1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166

use std::marker::PhantomData;
use std::mem;
use std::os::raw::c_ulong;
use std::ptr;
use std::slice;

use objc::runtime::Object;
use objc_id::Id;

use INSObject;

pub struct NSEnumerator<'a, T> where T: INSObject {
    id: Id<Object>,
    item: PhantomData<&'a T>,
}

impl<'a, T> NSEnumerator<'a, T> where T: INSObject {
    pub unsafe fn from_ptr(ptr: *mut Object) -> NSEnumerator<'a, T> {
        NSEnumerator { id: Id::from_ptr(ptr), item: PhantomData }
    }
}

impl<'a, T> Iterator for NSEnumerator<'a, T> where T: INSObject {
    type Item = &'a T;

    fn next(&mut self) -> Option<&'a T> {
        unsafe {
            let obj: *mut T = msg_send![self.id, nextObject];
            if obj.is_null() { None } else { Some(&*obj) }
        }
    }
}

pub trait INSFastEnumeration: INSObject {
    type Item: INSObject;

    fn enumerator(&self) -> NSFastEnumerator<Self> {
        NSFastEnumerator::new(self)
    }
}

#[repr(C)]
struct NSFastEnumerationState<T> {
    state: c_ulong,
    items_ptr: *const *const T,
    mutations_ptr: *mut c_ulong,
    extra: [c_ulong; 5],
}

fn enumerate<'a, 'b: 'a, C: INSFastEnumeration>(object: &'b C,
        state: &mut NSFastEnumerationState<C::Item>,
        buf: &'a mut [*const C::Item]) -> Option<&'a [*const C::Item]> {
    let count: usize = unsafe {
        // Reborrow state so that we don't move it
        let state = &mut *state;
        msg_send![object, countByEnumeratingWithState:state
                                              objects:buf.as_mut_ptr()
                                                count:buf.len()]
    };

    if count > 0 {
        unsafe { Some(slice::from_raw_parts(state.items_ptr, count)) }
    } else {
        None
    }
}

const FAST_ENUM_BUF_SIZE: usize = 16;

pub struct NSFastEnumerator<'a, C: 'a + INSFastEnumeration> {
    object: &'a C,

    ptr: *const *const C::Item,
    end: *const *const C::Item,

    state: NSFastEnumerationState<C::Item>,
    buf: [*const C::Item; FAST_ENUM_BUF_SIZE],
}

impl<'a, C: INSFastEnumeration> NSFastEnumerator<'a, C> {
    fn new(object: &C) -> NSFastEnumerator<C> {
        NSFastEnumerator {
            object: object,

            ptr: ptr::null(),
            end: ptr::null(),

            state: unsafe { mem::zeroed() },
            buf: [ptr::null(); FAST_ENUM_BUF_SIZE],
        }
    }

    fn update_buf(&mut self) -> bool {
        // If this isn't our first time enumerating, record the previous value
        // from the mutations pointer.
        let mutations = if !self.ptr.is_null() {
            Some(unsafe { *self.state.mutations_ptr })
        } else {
            None
        };

        let next_buf = enumerate(self.object, &mut self.state, &mut self.buf);
        if let Some(buf) = next_buf {
            // Check if the collection was mutated
            if let Some(mutations) = mutations {
                assert!(mutations == unsafe { *self.state.mutations_ptr },
                    "Mutation detected during enumeration of object {:p}",
                    self.object);
            }

            self.ptr = buf.as_ptr();
            self.end = unsafe { self.ptr.offset(buf.len() as isize) };
            true
        } else {
            self.ptr = ptr::null();
            self.end = ptr::null();
            false
        }
    }
}

impl<'a, C: INSFastEnumeration> Iterator for NSFastEnumerator<'a, C> {
    type Item = &'a C::Item;

    fn next(&mut self) -> Option<&'a C::Item> {
        if self.ptr == self.end && !self.update_buf() {
            None
        } else {
            unsafe {
                let obj = *self.ptr;
                self.ptr = self.ptr.offset(1);
                Some(&*obj)
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use {INSArray, INSValue, NSArray, NSValue};
    use super::INSFastEnumeration;

    #[test]
    fn test_enumerator() {
        let vec = (0u32..4).map(NSValue::from_value).collect();
        let array = NSArray::from_vec(vec);

        let enumerator = array.object_enumerator();
        assert!(enumerator.count() == 4);

        let enumerator = array.object_enumerator();
        assert!(enumerator.enumerate().all(|(i, obj)| obj.value() == i as u32));
    }

    #[test]
    fn test_fast_enumerator() {
        let vec = (0u32..4).map(NSValue::from_value).collect();
        let array = NSArray::from_vec(vec);

        let enumerator = array.enumerator();
        assert!(enumerator.count() == 4);

        let enumerator = array.enumerator();
        assert!(enumerator.enumerate().all(|(i, obj)| obj.value() == i as u32));
    }
}