96 lines
2.8 KiB
Rust
96 lines
2.8 KiB
Rust
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use std::io::Write;
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use std::mem::size_of;
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pub enum StatementType {
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Insert {
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row: Row
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},
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Select,
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}
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const COLUMN_USERNAME_SIZE: usize = 32;
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const COLUMN_EMAIL_SIZE: usize = 255;
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pub struct Row {
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id: u32,
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username: [u8; COLUMN_USERNAME_SIZE],
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email: [u8; COLUMN_EMAIL_SIZE],
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}
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impl Row {
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fn new(id: u32, username: String, email: String) -> Result<Self, String> {
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let username_bytes = username.as_bytes();
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let email_bytes = email.as_bytes();
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if username_bytes.len() > COLUMN_USERNAME_SIZE {
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Err(String::from("username is too long"))
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} else if email_bytes.len() > COLUMN_EMAIL_SIZE {
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Err(String::from("email is too long"))
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} else {
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let username_buffer = &mut [0; COLUMN_USERNAME_SIZE];
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if let Err(_) = pad_buffer(username_buffer, username_bytes) {
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panic!("could not pad username buffer")
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}
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let email_buffer = &mut [0; COLUMN_EMAIL_SIZE];
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if let Err(_) = pad_buffer(email_buffer, username_bytes) {
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panic!("could not pad username buffer")
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}
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Ok(Self {
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id,
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username: *username_buffer,
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email: *email_buffer,
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})
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}
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}
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}
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fn pad_buffer(mut bytes: &mut [u8], source: &[u8]) -> std::io::Result<usize> {
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bytes.write(source)
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}
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pub struct Statement {
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statement_type: StatementType,
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}
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impl Statement {
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pub fn new(statement_type: StatementType) -> Self {
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Self {
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statement_type,
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}
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}
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pub fn parse_statement(command: &String) -> Result<Self, String> {
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if command.starts_with("insert") {
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match sscanf::scanf!(command, "insert {} {} {}", usize, str, str) {
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Ok((id, username, email)) => {
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match Row::new(u32::try_from(id).unwrap(), username.to_string(), email.to_string()) {
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Ok(row) => {
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Ok(Statement::new(StatementType::Insert { row: row }))
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}
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Err(e) => { Err(e) }
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}
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}
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_ => {
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Err(String::from("could not parse insert statement"))
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}
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}
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} else if command.starts_with("select") {
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Ok(Statement::new(StatementType::Select))
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} else {
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return Err(String::from("Could not parse command"));
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}
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}
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pub(crate) fn execute(&self) {
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match &self.statement_type {
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StatementType::Insert { row } => {
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println!("This is where you do an insert {}", row.id)
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}
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StatementType::Select => {
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println!("This is where you do an select")
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}
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}
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}
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}
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