Add broken error test case

city-pop/Cargo.lock

@@ -0,0 +1,33 @@
+[root]
+name = "city-pop"
+version = "0.1.0"
+dependencies = [
+ "csv 0.14.3 (registry+https://github.com/rust-lang/crates.io-index)",
+ "getopts 0.2.14 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-serialize 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "byteorder"
+version = "0.3.13"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "csv"
+version = "0.14.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+dependencies = [
+ "byteorder 0.3.13 (registry+https://github.com/rust-lang/crates.io-index)",
+ "rustc-serialize 0.3.16 (registry+https://github.com/rust-lang/crates.io-index)",
+]
+
+[[package]]
+name = "getopts"
+version = "0.2.14"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
+[[package]]
+name = "rustc-serialize"
+version = "0.3.16"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+

city-pop/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "city-pop"
+version = "0.1.0"
+authors = ["Tim Warren <twarren@nexient.com>"]
+
+[[bin]]
+name = "city-pop"
+
+[dependencies]
+csv = "0.*"
+rustc-serialize = "0.*"
+getopts = "0.*"

city-pop/src/main.rs

@@ -0,0 +1,146 @@
+extern crate getopts;
+extern crate rustc_serialize;
+extern crate csv;
+
+use getopts::Options;
+use std::{env, io, fmt, fs, process, str};
+use std::path::Path;
+use std::error::Error;
+
+// This struct represents the data in each row of the CSV file.
+// Type based decoding absolves us of a lot of the nitty gritty error
+// handling, like parsing strings as integers or floats
+#[derive(Debug, RustcDecodable)]
+struct Row {
+    country: String,
+    city: String,
+    accent_city: String,
+    region: String,
+
+    // Not every row has data for the population, latitude or logitude!
+    // So we express them as `Option` types, which admits the possiblity of
+    // absence. The CSV parser will fill in the correct value for us.
+    population: Option<u64>,
+    latitude: Option<f64>,
+    longitude: Option<f64>,
+}
+
+struct PopulationCount {
+    city: String,
+    country: String,
+    // This is no longer an `Option` because values of this type are only
+    // constructed if they have a population count.
+    count: u64,
+}
+
+#[derive(Debug)]
+enum CliError {
+    Io(io::Error),
+    Csv(csv::Error),
+    NotFound
+}
+
+impl fmt::Display for CliError {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        match *self {
+            CliError::Io(ref err) => err.fmt(f),
+            CliError::Csv(ref err) => err.fmt(f),
+            CliError::NotFound => write!(f, "No matching cities with a population were found"),
+        }
+    }
+}
+
+impl Error for CliError {
+    fn description(&self) -> &str {
+        match *self {
+            CliError::Io(ref err) => err.description(),
+            CliError::Csv(ref err) => err.description(),
+            CliError::NotFound => "not found",
+        }
+    }
+}
+
+impl From<io::Error> for CliError {
+    fn from(err: io::Error) -> CliError {
+        CliError::Io(err)
+    }
+}
+
+impl From<csv::Error> for CliError {
+    fn from(err: csv::Error) -> CliError {
+        CliError::Csv(err)
+    }
+}
+
+fn print_usage(program: &str, opts: Options) {
+    println!("{}", opts.usage(&format!("Usage: {} [options] <city>", program)));
+}
+
+fn search<P: AsRef<Path>>
+    (file_path: &Option<P>, city: &str)
+    -> Result<Vec<PopulationCount>, CliError> {
+    let mut found = vec![];
+    let input: Box<io::Read> = match *file_path {
+        None => Box::new(io::stdin()),
+        Some(ref file_path) => Box::new(try!(fs::File::open(file_path))),
+    };
+    let mut rdr = csv::Reader::from_reader(input);
+
+    for row in rdr.decode::<Row>() {
+        let row = try!(row);
+        match row.population {
+            None => {} // Skip it
+            Some(count) => if row.city == city {
+                found.push(PopulationCount {
+                    city: row.city,
+                    country: row.country,
+                    count: count,
+                });
+            },
+        }
+    }
+
+    if found.is_empty() {
+        Err(CliError::NotFound)
+    } else {
+        Ok(found)
+    }
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let program = args[0].clone();
+
+    let mut opts = Options::new();
+    opts.optopt("f", "file", "Choose an input file instead of using STDIN.", "NAME");
+    opts.optflag("h", "help", "Show this usage message.");
+    opts.optflag("q", "quiet", "Silences errors and warnings.");
+
+    let matches = match opts.parse(&args[1..]) {
+        Ok(m) => { m }
+        Err(e) => { panic!(e.to_string()) }
+    };
+
+    if matches.opt_present("h") {
+        print_usage(&program, opts);
+        return;
+    }
+
+    let file = matches.opt_str("f");
+    let data_file = file.as_ref().map(Path::new);
+
+    let city = if !matches.free.is_empty() {
+        matches.free[0].clone();
+    } else {
+        print_usage(&program, opts);
+        return;
+    };
+
+    match search(&data_file, &city) {
+        Err(CliError::NotFound) if matches.opt_present("q") => process::exit(1),
+        Err(err) => panic!("{}", err),
+        Ok(pops) => for pop in pops {
+            println!("{}, {}: {:?}", pop.city, pop.country, pop.count);
+        }
+    }
+}