Add a CLI entry point for SciJava scripts

See #451.

src/main/java/org/scijava/script/ScriptCLI.java

@@ -0,0 +1,169 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2023 SciJava developers.
+ * %%
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * 
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright notice,
+ *    this list of conditions and the following disclaimer in the documentation
+ *    and/or other materials provided with the distribution.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ * #L%
+ */
+
+package org.scijava.script;
+
+import java.io.File;
+import java.io.FileReader;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Map.Entry;
+
+import org.scijava.Context;
+import org.scijava.log.LogLevel;
+import org.scijava.log.LogService;
+import org.scijava.module.Module;
+
+/**
+ * A command-line entry point for running SciJava scripts.
+ *
+ * @author Curtis Rueden
+ */
+public class ScriptCLI {
+
+	private static final String USAGE = "" + //
+		"Usage: " + ScriptCLI.class.getSimpleName() + //
+		" [-d] [-h] [-l language] [-o] [-r] /path/to/script [script-args]\n" + //
+		"\n" + //
+		"Options:\n" + //
+		"  -d, --debug              : enable debug-level log output\n" + //
+		"  -h, --help               : display this help message\n" + //
+		"  -l, --language           : specify language of script to execute\n" + //
+		"                             otherwise, inferred from script extension\n" + //
+		"  -o, --print-outputs      : print output values\n" + //
+		"  -r, --print-return-value : print return value\n" + //
+		"\n" + //
+		"To read from stdin, use a dash (-) symbol for the script path.\n" + //
+		"\n" + //
+		"For script-args, give space-separated key=value pairs,\n" + //
+		"while will be passed in as SciJava script arguments.";
+
+	public static void main(String... args) throws Exception {
+		final Map<String, Object> inputs = new HashMap<>();
+		File file = null;
+		String language = null;
+		boolean printOutputs = false;
+		boolean printReturnValue = false;
+		boolean parsingOptions = true;
+		try (final Context context = new Context()) {
+			// Parse command-line arguments.
+			if (args.length == 0) args = new String[] {"-h"};
+			for (int i = 0; i < args.length; i++) {
+				if (parsingOptions) {
+					// Parse options and filename.
+					if (args[i].equals("-d") || args[i].equals("--debug")) {
+						final LogService log = context.getService(LogService.class);
+						if (log != null) log.setLevel(LogLevel.DEBUG);
+					}
+					else if (args[i].equals("-h") || args[i].equals("--help")) {
+						System.err.println(USAGE);
+						System.exit(1);
+					}
+					else if (i < args.length - 1 && //
+						args[i].equals("-l") || args[i].equals("--language"))
+					{
+						language = args[++i];
+					}
+					else if (args[i].equals("-o") || args[i].equals("--print-outputs")) {
+						printOutputs = true;
+					}
+					else if (args[i].equals("-r") || args[i].equals("--print-return-value")) {
+						printReturnValue = true;
+					}
+					else if (args[i].equals("-")) {
+						// read from stdin
+						parsingOptions = false;
+					}
+					else if (i < args.length - 1 && args[i].equals("--")) {
+						// argument after the -- separator must be the filename.
+						file = new File(args[++i]);
+						parsingOptions = false;
+					}
+					else if (new File(args[i]).exists()) {
+						file = new File(args[i]);
+						parsingOptions = false;
+					}
+					else {
+						System.err.println("Invalid argument: " + args[i]);
+						System.exit(2);
+					}
+				}
+				else {
+					// Parse script arguments.
+					final int equals = args[i].indexOf("=");
+					if (equals < 0) {
+						System.err.println("Invalid argument: " + args[i]);
+						System.exit(3);
+					}
+					final String key = args[i].substring(0, equals);
+					final String val = args[i].substring(equals + 1);
+					inputs.put(key, val);
+				}
+			}
+
+			final ScriptService ss = context.getService(ScriptService.class);
+			if (ss == null) {
+				System.err.println("Error: No script service available.");
+				System.exit(4);
+			}
+			if (file == null && language == null) {
+				System.err.println("Error: Must specify language when using stdin.");
+				System.exit(5);
+			}
+
+			final Module m;
+			if (language == null) {
+				m = ss.run(file, true, inputs).get();
+			}
+			else {
+				ScriptLanguage lang = ss.getLanguageByName(language);
+				if (lang == null) lang = ss.getLanguageByExtension(language);
+				if (lang == null) {
+					System.err.println("Error: Unsupported language: " + language);
+					System.exit(6);
+				}
+				final Reader reader = file == null ? //
+					new InputStreamReader(System.in) : //
+					new FileReader(file);
+				m = ss.run("." + language, reader, true, inputs).get();
+			}
+			if (printOutputs) {
+				for (Entry<String, Object> output : m.getOutputs().entrySet()) {
+					System.out.println(output.getKey() + " = " + output.getValue());
+				}
+			}
+			if (printReturnValue && m instanceof ScriptModule) {
+				System.out.println(((ScriptModule) m).getReturnValue());
+			}
+		}
+		System.exit(0);
+	}
+}