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#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_);
}
unsigned node_idx() const { return q_.front().node; }
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;
}
unsigned child_node() const {
assert(IsRHS(sym));
return q_.back().node;
}
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
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