| vec_bytes() + (usize_bytes() * v.len()))
                  .fold(0, |a, b| a + b)
            + self.start_bytes.len()
        }

        #[doc(hidden)]
        pub fn heap_bytes(&self) -> usize {
            self.pats.iter()
                .map(|p| mem::size_of::<P>() + p.as_ref().len())
                .fold(0, |a, b| a + b)
            + (4 * self.trans.len())
            + self.out.iter()
                  .map(|v| vec_bytes() + (usize_bytes() * v.len()))
                  .fold(0, |a, b| a + b)
            + self.start_bytes.len()
        }

        fn set(&mut self, si: StateIdx, i: u8, goto: StateIdx) {
            let ns = self.num_states();
            self.trans[i as usize * ns + si as usize] = goto;
        }

        #[doc(hidden)]
        #[inline]
        pub fn num_states(&self) -> usize {
            self.out.len()
        }
    }

    impl<P: AsRef<[u8]>> Automaton<P> for FullAcAutomaton<P> {
        #[inline]
        fn next_state(&self, si: StateIdx, i: u8) -> StateIdx {
            let at = i as usize * self.num_states() + si as usize;
            unsafe { *self.trans.get_unchecked(at) }
        }

        #[inline]
        fn get_match(&self, si: StateIdx, outi: usize, texti: usize) -> Match {
            let pati = self.out[si as usize][outi];
            let patlen = self.pats[pati].as_ref().len();
            let start = texti + 1 - patlen;
            Match {
                pati: pati,
                start: start,
                end: start + patlen,
            }
        }

        #[inline]
        fn has_match(&self, si: StateIdx, outi: usize) -> bool {
            unsafe { outi < self.out.get_unchecked(si as usize).len() }
        }

        #[inline]
        fn start_bytes(&self) -> &[u8] {
            &self.start_bytes
        }

        #[inline]
        fn patterns(&self) -> &[P] {
            &self.pats
        }

        #[inline]
        fn pattern(&self, i: usize) -> &P {
            &self.pats[i]
        }
    }

    impl<P: AsRef<[u8]>> FullAcAutomaton<P> {
        fn build_matrix<T: Transitions>(&mut self, ac: &AcAutomaton<P, T>) {
            for (si, s) in ac.states.iter().enumerate().skip(1) {
                for b in (0..256).map(|b| b as u8) {
                    self.set(si as StateIdx, b, ac.next_state(si as StateIdx, b));
                }
                for &pati in &s.out {
                    self.out[si].push(pati);
                }
            }
        }
    }

    impl<P: AsRef<[u8]> + fmt::Debug> fmt::Debug for FullAcAutomaton<P> {
        fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
            write!(f, "FullAcAutomaton({:?})", self.pats)
        }
    }

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