Optimize for 3 char currency-codes, since ECB only sends those

src/cli/sort_by.rs

@@ -1,5 +1,7 @@
 use clap::ValueEnum;
 
+use crate::models::Currency;
+
 #[derive(Debug, ValueEnum, Clone)]
 pub enum SortBy {
     Currency,
@@ -7,9 +9,9 @@ pub enum SortBy {
 }
 
 impl SortBy {
-    pub fn get_comparer(&self) -> fn(&(&str, f64), &(&str, f64)) -> std::cmp::Ordering {
+    pub fn get_comparer(&self) -> fn(&(&Currency, f64), &(&Currency, f64)) -> std::cmp::Ordering {
         match self {
-            Self::Currency => |a, b| a.0.cmp(&b.0),
+            Self::Currency => |a, b| a.0.as_ref().cmp(b.0.as_ref()),
             Self::Rate => |a, b| a.1.total_cmp(&b.1),
         }
     }

src/main.rs

@@ -3,9 +3,10 @@ use ecb_rates::cache::{Cache, CacheLine};
 use ecb_rates::HeaderDescription;
 use reqwest::{Client, IntoUrl};
 use std::process::ExitCode;
+use std::str::FromStr;
 
 use ecb_rates::cli::{Cli, FormatOption};
-use ecb_rates::models::ExchangeRateResult;
+use ecb_rates::models::{Currency, ExchangeRateResult};
 use ecb_rates::parsing::parse;
 use ecb_rates::table::{TableRef, TableTrait as _};
 use ecb_rates::utils_calc::{change_perspective, filter_currencies, invert_rates, round};
@@ -79,8 +80,18 @@ async fn main() -> ExitCode {
     };
 
     cli.perspective = cli.perspective.map(|s| s.to_uppercase());
-    if let Some(currency) = cli.perspective.as_ref() {
-        header_description.replace_eur(&currency);
+    let parsed_currency = match cli.perspective.as_ref() {
+        Some(currency) => match Currency::from_str(currency) {
+            Ok(k) => Some(k),
+            Err(e) => {
+                eprintln!("The currency code '{}' is invalid: {:?}", currency, e);
+                return ExitCode::FAILURE;
+            }
+        },
+        None => None,
+    };
+    if let Some(currency) = parsed_currency.as_ref() {
+        header_description.replace_eur(currency.as_ref());
         let error_occured = change_perspective(&mut parsed, &currency).is_none();
         if error_occured {
             eprintln!("The currency wasn't in the data from the ECB!");
@@ -96,11 +107,19 @@ async fn main() -> ExitCode {
     round(&mut parsed, cli.max_decimals);
 
     if !cli.currencies.is_empty() {
-        let currencies = cli
+        let currencies = match cli
             .currencies
             .iter()
             .map(|x| x.to_uppercase())
-            .collect::<Vec<_>>();
+            .map(|x| Currency::from_str(&x))
+            .collect::<anyhow::Result<Vec<_>>>()
+        {
+            Ok(k) => k,
+            Err(e) => {
+                eprintln!("Failed to parse currenc(y/ies): {:?}", e);
+                return ExitCode::FAILURE;
+            }
+        };
 
         filter_currencies(&mut parsed, &currencies);
     }

src/models/currency.rs

@@ -0,0 +1,97 @@
+use std::{
+    fmt,
+    ops::Index,
+    slice::Iter,
+    str::{self, FromStr},
+};
+
+use serde::{de, Deserialize, Serialize};
+
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct Currency {
+    name: [u8; 3],
+}
+
+impl Currency {
+    pub fn as_str(&self) -> &str {
+        // SAFETY: We validate that bytes are ASCII in FromStr.
+        unsafe { str::from_utf8_unchecked(&self.name) }
+    }
+
+    pub fn iter(&self) -> Iter<'_, u8> {
+        self.name.iter()
+    }
+}
+
+impl AsRef<str> for Currency {
+    fn as_ref(&self) -> &str {
+        self.as_str()
+    }
+}
+
+impl Serialize for Currency {
+    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
+    where
+        S: serde::Serializer,
+    {
+        serializer.serialize_str(self.as_str())
+    }
+}
+
+impl<'de> Deserialize<'de> for Currency {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: serde::Deserializer<'de>,
+    {
+        let s = String::deserialize(deserializer)?;
+        FromStr::from_str(&s).map_err(de::Error::custom)
+    }
+}
+
+impl FromStr for Currency {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        if s.len() != 3 {
+            anyhow::bail!("Currency code must be exactly 3 chars");
+        }
+        if !s.is_ascii() {
+            anyhow::bail!("Currency code must be ASCII");
+        }
+
+        let b = s.as_bytes();
+        Ok(Self {
+            name: [b[0], b[1], b[2]],
+        })
+    }
+}
+
+impl TryFrom<&str> for Currency {
+    type Error = anyhow::Error;
+    fn try_from(value: &str) -> Result<Self, Self::Error> {
+        Currency::from_str(value)
+    }
+}
+
+impl fmt::Display for Currency {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.write_str(self.as_str())
+    }
+}
+
+impl Index<usize> for Currency {
+    type Output = u8;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        &self.name[index]
+    }
+}
+
+impl<'a> IntoIterator for &'a Currency {
+    type Item = &'a u8;
+    type IntoIter = Iter<'a, u8>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.iter()
+    }
+}

