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/*
* This file contains code from "C++ Primer, Fourth Edition", by Stanley B.
* Lippman, Jose Lajoie, and Barbara E. Moo, and is covered under the
* copyright and warranty notices given in that book:
*
* "Copyright (c) 2005 by Objectwrite, Inc., Jose Lajoie, and Barbara E. Moo."
*
*
* "The authors and publisher have taken care in the preparation of this book,
* but make no expressed or implied warranty of any kind and assume no
* responsibility for errors or omissions. No liability is assumed for
* incidental or consequential damages in connection with or arising out of the
* use of the information or programs contained herein."
*
* Permission is granted for this code to be used for educational purposes in
* association with the book, given proper citation if and when posted or
* reproduced.Any commercial use of this code requires the explicit written
* permission of the publisher, Addison-Wesley Professional, a division of
* Pearson Education, Inc. Send your request for permission, stating clearly
* what code you would like to use, and in what specific way, to the following
* address:
*
* Pearson Education, Inc.
* Rights and Contracts Department
* 75 Arlington Street, Suite 300
* Boston, MA 02216
* Fax: (617) 848-7047
*/
#include "3ed_query.h"
#include <string>
#include <vector>
#include <map>
#include <set>
#include <iostream>
#include <fstream>
#include <cctype>
#include <cstring>
using std::set;
using std::string;
using std::getline;
using std::map;
using std::vector;
using std::cerr;
using std::cout;
using std::cin;
using std::ifstream;
using std::endl;
using std::pair;
using std::make_pair;
using std::ispunct;
using std::tolower;
using std::strlen;
// read input file: store each line as element in lines_of_text
void TextQuery::store_file(ifstream &is)
{
string textline;
while (getline(is, textline))
lines_of_text.push_back(textline);
}
set<string> TextQuery::exclusion_set = build_exclusion_set();
// \v: vertical tab; \f: formfeed; \r: carriage return are
// treated as whitespace characters along with space, tab and newline
string TextQuery::whitespace_chars(" \t\n\v\r\f");
// finds the whitespace separated words in the input vector
// then puts them in a cannonical form: eliminate suffixes,
// make lowercase etc. Finally, test if its an excluded word or not.
// If not excluded store the word in word_map along with
// its location (line # and character position) info
void TextQuery::build_map()
{
// process each line from the input vector
for (line_no line_num = 0;
line_num != lines_of_text.size();
++line_num)
{
string textline = lines_of_text[line_num];
if (textline.empty()) continue; //ignore blank lines
// make line lower case and remove extraneous punctuation
strip_caps(textline);
strip_punct(textline);
/*
* Because we want to keep track of position as well as
* line number, we have to process the line a character at a time.
* We can't use an istringstream to read the words.
* prev_pos will denote first character in each word,
* pos will denote whitespace that separates the word from the next
* initially pos denotes first non-whitespace at beginning of line
*/
str_size pos = skip_whitespace(textline, 0), prev_pos = pos;
// find each whitespace separated word
while ((pos = textline.find_first_of(whitespace_chars, pos))
!= string::npos)
{
// remove suffixes and put the word into the map if apporpriate
test_insert(textline, prev_pos, pos, line_num);
// if there's more text to process, increment pos to get next char
if (pos != textline.size())
++pos;
// read and discard adjacent spaces, if any, updating prev_pos too
pos = prev_pos = skip_whitespace(textline, pos);
}
// don't forget last word in the line
if (pos != prev_pos) // false if line ends in whitespace
test_insert(textline, prev_pos, pos, line_num);
}
}
TextQuery::str_size
TextQuery::skip_whitespace(const string &line, str_size pos)
{
// ignore adjacent whitespace
str_size next = line.find_first_not_of(whitespace_chars, pos);
if (next != string::npos)
return next;
else
return line.size();
}
void TextQuery::test_insert(const string &line, str_size prev_pos,
str_size pos, line_no line_num)
{
// make copy of the whitespace delimited word
string word(line.substr(prev_pos, pos - prev_pos));
strip_suffixes(word); // last of the cleanup operations
// if there's anything left after stripping punctuation
// and it's not an excluded word, add to the map
// appending line num & char pos to vector for this word
if (!word.empty() && !exclude_word(word))
word_map[word].push_back(make_pair(line_num,prev_pos));
return;
}
void TextQuery::strip_suffixes(string &word)
{
if (word.size() <= 3) // too short to have any suffixes
return;
if (word[word.size() - 1] == 's') // only handle plurals so far
suffix_s(word);
// additional suffix handling goes here
}
void TextQuery::suffix_s(string &word)
{
// some words ending in s aren't suffixes, they're part of the word
static char* ok_endings[] = {"ous", "ius", "ss", "is"};
size_t sz = sizeof(ok_endings)/sizeof(char*); // how many elements?
