Better string handling
The text and pattern are now streamed directly (skipping saving them to strings). Knowing exactly what string was matched has now been delegated to the Rabin_fingerprint_process.
This commit is contained in:
parent
c6b6329134
commit
b9645f15ff
13
README.md
13
README.md
@ -2,9 +2,20 @@
|
|||||||
|
|
||||||
Code used for my Bachelor's Thesis
|
Code used for my Bachelor's Thesis
|
||||||
|
|
||||||
|
# Issues
|
||||||
|
When reading the pattern from a file, according to UNIX standards ([read details here](https://unix.stackexchange.com/questions/18743/whats-the-point-in-adding-a-new-line-to-the-end-of-a-file)) a "text file" has to end on a newline.
|
||||||
|
This adds an unintended newline to the end of the pattern, so to avoid adding said newline, write the file using:
|
||||||
|
`echo -n word > pattern.txt`
|
||||||
|
or if you use Vim, remove the newline using
|
||||||
|
```
|
||||||
|
:set binary
|
||||||
|
:set noeol
|
||||||
|
:wq
|
||||||
|
```
|
||||||
|
|
||||||
# Versions
|
# Versions
|
||||||
## Current Version
|
## Current Version
|
||||||
Compared to V1, this current state `generate_initial_irreducible_polynomials.sage`, `generate_random_irreducible_polynomial.sage`, and `multiply_polynomials_modulo_polynomial.sage` have been removed from the main folder, as they have already been used for implementing their corresponding features in `general_library.cpp`. They will be preserved in the V1 folder.
|
Compared to V1, in this current state `generate_initial_irreducible_polynomials.sage`, `generate_random_irreducible_polynomial.sage`, and `multiply_polynomials_modulo_polynomial.sage` have been removed from the main folder, as they have already been used for implementing their corresponding features in `general_library.cpp`. They will be preserved in the V1 folder.
|
||||||
|
|
||||||
This version also contains code relating to Porat-Porat and other random code stumps. This code is going to be completely reimplemented, but is preserved for now to avoid redoing work.
|
This version also contains code relating to Porat-Porat and other random code stumps. This code is going to be completely reimplemented, but is preserved for now to avoid redoing work.
|
||||||
|
|
||||||
|
Binary file not shown.
1
books/pattern.txt
Normal file
1
books/pattern.txt
Normal file
@ -0,0 +1 @@
|
|||||||
|
word
|
@ -5,14 +5,14 @@ Rabin_fingerprint_process::Rabin_fingerprint_process(uint32_t irr_poly, size_t w
|
|||||||
phi(irr_poly, window_size_in_bits)
|
phi(irr_poly, window_size_in_bits)
|
||||||
{}
|
{}
|
||||||
|
|
||||||
void Rabin_fingerprint_process::stream_char (char c) {
|
void Rabin_fingerprint_process::stream_char(char c) {
|
||||||
std::bitset<8> b(c);
|
std::bitset<8> b(c);
|
||||||
for (char i = 7; i >= 0; i--) {
|
for (char i = 7; i >= 0; i--) {
|
||||||
stream_bit((bool)b[i]);
|
stream_bit((bool)b[i]);
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
void Rabin_fingerprint_process::stream_bit (bool b) {
|
void Rabin_fingerprint_process::stream_bit(bool b) {
|
||||||
if (window.size() == window_size_in_bits) {
|
if (window.size() == window_size_in_bits) {
|
||||||
window.push(b);
|
window.push(b);
|
||||||
bool b_out = window.front();
|
bool b_out = window.front();
|
||||||
@ -24,6 +24,36 @@ void Rabin_fingerprint_process::stream_bit (bool b) {
|
|||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
uint32_t Rabin_fingerprint_process::get_fingerprint () {
|
uint32_t Rabin_fingerprint_process::get_fingerprint() {
|
||||||
return phi.get_fingerprint();
|
return phi.get_fingerprint();
|
||||||
}
|
}
|
||||||
|
|
||||||
|
std::string Rabin_fingerprint_process::get_string_in_window() {
|
||||||
|
// check if window contains a whole number of chars
|
||||||
|
if ((window_size_in_bits & 0b111) != 0)
|
||||||
|
throw std::logic_error("The fingerprinting window doesn't contain a whole number of chars (counting the bits), so it doesn't make sense to return it as a string.");
|
||||||
|
|
||||||
|
#ifndef NDEBUG
|
||||||
|
if (window.size() != window_size_in_bits)
|
||||||
|
throw std::logic_error("False match! The sliding window isn't even filled yet, which means you matched the pattern of a substring shorter than the pattern. This case should be handled/avoided elsewhere, so we throw an error.");
|
||||||
|
#endif
|
||||||
|
|
||||||
|
std::ostringstream os;
|
||||||
|
for (size_t i = 0; i < window.size()>>3; i++) {
|
||||||
|
// cycle the char
|
||||||
|
char c = 0;
|
||||||
|
for (size_t j = 0; j < 8; j++) {
|
||||||
|
bool b = window.front();
|
||||||
|
window.pop();
|
||||||
|
window.push(b);
|
||||||
|
c <<= 1;
|
||||||
|
c |= b;
|
||||||
|
}
|
||||||
|
|
||||||
|
os << c;
|
||||||
|
}
|
||||||
|
|
||||||
|
std::string s = os.str();
|
||||||
|
|
||||||
|
return s;
|
||||||
|
}
|
||||||
|
@ -6,6 +6,8 @@
|
|||||||
|
|
||||||
#include <stdint.h>
|
#include <stdint.h>
|
||||||
#include <queue>
|
#include <queue>
|
||||||
|
#include <string>
|
||||||
|
#include <sstream>
|
||||||
|
|
||||||
class Rabin_fingerprint_process {
|
class Rabin_fingerprint_process {
|
||||||
public:
|
public:
|
||||||
@ -13,6 +15,7 @@ class Rabin_fingerprint_process {
|
|||||||
void stream_char(char c);
|
void stream_char(char c);
|
||||||
void stream_bit(bool b);
|
void stream_bit(bool b);
|
||||||
uint32_t get_fingerprint();
|
uint32_t get_fingerprint();
|
||||||
|
std::string get_string_in_window();
|
||||||
|
|
||||||
private:
|
private:
|
||||||
std::queue<bool> window;
|
std::queue<bool> window;
|
||||||
|
Binary file not shown.
