tesseract/dict/permdawg.cpp

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/* -*-C-*-
********************************************************************************
*
2017-07-03 05:35:47 +08:00
* File: permdawg.cpp (Formerly permdawg.c)
* Description: Scale word choices by a dictionary
* Author: Mark Seaman, OCR Technology
* Created: Fri Oct 16 14:37:00 1987
* Modified: Tue Jul 9 15:43:18 1991 (Mark Seaman) marks@hpgrlt
* Language: C
* Package: N/A
* Status: Reusable Software Component
*
* (c) Copyright 1987, Hewlett-Packard Company.
** Licensed under the Apache License, Version 2.0 (the "License");
** you may not use this file except in compliance with the License.
** You may obtain a copy of the License at
** http://www.apache.org/licenses/LICENSE-2.0
** Unless required by applicable law or agreed to in writing, software
** distributed under the License is distributed on an "AS IS" BASIS,
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
** See the License for the specific language governing permissions and
** limitations under the License.
*
*********************************************************************************/
/*----------------------------------------------------------------------
I n c l u d e s
----------------------------------------------------------------------*/
#include "cutil.h"
#include "dawg.h"
#include "globals.h"
#include "ndminx.h"
#include "stopper.h"
#include "tprintf.h"
#include "params.h"
#include <ctype.h>
#include "dict.h"
/*----------------------------------------------------------------------
F u n c t i o n s
----------------------------------------------------------------------*/
namespace tesseract {
/**
* @name go_deeper_dawg_fxn
*
* If the choice being composed so far could be a dictionary word
* keep exploring choices.
*/
void Dict::go_deeper_dawg_fxn(
const char *debug, const BLOB_CHOICE_LIST_VECTOR &char_choices,
int char_choice_index, const CHAR_FRAGMENT_INFO *prev_char_frag_info,
bool word_ending, WERD_CHOICE *word, float certainties[], float *limit,
WERD_CHOICE *best_choice, int *attempts_left, void *void_more_args) {
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DawgArgs *more_args = static_cast<DawgArgs*>(void_more_args);
word_ending = (char_choice_index == char_choices.size()-1);
int word_index = word->length() - 1;
if (best_choice->rating() < *limit) return;
// Look up char in DAWG
// If the current unichar is an ngram first try calling
// letter_is_okay() for each unigram it contains separately.
UNICHAR_ID orig_uch_id = word->unichar_id(word_index);
bool checked_unigrams = false;
if (getUnicharset().get_isngram(orig_uch_id)) {
if (dawg_debug_level) {
tprintf("checking unigrams in an ngram %s\n",
getUnicharset().debug_str(orig_uch_id).string());
}
int num_unigrams = 0;
word->remove_last_unichar_id();
GenericVector<UNICHAR_ID> encoding;
const char *ngram_str = getUnicharset().id_to_unichar(orig_uch_id);
// Since the string came out of the unicharset, failure is impossible.
ASSERT_HOST(getUnicharset().encode_string(ngram_str, true, &encoding, NULL,
NULL));
bool unigrams_ok = true;
// Construct DawgArgs that reflect the current state.
DawgPositionVector unigram_active_dawgs = *(more_args->active_dawgs);
DawgPositionVector unigram_updated_dawgs;
DawgArgs unigram_dawg_args(&unigram_active_dawgs,
&unigram_updated_dawgs,
more_args->permuter);
// Check unigrams in the ngram with letter_is_okay().
for (int i = 0; unigrams_ok && i < encoding.size(); ++i) {
UNICHAR_ID uch_id = encoding[i];
ASSERT_HOST(uch_id != INVALID_UNICHAR_ID);
++num_unigrams;
word->append_unichar_id(uch_id, 1, 0.0, 0.0);
unigrams_ok = (this->*letter_is_okay_)(
&unigram_dawg_args,
word->unichar_id(word_index+num_unigrams-1),
word_ending && i == encoding.size() - 1);
(*unigram_dawg_args.active_dawgs) = *(unigram_dawg_args.updated_dawgs);
if (dawg_debug_level) {
tprintf("unigram %s is %s\n",
getUnicharset().debug_str(uch_id).string(),
unigrams_ok ? "OK" : "not OK");
}
}
// Restore the word and copy the updated dawg state if needed.
while (num_unigrams-- > 0) word->remove_last_unichar_id();
word->append_unichar_id_space_allocated(orig_uch_id, 1, 0.0, 0.0);
if (unigrams_ok) {
checked_unigrams = true;
more_args->permuter = unigram_dawg_args.permuter;
*(more_args->updated_dawgs) = *(unigram_dawg_args.updated_dawgs);
}
}
// Check which dawgs from the dawgs_ vector contain the word
// up to and including the current unichar.
