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diff --git a/src/main/java/bjc/rgens/parser/RGrammar.java b/src/main/java/bjc/rgens/parser/RGrammar.java
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+++ b/src/main/java/bjc/rgens/parser/RGrammar.java
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+package bjc.rgens.parser;
+
+import bjc.rgens.parser.elements.CaseElement;
+import bjc.rgens.parser.elements.LiteralCaseElement;
+import bjc.rgens.parser.elements.RangeCaseElement;
+import bjc.rgens.parser.elements.RuleCaseElement;
+import bjc.rgens.parser.elements.VariableCaseElement;
+import bjc.utils.funcutils.StringUtils;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Random;
+import java.util.Set;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+import org.apache.commons.text.similarity.LevenshteinDistance;
+
+import edu.gatech.gtri.bktree.BkTreeSearcher;
+import edu.gatech.gtri.bktree.BkTreeSearcher.Match;
+import edu.gatech.gtri.bktree.Metric;
+import edu.gatech.gtri.bktree.MutableBkTree;
+
+/**
+ * Represents a randomized grammar.
+ *
+ * @author EVE
+ */
+public class RGrammar {
+	/* The max distance between possible alternate rules. */
+	private static final int MAX_DISTANCE = 6;
+
+	/* The metric for the levenshtein distance. */
+	private static final class LevenshteinMetric implements Metric<String> {
+		private static LevenshteinDistance DIST;
+
+		static {
+			DIST = LevenshteinDistance.getDefaultInstance();
+		}
+
+		public LevenshteinMetric() {
+		}
+
+		@Override
+		public int distance(String x, String y) {
+			return DIST.apply(x, y);
+		}
+	}
+
+	/* The current state during generation. */
+	private static class GenerationState {
+		/* The current string. */
+		public StringBuilder contents;
+		/* The RNG. */
+		public Random rnd;
+
+		/* The current set of variables. */
+		public Map<String, String> vars;
+
+		/**
+		 * Create a new generation state.
+		 * 
+		 * @param cont
+		 *            The string being generated.
+		 *
+		 * @param rand
+		 *            The RNG to use.
+		 *
+		 * @param vs
+		 *            The variables to use.
+		 */
+		public GenerationState(StringBuilder cont, Random rand, Map<String, String> vs) {
+			contents = cont;
+			rnd = rand;
+			vars = vs;
+		}
+	}
+
+	/* The pattern for matching the name of a variable. */
+	private static Pattern NAMEVAR_PATTERN = Pattern.compile("\\$(\\w+)");
+
+	/* The rules of the grammar. */
+	private Map<String, Rule> rules;
+	/* The rules imported from other grammars. */
+	private Map<String, RGrammar> importRules;
+	/* The rules exported from this grammar. */
+	private Set<String> exportRules;
+	/* The initial rule of this grammar. */
+	private String initialRule;
+
+	/* The tree to use for finding rule suggestions. */
+	private BkTreeSearcher<String> ruleSearcher;
+
+	/**
+	 * Create a new randomized grammar using the specified set of rules.
+	 *
+	 * @param ruls
+	 *            The rules to use.
+	 */
+	public RGrammar(Map<String, Rule> ruls) {
+		rules = ruls;
+	}
+
+	/**
+	 * Sets the imported rules to use.
+	 *
+	 * Imported rules are checked for rule definitions after local definitions are
+	 * checked.
+	 *
+	 * @param importedRules
+	 *            The set of imported rules to use.
+	 */
+	public void setImportedRules(Map<String, RGrammar> importedRules) {
+		importRules = importedRules;
+	}
+
+	/**
+	 * Generates the data structure backing rule suggestions for unknown rules.
+	 */
+	public void generateSuggestions() {
+		MutableBkTree<String> ruleSuggester = new MutableBkTree<>(new LevenshteinMetric());
+
+		ruleSuggester.addAll(rules.keySet());
+		ruleSuggester.addAll(importRules.keySet());
+
+		ruleSearcher = new BkTreeSearcher<>(ruleSuggester);
+	}
+
+	/**
+	 * Generate a string from this grammar, starting from the specified rule.
