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#include "ff_context.h"
#include <stdlib.h>
#include <sstream>
#include <cassert>
#include <cmath>
#include "filelib.h"
#include "stringlib.h"
#include "sentence_metadata.h"
#include "lattice.h"
#include "fdict.h"
#include "verbose.h"
RuleContextFeatures::RuleContextFeatures(const string& param) {
// cerr << "initializing RuleContextFeatures with parameters: " << param;
kSOS = TD::Convert("<s>");
kEOS = TD::Convert("</s>");
macro_regex = sregex::compile("%([xy])\\[(-[1-9][0-9]*|0|[1-9][1-9]*)]");
ParseArgs(param);
}
string RuleContextFeatures::Escape(const string& x) const {
string y = x;
for (int i = 0; i < y.size(); ++i) {
if (y[i] == '=') y[i]='_';
if (y[i] == ';') y[i]='_';
}
return y;
}
// replace %x[relative_location] or %y[relative_location] with actual_token
// within feature_instance
void RuleContextFeatures::ReplaceMacroWithString(
string& feature_instance, bool token_vs_label, int relative_location,
const string& actual_token) const {
stringstream macro;
if (token_vs_label) {
macro << "%x[";
} else {
macro << "%y[";
}
macro << relative_location << "]";
int macro_index = feature_instance.find(macro.str());
if (macro_index == string::npos) {
cerr << "Can't find macro " << macro << " in feature template "
<< feature_instance;
abort();
}
feature_instance.replace(macro_index, macro.str().size(), actual_token);
}
void RuleContextFeatures::ReplaceTokenMacroWithString(
string& feature_instance, int relative_location,
const string& actual_token) const {
ReplaceMacroWithString(feature_instance, true, relative_location,
actual_token);
}
void RuleContextFeatures::ReplaceLabelMacroWithString(
string& feature_instance, int relative_location,
const string& actual_token) const {
ReplaceMacroWithString(feature_instance, false, relative_location,
actual_token);
}
void RuleContextFeatures::Error(const string& error_message) const {
cerr << "Error: " << error_message << "\n\n"
<< "RuleContextFeatures Usage: \n"
<< " feature_function=RuleContextFeatures -t <TEMPLATE>\n\n"
<< "Example <TEMPLATE>: U1:%x[-1]_%x[0]|%y[0]\n\n"
<< "%x[k] and %y[k] are macros to be instantiated with an input\n"
<< "token (for x) or a label (for y). k specifies the relative\n"
<< "location of the input token or label with respect to the current\n"
<< "position. For x, k is an integer value. For y, k must be 0 (to\n"
<< "be extended).\n\n";
abort();
}
void RuleContextFeatures::ParseArgs(const string& in) {
vector<string> const& argv = SplitOnWhitespace(in);
for (vector<string>::const_iterator i = argv.begin(); i != argv.end(); ++i) {
string const& s = *i;
if (s[0] == '-') {
if (s.size() > 2) {
stringstream msg;
msg << s << " is an invalid option for RuleContextFeatures.";
Error(msg.str());
}
switch (s[1]) {
// feature template
case 't': {
if (++i == argv.end()) {
Error("Can't find template.");
}
feature_template = *i;
string::const_iterator start = feature_template.begin();
string::const_iterator end = feature_template.end();
smatch macro_match;
// parse the template
while (regex_search(start, end, macro_match, macro_regex)) {
// get the relative location
string relative_location_str(macro_match[2].first,
macro_match[2].second);
int relative_location = atoi(relative_location_str.c_str());
// add it to the list of relative locations for token or label
// (i.e. x or y)
bool valid_location = true;
if (*macro_match[1].first == 'x') {
// add it to token locations
token_relative_locations.push_back(relative_location);
} else {
if (relative_location != 0) { valid_location = false; }
// add it to label locations
label_relative_locations.push_back(relative_location);
}
if (!valid_location) {
stringstream msg;
msg << "Relative location " << relative_location
<< " in feature template " << feature_template
<< " is invalid.";
Error(msg.str());
}
start = macro_match[0].second;
}
break;
}
// TODO: arguments to specify kSOS and kEOS
default: {
stringstream msg;
msg << "Invalid option on RuleContextFeatures: " << s;
Error(msg.str());
break;
}
} // end of switch
} // end of if (token starts with hyphen)
} // end of for loop (over arguments)
// the -t (i.e. template) option is mandatory in this feature function
if (label_relative_locations.size() == 0 ||
token_relative_locations.size() == 0) {
stringstream msg;
msg << "Feature template must specify at least one"
<< "token macro (e.g. x[-1]) and one label macro (e.g. y[0]).";
Error(msg.str());
}
}
void RuleContextFeatures::PrepareForInput(const SentenceMetadata& smeta) {
const Lattice& sl = smeta.GetSourceLattice();
current_input.resize(sl.size());
for (unsigned i = 0; i < sl.size(); ++i) {
if (sl[i].size() != 1) {
stringstream msg;
msg << "RuleContextFeatures don't support lattice inputs!\nid="
<< smeta.GetSentenceId() << endl;
Error(msg.str());
}
current_input[i] = sl[i][0].label;
}
}
void RuleContextFeatures::TraversalFeaturesImpl(
const SentenceMetadata& smeta, const Hypergraph::Edge& edge,
const vector<const void*>& ant_contexts, SparseVector<double>* features,
SparseVector<double>* estimated_features, void* context) const {
const TRule& rule = *edge.rule_;
// arity = 0, no nonterminals
// size = 1, predicted label is a single token
if (rule.Arity() != 0 ||
rule.e_.size() != 1) {
return;
}
// replace label macros with actual label strings
// NOTE: currently, this feature function doesn't allow any label
// macros except %y[0]. but you can look at as much of the source as you want
const WordID y0 = rule.e_[0];
string y0_str = TD::Convert(y0);
// start of the span in the input being labeled
const int from_src_index = edge.i_;
// end of the span in the input
const int to_src_index = edge.j_;
// in the case of tagging the size of the spans being labeled will
// always be 1, but in other formalisms, you can have bigger spans
if (to_src_index - from_src_index != 1) {
cerr << "RuleContextFeatures doesn't support input spans of length != 1";
abort();
}
string feature_instance = feature_template;
// replace token macros with actual token strings
for (unsigned i = 0; i < token_relative_locations.size(); ++i) {
int loc = token_relative_locations[i];
WordID x = loc < 0? kSOS: kEOS;
if(from_src_index + loc >= 0 &&
from_src_index + loc < current_input.size()) {
x = current_input[from_src_index + loc];
}
string x_str = TD::Convert(x);
ReplaceTokenMacroWithString(feature_instance, loc, x_str);
}
ReplaceLabelMacroWithString(feature_instance, 0, y0_str);
// pick a real value for this feature
double fval = 1.0;
// add it to the feature vector
// FD::Convert converts the feature string to a feature int
// Escape makes sure the feature string doesn't have any bad
// symbols that could confuse a parser somewhere
features->add_value(FD::Convert(Escape(feature_instance)), fval);
}
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