if (checked_unigrams || (this->*letter_is_okay_)(
more_args, word->unichar_id(word_index), word_ending)) {
// Add a new word choice
if (word_ending) {
if (dawg_debug_level) {
tprintf("found word = %s\n", word->debug_string().string());
}
if (strcmp(output_ambig_words_file.string(), "") != 0) {
if (output_ambig_words_file_ == NULL) {
output_ambig_words_file_ =
fopen(output_ambig_words_file.string(), "wb+");
if (output_ambig_words_file_ == NULL) {
tprintf("Failed to open output_ambig_words_file %s\n",
output_ambig_words_file.string());
exit(1);
}
STRING word_str;
word->string_and_lengths(&word_str, NULL);
word_str += " ";
fprintf(output_ambig_words_file_, "%s", word_str.string());
}
STRING word_str;
word->string_and_lengths(&word_str, NULL);
word_str += " ";
fprintf(output_ambig_words_file_, "%s", word_str.string());
}
WERD_CHOICE *adjusted_word = word;
adjusted_word->set_permuter(more_args->permuter);
update_best_choice(*adjusted_word, best_choice);
} else { // search the next letter
// Make updated_* point to the next entries in the DawgPositionVector
// arrays (that were originally created in dawg_permute_and_select)
++(more_args->updated_dawgs);
// Make active_dawgs and constraints point to the updated ones.
++(more_args->active_dawgs);
permute_choices(debug, char_choices, char_choice_index + 1,
prev_char_frag_info, word, certainties, limit,
best_choice, attempts_left, more_args);
// Restore previous state to explore another letter in this position.
--(more_args->updated_dawgs);
--(more_args->active_dawgs);
}
} else {
if (dawg_debug_level) {
tprintf("last unichar not OK at index %d in %s\n",
word_index, word->debug_string().string());
}
}
}
/**
* dawg_permute_and_select
*
* Recursively explore all the possible character combinations in
* the given char_choices. Use go_deeper_dawg_fxn() to search all the
* dawgs in the dawgs_ vector in parallel and discard invalid words.
*
* Allocate and return a WERD_CHOICE with the best valid word found.
*/
WERD_CHOICE *Dict::dawg_permute_and_select(
const BLOB_CHOICE_LIST_VECTOR &char_choices, float rating_limit) {
WERD_CHOICE *best_choice = new WERD_CHOICE(&getUnicharset());
best_choice->make_bad();
best_choice->set_rating(rating_limit);
if (char_choices.length() == 0 || char_choices.length() > MAX_WERD_LENGTH)
return best_choice;
DawgPositionVector *active_dawgs =
new DawgPositionVector[char_choices.length() + 1];
init_active_dawgs(&(active_dawgs[0]), true);
DawgArgs dawg_args(&(active_dawgs[0]), &(active_dawgs[1]), NO_PERM);
WERD_CHOICE word(&getUnicharset(), MAX_WERD_LENGTH);
float certainties[MAX_WERD_LENGTH];
this->go_deeper_fxn_ = &tesseract::Dict::go_deeper_dawg_fxn;
int attempts_left = max_permuter_attempts;
permute_choices((dawg_debug_level) ? "permute_dawg_debug" : NULL,
char_choices, 0, NULL, &word, certainties, &rating_limit, best_choice,
&attempts_left, &dawg_args);
delete[] active_dawgs;
return best_choice;
}
/**
* permute_choices
*
* Call append_choices() for each BLOB_CHOICE in BLOB_CHOICE_LIST
* with the given char_choice_index in char_choices.
*/
void Dict::permute_choices(
const char *debug,
const BLOB_CHOICE_LIST_VECTOR &char_choices,
int char_choice_index,
const CHAR_FRAGMENT_INFO *prev_char_frag_info,
WERD_CHOICE *word,
float certainties[],
float *limit,
WERD_CHOICE *best_choice,
int *attempts_left,
void *more_args) {
if (debug) {
tprintf("%s permute_choices: char_choice_index=%d"
" limit=%g rating=%g, certainty=%g word=%s\n",
debug, char_choice_index, *limit, word->rating(),
word->certainty(), word->debug_string().string());
}
if (char_choice_index < char_choices.length()) {
BLOB_CHOICE_IT blob_choice_it;
blob_choice_it.set_to_list(char_choices.get(char_choice_index));
for (blob_choice_it.mark_cycle_pt(); !blob_choice_it.cycled_list();
blob_choice_it.forward()) {
(*attempts_left)--;
append_choices(debug, char_choices, *(blob_choice_it.data()),
char_choice_index, prev_char_frag_info, word,
certainties, limit, best_choice, attempts_left, more_args);
if (*attempts_left <= 0) {
if (debug) tprintf("permute_choices(): attempts_left is 0\n");
break;
}
}
}
}
/**
* append_choices
*
* Checks to see whether or not the next choice is worth appending to
* the word being generated. If so then keeps going deeper into the word.
*
* This function assumes that Dict::go_deeper_fxn_ is set.
*/
void Dict::append_choices(
const char *debug,
const BLOB_CHOICE_LIST_VECTOR &char_choices,
const BLOB_CHOICE &blob_choice,
int char_choice_index,
const CHAR_FRAGMENT_INFO *prev_char_frag_info,
WERD_CHOICE *word,
float certainties[],
float *limit,
WERD_CHOICE *best_choice,
int *attempts_left,
void *more_args) {
int word_ending =
(char_choice_index == char_choices.length() - 1) ? true : false;
// Deal with fragments.