+	 *
+	 * @param startRule
+	 *            The rule to start generating at, or null to use the initial rule
+	 *            for this grammar.
+	 *
+	 * @return A possible string from the grammar.
+	 */
+	public String generate(String startRule) {
+		return generate(startRule, new Random(), new HashMap<>());
+	}
+
+	/**
+	 * Generate a string from this grammar, starting from the specified rule.
+	 *
+	 * @param startRule
+	 *            The rule to start generating at, or null to use the initial rule
+	 *            for this grammar.
+	 *
+	 * @param rnd
+	 *            The random number generator to use.
+	 *
+	 * @param vars
+	 *            The set of variables to use.
+	 *
+	 * @return A possible string from the grammar.
+	 */
+	public String generate(String startRule, Random rnd, Map<String, String> vars) {
+		String fromRule = startRule;
+
+		if (startRule == null) {
+			if (initialRule == null) {
+				throw new GrammarException("Must specify a start rule for grammars with no initial rule");
+			}
+
+			fromRule = initialRule;
+		} else {
+			if (startRule.equals("")) {
+				throw new GrammarException("The empty string is not a valid rule name");
+			}
+		}
+
+		RuleCase start = rules.get(fromRule).getCase(rnd);
+
+		StringBuilder contents = new StringBuilder();
+
+		generateCase(start, new GenerationState(contents, rnd, vars));
+
+		String body = contents.toString();
+		/*
+		 * Collapse duplicate spaces.
+		 */
+		body = body.replaceAll("\\s+", " ");
+
+		/*
+		 * Remove extraneous spaces around punctutation marks.
+		 *
+		 * This can be done in the grammars, but it is very tedious to do so.
+		 */
+
+		/* Handle 's */
+		body = body.replaceAll(" 's ", "'s ");
+
+		/* Handle opening/closing punctuation. */
+		body = body.replaceAll("([(\\[]) ", " $1");
+		body = body.replaceAll(" ([)\\]'\"])", "$1 ");
+
+		/* Remove spaces around series of opening/closing punctuation. */
+		body = body.replaceAll("([(\\[])\\s+([(\\[])", "$1$2");
+		body = body.replaceAll("([)\\]])\\s+([)\\]])", "$1$2");
+
+		/* Handle inter-word punctuation. */
+		body = body.replaceAll(" ([,:.!])", "$1 ");
+
+		/* Handle intra-word punctuation. */
+		body = body.replaceAll("\\s?([-/])\\s?", "$1");
+
+		/*
+		 * Collapse duplicate spaces.
+		 */
+		body = body.replaceAll("\\s+", " ");
+
+		/*
+		 * @TODO 11/01/17 Ben Culkin :RegexRule Replace this once it is no longer
+		 * needed.