for (size_t i = 0; i != sz; ++i)
if (chk_ending(word, ok_endings[i]) == 0)
return;
// replace common suffixes by their base word ending
// repl_endings first dimension is the ending we'll remove
// second dimension is the new ending we'll insert
static char* repl_endings[][2] =
{ {"ies", "y"}, {"ses", "s"}, {"\'s", ""}, {"s", ""} };
sz = sizeof(repl_endings)/(sizeof(char*) * 2); // two-dimensions
for (size_t i = 0; i != sz; ++i)
if (chk_ending(word, repl_endings[i][0]) == 0) {
size_t sz = strlen(repl_endings[i][0]);
word.replace(word.size() - sz, sz, repl_endings[i][1]);
return;
}
}
// compare end of the word with the ending we're given
int TextQuery::chk_ending(const string &word, const char *ending)
{
size_t sz = strlen(ending);
return word.compare(word.size() - sz, sz, ending);
}
void TextQuery::strip_caps(string &line)
{
// not changing the size of line, so safe to cache the size
str_size sz = line.size();
for (str_size pos = 0; pos != sz; ++pos)
line[pos] = tolower(line[pos]);
}
// except for apostrophe, replace punctuation by a space
// apostrophe is special: it might precede by 's, which is a suffix
void TextQuery::strip_punct(string &line)
{
for (str_size pos = 0; pos != line.size(); ++pos)
if (ispunct(line[pos])) {
if (line[pos] != '\'') line[pos] = ' ';
}
}
// this function should be changed to let the user specify a
// file of words to ignore, but for now, we'll keep it simple
// and assume a specific file
set<string> TextQuery::build_exclusion_set()
{
set<string> ret;
ifstream infile("exclusion_set");
if (!infile)
{
static string default_excluded_words[] = {
"the","and","but","that","then","are","been",
"can","can't","cannot","could","did","for",
"had","have","him","his","her","its","into",
"were","which","when","with","would"
};
cerr << "warning! unable to open word exclusion file! -- "
<< "using default set" << endl;
ret = set<string>(default_excluded_words,
default_excluded_words +
sizeof(default_excluded_words)/sizeof(string));
} else {
string word;
while (infile >> word) ret.insert(word);
}
return ret;
}
bool TextQuery::exclude_word(const string &word)
{
return (exclusion_set.find(word) != exclusion_set.end());
}
vector<TextQuery::location> TextQuery::run_query(const string &s)
{
// make local copy so we can clean it up to match words
// entered in the map; but when communicate back to the
// user always use their original version
string sought = s;
strip_caps(sought);
strip_punct(sought);
strip_suffixes(sought);
// Note: must use find and not subscript the map directly
// Subscripting a map adds the element if it's not already there
// We want to know whether the element was there to begin with
if (word_map.find(sought) == word_map.end())
return vector<location>(); // not found, return empty location vector
else
// fetch list of locations for this word
return word_map[sought];
}
void TextQuery::display_map()
{
typedef map< string,vector<location> > map_text;
map_text::iterator iter = word_map.begin(),
iter_end = word_map.end();
// Note: map iter returns index, value pair
// so iter->first is the index word,
// iter->second the vector of its locations
// for each word in the map
while (iter != iter_end) {
cout << "word: " << iter->first << " {";
vector<location> text_locs = iter->second;
vector<location>::iterator liter = text_locs.begin(),
liter_end = text_locs.end();
// print all (line,char) locations for this word
// because this is a debugging routine, don't adjust
// line/pos numbers. As normal for programmers, start from 0
while (liter != liter_end)
{
cout << "(" << liter->first
<< "," << liter->second << ")";
if (++liter != liter_end)
cout << ", ";
}
cout << "}\n"; // end list of output this word
++iter; // get next word in the map
}
cout << endl; // finished printing entire map
}