Re-implement command inspection feature based on new argument parsing

CommandUtils.splitArgs now takes an extra (optional) parameter to ask
it to not split the entire argument string, but only up to the argument
at the given offset in the string. The returned SplitResult contains
information about which parameter the argument splitting stopped at.

This is used in the new implementation of the inspection feature: when
the kernel is asked to inspect at a certain position, the arguments are
split up to that position, and the argument at that position is
inspected. (The arguments are only split and not fully parsed, because
inspection should be possible even if the command arguments are still
incomplete or otherwise invalid.)

This new implementation replaces the old separate implementation in
CommandUtils.splitArgs.

src/main/java/de/prob2/jupyter/Command.java

@@ -43,7 +43,7 @@ public interface Command {
 	
 	public abstract @Nullable DisplayData run(final @NotNull ParsedArguments args);
 	
-	public abstract @Nullable DisplayData inspect(final @NotNull String argString, final int at);
+	public abstract @NotNull ParameterInspectors getParameterInspectors();
 	
 	public abstract @Nullable ReplacementOptions complete(final @NotNull String argString, final int at);
 }

src/main/java/de/prob2/jupyter/CommandUtils.java

@@ -90,7 +90,7 @@ public final class CommandUtils {
 		}
 	}
 	
-	public static @NotNull SplitResult splitArgs(final @NotNull Parameters parameters, final @NotNull String argString) {
+	public static @NotNull SplitResult splitArgs(final @NotNull Parameters parameters, final @NotNull String argString, final int upToPosition) {
 		final SplitArguments splitArgs = new SplitArguments(Collections.emptyMap());
 		PositionedString remainingArgs = new PositionedString(argString, 0);
 		if (parameters.getBodyParam().isPresent()) {
@@ -102,6 +102,7 @@ public final class CommandUtils {
 			}
 		}
 		
+		Parameter<?> parameterAtPosition = null;
 		for (int i = 0; i < parameters.getPositionalParameters().size();) {
 			final Parameter<?> param = parameters.getPositionalParameters().get(i);
 			if (remainingArgs.getValue().isEmpty()) {
@@ -112,12 +113,29 @@ public final class CommandUtils {
 			splitArgs.add(param, splitSingleArg.getSplitArg());
 			remainingArgs = splitSingleArg.getRemainingArgString();
 			
+			if (remainingArgs.getValue().isEmpty() || remainingArgs.getStartPosition() > upToPosition) {
+				parameterAtPosition = param;
+				break;
+			}
+			
 			if (!param.isRepeating()) {
 				i++;
 			}
 		}
 		
-		return new SplitResult(splitArgs, remainingArgs);
+		if (parameters.getBodyParam().isPresent() && splitArgs.containsKey(parameters.getBodyParam().get())) {
+			final List<PositionedString> bodyParamValues = splitArgs.get(parameters.getBodyParam().get());
+			assert bodyParamValues.size() == 1;
+			if (upToPosition >= bodyParamValues.get(0).getStartPosition()) {
+				parameterAtPosition = parameters.getBodyParam().get();
+			}
+		}
+		
+		return new SplitResult(splitArgs, parameterAtPosition, remainingArgs);
+	}
+	
+	public static @NotNull SplitResult splitArgs(final @NotNull Parameters parameters, final @NotNull String argString) {
+		return splitArgs(parameters, argString, argString.length());
 	}
 	
 	private static <T> void validateSplitParameter(final @NotNull ParsedArguments parsed, final @NotNull SplitArguments splitArgs, final @NotNull Parameter<T> param) {
@@ -290,25 +308,6 @@ public final class CommandUtils {
 		);
 	}
 	
-	public static @Nullable DisplayData inspectArgs(final @NotNull String argString, final int at, final @NotNull Inspector @NotNull... inspectors) {
-		final Matcher argSplitMatcher = ARG_SPLIT_PATTERN.matcher(argString);
-		int argStart = 0;
-		int argEnd = argString.length();
-		int i = 0;
-		while (argSplitMatcher.find()) {
-			if (argSplitMatcher.end() > at) {
-				argEnd = argSplitMatcher.start();
-				break;
-			}
-			argStart = argSplitMatcher.end();
-			if (i >= inspectors.length-1) {
-				break;
-			}
-			i++;
-		}
-		return inspectors[i].inspect(argString.substring(argStart, argEnd), at - argStart);
-	}
-	
 	public static @Nullable ReplacementOptions completeArgs(final @NotNull String argString, final int at, final @NotNull Completer @NotNull... completers) {
 		final Matcher argSplitMatcher = ARG_SPLIT_PATTERN.matcher(argString);
 		int argStart = 0;