src/models/exchange_rate_result.rs

@@ -1,8 +1,10 @@
 use serde::{Deserialize, Serialize};
 use std::collections::HashMap;
 
+use super::Currency;
+
 #[derive(Debug, Serialize, Deserialize, Clone, PartialEq)]
 pub struct ExchangeRateResult {
     pub time: String,
-    pub rates: HashMap<String, f64>,
+    pub rates: HashMap<Currency, f64>,
 }

src/models/mod.rs

@@ -0,0 +1,5 @@
+mod currency;
+mod exchange_rate_result;
+
+pub use currency::Currency;
+pub use exchange_rate_result::ExchangeRateResult;

src/parsing.rs

@@ -1,9 +1,9 @@
-use std::collections::HashMap;
+use std::{collections::HashMap, str::FromStr};
 
 use quick_xml::events::Event;
 use quick_xml::Reader;
 
-use crate::models::ExchangeRateResult;
+use crate::models::{Currency, ExchangeRateResult};
 
 pub fn parse(xml: &str) -> anyhow::Result<Vec<ExchangeRateResult>> {
     let mut reader = Reader::from_str(xml);
@@ -18,7 +18,7 @@ pub fn parse(xml: &str) -> anyhow::Result<Vec<ExchangeRateResult>> {
         e: &quick_xml::events::BytesStart,
         current_time: &mut Option<String>,
         inside_cube_time: &mut bool,
-        current_rates: &mut HashMap<String, f64>,
+        current_rates: &mut HashMap<Currency, f64>,
         results: &mut Vec<ExchangeRateResult>,
     ) -> anyhow::Result<()> {
         if e.name().local_name().as_ref() != b"Cube" {
@@ -26,7 +26,7 @@ pub fn parse(xml: &str) -> anyhow::Result<Vec<ExchangeRateResult>> {
         }
 
         let mut time_attr: Option<String> = None;
-        let mut currency_attr: Option<String> = None;
+        let mut currency_attr: Option<Currency> = None;
         let mut rate_attr: Option<String> = None;
 
         for attr_result in e.attributes() {
@@ -39,7 +39,7 @@ pub fn parse(xml: &str) -> anyhow::Result<Vec<ExchangeRateResult>> {
                     time_attr = Some(val);
                 }
                 b"currency" => {
-                    currency_attr = Some(val);
+                    currency_attr = Some(Currency::from_str(&val)?);
                 }
                 b"rate" => {
                     rate_attr = Some(val);

src/table/table_owned.rs

@@ -1,7 +1,7 @@
 use std::fmt::Display;
 
 use crate::cli::SortBy;
-use crate::models::ExchangeRateResult;
+use crate::models::{Currency, ExchangeRateResult};
 use crate::DEFAULT_WIDTH;
 
 use super::table_display::helper_table_print;
@@ -11,7 +11,7 @@ pub struct Table {
     pub(super) header: Option<String>,
     pub(super) column_left: String,
     pub(super) column_right: String,
-    pub(super) rows: Vec<(String, f64)>,
+    pub(super) rows: Vec<(Currency, f64)>,
     pub color: bool,
     pub width: usize,
     pub left_offset: usize,
@@ -21,7 +21,7 @@ impl<'a> TableTrait<'a> for Table {
     type Header = String;
     type ColumnLeft = String;
     type ColumnRight = String;
-    type RowLeft = String;
+    type RowLeft = Currency;
 