+		 */
+		body = body.replaceAll("\\s(ish|burg|ton|ville|opolis|field|boro|dale)", "$1");
+
+		return body;
+	}
+
+	/* Generate a rule case. */
+	private void generateCase(RuleCase start, GenerationState state) {
+		try {
+			switch (start.type) {
+			case NORMAL:
+				for (CaseElement elm : start.getElements()) {
+					generateElement(elm, state);
+
+					if (elm.type != CaseElement.ElementType.VARDEF) {
+						state.contents.append(" ");
+					}
+				}
+				break;
+			case SPACEFLATTEN:
+				for (CaseElement elm : start.getElements()) {
+					generateElement(elm, state);
+				}
+				break;
+			default:
+				String msg = String.format("Unknown case type '%s'", start.type);
+				throw new GrammarException(msg);
+			}
+		} catch (GrammarException gex) {
+			String msg = String.format("Error in generating case (%s)", start);
+			throw new GrammarException(msg, gex);
+		}
+	}
+
+	/* Generate a case element. */
+	private void generateElement(CaseElement elm, GenerationState state) {
+		try {
+			switch (elm.type) {
+			case LITERAL: {
+				LiteralCaseElement lit = (LiteralCaseElement)elm;
+				
+				state.contents.append(lit.val);
+				break;
+			}
+			case RULEREF: {
+				RuleCaseElement rle = (RuleCaseElement)elm;
+				
+				generateRuleReference(rle, state);
+				break;
+			}
+			case RANGE: {
+				RangeCaseElement rang = (RangeCaseElement)elm;
+
+				int val = state.rnd.nextInt(rang.end - rang.begin);
+				val += rang.begin;
+
+				state.contents.append(val);
+				break;
+			}
+			case VARDEF:
+				generateVarDef(((VariableCaseElement)elm).varName, ((VariableCaseElement)elm).varDef, state);
+				break;
+			case EXPVARDEF:
+				generateExpVarDef(((VariableCaseElement)elm).varName, ((VariableCaseElement)elm).varDef, state);
+				break;
+			default:
+				String msg = String.format("Unknown element type '%s'", elm.type);
+				throw new GrammarException(msg);
+			}
+		} catch (GrammarException gex) {
+			String msg = String.format("Error in generating case element (%s)", elm);
+			throw new GrammarException(msg, gex);
+		}
+	}
+
+	/* Generate a expanding variable definition. */
+	private void generateExpVarDef(String name, String defn, GenerationState state) {
+		GenerationState newState = new GenerationState(new StringBuilder(), state.rnd, state.vars);
+
+		if (rules.containsKey(defn)) {
+			RuleCase destCase = rules.get(defn).getCase();
+
+			generateCase(destCase, newState);
+		} else if (importRules.containsKey(defn)) {
+			RGrammar destGrammar = importRules.get(defn);
+			String res = destGrammar.generate(defn, state.rnd, state.vars);
+
+			newState.contents.append(res);
+		} else {
+			String msg = String.format("No rule '%s' defined", defn);
+			throw new GrammarException(msg);
+		}
+
+		state.vars.put(name, newState.contents.toString());
+	}
+
+	/* Generate a variable definition. */
+	private static void generateVarDef(String name, String defn, GenerationState state) {
+		state.vars.put(name, defn);
+	}
+
+	/* Generate a rule reference. */
+	private void generateRuleReference(RuleCaseElement elm, GenerationState state) {
+		String refersTo = elm.val;
+
+		GenerationState newState = new GenerationState(new StringBuilder(), state.rnd, state.vars);
+
+		if (refersTo.contains("$")) {
+			/* Parse variables */
+			String refBody = refersTo.substring(1, refersTo.length() - 1);
+
+			if (refBody.contains("-")) {
+				/* Handle dependent rule names. */
+				StringBuffer nameBuffer = new StringBuffer();
+
+				Matcher nameMatcher = NAMEVAR_PATTERN.matcher(refBody);
+
+				while (nameMatcher.find()) {
+					String var = nameMatcher.group(1);
+
+					if (!state.vars.containsKey(var)) {
+						String msg = String.format("No variable '%s' defined", var);
+						throw new GrammarException(msg);
+					}
+
+					String name = state.vars.get(var);
+
+					if (name.contains(" ")) {
+						throw new GrammarException("Variables substituted into names cannot contain spaces");
