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
167
168
169
170
171
172
173
174
175
176
177
|
#ifndef TREE_FRAGMENT
#define TREE_FRAGMENT
#include <deque>
#include <iostream>
#include <vector>
#include <string>
#include "tdict.h"
namespace cdec {
class BreadthFirstIterator;
static const unsigned LHS_BIT = 0x10000000u;
static const unsigned RHS_BIT = 0x20000000u;
static const unsigned FRONTIER_BIT = 0x40000000u;
static const unsigned RESERVED_BIT = 0x80000000u;
static const unsigned ALL_MASK = 0x0FFFFFFFu;
inline bool IsNT(unsigned x) {
return (x & (LHS_BIT | RHS_BIT | FRONTIER_BIT));
}
inline bool IsLHS(unsigned x) {
return (x & LHS_BIT);
}
inline bool IsRHS(unsigned x) {
return (x & RHS_BIT);
}
inline bool IsFrontier(unsigned x) {
return (x & FRONTIER_BIT);
}
inline bool IsTerminal(unsigned x) {
return (x & ALL_MASK) == x;
}
struct TreeFragmentProduction {
TreeFragmentProduction() {}
TreeFragmentProduction(int nttype, const std::vector<unsigned>& r) : lhs(nttype), rhs(r) {}
unsigned lhs;
std::vector<unsigned> rhs;
};
// this data structure represents a tree or forest
// productions can have mixtures of terminals and nonterminal symbols and non-terminal frontier sites
class TreeFragment {
public:
TreeFragment() : frontier_sites(), terminals() {}
// (S (NP a (X b) c d) (VP (V foo) (NP (NN bar))))
explicit TreeFragment(const std::string& tree, bool allow_frontier_sites = false);
void DebugRec(unsigned cur, std::ostream* out) const;
typedef BreadthFirstIterator iterator;
typedef ptrdiff_t difference_type;
typedef unsigned value_type;
typedef const unsigned * pointer;
typedef const unsigned & reference;
iterator begin() const;
iterator begin(unsigned node_idx) const;
iterator end() const;
private:
// cp is the character index in the tree
// np keeps track of the nodes (nonterminals) that have been built
// symp keeps track of the terminal symbols that have been built
void ParseRec(const std::string& tree, bool afs, unsigned cp, unsigned symp, unsigned np, unsigned* pcp, unsigned* psymp, unsigned* pnp);
public:
unsigned root;
unsigned char frontier_sites;
unsigned short terminals;
std::vector<TreeFragmentProduction> nodes;
};
struct TFIState {
TFIState() : node(), rhspos(), state() {}
TFIState(unsigned n, unsigned p, unsigned s) : node(n), rhspos(p), state(s) {}
bool operator==(const TFIState& o) const { return node == o.node && rhspos == o.rhspos && state == o.state; }
bool operator!=(const TFIState& o) const { return node != o.node || rhspos != o.rhspos || state != o.state; }
unsigned short node;
unsigned short rhspos;
unsigned char state;
};
class BreadthFirstIterator : public std::iterator<std::forward_iterator_tag, unsigned> {
const TreeFragment* tf_;
std::deque<TFIState> q_;
unsigned sym;
public:
BreadthFirstIterator() : tf_(), sym() {}
// used for begin
explicit BreadthFirstIterator(const TreeFragment* tf, unsigned node_idx) : tf_(tf) {
q_.push_back(TFIState(node_idx, 0, 0));
Stage();
}
// used for end
explicit BreadthFirstIterator(const TreeFragment* tf) : tf_(tf) {}
const unsigned& operator*() const { return sym; }
const unsigned* operator->() const { return &sym; }
bool operator==(const BreadthFirstIterator& other) const {
return (tf_ == other.tf_) && (q_ == other.q_);
}
bool operator!=(const BreadthFirstIterator& other) const {
return (tf_ != other.tf_) || (q_ != other.q_);
}
const BreadthFirstIterator& operator++() {
TFIState& s = q_.front();
if (s.state == 0) {
s.state++;
Stage();
} else {
const unsigned len = tf_->nodes[s.node].rhs.size();
s.rhspos++;
if (s.rhspos >= len) {
q_.pop_front();
Stage();
} else {
Stage();
}
}
return *this;
}
BreadthFirstIterator operator++(int) {
BreadthFirstIterator res = *this;
++(*this);
return res;
}
// tell iterator not to explore the subtree rooted at sym
// should only be called once per NT symbol encountered
const BreadthFirstIterator& truncate() {
assert(IsRHS(sym));
sym &= ALL_MASK;
sym |= FRONTIER_BIT;
q_.pop_back();
return *this;
}
BreadthFirstIterator remainder() const {
assert(IsRHS(sym));
return BreadthFirstIterator(tf_, q_.back());
}
bool at_end() const {
return q_.empty();
}
private:
void Stage() {
if (q_.empty()) return;
const TFIState& s = q_.front();
if (s.state == 0) {
sym = (tf_->nodes[s.node].lhs & ALL_MASK) | LHS_BIT;
} else {
sym = tf_->nodes[s.node].rhs[s.rhspos];
if (IsRHS(sym)) {
q_.push_back(TFIState(sym & ALL_MASK, 0, 0));
sym = tf_->nodes[sym & ALL_MASK].lhs | RHS_BIT;
}
}
}
// used by remainder
BreadthFirstIterator(const TreeFragment* tf, const TFIState& s) : tf_(tf) {
q_.push_back(s);
Stage();
}
};
inline std::ostream& operator<<(std::ostream& os, const TreeFragment& x) {
x.DebugRec(x.nodes.size() - 1, &os);
return os;
}
}
#endif
|