src/main/java/de/prob2/jupyter/ParameterInspectors.java

+package de.prob2.jupyter;
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+import com.google.common.base.MoreObjects;
+
+import org.jetbrains.annotations.NotNull;
+
+public final class ParameterInspectors {
+	public static final @NotNull ParameterInspectors NONE = new ParameterInspectors(Collections.emptyMap());
+	
+	private final @NotNull Map<@NotNull Parameter<?>, CommandUtils.@NotNull Inspector> inspectors;
+	
+	public ParameterInspectors(final @NotNull Map<@NotNull Parameter<?>, CommandUtils.@NotNull Inspector> inspectors) {
+		super();
+		
+		this.inspectors = Collections.unmodifiableMap(new HashMap<>(inspectors));
+	}
+	
+	public @NotNull Map<@NotNull Parameter<?>, CommandUtils.@NotNull Inspector> getInspectors() {
+		return this.inspectors;
+	}
+	
+	@Override
+	public String toString() {
+		return MoreObjects.toStringHelper(this)
+			.add("inspectors", this.getInspectors())
+			.toString();
+	}
+	
+	public @NotNull Optional<CommandUtils.Inspector> getInspectorForParameter(final @NotNull Parameter<?> parameter) {
+		if (this.getInspectors().containsKey(parameter)) {
+			return Optional.of(this.getInspectors().get(parameter));
+		} else {
+			return Optional.empty();
+		}
+	}
+}

src/main/java/de/prob2/jupyter/ProBKernel.java

@@ -13,6 +13,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Optional;
 import java.util.Properties;
 import java.util.concurrent.atomic.AtomicReference;
 import java.util.regex.Matcher;
@@ -353,6 +354,23 @@ public final class ProBKernel extends BaseKernel {
 		}
 	}
 	
+	private static @Nullable DisplayData inspectCommandArguments(final @NotNull Command command, final @NotNull String argString, final int at) {
+		final SplitResult split = CommandUtils.splitArgs(command.getParameters(), argString, at);
+		if (split.getParameterAtPosition().isPresent()) {
+			final Optional<CommandUtils.Inspector> inspector = command.getParameterInspectors().getInspectorForParameter(split.getParameterAtPosition().get());
+			if (inspector.isPresent()) {
+				final List<PositionedString> argsAtPosition = split.getArguments().get(split.getParameterAtPosition().get());
+				assert !argsAtPosition.isEmpty();
+				final PositionedString lastArgument = argsAtPosition.get(argsAtPosition.size() - 1);
+				return inspector.get().inspect(lastArgument.getValue(), at - lastArgument.getStartPosition());
+			} else {
+				return null;
+			}
+		} else {
+			return null;
+		}
+	}
+	
 	@Override
 	public @Nullable DisplayData inspect(final @NotNull String code, final int at, final boolean extraDetail) {
 		// Note: We ignore the extraDetail parameter, because in practice it is always false. This is because the inspect_request messages sent by Jupyter Notebook always have their detail_level set to 0.
@@ -373,7 +391,7 @@ public final class ProBKernel extends BaseKernel {
 					// The cursor is somewhere in the command arguments, ask the command to inspect.
 					assert name != null;
 					final String argString = commandMatcher.group(2) == null ? "" : commandMatcher.group(2);
-					return command.inspect(argString, at - argOffset);
+					return inspectCommandArguments(command, argString, at - argOffset);
 				}
 			} else {
 				// Invalid command, can't inspect.
@@ -381,7 +399,7 @@ public final class ProBKernel extends BaseKernel {
 			}
 		} else {
 			// The code is not a valid command, ask :eval to inspect.
-			return this.getCommands().get(":eval").inspect(code, at);
+			return inspectCommandArguments(this.getCommands().get(":eval"), code, at);
 		}
 	}
 	

src/main/java/de/prob2/jupyter/SplitResult.java

 package de.prob2.jupyter;
 
