skyfire

1. to generate Lexer, Parser, Visitor automatically

add antlr-4.7-complete.jar to classpath

xml:

java org.antlr.v4.Tool -o E:\xml\ -visitor -no-listener -Dlanguage=Java E:\xml\XMLLexer.g4 java org.antlr.v4.Tool -o E:\xml\ -visitor -no-listener -Dlanguage=Java E:\xml\XMLParser.g4

javascript:

java org.antlr.v4.Tool -o E:\jsgrammar\ -visitor -no-listener -Dlanguage=Java E:\jsgrammar\JavaScriptLexer.g4 java org.antlr.v4.Tool -o E:\jsgrammar\ -visitor -no-listener -Dlanguage=Java E:\jsgrammar\JavaScriptParser.g4

2. install MySQL

download MySQL community version: mysql-installer-community-5.7.21.0.msi double click and install create new database pcsg create new table pcsg

xml

create table xmlpcsg ( id int auto_increment, parent varchar(100) not null, context varchar(500) not null, rule varchar(4000) not null, prob float not null, primary key(id) );

javascript

create table jspcsg ( id int auto_increment, parent varchar(100) not null, context varchar(500) not null, rule varchar(4000) not null, prob float not null, primary key(id) );

download mysql-connector-java-5.1.46.tar.gz from http://dev.mysql.com/downloads/connector/j/ and unzip it add mysql-connector-java-5.1.46-bin.jar to build path

3.change Visitor

change the original visitor function to extract context and rule information

public T visitDocument(XMLParser.DocumentContext ctx) {
	return visitChildren(ctx);
}

xml:

public T visitDocument(XMLParser.DocumentContext ctx) {
	String parent = "null", grandparent = "null", greatparent = "null", sibling = "null";
	if (ctx.getParent() != null) {
		parent = ctx.getParent().getClass().getSimpleName();
		if (ctx.getParent().getParent() != null) {
			grandparent = ctx.getParent().getParent().getClass().getSimpleName();
			if (ctx.getParent().getParent().getParent() != null) {
				greatparent = ctx.getParent().getParent().getParent().getClass().getSimpleName();
			}
		}
		if (ctx.getParent().getChild(0) != null) {
			// sibling = ctx.getParent().getChild(0).getClass().getSimpleName();
		}
	}
	String rule = "<" + greatparent + "," + grandparent + "," + parent + "," + sibling + ">";
	rule += ctx.getClass().getSimpleName() + "->";
	if (ctx.getChildCount() > 0 && ctx.getChildCount() < PCSGLearner.maxChildCount) {
		for (int i = 0; i < ctx.children.size(); i++) {
			if (ctx.getChild(i).getClass().getSimpleName().equals("TerminalNodeImpl")) {
				rule += ctx.getChild(i).getText().length() > PCSGLearner.maxChildLength
						? ctx.getChild(i).getText().substring(0, PCSGLearner.maxChildLength).trim()
						: ctx.getChild(i).getText().trim();
			} else {
				rule += "@@@@@" + ctx.getChild(i).getClass().getSimpleName() + "#####";
			}
		}
	} else {
		return visitChildren(ctx);
	}
	// System.out.println(rule);
	PCSGLearner.updateParentCount(ctx.getClass().getSimpleName());
	PCSGLearner.updateRuleCount(rule);
	return visitChildren(ctx);

}

javascript: pay special attention to ErrorNodeImpl.

public T visitDocument(XMLParser.DocumentContext ctx) {
	String parent = "null", grandparent = "null", greatparent = "null", sibling = "null";
	if (ctx.getParent() != null) {
		parent = ctx.getParent().getClass().getSimpleName();
		if (ctx.getParent().getParent() != null) {
			grandparent = ctx.getParent().getParent().getClass().getSimpleName();
			if (ctx.getParent().getParent().getParent() != null) {
				greatparent = ctx.getParent().getParent().getParent().getClass().getSimpleName();
			}
		}
		if (ctx.getParent().getChild(0) != null) {
			// sibling = ctx.getParent().getChild(0).getClass().getSimpleName();
		}
	}
	String rule = "<" + greatparent + "," + grandparent + "," + parent + "," + sibling + ">";
	rule += ctx.getClass().getSimpleName() + "->";
	if (ctx.getChildCount() > 0 && ctx.getChildCount() < JSPCSGLearner.maxChildCount) {
		for (int i = 0; i < ctx.children.size(); i++) {
			if (ctx.getChild(i).getClass().getSimpleName().equals("TerminalNodeImpl")) {
				rule += ctx.getChild(i).getText().length() > JSPCSGLearner.maxChildLength
						? ctx.getChild(i).getText().substring(0, JSPCSGLearner.maxChildLength).trim()
						: ctx.getChild(i).getText().trim();
			} else if (!ctx.getChild(i).getClass().getSimpleName().equals("ErrorNodeImpl")){
				rule += "@@@@@" + ctx.getChild(i).getClass().getSimpleName() + "#####";
			}
		}
	} else {
		return visitChildren(ctx);
	}
	// System.out.println(rule);
	JSPCSGLearner.updateParentCount(ctx.getClass().getSimpleName());
	JSPCSGLearner.updateRuleCount(rule);
	return visitChildren(ctx);

} 4. first run PCSGLearner class to learn from samples

some optimizations for XML: ChardataContext and MiscContext nodes normally contain a string whose value is useless to grammar. Therefore, we omit those nodes to get a much smaller PCSG. The non-terminal child of ContentContext contains comment and we omit them to reduce size of PCSG.

5. run Generator class to generate samples

Several parameters affect the seed and complexity of generation and users can change them as their needs.

static int maxDerivation = 50;			// the max number of derivation
static int maxDerivationDepth = 8;		// the max iteration depth of derivation
int numOfSamplesToGenerate = 10; 		// the number of seeds to generate
String outputPath = "E:\\xml_gen\\";	//the path to save generated seeds