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Diffstat (limited to 'python/cdec/sa/veb.pxi')
| -rw-r--r-- | python/cdec/sa/veb.pxi | 392 |
1 files changed, 392 insertions, 0 deletions
diff --git a/python/cdec/sa/veb.pxi b/python/cdec/sa/veb.pxi new file mode 100644 index 00000000..40af3a68 --- /dev/null +++ b/python/cdec/sa/veb.pxi @@ -0,0 +1,392 @@ +"""This module implements a partial stratified tree (van Emde Boas, 1977). +Only insert findsucc, __iter__, and __contains__ are implemented. +Delete is currently not supported. +There is very little error-checking in this code -- it is designed +to be used in the limited situation described in Lopez (EMNLP-CoNLL 2007), +which doesn't cover all of the possible ways that you could misuse it +(e.g. trying to insert a key larger than the universe size) +Other notes -- this code is really rather ugly C code masquerading as +Pyrex/Python. Virtual function calls are bypassed by hand in several +places for the sake of efficiency, and other Python niceties are +removed for the same reason.""" + +from libc.stdlib cimport malloc, free +from libc.math cimport log, ceil +from libc.string cimport memset + +cdef int MIN_BOTTOM_SIZE = 32 +cdef int MIN_BOTTOM_BITS = 5 +cdef int LOWER_MASK[32] + +cdef void _init_lower_mask(): + cdef unsigned i + cdef int mask = 0 + for i in range(MIN_BOTTOM_SIZE): + mask = (mask << 1) + 1 + LOWER_MASK[i] = mask + +_init_lower_mask() + +cdef struct _BitSet: + long bitset + int min_val + int max_val + int size + + +cdef _BitSet* new_BitSet(): + cdef _BitSet* b + + b = <_BitSet*> malloc(sizeof(_BitSet)) + b.bitset = 0 + b.min_val = -1 + b.max_val = -1 + b.size = 0 + return b + + +cdef int bitset_findsucc(_BitSet* b, int i): + cdef int bitset, mask + cdef int low, high, mid + + if b.max_val == -1 or i >= b.max_val: + return -1 + if i < b.min_val: + return b.min_val + + bitset = b.bitset & ~LOWER_MASK[i] + low = i+1 + high = b.max_val+1 + while low < high-1: + mid = (high + low)/2 + mask = ~(LOWER_MASK[high-1] ^ LOWER_MASK[mid-1]) + if bitset & mask == 0: + low = mid + else: + bitset = bitset & mask + high = mid + return low + + +cdef int bitset_insert(_BitSet* b, int i): + cdef int val + + val = 1 << i + if b.bitset & val == 0: + b.bitset = b.bitset | val + if b.size == 0: + b.min_val = i + b.max_val = i + else: + if i < b.min_val: + b.min_val = i + if i > b.max_val: + b.max_val = i + b.size = b.size + 1 + return 1 + return 0 + + +cdef int bitset_contains(_BitSet* b, int i): + cdef int val + + val = 1 << i + if b.bitset & val == 0: + return 0 + else: + return 1 + + +cdef class BitSetIterator: + cdef _BitSet* b + cdef int next_val + + def __next__(self): + cdef int ret_val + + if self.next_val == -1: + raise StopIteration() + ret_val = self.next_val + self.next_val = bitset_findsucc(self.b, ret_val) + return ret_val + + + +# This is a Python wrapper class to give access to the +# (entirely C-implemented) _BitSet struct. +# Very slow; use only for debugging +cdef class BitSet: + + cdef _BitSet* b + + def __cinit__(self): + self.b = new_BitSet() + + def __dealloc__(self): + free(self.b) + + def __iter__(self): + cdef BitSetIterator it + it = BitSetIterator() + it.b = self.b + it.next_val = self.b.min_val + return it + + def insert(self, i): + return bitset_insert(self.b, i) + + def findsucc(self, i): + return bitset_findsucc(self.b, i) + + def __str__(self): + return dec2bin(self.b.bitset)+" ("+str(self.b.size)+","+str(self.b.min_val)+","+str(self.b.max_val)+")" + + def min(self): + return self.b.min_val + + def max(self): + return self.b.max_val + + def __len__(self): + return self.b.size + + def __contains__(self, i): + return bool(bitset_contains(self.b, i)) + + +cdef str dec2bin(long i): + cdef str result = "" + cdef unsigned d + for d in range(MIN_BOTTOM_SIZE): + if i & LOWER_MASK[0] == 0: + result = "0"+result + else: + result = "1"+result + i = i >> 1 + return result + +cdef struct _VEB: + int top_universe_size + int num_bottom_bits + int max_val + int min_val + int size + void* top + void** bottom + +cdef _VEB* new_VEB(int n): + cdef _VEB* veb + cdef int num_bits, num_top_bits, i + + veb = <_VEB*> malloc(sizeof(_VEB)) + + num_bits = int(ceil(log(n) / log(2))) + veb.num_bottom_bits = num_bits/2 + if veb.num_bottom_bits < MIN_BOTTOM_BITS: + veb.num_bottom_bits = MIN_BOTTOM_BITS + veb.top_universe_size = (n >> veb.num_bottom_bits) + 1 + + veb.bottom = <void**> malloc(veb.top_universe_size * sizeof(void*)) + memset(veb.bottom, 