Add split option support

Author: Planeshifter

lib/node_modules/@stdlib/string/substring-before/README.md

@@ -120,6 +120,7 @@ Options:
   -h,    --help                Print this message.
   -V,    --version             Print the package version.
          --search string       Search string.
+         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
 ```
 
 </section>
@@ -130,6 +131,20 @@ Options:
 
 <section class="notes">
 
+### Notes
+
+-   If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.
+
+    ```bash
+    # Not escaped...
+    $ echo -n $'foo\nbar\nbaz' | substring-before --search a --split /\r?\n/
+
+    # Escaped...
+    $ echo -n $'foo\nbar\nbaz' | substring-before --search a --split /\\r?\\n/
+    ```
+
+-   The implementation ignores trailing delimiters.
+
 </section>
 
 <!-- /.notes -->
@@ -145,6 +160,22 @@ $ substring-before abcdefg --search d
 abc
 ```
 
+To use as a [standard stream][standard-streams],
+
+```bash
+$ echo -n $'beep\nboop' | substring-before --search p
+bee
+boo
+```
+
+By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.
+
+```bash
+$ echo -n 'beep\tboop' | substring-before --search p --split '\t'
+bee
+boo
+```
+
 </section>
 
 <!-- /.examples -->
@@ -181,6 +212,10 @@ abc
 
 <section class="links">
 
+[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams
+
+[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions
+
 <!-- <related-links> -->
 
 [@stdlib/string/substring-before-last]: https://github.com/stdlib-js/stdlib/tree/develop/lib/node_modules/%40stdlib/string/substring-before-last

lib/node_modules/@stdlib/string/substring-before/bin/cli

@@ -28,6 +28,8 @@ var CLI = require( '@stdlib/cli/ctor' );
 var stdin = require( '@stdlib/process/read-stdin' );
 var stdinStream = require( '@stdlib/streams/node/stdin' );
 var RE_EOL = require( '@stdlib/regexp/eol' ).REGEXP;
+var isRegExpString = require( '@stdlib/assert/is-regexp-string' );
+var reFromString = require( '@stdlib/utils/regexp-from-string' );
 var substringBefore = require( './../lib' );
 
 
@@ -40,6 +42,7 @@ var substringBefore = require( './../lib' );
 * @returns {void}
 */
 function main() {
+	var split;
 	var flags;
 	var args;
 	var cli;
@@ -71,6 +74,14 @@ function main() {
 	}
 	// Check if we are receiving data from `stdin`...
 	if ( !stdinStream.isTTY ) {
+		if ( flags.split ) {
+			if ( !isRegExpString( flags.split ) ) {
+				flags.split = '/'+flags.split+'/';
+			}
+			split = reFromString( flags.split );
+		} else {
+			split = RE_EOL;
+		}
 		return stdin( onRead );
 	}
 	console.log( substringBefore( str, flags.search ) ); // eslint-disable-line no-console
@@ -89,7 +100,12 @@ function main() {
 		if ( error ) {
 			return cli.error( error );
 		}
-		lines = data.toString().split( RE_EOL );
+		lines = data.toString().split( split );
+
+		// Remove any trailing separators (e.g., trailing newline)...
+		if ( lines[ lines.length-1 ] === '' ) {
+			lines.pop();
+		}
 		for ( i = 0; i < lines.length; i++ ) {
 			console.log( substringBefore( lines[ i ], flags.search ) ); // eslint-disable-line no-console
 		}

lib/node_modules/@stdlib/string/substring-before/docs/usage.txt

@@ -6,3 +6,4 @@ Options:
   -h,    --help                Print this message.
   -V,    --version             Print the package version.
          --search string       Search string.
+         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.

lib/node_modules/@stdlib/string/substring-before/etc/cli_opts.json

@@ -1,6 +1,7 @@
 {
 	"string": [
-		"search"
+		"search",
+		"split"
 	],
 	"boolean": [
 		"help",

lib/node_modules/@stdlib/string/substring-before/test/test.cli.js

@@ -186,6 +186,52 @@ tape( 'the command-line interface supports use as a standard stream', opts, func
 	}
 });
 
+tape( 'the command-line interface supports specifying a custom delimiter when used as a standard stream (string)', opts, function test( t ) {
+	var cmd = [
+		'printf \'beep boop\tboop beep\'',
+		'|',
+		EXEC_PATH,
+		fpath,
+		'--search="e"',
+		'--split \'\t\''
+	];
+
+	exec( cmd.join( ' ' ), done );
+
+	function done( error, stdout, stderr ) {
+		if ( error ) {
+			t.fail( error.message );
+		} else {
+			t.strictEqual( stdout.toString(), 'b\nboop b\n', 'expected value' );
+			t.strictEqual( stderr.toString(), '', 'does not print to `stderr`' );
+		}
+		t.end();
+	}
+});
+
+tape( 'the command-line interface supports specifying a custom delimiter when used as a standard stream (regexp)', opts, function test( t ) {
+	var cmd = [
+		'printf \'beep boop\tboop beep\'',
+		'|',
+		EXEC_PATH,
+		fpath,
+		'--search="e"',
+		'--split=/\\\\t/'
+	];
+
+	exec( cmd.join( ' ' ), done );
+
+	function done( error, stdout, stderr ) {
+		if ( error ) {
+			t.fail( error.message );
+		} else {
+			t.strictEqual( stdout.toString(), 'b\nboop b\n', 'expected value' );
+			t.strictEqual( stderr.toString(), '', 'does not print to `stderr`' );
+		}
+		t.end();
+	}
+});
+
 tape( 'when used as a standard stream, if an error is encountered when reading from `stdin`, the command-line interface prints an error and sets a non-zero exit code', opts, function test( t ) {
 	var script;
 	var opts;