+import java.util.Optional;
+
+import com.google.common.base.MoreObjects;
+
 import org.jetbrains.annotations.NotNull;
+import org.jetbrains.annotations.Nullable;
 
 public final class SplitResult {
 	private final @NotNull SplitArguments arguments;
+	private final @Nullable Parameter<?> parameterAtPosition;
 	private final @NotNull PositionedString remaining;
 	
-	public SplitResult(final @NotNull SplitArguments arguments, final @NotNull PositionedString remaining) {
+	public SplitResult(final @NotNull SplitArguments arguments, final @Nullable Parameter<?> parameterAtPosition, final @NotNull PositionedString remaining) {
 		super();
 		
 		this.arguments = arguments;
+		this.parameterAtPosition = parameterAtPosition;
 		this.remaining = remaining;
 	}
 	
@@ -17,7 +24,20 @@ public final class SplitResult {
 		return this.arguments;
 	}
 	
+	public @NotNull Optional<Parameter<?>> getParameterAtPosition() {
+		return Optional.ofNullable(this.parameterAtPosition);
+	}
+	
 	public @NotNull PositionedString getRemaining() {
 		return this.remaining;
 	}
+	
+	@Override
+	public String toString() {
+		return MoreObjects.toStringHelper(this)
+			.add("arguments", this.getArguments())
+			.add("parameterAtPosition", this.getParameterAtPosition())
+			.add("remaining", this.getRemaining())
+			.toString();
+	}
 }

src/main/java/de/prob2/jupyter/commands/AssertCommand.java

@@ -12,6 +12,7 @@ import de.prob.statespace.AnimationSelector;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -22,7 +23,6 @@ import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 import io.github.spencerpark.jupyter.kernel.display.mime.MIMEType;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class AssertCommand implements Command {
 	private static final @NotNull Parameter.RequiredSingle FORMULA_PARAM = Parameter.requiredRemainder("formula");
@@ -84,8 +84,10 @@ public final class AssertCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(Collections.singletonMap(
+			FORMULA_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/BrowseCommand.java

@@ -12,6 +12,7 @@ import de.prob.statespace.LoadedMachine;
 import de.prob.statespace.Trace;
 import de.prob.statespace.Transition;
 import de.prob2.jupyter.Command;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 
@@ -90,8 +91,8 @@ public final class BrowseCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/BsymbCommand.java

@@ -3,6 +3,7 @@ package de.prob2.jupyter.commands;
 import com.google.inject.Inject;
 
 import de.prob2.jupyter.Command;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 
@@ -53,8 +54,8 @@ public final class BsymbCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/CheckCommand.java

@@ -23,6 +23,7 @@ import de.prob.unicode.UnicodeTranslator;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.UserErrorException;
@@ -31,7 +32,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class CheckCommand implements Command {
 	private static final @NotNull Parameter.RequiredSingle WHAT_PARAM = Parameter.required("what");
@@ -113,8 +113,8 @@ public final class CheckCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/ConstantsCommand.java

@@ -13,6 +13,7 @@ import de.prob.statespace.Transition;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -21,7 +22,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class ConstantsCommand implements Command {
 	private static final @NotNull Parameter.OptionalSingle PREDICATE_PARAM = Parameter.optionalRemainder("predicate");
@@ -80,8 +80,10 @@ public final class ConstantsCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(Collections.singletonMap(
+			PREDICATE_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/DotCommand.java

@@ -10,6 +10,7 @@ import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.Stream;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
@@ -23,6 +24,7 @@ import de.prob.statespace.Trace;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -135,12 +137,11 @@ public final class DotCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectArgs(
-			argString, at,
-			(commandName, at0) -> null, // TODO
-			CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
-		);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(ImmutableMap.of(
+			COMMAND_PARAM, (commandName, at) -> null, // TODO
+			FORMULA_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/EvalCommand.java

@@ -10,6 +10,7 @@ import de.prob.statespace.AnimationSelector;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -18,7 +19,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class EvalCommand implements Command {
 	private static final @NotNull Parameter.RequiredSingle FORMULA_PARAM = Parameter.requiredRemainder("formula");
@@ -67,8 +67,10 @@ public final class EvalCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(Collections.singletonMap(
+			FORMULA_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/ExecCommand.java

