Support reading from stdin in join

src/cmd/join.rs

@@ -1,6 +1,5 @@
 use std::collections::hash_map::{HashMap, Entry};
 use std::fmt;
-use std::fs;
 use std::io;
 use std::iter::repeat;
 use std::str;
@@ -9,7 +8,7 @@ use byteorder::{WriteBytesExt, BigEndian};
 use csv;
 
 use CliResult;
-use config::{Config, Delimiter};
+use config::{Config, Delimiter, SeekRead};
 use index::Indexed;
 use select::{SelectColumns, Selection};
 use util;
@@ -278,7 +277,7 @@ impl<R: io::Read + io::Seek, W: io::Write> IoState<R, W> {
 
 impl Args {
     fn new_io_state(&self)
-        -> CliResult<IoState<fs::File, Box<io::Write+'static>>> {
+        -> CliResult<IoState<Box<SeekRead+'static>, Box<io::Write+'static>>> {
         let rconf1 = Config::new(&Some(self.arg_input1.clone()))
             .delimiter(self.flag_delimiter)
             .no_headers(self.flag_no_headers)
@@ -288,8 +287,8 @@ impl Args {
             .no_headers(self.flag_no_headers)
             .select(self.arg_columns2.clone());
 
-        let mut rdr1 = rconf1.reader_file()?;
-        let mut rdr2 = rconf2.reader_file()?;
+        let mut rdr1 = rconf1.reader_file_stdin()?;
+        let mut rdr2 = rconf2.reader_file_stdin()?;
         let (sel1, sel2) = self.get_selections(
             &rconf1, &mut rdr1, &rconf2, &mut rdr2)?;
         Ok(IoState {

src/config.rs

@@ -70,6 +70,10 @@ pub struct Config {
     quoting: bool,
 }
 
+// Empty trait as an alias for Seek and Read that avoids auto trait errors
+pub trait SeekRead: io::Seek + io::Read {}
+impl<T: io::Seek + io::Read> SeekRead for T {}
+
 impl Config {
     pub fn new(path: &Option<String>) -> Config {
         let (path, delim) = match *path {
@@ -212,6 +216,21 @@ impl Config {
         }
     }
 
+    pub fn reader_file_stdin(&self) -> io::Result<csv::Reader<Box<SeekRead+'static>>> {
+        Ok(match self.path {
+            None => {
+                // Create a buffer in memory when stdin needs to be indexed
+                let mut buffer: Vec<u8> = Vec::new();
+                let stdin = io::stdin();
+                stdin.lock().read_to_end(&mut buffer)?;
+                self.from_reader(Box::new(io::Cursor::new(buffer)))
+            },
+            Some(ref p) => {
+                self.from_reader(Box::new(fs::File::open(p).unwrap()))
+            },
+        })
+    }
+
     pub fn index_files(&self)
            -> io::Result<Option<(csv::Reader<fs::File>, fs::File)>> {
         let (csv_file, idx_file) = match (&self.path, &self.idx_path) {