Add script processor for shebang syntax

This lets a script declare its own intended language.

See:
scijava/scijava-jupyter-kernel#51 (comment)

Author: ctrueden

src/main/java/org/scijava/script/process/ShebangScriptProcessor.java

@@ -0,0 +1,78 @@
+/*
+ * #%L
+ * SciJava Common shared library for SciJava software.
+ * %%
+ * Copyright (C) 2009 - 2017 Board of Regents of the University of
+ * Wisconsin-Madison, Broad Institute of MIT and Harvard, and Max Planck
+ * Institute of Molecular Cell Biology and Genetics.
+ * %%
+ * 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.process;
+
+import org.scijava.log.LogService;
+import org.scijava.plugin.Parameter;
+import org.scijava.plugin.Plugin;
+import org.scijava.script.ScriptInfo;
+import org.scijava.script.ScriptLanguage;
+import org.scijava.script.ScriptService;
+
+/**
+ * A {@link ScriptProcessor} which looks for a {@code #!} at the beginning of a
+ * script, and set the language accordingly.
+ * 
+ * @author Curtis Rueden
+ */
+@Plugin(type = ScriptProcessor.class)
+public class ShebangScriptProcessor implements ScriptProcessor {
+
+	@Parameter
+	private ScriptService scriptService;
+
+	@Parameter
+	private LogService log;
+
+	private ScriptInfo info;
+	private boolean first = true;
+
+	// -- ScriptProcessor methods --
+
+	@Override
+	public void begin(final ScriptInfo scriptInfo) {
+		info = scriptInfo;
+	}
+
+	@Override
+	public void process(final String line) {
+		if (!first) return;
+		if (line.startsWith("#!")) {
+			// shebang!
+			final String langName = line.substring(2);
+			final ScriptLanguage lang = scriptService.getLanguageByName(langName);
+			if (lang != null) info.setLanguage(lang);
+			else log.warn("Unknown script language: " + langName);
+		}
+		first = false;
+	}
+}