Add a base for directive-oriented ScriptProcessors

Now they can all extend the DirectiveScriptProcessor
abstract base class, saving a lot of boilerplate code.

Author: ctrueden

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

@@ -0,0 +1,140 @@
+/*
+ * #%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, Max Planck
+ * Institute of Molecular Cell Biology and Genetics, University of
+ * Konstanz, and KNIME GmbH.
+ * %%
+ * 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 java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Predicate;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.scijava.convert.ConvertService;
+import org.scijava.parse.ParseService;
+import org.scijava.plugin.Parameter;
+import org.scijava.script.ScriptInfo;
+
+/**
+ * Abstract base class for {@link ScriptProcessor} plugins that parse lines
+ * of the form {@code #@directive(...) ...}.
+ * 
+ * @author Curtis Rueden
+ */
+public abstract class DirectiveScriptProcessor implements ScriptProcessor {
+
+	private final Pattern p = //
+		Pattern.compile("^#@(\\w*)\\s*(\\((.*)\\))?\\s*(.*)$");
+
+	@Parameter
+	private ConvertService convertService;
+
+	@Parameter
+	private ParseService parser;
+
+	private ScriptInfo info;
+
+	private Predicate<String> directivesToMatch;
+
+	public DirectiveScriptProcessor(final Predicate<String> directivesToMatch) {
+		this.directivesToMatch = directivesToMatch;
+	}
+
+	// -- ScriptProcessor methods --
+
+	@Override
+	public void begin(final ScriptInfo scriptInfo) {
+		info = scriptInfo;
+	}
+
+	@Override
+	public String process(final String line) {
+		// as quickly as possible, verify that this line is a directive
+		if (!line.startsWith("#@")) return line;
+
+		// parse the directive, and ensure it is well-formed
+		final Matcher m = p.matcher(line);
+		if (!m.matches()) return line;
+
+		// ensure directive is relevant
+		final String directive = m.group(1);
+		if (!directivesToMatch.test(directive)) return line;
+
+		// parse attributes (inner match without parentheses)
+		final String attrString = m.group(3);
+		final Map<String, Object> attrs = attrString == null ? //
+			Collections.emptyMap() : parser.parse(attrString, false).asMap();
+
+		// retain the rest of the string
+		final String theRest = m.group(4);
+
+		return process(directive, attrs, theRest);
+	}
+
+	// -- Internal methods --
+
+	/** Processes the given directive. */
+	protected abstract String process(final String directive,
+		final Map<String, Object> attrs, final String theRest);
+
+	/** Gets the active {@link ScriptInfo} instance. */
+	protected ScriptInfo info() {
+		return info;
+	}
+
+	/** Checks whether some key matches the desired value, ignoring case. */
+	protected boolean is(final String key, final String desired) {
+		return desired.equalsIgnoreCase(key);
+	}
+
+	/** Coerces some object into another object of the given type. */
+	protected <T> T as(final Object v, final Class<T> type) {
+		final T converted = convertService.convert(v, type);
+		if (converted != null) return converted;
+		// NB: Attempt to convert via string.
+		// This is useful in cases where a weird type of object came back
+		// (e.g., org.scijava.parse.eval.Unresolved), but which happens to have a
+		// nice string representation which ultimately is expressible as the type.
+		return convertService.convert(v.toString(), type);
+	}
+
+	/** Coerces some object into a list of objects of the given type. */
+	protected <T> List<T> asList(final Object v, final Class<T> type) {
+		final ArrayList<T> result = new ArrayList<>();
+		final List<?> list = as(v, List.class);
+		for (final Object item : list) {
+			result.add(as(item, type));
+		}
+		return result;
+	}
+}