add format flag with json support

Cargo.toml

@@ -19,6 +19,9 @@ num_cpus      = "1.8.0"
 ignore        = "0.4.2"
 edit-distance = "2.0.1"
 smallvec      = "0.6.5"
+serde         = "1.0.101"
+serde_json    = "1.0.41"
+serde_derive  = "1.0.101"
 
 [profile.release]
 incremental = false

src/lib.rs

@@ -1,5 +1,7 @@
 extern crate memchr;
 extern crate smallvec;
+#[macro_use]
+extern crate serde_derive;
 
 use std::path::Path;
 use std::fs::File;
@@ -11,7 +13,7 @@ use memchr::memchr;
 use smallvec::*;
 
 // Why is it called partialEq?
-#[derive(Debug, PartialEq, Default, Clone)]
+#[derive(Debug, PartialEq, Default, Copy, Clone, Serialize)]
 pub struct Count {
     pub code:    u32,
     pub comment: u32,
@@ -28,6 +30,7 @@ impl Count {
     }
 }
 
+#[derive(Serialize, Copy, Clone)]
 pub struct LangTotal {
     pub files: u32,
     pub count: Count,
@@ -37,7 +40,7 @@ pub struct LangTotal {
 // We can probably do something with the encoding crate where we decode
 // as ascii, and then use unsafe_from_utf8. If decoding fails,
 // we catch it and just use the safe from_utf8 as we're doing now.
-#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Clone)]
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Clone, Serialize)]
 pub enum Lang {
     ActionScript,
     Ada,

src/main.rs

@@ -7,6 +7,7 @@ extern crate num_cpus;
 extern crate regex;
 extern crate ignore;
 extern crate edit_distance;
+extern crate serde_json;
 
 use clap::{Arg, App, AppSettings};
 use ignore::WalkBuilder;
@@ -99,6 +100,23 @@ impl FromStr for Sort {
     }
 }
 
+#[derive(PartialEq)]
+enum Format {
+    Table,
+    JSON
+}
+
+impl FromStr for Format {
+    type Err = Option<String>;
+    fn from_str(s: &str) -> Result<Format, Self::Err> {
+        match s {
+            "table" | "Table"         => Ok(Format::Table),
+            "json"  | "Json" | "JSON" => Ok(Format::JSON),
+            _ => Err(None)
+        }
+    }
+}
+
 // TODO(cgag): tune smallvec array sizes
 // TODO(cgag): try smallstring
 // TODO(cgag): more tests for nested comments
@@ -133,6 +151,12 @@ fn main() {
             .value_name("COLUMN")
             .takes_value(true)
             .help("Column to sort by"))
+        .arg(Arg::with_name("format")
+             .required(false)
+             .long("format")
+             .short("f")
+             .takes_value(true)
+             .help("The output format, defaults to 'table' and accepts 'json'."))
         .arg(Arg::with_name("unrestricted")
              .required(false)
              .multiple(true)
@@ -169,6 +193,18 @@ fn main() {
         None => Sort::Code,
     };
 
+    let format = match matches.value_of("format") {
+        Some(string) => match Format::from_str(string) {
+            Ok(format) => format,
+            Err(_) => {
+                println!("Error: invalid value for --format: '{}'", string);
+                println!(" Hint: legal values are Table and Json");
+                return
+            }
+        },
+        None => Format::Table,
+    };
+
     let by_file: bool = matches.is_present("files");
 
     if by_file && (sort == Sort::Language || sort == Sort::Files) {
@@ -339,7 +375,10 @@ fn main() {
             Sort::Lines    => totals_by_lang.sort_by(|&(_, c1), &(_, c2)| c2.count.lines.cmp(&c1.count.lines)),
         }
 
-        print_totals_by_lang(&linesep, &totals_by_lang);
+        match format {
+            Format::Table => print_totals_by_lang_table(&linesep, &totals_by_lang),
+            Format::JSON => print_totals_by_lang_json(&totals_by_lang),
+        }
     }
 
 }
@@ -357,7 +396,15 @@ fn str_repeat(s: &str, n: usize) -> String {
     std::iter::repeat(s).take(n).collect::<Vec<_>>().join("")
 }
 
-fn print_totals_by_lang(linesep: &str, totals_by_lang: &[(&&Lang, &LangTotal)]) {
+fn print_totals_by_lang_json(totals_by_lang: &[(&&Lang, &LangTotal)]) {
+    let mut langs = std::collections::HashMap::new();
+    for (l, t) in totals_by_lang {
+        langs.insert((***l).to_string(), **t);
+    }
+    println!("{}", serde_json::to_string(&langs).unwrap());
+}
+
+fn print_totals_by_lang_table(linesep: &str, totals_by_lang: &[(&&Lang, &LangTotal)]) {
     println!("{}", linesep);
     println!(" {0: <17} {1: >8} {2: >12} {3: >12} {4: >12} {5: >12}",
              "Language",