+					} else if (name.equals("")) {
+						throw new GrammarException("Variables substituted into names cannot be empty");
+					}
+
+					nameMatcher.appendReplacement(nameBuffer, name);
+				}
+
+				nameMatcher.appendTail(nameBuffer);
+
+				refersTo = "[" + nameBuffer.toString() + "]";
+			} else {
+				/* Handle string references. */
+				if (refBody.equals("$")) {
+					throw new GrammarException("Cannot refer to unnamed variables");
+				}
+
+				String key = refBody.substring(1);
+
+				if (!state.vars.containsKey(key)) {
+					String msg = String.format("No variable '%s' defined", key);
+					throw new GrammarException(msg);
+				}
+
+				state.contents.append(state.vars.get(key));
+
+				return;
+			}
+		}
+
+		if (refersTo.startsWith("[^")) {
+			refersTo = "[" + refersTo.substring(2);
+
+			RGrammar dst = importRules.get(refersTo);
+
+			newState.contents.append(dst.generate(refersTo, state.rnd, state.vars));
+		} else if (rules.containsKey(refersTo)) {
+			RuleCase cse = rules.get(refersTo).getCase(state.rnd);
+
+			generateCase(cse, newState);
+		} else if (importRules.containsKey(refersTo)) {
+			RGrammar dst = importRules.get(refersTo);
+
+			newState.contents.append(dst.generate(refersTo, state.rnd, state.vars));
+		} else {
+			if (ruleSearcher != null) {
+				Set<Match<? extends String>> results = ruleSearcher.search(refersTo, MAX_DISTANCE);
+
+				String[] resArray = results.stream().map(Match::getMatch).toArray((i) -> new String[i]);
+
+				String msg = String.format("No rule '%s' defined (perhaps you meant %s?)", refersTo,
+						StringUtils.toEnglishList(resArray, false));
+
+				throw new GrammarException(msg);
+			}
+
+			String msg = String.format("No rule '%s' defined", refersTo);
+			throw new GrammarException(msg);
+		}
+
+		if (refersTo.contains("+")) {
+			/* Rule names with pluses in them get space-flattened */
+			state.contents.append(newState.contents.toString().replaceAll("\\s+", ""));
+		} else {
+			state.contents.append(newState.contents.toString());
+		}
+	}
+
+	/**
+	 * Get the initial rule of this grammar.
+	 *
+	 * @return The initial rule of this grammar.
+	 */
+	public String getInitialRule() {
+		return initialRule;
+	}
+
+	/**
+	 * Set the initial rule of this grammar.
+	 *
+	 * @param initRule
+	 *            The initial rule of this grammar, or null to say there is no
+	 *            initial rule.
+	 */
+	public void setInitialRule(String initRule) {
+		/* Passing null, nulls our initial rule. */
+		if (initRule == null) {
+			this.initialRule = null;
+			return;
+		}
+
+		if (initRule.equals("")) {
+			throw new GrammarException("The empty string is not a valid rule name");
+		} else if (!rules.containsKey(initRule)) {
+			String msg = String.format("No rule '%s' local to this grammar defined.", initRule);
+
+			throw new GrammarException(msg);
+		}
+
+		initialRule = initRule;
+	}
+
+	/**
+	 * Gets the rules exported by this grammar.
+	 *
+	 * The initial rule is exported by default if specified.
+	 *
+	 * @return The rules exported by this grammar.
+	 */
+	public Set<Rule> getExportedRules() {
+		Set<Rule> res = new HashSet<>();
+
+		for (String rname : exportRules) {
+			if (!rules.containsKey(rname)) {
+				String msg = String.format("No rule '%s' local to this grammar defined", initialRule);
+
+				throw new GrammarException(msg);
+			}
+
+			res.add(rules.get(rname));
+		}
+
+		if (initialRule != null) {
+			res.add(rules.get(initialRule));
+		}
+
+		return res;
+	}
+
+	/**
+	 * Set the rules exported by this grammar.
+	 *
+	 * @param exportedRules
+	 *            The rules exported by this grammar.
+	 */
+	public void setExportedRules(Set<String> exportedRules) {
+		exportRules = exportedRules;
+	}
+
+	/**
+	 * Get all the rules in this grammar.
+	 *
+	 * @return All the rules in this grammar.
+	 */
+	public Map<String, Rule> getRules() {
+		return rules;
+	}
+}