     fn new(
         header: Option<Self::Header>,
@@ -59,7 +59,7 @@ impl<'a> TableTrait<'a> for Table {
 }
 
 impl TableGet for Table {
-    type RowLeftRef = String;
+    type RowLeftRef = Currency;
     type RowRightRef = String;
 
     fn get_header(&self) -> Option<&str> {
@@ -77,7 +77,7 @@ impl TableGet for Table {
     fn get_width(&self) -> usize {
         self.width
     }
-    
+
     fn get_left_offset(&self) -> usize {
         self.left_offset
     }

src/table/table_ref.rs

@@ -1,7 +1,7 @@
 use std::fmt::Display;
 
 use crate::cli::SortBy;
-use crate::models::ExchangeRateResult;
+use crate::models::{Currency, ExchangeRateResult};
 use crate::DEFAULT_WIDTH;
 
 use super::table_display::helper_table_print;
@@ -13,7 +13,7 @@ pub struct TableRef<'a> {
     header: Option<&'a str>,
     column_left: &'a str,
     column_right: &'a str,
-    rows: Vec<(&'a str, f64)>,
+    rows: Vec<(&'a Currency, f64)>,
     pub color: bool,
     pub width: usize,
     pub left_offset: usize,
@@ -23,7 +23,7 @@ impl<'a> TableTrait<'a> for TableRef<'a> {
     type Header = &'a str;
     type ColumnLeft = &'a str;
     type ColumnRight = &'a str;
-    type RowLeft = &'a str;
+    type RowLeft = &'a Currency;
 
     fn new(
         header: Option<Self::Header>,
@@ -60,7 +60,7 @@ impl<'a> TableTrait<'a> for TableRef<'a> {
 }
 
 impl<'a> TableGet for TableRef<'a> {
-    type RowLeftRef = &'a str;
+    type RowLeftRef = &'a Currency;
     type RowRightRef = &'a str;
 
     fn get_header(&self) -> Option<&str> {
@@ -78,7 +78,7 @@ impl<'a> TableGet for TableRef<'a> {
     fn get_width(&self) -> usize {
         self.width
     }
-    
+
     fn get_left_offset(&self) -> usize {
         self.left_offset
     }
@@ -106,7 +106,7 @@ impl<'a> From<&'a Table> for TableRef<'a> {
         let rows = table
             .rows
             .iter()
-            .map(|(left, right)| (left.as_str(), *right))
+            .map(|(left, right)| (left, *right))
             .collect();
 
         TableRef {

src/utils_calc.rs

@@ -1,10 +1,13 @@
-use std::{borrow::BorrowMut, collections::HashMap, ops::Deref};
+use std::{borrow::BorrowMut, collections::HashMap, ops::Deref, str::FromStr};
 
-use crate::models::ExchangeRateResult;
+use crate::models::{Currency, ExchangeRateResult};
 
-pub fn filter_currencies(exchange_rate_results: &mut [ExchangeRateResult], currencies: &[String]) {
+pub fn filter_currencies(
+    exchange_rate_results: &mut [ExchangeRateResult],
+    currencies: &[Currency],
+) {
     for exchange_rate in exchange_rate_results {
-        let rates_ptr: *mut HashMap<String, f64> = &mut exchange_rate.rates;
+        let rates_ptr: *mut HashMap<Currency, f64> = &mut exchange_rate.rates;
         exchange_rate
             .rates
             .keys()
@@ -22,7 +25,7 @@ pub fn filter_currencies(exchange_rate_results: &mut [ExchangeRateResult], curre
 
 pub fn change_perspective(
     exchange_rate_results: &mut [ExchangeRateResult],
-    currency: &str,
+    currency: &Currency,
 ) -> Option<()> {
     for rate_res in exchange_rate_results {
         let currency_rate = rate_res.rates.remove(currency)?;
@@ -32,7 +35,10 @@ pub fn change_perspective(
             *iter_rate = eur_rate * iter_rate.deref();
         }
 
-        rate_res.rates.insert("EUR".to_string(), eur_rate);
+        rate_res.rates.insert(
+            unsafe { Currency::from_str("EUR").unwrap_unchecked() },
+            eur_rate,
+        );
     }
     Some(())
 }