[Rust - Task 2] Implemented DELETE clause

Author: TrifanBogdan24

rust-method/src/queries/delete.rs

@@ -0,0 +1,101 @@
+use crate::Secretariat;
+
+
+use crate::queries::where_clause::*;
+
+/*
+TODO: daca stergerea se fac din tabelele Studenti/Materii,
+      sterge intrarile asociate din Inrolari
+ */
+
+fn delete_from_table<T: Matchable>(
+    entries: &mut Vec<T>,
+    conditii: &Vec<Conditie>
+) -> Result<(), String>
+{
+    let mut idx: usize = 0;
+    while idx < entries.len() {
+        match match_on_all_conditii(&entries[idx], conditii)? {
+            true => {
+                entries.remove(idx);
+            }
+            false =>
+                idx += 1
+        }
+
+    }
+
+    Ok(())
+}
+
+/* Template
+DELETE FROM <tabel> WHERE <conditie>;
+DELETE FROM <tabel> WHERE <conditie1> AND <conditie2>;
+*/
+pub fn delete(s: &mut Secretariat, query: &str) -> Result<(), String> {
+    // Gaseste "DELETE" urmat de cel putin un spatiu si "FROM"
+    let delete_from_pos = query.find("DELETE")
+        .ok_or_else(|| "DELETE nu a fost gasit".to_string())?;
+
+    // Avanseaza peste "DELETE"
+    let mut ptr = &query[delete_from_pos + "DELETE".len()..];
+
+    // Trebuie sa existe cel putin un spatiu
+    if !ptr.starts_with(char::is_whitespace) {
+        return Err("trebuie cel putin un spatiu intre DELETE si FROM".to_string());
+    }
+
+    // Sare peste toate spatiile
+    ptr = ptr.trim_start();
+
+    // Verifica ca urmeaza "FROM"
+    if !ptr.starts_with("FROM") {
+        return Err("DELETE trebuie urmat de FROM".to_string());
+    }
+
+    // Avanseaza peste "FROM"
+    ptr = &ptr["FROM".len()..];
+    ptr = ptr.trim_start();
+
+    // Gaseste WHERE daca exista
+    let where_pos = ptr.find("WHERE");
+
+    // Extrage numele tabelei
+    let nume_tabela = if let Some(pos) = where_pos {
+        ptr[..pos].trim()
+    } else {
+        // pana la ';' sau sfarsitul stringului
+        if let Some(end) = ptr.find(';') {
+            ptr[..end].trim()
+        } else {
+            ptr.trim()
+        }
+    };
+
+    // Extrage conditiile daca exista
+    let str_conditii = if let Some(pos) = where_pos {
+        let mut cond_ptr = &ptr[pos + "WHERE".len()..];
+        cond_ptr = cond_ptr.trim_start();
+        if let Some(end) = cond_ptr.find(';') {
+            cond_ptr[..end].trim()
+        } else {
+            cond_ptr.trim()
+        }
+    } else {
+        ""
+    };
+
+
+    // Aici poti implementa logica de stergere din Secretariat
+    let conditii: Vec<Conditie> = parseaza_conditiile_where(str_conditii)?;
+    
+    match nume_tabela {
+        "studenti" => delete_from_table(&mut s.studenti, &conditii),
+        "materii" => delete_from_table(&mut s.materii, &conditii),
+        "inrolari" => delete_from_table(&mut s.inrolari, &conditii),
+        _ => Err(format!(
+            "Tabela {:?} nu exista in baza de date a facultati!",
+            nume_tabela
+        ))
+    }
+}

rust-method/src/queries/select.rs

@@ -132,7 +132,7 @@ pub fn select(s: &Secretariat, query: &str) -> Result<(), String> {
         }
     }
 
-    let mut campuri: Vec<&str>;
+    let campuri: Vec<&str>;
     if is_select_all {
         campuri = match nume_tabela {
             "studenti" => vec!["id", "nume", "an_studiu", "statut", "medie_generala"],
@@ -150,11 +150,7 @@ pub fn select(s: &Secretariat, query: &str) -> Result<(), String> {
             .collect();
     }
 
-    let conditii: Vec<Conditie> = if let Ok(array) = parseaza_conditiile_where(str_conditii) {
-        array
-    } else {
-        return Err("Eroare la parsarea conditiilor!".to_string());
-    };
+    let conditii: Vec<Conditie> = parseaza_conditiile_where(str_conditii)?;
 
     match nume_tabela {
         "studenti" => select_from_table(&s.studenti, &campuri, &conditii),
@@ -163,6 +159,6 @@ pub fn select(s: &Secretariat, query: &str) -> Result<(), String> {
         _ => Err(format!(
             "Tabela {:?} nu exista in baza de date a facultati!",
             nume_tabela
-        )),
+        ))
     }
 }

rust-method/src/queries/where_clause.rs

@@ -84,7 +84,7 @@ fn match_num_on_conditie<T>(num: T, cond: &Conditie) -> Result<bool, String>
 where
     T: FromStr + PartialEq + PartialOrd + std::fmt::Debug,
 {
-    let mut valoare: T;
+    let valoare: T;
     if let Ok(num) = cond.valoare.parse() {
         valoare = num;
     } else {

rust-method/src/task1.rs

@@ -155,7 +155,7 @@ pub fn calculeaza_medii_generale(s: &mut Secretariat) -> () {
             idx_inrolare += 1;
         }
 
-        student.medie_generala = suma_notelor / (idx_inrolare as f32);
+        student.medie_generala = suma_notelor / (nr_materii as f32);
     }
 }
 

rust-method/src/task2.rs

@@ -3,21 +3,19 @@ mod task1;
 mod task3;
 
 mod queries {
-    pub mod select;
     pub mod where_clause;
+    pub mod select;
+    pub mod delete;
 }
 
 use crate::structuri::*;
 use crate::queries::select::select;
-use crate::queries::where_clause::*;
+use crate::queries::delete::delete;
 
 
-use std::fmt::format;
-use std::{env, process::exit, vec};
+use std::{env, process::exit};
 use crate::task1::citeste_secretariat;
-use std::io::{self, BufRead};
-
-use std::str::FromStr;
+use std::io::{self};
 
 
 
@@ -58,6 +56,10 @@ fn main() {
                 Err(message) => eprintln!("[EROARE] {:}", message)
             }
         } else if query.starts_with("DELETE") {
+            match delete(&mut secretariat, query) {
+                Ok(_) => (),
+                Err(message) => eprintln!("[EROARE] {:}", message)
+            }
         } else if query.starts_with("UPDATE") {
         } else {
             eprintln!("[EROARE] Interogare invalida!");

rust-method/src/task3.rs

@@ -1,5 +1,6 @@
 use crate::structuri::*;
 
-pub fn cripteaza_studenti(secretariat: &mut Secretariat, key: &String, iv: &String, cale_output: &String) {
+
+pub fn cripteaza_studenti(_secretariat: &mut Secretariat, _key: &str, _iv: &str, _cale_output: &str) {
     todo!("");
 }