0, veb.top_universe_size * sizeof(void*)) + + if veb.top_universe_size > MIN_BOTTOM_SIZE: + veb.top = new_VEB(veb.top_universe_size) + else: + veb.top = new_BitSet() + + veb.max_val = -1 + veb.min_val = -1 + veb.size = 0 + return veb + + +cdef int VEB_insert(_VEB* veb, int i): + cdef _VEB* subv + cdef _BitSet* subb + cdef int a, b, tmp + + if veb.size == 0: + veb.min_val = i + veb.max_val = i + elif i == veb.min_val or i == veb.max_val: + return 0 + else: + if i < veb.min_val: + tmp = i + i = veb.min_val + veb.min_val = tmp + a = i >> veb.num_bottom_bits + b = i & LOWER_MASK[veb.num_bottom_bits-1] + if veb.bottom[a] == NULL: + if veb.top_universe_size > MIN_BOTTOM_SIZE: + subv = <_VEB*> veb.top + VEB_insert(subv, a) + else: + subb = <_BitSet*> veb.top + bitset_insert(subb, a) + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + veb.bottom[a] = new_VEB(1 << veb.num_bottom_bits) + else: + veb.bottom[a] = new_BitSet() + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + subv = <_VEB*> veb.bottom[a] + if VEB_insert(subv, b) == 0: + return 0 + else: + subb = <_BitSet*> veb.bottom[a] + if bitset_insert(subb, b) == 0: + return 0 + + if i > veb.max_val: + veb.max_val = i + veb.size = veb.size + 1 + return 1 + + +cdef del_VEB(_VEB* veb): + cdef int i + + if veb.top_universe_size > MIN_BOTTOM_SIZE: + i = (<_VEB*> veb.top).min_val + else: + i = (<_BitSet*> veb.top).min_val + + while i != -1: + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + del_VEB(<_VEB*> veb.bottom[i]) + else: + free(<_BitSet*> veb.bottom[i]) + + if veb.top_universe_size > MIN_BOTTOM_SIZE: + i = VEB_findsucc(<_VEB*> veb.top, i) + else: + i = bitset_findsucc(<_BitSet*> veb.top, i) + + if veb.top_universe_size > MIN_BOTTOM_SIZE: + del_VEB(<_VEB*> veb.top) + else: + free(<_BitSet*> veb.top) + free(veb.bottom) + free(veb) + + +cdef int VEB_findsucc(_VEB* veb, int i): + cdef _VEB* subv + cdef _BitSet* subb + cdef int a, b, j, c, found + + if veb.max_val == -1 or i>=veb.max_val: + return -1 + if i < veb.min_val: + return veb.min_val + + a = i >> veb.num_bottom_bits + b = i & LOWER_MASK[veb.num_bottom_bits-1] + found = 0 + if veb.bottom[a] != NULL: + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + subv = <_VEB*> veb.bottom[a] + if subv.max_val > b: + j = (a << veb.num_bottom_bits) + VEB_findsucc(subv, b) + found = 1 + else: + subb = <_BitSet*> veb.bottom[a] + if subb.max_val > b: + j = (a << veb.num_bottom_bits) + bitset_findsucc(subb, b) + found = 1 + if found==0: + if veb.top_universe_size > MIN_BOTTOM_SIZE: + subv = <_VEB*> veb.top + c = VEB_findsucc(subv, a) + else: + subb = <_BitSet*> veb.top + c = bitset_findsucc(subb, a) + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + subv = <_VEB*> veb.bottom[c] + j = (c << veb.num_bottom_bits) + subv.min_val + else: + subb = <_BitSet*> veb.bottom[c] + j = (c << veb.num_bottom_bits) + subb.min_val + return j + + +cdef int VEB_contains(_VEB* veb, int i): + cdef _VEB* subv + cdef _BitSet* subb + cdef int a, b + + if veb.size == 0 or i < veb.min_val or i > veb.max_val: + return 0 + + if veb.min_val == i: + return 1 + else: + if veb.size == 1: + return 0 + + a = i >> veb.num_bottom_bits + b = i & LOWER_MASK[veb.num_bottom_bits-1] + if veb.bottom[a] == NULL: + return 0 + else: + if veb.num_bottom_bits > MIN_BOTTOM_BITS: + subv = <_VEB*> veb.bottom[a] + return VEB_contains(subv, b) + else: + subb = <_BitSet*> veb.bottom[a] + return bitset_contains(subb, b) + + +cdef class VEBIterator: + cdef _VEB* v + cdef int next_val + + def __next__(self): + cdef int ret_val + + if self.next_val == -1: + raise StopIteration() + ret_val = self.next_val + self.next_val = VEB_findsucc(self.v, ret_val) + return ret_val + + +cdef class VEB: + cdef _VEB* veb + cdef int _findsucc(self, int i) + cdef int _insert(self, int i) + cdef int _first(self) + + def __cinit__(self, int size): + self.veb = new_VEB(size) + + def __dealloc__(self): + del_VEB(self.veb) + + def __iter__(self): + cdef VEBIterator it + it = VEBIterator() + it.v = self.veb + it.next_val = self.veb.min_val + return it + + def insert(self, i): + return VEB_insert(self.veb, i) + + cdef int _insert(self, int i): + return VEB_insert(self.veb, i) + + def findsucc(self, i): + return VEB_findsucc(self.veb, i) + + cdef int _first(self): + return self.veb.min_val + + cdef int _findsucc(self, int i): + return VEB_findsucc(self.veb, i) + + def __len__(self): + return self.veb.size + + def __contains__(self, i): + return VEB_contains(self.veb, i) |