ScriptInfo: use SJEP for more robust attr parsing

SJEP version 3.0.0 includes improved support for "group" operators,
including parentheses, square brackets and curly braces. And its
default expression evaluator aggregates groups into List objects,
which can be easily consumed by the ScriptInfo attribute parser.

Closes #156.

Author: ctrueden

pom.xml

@@ -116,9 +116,16 @@
 
 	<properties>
 		<scijava.jvm.test.version>1.8</scijava.jvm.test.version>
+		<scijava-expression-parser.version>3.0.0</scijava-expression-parser.version>
 	</properties>
 
 	<dependencies>
+		<!-- SciJava dependencies -->
+		<dependency>
+			<groupId>org.scijava</groupId>
+			<artifactId>scijava-expression-parser</artifactId>
+		</dependency>
+
 		<!-- Third-party dependencies -->
 		<dependency>
 			<groupId>com.googlecode.gentyref</groupId>

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

@@ -38,8 +38,11 @@
 import java.io.Reader;
 import java.io.StringReader;
 import java.text.SimpleDateFormat;
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.Date;
 import java.util.HashMap;
+import java.util.List;
 import java.util.Map;
 
 import javax.script.ScriptException;
@@ -56,6 +59,8 @@
 import org.scijava.module.DefaultMutableModuleItem;
 import org.scijava.module.ModuleException;
 import org.scijava.plugin.Parameter;
+import org.scijava.sjep.Variable;
+import org.scijava.sjep.eval.DefaultEvaluator;
 import org.scijava.util.DigestUtils;
 import org.scijava.util.FileUtils;
 
@@ -337,11 +342,11 @@ private void parseParam(final String param) throws ScriptException {
 		if (rParen < lParen) {
 			throw new ScriptException("Invalid parameter: " + param);
 		}
-		if (lParen < 0) parseParam(param, parseAttrs(""));
+		if (lParen < 0) parseParam(param, parseAttrs("()"));
 		else {
 			final String cutParam =
 				param.substring(0, lParen) + param.substring(rParen + 1);
-			final String attrs = param.substring(lParen + 1, rParen);
+			final String attrs = param.substring(lParen, rParen + 1);
 			parseParam(cutParam, parseAttrs(attrs));
 		}
 	}
@@ -374,20 +379,39 @@ private void parseParam(final String param,
 	private HashMap<String, Object> parseAttrs(final String attrs)
 		throws ScriptException
 	{
-		// TODO: We probably want to use a real CSV parser.
-		final HashMap<String, Object> attrsMap = new HashMap<String, Object>();
-		for (final String token : attrs.split(",")) {
-			if (token.isEmpty()) continue;
-			final int equals = token.indexOf("=");
-			if (equals < 0) throw new ScriptException("Invalid attribute: " + token);
-			final String key = token.substring(0, equals).trim();
-			String value = token.substring(equals + 1).trim();
-			if (value.startsWith("\"") && value.endsWith("\"")) {
-				value = value.substring(1, value.length() - 1);
+		// NB: Parse the attributes using the SciJava Expression Parser.
+		final DefaultEvaluator e = new DefaultEvaluator();
+		try {
+			final Object result = e.evaluate(attrs);
+			if (result == null) throw new ScriptException("Unparseable attributes");
+			final List<?> list;
+			if (result instanceof List) list = (List<?>) result;
+			else if (result instanceof Variable) {
+				list = Collections.singletonList(result);
+			}
+			else {
+				throw new ScriptException("Unexpected attributes type: " +
+					result.getClass().getName());
+			}
+
+			final HashMap<String, Object> attrsMap = new HashMap<String, Object>();
+			for (final Object o : list) {
+				if (o instanceof Variable) {
+					final Variable v = (Variable) o;
+					attrsMap.put(v.getToken(), e.value(v));
+				}
+				else {
+					throw new ScriptException("Invalid attribute: " + o);
+				}
 			}
-			attrsMap.put(key, value);
+			return attrsMap;
+		}
+		catch (final IllegalArgumentException exc) {
+			final ScriptException se = new ScriptException(
+				"Error parsing attributes");
+			se.initCause(exc);
+			throw se;
 		}
-		return attrsMap;
 	}
 
 	private boolean isIOType(final String token) {