Add a new rename command to change the headers

src/cmd/mod.rs

@@ -9,6 +9,7 @@ pub mod index;
 pub mod input;
 pub mod join;
 pub mod partition;
+pub mod rename;
 pub mod reverse;
 pub mod sample;
 pub mod search;

src/cmd/rename.rs

@@ -0,0 +1,65 @@
+use csv;
+
+use CliResult;
+use config::{Config, Delimiter};
+use util;
+
+static USAGE: &'static str = "
+Rename the columns of CSV data efficiently.
+
+This command lets you rename the columns in CSV data. You must specify
+all of the headers, and separate them by a comma.
+
+  Change the name of the columns:
+  $ xsv rename id,name,title
+
+  Use column names that contains commas and conflict with the separator:
+  $ xsv rename '\"Date - Opening\",\"Date - Actual Closing\"'
+
+Usage:
+    xsv rename [options] [--] <headers> [<input>]
+    xsv rename --help
+
+Common options:
+    -h, --help             Display this message
+    -o, --output <file>    Write output to <file> instead of stdout.
+    -d, --delimiter <arg>  The field delimiter for reading CSV data.
+                           Must be a single character. (default: ,)
+";
+
+#[derive(Deserialize)]
+struct Args {
+    arg_input: Option<String>,
+    arg_headers: String,
+    flag_output: Option<String>,
+    flag_delimiter: Option<Delimiter>,
+}
+
+pub fn run(argv: &[&str]) -> CliResult<()> {
+    let args: Args = util::get_args(USAGE, argv)?;
+
+    let rconfig = Config::new(&args.arg_input)
+        .delimiter(args.flag_delimiter);
+
+    let mut rdr = rconfig.reader()?;
+    let mut wtr = Config::new(&args.flag_output).writer()?;
+    let headers = rdr.byte_headers()?;
+
+    let mut new_rdr = csv::Reader::from_reader(args.arg_headers.as_bytes());
+    let new_headers = new_rdr.byte_headers()?;
+
+    if headers.len() != new_headers.len() {
+        return fail!("The length of the CSV headers is different from the provided one.");
+    }
+
+    if !rconfig.no_headers {
+        wtr.write_record(new_headers)?;
+    }
+
+    let mut record = csv::ByteRecord::new();
+    while rdr.read_byte_record(&mut record)? {
+        wtr.write_record(&record)?;
+    }
+    wtr.flush()?;
+    Ok(())
+}

src/main.rs

@@ -152,6 +152,7 @@ enum Command {
     Input,
     Join,
     Partition,
+    Rename,
     Reverse,
     Sample,
     Search,
@@ -171,7 +172,7 @@ impl Command {
 
         if !argv[1].chars().all(char::is_lowercase) {
             return Err(CliError::Other(format!(
-                "xsv expects commands in lowercase. Did you mean '{}'?", 
+                "xsv expects commands in lowercase. Did you mean '{}'?",
                 argv[1].to_lowercase()).to_string()));
         }
         match self {
@@ -187,6 +188,7 @@ impl Command {
             Command::Input => cmd::input::run(argv),
             Command::Join => cmd::join::run(argv),
             Command::Partition => cmd::partition::run(argv),
+            Command::Rename => cmd::rename::run(argv),
             Command::Reverse => cmd::reverse::run(argv),
             Command::Sample => cmd::sample::run(argv),
             Command::Search => cmd::search::run(argv),