Add "--align" flag to table command.

This flag allows the user to specify how data should be aligned within
columns. The options are:

   * left
   * right
   * center

This alignment is applied to all columns.

Per the tabwriter crate, center alignment breaks ties in favor of being
closer to the left. Thus if "hi" appears in a column of width 5, it will
be printed as " hi  ".

resolves BurntSushi#165.

Cargo.toml

@@ -40,7 +40,7 @@ regex = "1"
 serde = "1"
 serde_derive = "1"
 streaming-stats = "0.2"
-tabwriter = "1"
+tabwriter = "1.2"
 threadpool = "1.3"
 
 [dev-dependencies]

src/cmd/table.rs

@@ -1,7 +1,8 @@
 use std::borrow::Cow;
+use std::convert::From;
 
 use csv;
-use tabwriter::TabWriter;
+use tabwriter::{Alignment, TabWriter};
 
 use CliResult;
 use config::{Config, Delimiter};
@@ -24,7 +25,10 @@ table options:
                            [default: 2]
     -p, --pad <arg>        The minimum number of spaces between each column.
                            [default: 2]
-    -c, --condense <arg>  Limits the length of each field to the value
+    -a, --align <arg>      How entries should be aligned in a column.
+                           Options: \"left\", \"right\", \"center\".
+                           [default: left]
+    -c, --condense <arg>   Limits the length of each field to the value
                            specified. If the field is UTF-8 encoded, then
                            <arg> refers to the number of code points.
                            Otherwise, it refers to the number of bytes.
@@ -43,9 +47,27 @@ struct Args {
     flag_pad: usize,
     flag_output: Option<String>,
     flag_delimiter: Option<Delimiter>,
+    flag_align: Align,
     flag_condense: Option<usize>,
 }
 
+#[derive(Deserialize, Clone, Copy)]
+enum Align {
+    Left,
+    Right,
+    Center,
+}
+
+impl From<Align> for Alignment {
+    fn from(align: Align) -> Self {
+        match align {
+            Align::Left => Alignment::Left,
+            Align::Right => Alignment::Right,
+            Align::Center => Alignment::Center,
+        }
+    }
+}
+
 pub fn run(argv: &[&str]) -> CliResult<()> {
     let args: Args = util::get_args(USAGE, argv)?;
     let rconfig = Config::new(&args.arg_input)
@@ -56,7 +78,8 @@ pub fn run(argv: &[&str]) -> CliResult<()> {
 
     let tw = TabWriter::new(wconfig.io_writer()?)
         .minwidth(args.flag_width)
-        .padding(args.flag_pad);
+        .padding(args.flag_pad)
+        .alignment(args.flag_align.into());
     let mut wtr = wconfig.from_writer(tw);
     let mut rdr = rconfig.reader()?;
 

tests/test_table.rs

@@ -23,3 +23,39 @@ abcdefg  a    a
 a        abc  z\
 ")
 }
+
+#[test]
+fn table_right_align() {
+    let wrk = Workdir::new("table");
+    wrk.create("in.csv", data());
+
+    let mut cmd = wrk.command("table");
+    cmd.arg("--align");
+    cmd.arg("right");
+    cmd.arg("in.csv");
+
+    let got: String = wrk.stdout(&mut cmd);
+    assert_eq!(&*got, concat!(
+"     h1   h2  h3\n",
+"abcdefg    a  a\n",
+"      a  abc  z",
+    ));
+}
+
+#[test]
+fn table_center_align() {
+    let wrk = Workdir::new("table");
+    wrk.create("in.csv", data());
+
+    let mut cmd = wrk.command("table");
+    cmd.arg("-a");
+    cmd.arg("center");
+    cmd.arg("in.csv");
+
+    let got: String = wrk.stdout(&mut cmd);
+    assert_eq!(&*got, concat!(
+"  h1     h2   h3\n",
+"abcdefg   a   a\n",
+"   a     abc  z",
+    ));
+}