@@ -5,6 +5,7 @@ import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
@@ -15,6 +16,7 @@ import de.prob.statespace.Transition;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -86,12 +88,11 @@ public final class ExecCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectArgs(
-			argString, at,
-			(operation, at0) -> null, // TODO
-			CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
-		);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(ImmutableMap.of(
+			OPERATION_PARAM, (operation, at) -> null, // TODO
+			PREDICATE_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/FindCommand.java

@@ -12,6 +12,7 @@ import de.prob.statespace.Trace;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -20,7 +21,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class FindCommand implements Command {
 	private static final @NotNull Parameter.RequiredSingle PREDICATE_PARAM = Parameter.requiredRemainder("predicate");
@@ -75,8 +75,10 @@ public final class FindCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(Collections.singletonMap(
+			PREDICATE_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/GotoCommand.java

@@ -8,6 +8,7 @@ import de.prob.statespace.AnimationSelector;
 import de.prob.statespace.Trace;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.UserErrorException;
@@ -68,8 +69,8 @@ public final class GotoCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/GroovyCommand.java

@@ -12,6 +12,7 @@ import com.google.inject.Injector;
 import de.prob.scripting.ScriptEngineProvider;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -76,8 +77,8 @@ public final class GroovyCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/HelpCommand.java

@@ -14,6 +14,7 @@ import com.google.inject.Injector;
 
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -23,7 +24,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class HelpCommand implements Command {
 	private static final @NotNull Parameter.OptionalSingle COMMAND_NAME_PARAM = Parameter.optional("commandName");
@@ -170,8 +170,8 @@ public final class HelpCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return null;
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/InitialiseCommand.java

@@ -13,6 +13,7 @@ import de.prob.statespace.Transition;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -21,7 +22,6 @@ import io.github.spencerpark.jupyter.kernel.ReplacementOptions;
 import io.github.spencerpark.jupyter.kernel.display.DisplayData;
 
 import org.jetbrains.annotations.NotNull;
-import org.jetbrains.annotations.Nullable;
 
 public final class InitialiseCommand implements Command {
 	private static final @NotNull Parameter.OptionalSingle PREDICATE_PARAM = Parameter.optionalRemainder("predicate");
@@ -80,8 +80,10 @@ public final class InitialiseCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(Collections.singletonMap(
+			PREDICATE_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/LetCommand.java

@@ -12,6 +12,7 @@ import de.prob.statespace.AnimationSelector;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -76,9 +77,9 @@ public final class LetCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
+	public @NotNull ParameterInspectors getParameterInspectors() {
 		// TODO
-		return null;
+		return ParameterInspectors.NONE;
 	}
 	
 	@Override

src/main/java/de/prob2/jupyter/commands/LoadCellCommand.java

@@ -4,6 +4,7 @@ import java.nio.file.Paths;
 import java.util.Collections;
 import java.util.Map;
 
+import com.google.common.collect.ImmutableMap;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
@@ -13,6 +14,7 @@ import de.prob.statespace.Trace;
 import de.prob2.jupyter.Command;
 import de.prob2.jupyter.CommandUtils;
 import de.prob2.jupyter.Parameter;
+import de.prob2.jupyter.ParameterInspectors;
 import de.prob2.jupyter.Parameters;
 import de.prob2.jupyter.ParsedArguments;
 import de.prob2.jupyter.ProBKernel;
@@ -84,15 +86,11 @@ public final class LoadCellCommand implements Command {
 	}
 	
 	@Override
-	public @Nullable DisplayData inspect(final @NotNull String argString, final int at) {
-		final int newlinePos = argString.indexOf('\n');
-		if (newlinePos == -1 || at < newlinePos) {
-			// Cursor is on the first line, provide preference inspections.
-			return CommandUtils.inspectInPreferences(this.animationSelector.getCurrentTrace(), argString, at);
-		} else {
-			// Cursor is in the body, provide B inspections.
-			return CommandUtils.inspectInBExpression(this.animationSelector.getCurrentTrace(), argString, at);
-		}
+	public @NotNull ParameterInspectors getParameterInspectors() {
+		return new ParameterInspectors(ImmutableMap.of(
+			PREFS_PARAM, CommandUtils.preferencesInspector(this.animationSelector.getCurrentTrace()),
+			CODE_PARAM, CommandUtils.bExpressionInspector(this.animationSelector.getCurrentTrace())
+		));
 	}
 	
 	@Override