CHAR_FRAGMENT_INFO char_frag_info;
if (!fragment_state_okay(blob_choice.unichar_id(), blob_choice.rating(),
blob_choice.certainty(), prev_char_frag_info, debug,
word_ending, &char_frag_info)) {
return; // blob_choice must be an invalid fragment
}
// Search the next letter if this character is a fragment.
if (char_frag_info.unichar_id == INVALID_UNICHAR_ID) {
permute_choices(debug, char_choices, char_choice_index + 1,
&char_frag_info, word, certainties, limit,
best_choice, attempts_left, more_args);
return;
}
// Add the next unichar.
float old_rating = word->rating();
float old_certainty = word->certainty();
uinT8 old_permuter = word->permuter();
certainties[word->length()] = char_frag_info.certainty;
word->append_unichar_id_space_allocated(
char_frag_info.unichar_id, char_frag_info.num_fragments,
char_frag_info.rating, char_frag_info.certainty);
// Explore the next unichar.
(this->*go_deeper_fxn_)(debug, char_choices, char_choice_index,
&char_frag_info, word_ending, word, certainties,
limit, best_choice, attempts_left, more_args);
// Remove the unichar we added to explore other choices in it's place.
word->remove_last_unichar_id();
word->set_rating(old_rating);
word->set_certainty(old_certainty);
word->set_permuter(old_permuter);
}
/**
* @name fragment_state
*
* Given the current char choice and information about previously seen
* fragments, determines whether adjacent character fragments are
* present and whether they can be concatenated.
*
* The given prev_char_frag_info contains:
* - fragment: if not NULL contains information about immediately
* preceding fragmented character choice
* - num_fragments: number of fragments that have been used so far
* to construct a character
* - certainty: certainty of the current choice or minimum
* certainty of all fragments concatenated so far
* - rating: rating of the current choice or sum of fragment
* ratings concatenated so far
*
* The output char_frag_info is filled in as follows:
* - character: is set to be NULL if the choice is a non-matching
* or non-ending fragment piece; is set to unichar of the given choice
* if it represents a regular character or a matching ending fragment
* - fragment,num_fragments,certainty,rating are set as described above
*
* @returns false if a non-matching fragment is discovered, true otherwise.
*/
bool Dict::fragment_state_okay(UNICHAR_ID curr_unichar_id,
float curr_rating, float curr_certainty,
const CHAR_FRAGMENT_INFO *prev_char_frag_info,
const char *debug, int word_ending,
CHAR_FRAGMENT_INFO *char_frag_info) {
const CHAR_FRAGMENT *this_fragment =
getUnicharset().get_fragment(curr_unichar_id);
const CHAR_FRAGMENT *prev_fragment =
prev_char_frag_info != NULL ? prev_char_frag_info->fragment : NULL;
// Print debug info for fragments.
if (debug && (prev_fragment || this_fragment)) {
tprintf("%s check fragments: choice=%s word_ending=%d\n", debug,
getUnicharset().debug_str(curr_unichar_id).string(),
word_ending);
if (prev_fragment) {
tprintf("prev_fragment %s\n", prev_fragment->to_string().string());
}
if (this_fragment) {
tprintf("this_fragment %s\n", this_fragment->to_string().string());
}
}
char_frag_info->unichar_id = curr_unichar_id;
char_frag_info->fragment = this_fragment;
char_frag_info->rating = curr_rating;
char_frag_info->certainty = curr_certainty;
char_frag_info->num_fragments = 1;
if (prev_fragment && !this_fragment) {
if (debug) tprintf("Skip choice with incomplete fragment\n");
return false;
}
if (this_fragment) {
// We are dealing with a fragment.
char_frag_info->unichar_id = INVALID_UNICHAR_ID;
if (prev_fragment) {
if (!this_fragment->is_continuation_of(prev_fragment)) {
if (debug) tprintf("Non-matching fragment piece\n");
return false;
}
if (this_fragment->is_ending()) {
char_frag_info->unichar_id =
getUnicharset().unichar_to_id(this_fragment->get_unichar());
char_frag_info->fragment = NULL;
if (debug) {
tprintf("Built character %s from fragments\n",
getUnicharset().debug_str(
char_frag_info->unichar_id).string());
}
} else {
if (debug) tprintf("Record fragment continuation\n");
char_frag_info->fragment = this_fragment;
}
// Update certainty and rating.
char_frag_info->rating =
prev_char_frag_info->rating + curr_rating;
char_frag_info->num_fragments = prev_char_frag_info->num_fragments + 1;
char_frag_info->certainty =
MIN(curr_certainty, prev_char_frag_info->certainty);
} else {
if (this_fragment->is_beginning()) {
if (debug) tprintf("Record fragment beginning\n");
} else {
if (debug) {
tprintf("Non-starting fragment piece with no prev_fragment\n");
}
return false;
}
}
}
if (word_ending && char_frag_info->fragment) {
if (debug) tprintf("Word can not end with a fragment\n");
return false;
}
return true;
}
} // namespace tesseract