Add CodeMirror syntax highlighting in notebooks

The B syntax highlighter is currently very primitive and does not work
well yet.

kernelspec/prob2/kernel.js

+define([
+	"codemirror/lib/codemirror",
+	"codemirror/mode/groovy/groovy",
+], function(
+	CodeMirror,
+) {
+	"use strict";
+	
+	return {
+		onload: function() {
+			console.info("Loading custom kernel.js");
+			CodeMirror.defineMode("classicalb", function(config, parserConfig) {
+				return {
+					startState: function() {
+						return {
+							state: "initial",
+						};
+					},
+					
+					token: function(stream, state) {
+						if (stream.match(/^[A-Z_]+/)) {
+							return "keyword";
+						} else {
+							stream.match(/^.+/);
+							return null;
+						}
+					},
+				};
+			});
+			
+			CodeMirror.defineMode("prob2_jupyter_repl", function(config, parserConfig) {
+				const switchToMode = function(state, mode) {
+					state.state = "inner";
+					state.innerMode = CodeMirror.getMode(config, mode);
+					state.innerState = CodeMirror.startState(state.innerMode);
+				};
+				
+				return {
+					startState: function() {
+						return {
+							state: "command",
+							innerMode: null,
+							innerState: null,
+						};
+					},
+					
+					copyState: function(state) {
+						return {
+							state: state.state,
+							innerMode: state.innerMode,
+							innerState: state.innerState === null ? null : CodeMirror.copyState(state.innerMode, state.innerState),
+						};
+					},
+					
+					innerMode: function(state) {
+						if (state.innerMode === null) {
+							return null;
+						} else {
+							return {mode: state.innerMode, state: state.innerState};
+						}
+					},
+					
+					token: function(stream, state) {
+						// Consume leading whitespace.
+						stream.match(/^\s+/);
+						if (stream.eol()) {
+							return null;
+						}
+						switch (state.state) {
+							case "command":
+								// Initial state: try to consume a command name.
+								const command = stream.match(/^\:[^\s]*/);
+								if (command) {
+									// Command found, switch to the appropriate state or mode.
+									switch (command[0]) {
+										case "::load":
+										case ":constants":
+										case ":eval":
+										case ":exec":
+										case ":init":
+										case ":initialise":
+										case ":prettyprint":
+										case ":solve":
+										case ":table":
+										case ":type":
+											switchToMode(state, "classicalb");
+											break;
+										
+										case "::render":
+											state.state = "render_mimetype";
+											break;
+										
+										case ":groovy":
+											switchToMode(state, "groovy");
+											break;
+										
+										case ":time":
+											state.state = "command";
+											break;
+										
+										default:
+											switchToMode(state, null);
+									}
+									return "meta";
+								} else {
+									// No command found, switch to B mode.
+									switchToMode(state, "classicalb");
+									return state.innerMode.token(stream, state.innerState);
+								}
+							
+							case "render_mimetype":
+								// Try to consume the MIME type argument of ::render.
+								const mimetype = stream.match(/^\S+/);
+								if (mimetype) {
+									// MIME type found, try to switch to the appropriate mode.
+									switchToMode(state, mimetype[0]);
+								} else {
+									// No MIME type found, switch to plaintext mode.
+									switchToMode(state, null);
+								}
+								break;
+							
+							case "inner":
+								// If an inner mode is active, delegate to its token method.
+								return state.innerMode.token(stream, state.innerState);
+							
+							default:
+								throw new Error("Unhandled state: " + state.state);
+						}
+					},
+				};
+			});
+			
+			CodeMirror.defineMIME("text/x-classicalb", "classicalb");
+			CodeMirror.defineMIME("text/x-prob2-jupyter-repl", "prob2_jupter_repl");
+			
+			// CodeMirror doesn't understand the text/latex MIME type by default.
+			CodeMirror.defineMIME("text/latex", "stex");
+		},
+	};
+});

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

@@ -134,8 +134,9 @@ public final class ProBKernel extends BaseKernel {
 	@Override
 	public @NotNull LanguageInfo getLanguageInfo() {
 		return new LanguageInfo.Builder("prob")
-			.mimetype("text/x-prob")
+			.mimetype("text/x-prob2-jupyter-repl")
 			.fileExtension(".prob")
+			.codemirror("prob2_jupyter_repl")
 			.build();
 	}