LCS diff (WIP)

This commit is contained in:
FyloZ 2023-05-31 22:31:49 -04:00
parent 71210dfdac
commit c124d6ccdb
Signed by: william
GPG Key ID: 835378AE9AF4AE97
2 changed files with 81 additions and 45 deletions

74
src/lcs.rs Normal file
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@ -0,0 +1,74 @@
use std::cmp::max;
use std::str::Chars;
use crate::matrix::Matrix;
pub fn diff(a: &str, b: &str) {
let m = build_matrix(a, b);
print_diff(m, &mut a.chars(), &mut b.chars(), a.len() - 1, b.len() - 1);
}
fn build_matrix(a: &str, b: &str) -> Matrix<i32> {
let mut a = a.chars();
let mut b = b.chars();
let mut m = Matrix::new(*(&a.count()), *(&b.count()), 0i32);
for i in 0..a.count() {
for j in 0..b.count() {
let x = a.nth(i).unwrap();
let y = b.nth(j).unwrap();
let v = if x == y {
if i == 0 || j == 0 {
0
} else {
m.get(i - 1, j - 1).unwrap() + 1
}
} else {
max(
if j == 0 { 0 } else { *m.get(i, j - 1).unwrap() },
if i == 0 { 0 } else { *m.get(i - 1, j).unwrap() })
};
m.set(v, i, j).unwrap();
}
}
m
}
fn print_diff(m: Matrix<i32>, a: &mut Chars, b: &mut Chars, i: usize, j: usize) {
if i < 0 && j < 0 {
println!();
return;
}
let char_i = a.nth(i).unwrap();
let char_j = b.nth(j).unwrap();
if i < 0 {
print_diff(m, a, b, i, j - 1);
println!("+ {char_i}");
return;
}
if j < 0 {
print_diff(m, a, b, i - 1, j);
println!("- {char_j}");
return;
}
if char_i == char_j {
print_diff(m, a, b, i - 1, j - 1);
println!(" {char_i}");
return;
}
if m.get(i, j - 1).unwrap() >= m.get(i - 1, j).unwrap() {
print_diff(m, a, b, i, j - 1);
println!("+ {char_j}");
return;
}
print_diff(m, a, b, i - 1, j);
println!("- {char_i}");
}

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@ -1,50 +1,12 @@
use std::cmp::min; use crate::lcs::diff;
use std::io;
use crate::matrix::Matrix;
mod matrix; mod matrix;
mod lcs;
const ADD_VAL: i32 = 1; fn main() {
const MATCH_VAL: i32 = 0; let a = "let a = \"ABCDE\";";
let b = "let b = \"ABCDE\";";
fn main() -> io::Result<()> { diff(a, b);
let str_a = "String A";
let str_b = "String B";
let mut diff_mat = Matrix::new(str_a.len(), str_b.len(), 0i32);
for col in 1..diff_mat.col_count {
let previous = diff_mat.get(0, col - 1).unwrap();
diff_mat.set(previous + ADD_VAL, 0, col).expect("Failed to initialize diff matrix");
}
for row in 1..diff_mat.row_count {
let previous = diff_mat.get(row - 1, 0).unwrap();
diff_mat.set(previous - ADD_VAL, row, 0).expect("Failed to initialize diff matrix");
}
for row in 1..diff_mat.row_count {
for col in 1..diff_mat.col_count {
let char_a = str_a.chars().nth(row).unwrap();
let char_b = str_b.chars().nth(col).unwrap();
let add_from = diff_mat.get(row, col - 1).unwrap();
let sub_from = diff_mat.get(row - 1, col).unwrap();
let substitute_from = diff_mat.get(row - 1, col - 1).unwrap();
let add = add_from + ADD_VAL;
let sub = sub_from - ADD_VAL;
let substitute = substitute_from + if char_a == char_b {
MATCH_VAL
} else {
1
};
let val = min(add, min(sub, substitute));
diff_mat.set(val, row, col).unwrap();
}
}
diff_mat.print();
Ok(())
} }