feat: implement stdin option

src/main/kotlin/Main.kt

@@ -1,53 +1,58 @@
 import com.github.ajalt.clikt.core.CliktCommand
 import com.github.ajalt.clikt.parameters.arguments.argument
+import com.github.ajalt.clikt.parameters.arguments.optional
 import com.github.ajalt.clikt.parameters.options.flag
 import com.github.ajalt.clikt.parameters.options.help
 import com.github.ajalt.clikt.parameters.options.option
+import java.io.InputStreamReader
 import java.nio.charset.Charset
 import java.nio.file.Files
 import java.nio.file.Path
 
 class WordCount : CliktCommand(name = "wk") {
     private val countBytes by option("-c").flag()
-        .help { "The number of bytes in the input file is written to the standard output." }
+        .help { "The number of bytes in the input file or stdin is written to the stdout." }
     private val countLines by option("-l").flag()
-        .help { "The number of lines in the input file is written to the standard output." }
+        .help { "The number of lines in the input file or stdin is written to the stdout." }
     private val countCharacters by option("-m").flag()
-        .help { "The number of characters in the input file is written to the standard output. " +
+        .help { "The number of characters in the input file or stdin is written to the stdout. " +
                 "If the current locale does not support multibyte characters, this is equivalent to the -c option. " +
                 "This will cancel out any prior usage of the -c option." }
     private val countWords by option("-w").flag()
-        .help { "The number of words in the input file is written to the standard output." }
-    private val fileName by argument()
+        .help { "The number of words in the input file or stdin is written to the stdout." }
+    private val fileName by argument().optional()
 
     override fun run() {
-        val filePath = Path.of(fileName)
-        val counter = when {
-            countBytes -> countBytes(filePath)
-            countLines -> countLines(filePath)
-            countWords -> countWords(filePath)
-            countCharacters -> countCharacters(filePath)
-            else -> defaultCount(filePath)
+        val bufferedReader = if (fileName.isNullOrBlank()) {
+            InputStreamReader(System.`in`).buffered()
+        } else {
+            Files.newBufferedReader(Path.of(fileName!!))
+        }
+        bufferedReader.use {
+            val content = it.readText()
+            val counter = when {
+                countBytes -> countBytes(content)
+                countLines -> countLines(content)
+                countWords -> countWords(content)
+                countCharacters -> countCharacters(content)
+                else -> defaultCount(content)
+            }
+            echo("  $counter ${fileName ?: ""}".trimEnd())
         }
-        echo("  $counter $fileName")
     }
 
-    private fun defaultCount(filePath: Path): String {
-        val lines = countLines(filePath)
-        val words = countWords(filePath)
-        val characters = countCharacters(filePath)
-        return "$lines  $words  $characters"
-    }
+    private fun defaultCount(content: String) =
+        "${countLines(content)}  ${countWords(content)}  ${countCharacters(content)}"
 
-    private fun countBytes(filePath: Path): Int = Files.readAllBytes(filePath).size
-    private fun countLines(filePath: Path): Int = Files.readAllLines(filePath).size
-    private fun countWords(filePath: Path): Int = Files.readString(filePath).trim().split("\\s+".toRegex()).size
+    private fun countBytes(content: String) = content.toByteArray(Charsets.UTF_8).size
+    private fun countLines(content: String) = content.split("\n").size - 1
+    private fun countWords(content: String) = content.trim().split("\\s+".toRegex()).size
 
-    private fun countCharacters(filePath: Path): Int {
-        return if (Charset.defaultCharset().displayName().contains("UTF-8", ignoreCase = true)) {
-            Files.readString(filePath).length
+    private fun countCharacters(content: String): Int {
+        return if (Charset.defaultCharset().displayName().contains(Charsets.UTF_8.name(), ignoreCase = true)) {
+            content.length
         } else {
-            countBytes(filePath)
+            countBytes(content)
         }
     }
 }

src/test/kotlin/WordCountTests.kt

@@ -17,19 +17,19 @@ class WordCountTests {
     fun `test help output`() {
         val result = wk.test("-h")
         assertEquals("""
-Usage: wk [<options>] <filename>
+Usage: wk [<options>] [<filename>]
 
 Options:
-  -c          The number of bytes in the input file is written to the standard
-              output.
-  -l          The number of lines in the input file is written to the standard
-              output.
-  -m          The number of characters in the input file is written to the
-              standard output. If the current locale does not support multibyte
+  -c          The number of bytes in the input file or stdin is written to the
+              stdout.
+  -l          The number of lines in the input file or stdin is written to the
+              stdout.
+  -m          The number of characters in the input file or stdin is written to
+              the stdout. If the current locale does not support multibyte
               characters, this is equivalent to the -c option. This will cancel
               out any prior usage of the -c option.
-  -w          The number of words in the input file is written to the standard
-              output.
+  -w          The number of words in the input file or stdin is written to the
+              stdout.
   -h, --help  Show this message and exit
 """.trimStart(), result.stdout)
         assertEquals("", result.stderr)
@@ -39,13 +39,9 @@ Options:
     @Test
     fun `test missing file name`() {
         val result = wk.test("-c")
-        assertEquals("""
-Usage: wk [<options>] <filename>
-
-Error: missing argument <filename>
-""".trimStart(), result.stderr)
-        assertEquals("", result.stdout)
-        assertEquals(1, result.statusCode)
+        assertEquals("  0\n", result.stdout)
+        assertEquals("", result.stderr)
+        assertEquals(0, result.statusCode)
     }
 
     @Test

wk.1

@@ -2,11 +2,11 @@
 .\" Adapted from the example at https://www.systutorials.com/docs/linux/man/7-man-pages/
 .TH WK 1 "January 2024" "1.0.0" "wk man page"
 .SH NAME
-wk \- Count bytes, lines, or words in a file (wc clone written in Kotlin)
+wk \- Count bytes, lines, or words in a file or from standard input (wc clone written in Kotlin)
 .SH SYNOPSIS
 .B wk
 .RI [ options ]
-.I filename
+.I [ filename ]
 .SH DESCRIPTION
 .B wk
 counts the number of bytes, lines, or words in a file and writes the result to the standard output.
@@ -26,15 +26,23 @@ Count the number of words in the input file.
 .SH ARGUMENTS
 .TP
 .I filename
-The path to the input file.
+The path to the input file. If not specified, read from standard input.
 .SH EXAMPLES
 Count the number of lines in a file:
 .PP
 .B wk -l myfile.txt
+.PP
+Count the number of bytes from standard input:
+.PP
+.B echo Hello, World! | wk -c
 .SH SEE ALSO
 .BR wc (1)
 .SH AUTHOR
 Vladas Maier <vladas.mr@gmail.com>.
 .SH COPYRIGHT
-Copyright © 2024 Vladas Maier. This is free software; you are free to change and redistribute it. There is NO WARRANTY, to the extent permitted by law.
+Copyright © 2024 Vladas Maier.
+.PP
+This is free software; you are free to change and redistribute it.
+.PP
+There is NO WARRANTY, to the extent permitted by law.
 .\" End of man page