--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/goodjava/parser/Parser.java	Tue Sep 17 01:35:01 2019 -0400
@@ -0,0 +1,156 @@
+package goodjava.parser;
+
+
+public class Parser {
+	public final String text;
+	private final int len;
+	private int[] stack = new int[256];
+	private int frame = 0;
+	private int iHigh;
+
+	public Parser(String text) {
+		this.text = text;
+		this.len = text.length();
+	}
+
+	private int i() {
+		return stack[frame];
+	}
+
+	private void i(int i) {
+		stack[frame] += i;
+		if( iHigh < stack[frame] )
+			iHigh = stack[frame];
+	}
+
+	public int begin() {
+		frame++;
+		if( frame == stack.length ) {
+			int[] a = new int[2*frame];
+			System.arraycopy(stack,0,a,0,frame);
+			stack = a;
+		}
+		stack[frame] = stack[frame-1];
+		return i();
+	}
+
+	public void rollback() {
+		stack[frame] = frame==0 ? 0 : stack[frame-1];
+	}
+
+	public <T> T success(T t) {
+		success();
+		return t;
+	}
+
+	public boolean success() {
+		frame--;
+		stack[frame] = stack[frame+1];
+		return true;
+	}
+
+	public <T> T failure(T t) {
+		failure();
+		return t;
+	}
+
+	public boolean failure() {
+		frame--;
+		return false;
+	}
+
+	public int currentIndex() {
+		return i();
+	}
+/*
+	public int errorIndex() {
+		return frame > 0 ? stack[frame-1] : 0;
+	}
+*/
+	public int highIndex() {
+		return iHigh;
+	}
+
+	public char lastChar() {
+		return text.charAt(i()-1);
+	}
+
+	public char currentChar() {
+		return text.charAt(i());
+	}
+
+	public boolean endOfInput() {
+		return i() >= len;
+	}
+
+	public boolean match(char c) {
+		if( endOfInput() || text.charAt(i()) != c )
+			return false;
+		i(1);
+		return true;
+	}
+
+	public boolean match(String s) {
+		int n = s.length();
+		if( !text.regionMatches(i(),s,0,n) )
+			return false;
+		i(n);
+		return true;
+	}
+
+	public boolean matchIgnoreCase(String s) {
+		int n = s.length();
+		if( !text.regionMatches(true,i(),s,0,n) )
+			return false;
+		i(n);
+		return true;
+	}
+
+	public boolean anyOf(String s) {
+		if( endOfInput() || s.indexOf(text.charAt(i())) == -1 )
+			return false;
+		i(1);
+		return true;
+	}
+
+	public boolean noneOf(String s) {
+		if( endOfInput() || s.indexOf(text.charAt(i())) != -1 )
+			return false;
+		i(1);
+		return true;
+	}
+
+	public boolean inCharRange(char cLow, char cHigh) {
+		if( endOfInput() )
+			return false;
+		char c = text.charAt(i());
+		if( !(cLow <= c && c <= cHigh) )
+			return false;
+		i(1);
+		return true;
+	}
+
+	public boolean anyChar() {
+		if( endOfInput() )
+			return false;
+		i(1);
+		return true;
+	}
+
+	public boolean test(char c) {
+		return !endOfInput() && text.charAt(i()) == c;
+	}
+
+	public boolean test(String s) {
+		return text.regionMatches(i(),s,0,s.length());
+	}
+
+	public boolean testIgnoreCase(String s) {
+		return text.regionMatches(true,i(),s,0,s.length());
+	}
+
+	public String textFrom(int start) {
+		return text.substring(start,i());
+	}
+
+}