added day 13

Author: jsoverson

Cargo.lock

@@ -58,3 +58,14 @@ Modules
 
 - `cargo run -p day-11-modules --bin nested-submodules`
 - `cargo run -p day-11-traffic-light`
+
+### Day 12
+
+- `cargo run -p day-12-impl-tostring`
+- `cargo run -p day-12-impl-asref-str`
+
+### Day 13
+
+- `cargo run -p day-13-option`
+- `cargo run -p day-13-result`
+- `cargo run -p day-13-question-mark`

README.md

@@ -0,0 +1,8 @@
+[package]
+name = "day-13-option"
+version = "0.0.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

crates/day-13/option/Cargo.toml

@@ -0,0 +1,48 @@
+use std::time::Instant;
+
+fn main() {
+ let some = returns_some();
+ println!("{:?}", some);
+
+ let none = returns_none();
+ println!("{:?}", none);
+
+ let default_string = "Default value".to_owned();
+
+ let unwrap_or = returns_none().unwrap_or(default_string);
+ println!("returns_none().unwrap_or(...): {:?}", unwrap_or);
+
+ let unwrap_or_else = returns_none()
+ .unwrap_or_else(|| format!("Default value from a function at time {:?}", Instant::now()));
+
+ println!(
+ "returns_none().unwrap_or_else(|| {{...}}): {:?}",
+ unwrap_or_else
+ );
+
+ let unwrap_or_default = returns_none().unwrap_or_default();
+
+ println!(
+ "returns_none().unwrap_or_default(): {:?}",
+ unwrap_or_default
+ );
+
+ let match_value = match returns_some() {
+ Some(val) => val,
+ None => "My default value".to_owned(),
+ };
+
+ println!("match {{...}}: {:?}", match_value);
+
+ if let Some(val) = returns_some() {
+ println!("if let : {:?}", val);
+ }
+}
+
+fn returns_some() -> Option<String> {
+ Some("my string".to_owned())
+}
+
+fn returns_none() -> Option<String> {
+ None
+}

crates/day-13/option/src/main.rs

@@ -0,0 +1,9 @@
+[package]
+name = "day-13-question-mark"
+version = "0.0.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+markdown = "0.3.0"

crates/day-13/question-mark/Cargo.toml

@@ -0,0 +1,12 @@
+use std::fs::read_to_string;
+
+fn main() -> Result<(), std::io::Error> {
+ let html = render_markdown("./README.md")?;
+ println!("{}", html);
+ Ok(())
+}
+
+fn render_markdown(file: &str) -> Result<String, std::io::Error> {
+ let source = read_to_string(file)?;
+ Ok(markdown::to_html(&source))
+}

crates/day-13/question-mark/src/main.rs

@@ -0,0 +1,8 @@
+[package]
+name = "day-13-result"
+version = "0.0.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

crates/day-13/result/Cargo.toml

@@ -0,0 +1,18 @@
+fn main() {
+ let value = returns_ok();
+ println!("{:?}", value);
+
+ let value = returns_err();
+ println!("{:?}", value);
+}
+
+fn returns_ok() -> Result<String, MyError> {
+ Ok("This turned out great!".to_owned())
+}
+
+fn returns_err() -> Result<String, MyError> {
+ Err(MyError("This failed horribly.".to_owned()))
+}
+
+#[derive(Debug)]
+struct MyError(String);