@ -1,6 +1,6 @@
|
|||||||
/* #define NDEBUG */
|
/* #define NDEBUG */
|
||||||
/* #include "Rabin_fingerprint.hpp" */
|
/* #include "Rabin_fingerprint.hpp" */
|
||||||
/* #include "general_library.hpp" */
|
#include "general_library.hpp"
|
||||||
#include "processes.hpp"
|
#include "processes.hpp"
|
||||||
|
|
||||||
#include <iostream>
|
#include <iostream>
|
||||||
@ -9,46 +9,42 @@
|
|||||||
#include <string>
|
#include <string>
|
||||||
#include <fstream>
|
#include <fstream>
|
||||||
|
|
||||||
void print_match (size_t index, size_t length, std::string &T) {
|
|
||||||
std::cout << "Match found at index " << index << " with the text \"";
|
|
||||||
for (size_t i = 0; i < length; i++)
|
|
||||||
std::cout << T[index + i];
|
|
||||||
std::cout << "\"" << std::endl;
|
|
||||||
}
|
|
||||||
|
|
||||||
int main() {
|
int main() {
|
||||||
/* std::ifstream ifs("books/the_complete_works_of_william_shakespeare.txt"); */
|
/* std::ifstream T("books/the_complete_works_of_william_shakespeare.txt"); */
|
||||||
std::ifstream ifs("books/genji_monogatari_english.txt");
|
std::ifstream T("books/genji_monogatari_english.txt");
|
||||||
std::string T( (std::istreambuf_iterator<char>(ifs) ),
|
std::ifstream P("books/pattern.txt");
|
||||||
(std::istreambuf_iterator<char>() ) );
|
|
||||||
|
|
||||||
std::string P = "word";
|
|
||||||
|
|
||||||
|
char c;
|
||||||
|
size_t P_length = 0;
|
||||||
std::cout << "Searching for pattern:" << std::endl;
|
std::cout << "Searching for pattern:" << std::endl;
|
||||||
std::cout << " " << P << std::endl;
|
std::cout << " ";
|
||||||
/* std::cout << "in text:" << std::endl; */
|
while(P.get(c)) {
|
||||||
/* std::cout << " " << T << std::endl; */
|
std::cout << c;
|
||||||
std::cout << std::endl;
|
P_length++;
|
||||||
|
|
||||||
|
}
|
||||||
|
std::cout << std::endl << std::endl;
|
||||||
|
|
||||||
|
P.clear(); // clear fail and eof bits
|
||||||
|
P.seekg(0, std::ios::beg); // back to the start!
|
||||||
|
|
||||||
uint32_t irreducible_polynomial = get_random_irreducible_polynomial_in_Z2(31);
|
uint32_t irreducible_polynomial = get_random_irreducible_polynomial_in_Z2(31);
|
||||||
size_t window_size_in_bits = P.length()*8;
|
size_t window_size_in_bits = P_length*8;
|
||||||
|
|
||||||
// Hash the pattern
|
// Hash the pattern
|
||||||
Rabin_fingerprint_process phiP(irreducible_polynomial, (size_t)window_size_in_bits);
|
Rabin_fingerprint_process phiP(irreducible_polynomial, (size_t)window_size_in_bits);
|
||||||
for (char c : P)
|
while(P.get(c)) {
|
||||||
phiP.stream_char(c);
|
phiP.stream_char(c);
|
||||||
|
}
|
||||||
|
|
||||||
// Hash the text
|
// Hash the text
|
||||||
Rabin_fingerprint_process phiT(irreducible_polynomial, window_size_in_bits);
|
Rabin_fingerprint_process phiT(irreducible_polynomial, window_size_in_bits);
|
||||||
for (size_t i = 0; i < P.length(); i++)
|
size_t index = 0;
|
||||||
phiT.stream_char(T[i]);
|
while(T.get(c)) {
|
||||||
|
phiT.stream_char(c);
|
||||||
|
index++;
|
||||||
if (phiT.get_fingerprint() == phiP.get_fingerprint())
|
if (phiT.get_fingerprint() == phiP.get_fingerprint())
|
||||||
print_match(0, P.length(), T);
|
std::cout << "Match found at index " << index-P_length << " with the text \"" << phiT.get_string_in_window() << "\"" << std::endl;
|
||||||
|
|
||||||
for (size_t i = P.length(); i < T.length(); i++) {
|
|
||||||
phiT.stream_char(T[i]);
|
|
||||||
if (phiT.get_fingerprint() == phiP.get_fingerprint())
|
|
||||||
print_match(i-P.length()+1, P.length(), T);
|
|
||||||
}
|
}
|
||||||
|
|
||||||
std::cout << std::endl;
|
std::cout << std::endl;
|
||||||
|
Loading…
Reference in New Issue
Block a user