move cnf code to a separate file

rust/dpll/src/cnf.rs

@@ -0,0 +1,68 @@
 pub struct CNF {
	  pub num_vars: u32,
	  pub num_clauses: u32,
	  pub clauses: Vec<Vec<i32>>
 }
 /// Parses a CNF formula in DIMAC format.
 ///
 /// # Examples
 ///
 /// A simple example for a formula in DIMAC format is below:
 ///
 /// ```text
 /// p cnf 5 3
 /// 1 2 3 0
 /// -2 3 4 0
 /// 4 5 0
 /// ```
 ///
 /// The above represents a formula with 5 variables and 3 clauses.  The first
 /// line specifies this.  Each following line represents a clause with possibly
 /// negated literals, terminated by 0 and a newline.
 pub fn parse_dimac(dimac: &str) -> Result<CNF, String> {
	  let mut lines = dimac.lines();
	  let mut num_vars;
	  let mut num_clauses;
	  
	  match lines.next() {
			None => { return Err("expected cnf description".to_string()) }
			Some(line) => {
				 let desc: Vec<&str> = line.split(" ").collect();
				 if desc.len() != 4 || desc[0] != "p" || desc[1] != "cnf" {
					  return Err("cnf description must be of the form 'p cnf <num vars> <num clauses>'".to_string())
				 }
				 match desc[2].parse::<u32>() {
					  Ok(n) => { num_vars = n }
					  Err(e) => { return Err(format!("<num vars> must be a positive integer: {}", e)) }
				 }
				 
				 match desc[3].parse::<u32>() {
					  Ok(n) => { num_clauses = n }
					  Err(e) => { return Err(format!("<num clauses> must be a positive integer: {}", e)) }
				 }
			}
	  }
	  let clause_lines: Vec<&str> = lines.collect();
	  if clause_lines.len() as u32 != num_clauses {
			return Err(format!("Wrong number of clauses: Expected {}, but got {}", num_clauses, clause_lines.len()))
	  }
	  let mut clauses: Vec<Vec<i32>> = Vec::with_capacity(num_clauses as usize);
	  for clause_line in clause_lines {
			let mut vars: Vec<i32> = clause_line.split(" ").map(|x| x.parse::<i32>().unwrap()).collect();
			if vars.is_empty() {
				 return Err("empty clause".to_string())
			}
			if vars[vars.len()-1] != 0 {
				 return Err("clause must be terminated with 0".to_string())
			}
			let l = vars.len();
			vars.truncate(l - 1);
			clauses.push(vars)
	  }
	  let cnf = CNF { num_vars: num_vars, num_clauses: num_clauses, clauses: clauses };
	  return Ok(cnf)
 }

rust/dpll/src/main.rs

@@ -10,76 +10,7 @@
use std::io;
use std::io::Read;
mod cnf {
    pub struct CNF {
        pub num_vars: u32,
        pub num_clauses: u32,
        pub clauses: Vec<Vec<i32>>
    }
    /// Parses a CNF formula in DIMAC format.
    ///
    /// # Examples
    ///
    /// A simple example for a formula in DIMAC format is below:
    ///
    /// ```text
    /// p cnf 5 3
    /// 1 2 3 0
    /// -2 3 4 0
    /// 4 5 0
    /// ```
    ///
    /// The above represents a formula with 5 variables and 3 clauses.  The first
    /// line specifies this.  Each following line represents a clause with possibly
    /// negated literals, terminated by 0 and a newline.
    pub fn parse_dimac(dimac: &str) -> Result<CNF, String> {
        let mut lines = dimac.lines();
        let mut num_vars;
        let mut num_clauses;
        
        match lines.next() {
            None => { return Err("expected cnf description".to_string()) }
            Some(line) => {
                let desc: Vec<&str> = line.split(" ").collect();
                if desc.len() != 4 || desc[0] != "p" || desc[1] != "cnf" {
                    return Err("cnf description must be of the form 'p cnf <num vars> <num clauses>'".to_string())
                }
                match desc[2].parse::<u32>() {
                    Ok(n) => { num_vars = n }
                    Err(e) => { return Err(format!("<num vars> must be a positive integer: {}", e)) }
                }
                
                match desc[3].parse::<u32>() {
                    Ok(n) => { num_clauses = n }
                    Err(e) => { return Err(format!("<num clauses> must be a positive integer: {}", e)) }
                }
            }
        }
        let clause_lines: Vec<&str> = lines.collect();
        if clause_lines.len() as u32 != num_clauses {
            return Err(format!("Wrong number of clauses: Expected {}, but got {}", num_clauses, clause_lines.len()))
        }
        let mut clauses: Vec<Vec<i32>> = Vec::with_capacity(num_clauses as usize);
        for clause_line in clause_lines {
            let mut vars: Vec<i32> = clause_line.split(" ").map(|x| x.parse::<i32>().unwrap()).collect();
            if vars.is_empty() {
                return Err("empty clause".to_string())
            }
            if vars[vars.len()-1] != 0 {
                return Err("clause must be terminated with 0".to_string())
            }
            let l = vars.len();
            vars.truncate(l - 1);
            clauses.push(vars)
        }
        let cnf = CNF { num_vars: num_vars, num_clauses: num_clauses, clauses: clauses };
        return Ok(cnf)
    }
}
mod cnf;
fn main() {
    let input: &mut String = &mut String::new();