Dressed day 1 up as a cli app

4 files changed, 237 insertions, 47 deletions

diff --git a/Cargo.lock b/Cargo.lock
index 3719353..149a347 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -3,4 +3,199 @@
 [[package]]
 name = "advent-of-code-2019"
 version = "0.1.0"
+dependencies = [
+ "derive_more 0.99.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
+]
 
+[[package]]
+name = "ansi_term"
+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "atty"
+version = "0.2.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "libc 0.2.66 (registry+https://github.com/rust-lang/crates.io-index)",
+ "winapi 0.3.8 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "bitflags"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "clap"
+version = "2.33.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "ansi_term 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "atty 0.2.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "bitflags 1.2.1 (registry+https://github.com/rust-lang/crates.io-index)",
+ "strsim 0.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "textwrap 0.11.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "unicode-width 0.1.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "vec_map 0.8.1 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "derive_more"
+version = "0.99.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
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+ "syn 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
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+
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
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+
+[[package]]
+name = "libc"
+version = "0.2.66"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "proc-macro-error"
+version = "0.2.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
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+ "syn 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
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+
+[[package]]
+name = "proc-macro2"
+version = "1.0.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
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+
+[[package]]
+name = "quote"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "strsim"
+version = "0.8.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "structopt"
+version = "0.3.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "clap 2.33.0 (registry+https://github.com/rust-lang/crates.io-index)",
+ "structopt-derive 0.3.5 (registry+https://github.com/rust-lang/crates.io-index)",
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+
+[[package]]
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+ "proc-macro2 1.0.6 (registry+https://github.com/rust-lang/crates.io-index)",
+ "quote 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)",
+ "syn 1.0.11 (registry+https://github.com/rust-lang/crates.io-index)",
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+[[package]]
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+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
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+ "unicode-xid 0.2.0 (registry+https://github.com/rust-lang/crates.io-index)",
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+
+[[package]]
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+version = "0.11.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
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+
+[[package]]
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+version = "1.6.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
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+version = "0.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
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+dependencies = [
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+source = "registry+https://github.com/rust-lang/crates.io-index"
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diff --git a/Cargo.toml b/Cargo.toml
index 870468a..69a0b81 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,3 +7,5 @@ edition = "2018"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+structopt = "0.3.5"
+derive_more = "0.99.2"
\ No newline at end of file
diff --git a/readme.org b/readme.org
index c1923ac..97f5511 100644
--- a/readme.org
+++ b/readme.org
@@ -10,3 +10,10 @@ program should only be pure expressions.
 
 - Limit the use of statements. Try to use expressions instead, or move
   the statement out to a function.
+
+** Findings
+
+- Having iterators that you can't clone (like stdin) makes certain
+  things difficult. Eg, doing part 1 and 2 together.
+- Using "new type" structs can be a pain. derive_more crate made most
+  of that pain go away.
diff --git a/src/bin/day_1.rs b/src/bin/day_1.rs
index 7c8f104..b9a6c18 100644
--- a/src/bin/day_1.rs
+++ b/src/bin/day_1.rs
@@ -1,57 +1,56 @@
+use derive_more;
 use std::io;
 use std::io::prelude::*;
 use std::iter;
-use std::iter::Sum;
-use std::num::ParseIntError;
-use std::ops::Add;
-use std::str::FromStr;
+
+use structopt::StructOpt;
+
+#[derive(Debug, StructOpt)]
+#[structopt(name = "Day 1: The Tyranny of the Rocket Equation")]
+/// Calculates the fuel needed for your rocket to save Santa.
+///
+/// The weight of each module is read from stdin, one module weight
+/// per line. See https://adventofcode.com/2019/day/1 for details.
+struct Opt {
+    /// Includes the weight of flue
+    #[structopt(short = "i", long = "include-fuel-weight")]
+    include_fuel_weight: bool,
+}
 
 fn main() {
     let stdin = io::stdin();
+    let opt = Opt::from_args();
 
     let input = stdin
         .lock()
         .lines()
         .map(|l| l.unwrap().parse::<Module>().unwrap());
 
-    dbg!(fuel_required(input));
+    println!("{}", fuel_required(input, opt.include_fuel_weight))
 }
 
-// TODO: If this were a nice CLI program, it would probably have a switch to choose between these two rather than doing both?
-fn fuel_required(it: impl Iterator<Item = Module>) -> (Fuel, Fuel) {
-    it.map(|m| {
-        (
-            m.fuel_excluding_fuel_weight(),
-            m.fuel_including_fuel_weight(),
-        )
-    })
-    .fold((Fuel(0), Fuel(0)), |(sum_x, sum_y), (x, y)| {
-        (sum_x + x, sum_y + y)
+fn fuel_required(it: impl Iterator<Item = Module>, include_fuel_weight: bool) -> Fuel {
+    it.map(if include_fuel_weight {
+        Module::fuel_including_fuel_weight
+    } else {
+        Module::fuel_excluding_fuel_weight
     })
+    .sum()
 }
 
+#[derive(Debug, derive_more::FromStr, Clone, Copy)]
 struct Module {
     weight: Weight,
 }
 
-impl FromStr for Module {
-    type Err = ParseIntError;
-
-    fn from_str(s: &str) -> Result<Self, Self::Err> {
-        Ok(Module {
-            weight: Weight(s.parse()?),
-        })
-    }
-}
-
 impl Module {
-    fn fuel_excluding_fuel_weight(&self) -> Fuel {
+    fn fuel_excluding_fuel_weight(self) -> Fuel {
         self.weight.required_fuel()
     }
 
-    fn fuel_including_fuel_weight(&self) -> Fuel {
+    fn fuel_including_fuel_weight(self) -> Fuel {
         iter::successors(Some(self.weight.required_fuel()), |fuel| {
-            if fuel.weight().is_zero() {
+            if fuel.is_zero() {
                 None
             } else {
                 Some(fuel.weight().required_fuel())
@@ -61,37 +60,24 @@ impl Module {
     }
 }
 
+#[derive(Debug, derive_more::FromStr, Clone, Copy)]
 struct Weight(u32);
 
 impl Weight {
-    fn is_zero(&self) -> bool {
-        self.0 == 0
-    }
-
-    fn required_fuel(&self) -> Fuel {
+    fn required_fuel(self) -> Fuel {
         Fuel((self.0 / 3).saturating_sub(2))
     }
 }
 
-#[derive(Debug)]
+#[derive(Debug, derive_more::Add, derive_more::Sum, Clone, Copy, derive_more::Display)]
 struct Fuel(u32);
 
 impl Fuel {
-    fn weight(&self) -> Weight {
+    fn weight(self) -> Weight {
         Weight(self.0)
     }
-}
-
-impl Add for Fuel {
-    type Output = Self;
-
-    fn add(self, other: Self) -> Self {
-        Fuel(self.0 + other.0)
-    }
-}
 
-impl Sum for Fuel {
-    fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
-        iter.fold(Fuel(0), Add::add)
+    fn is_zero(self) -> bool {
+        self.0 == 0
     }
 }