--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/luan/lib/StringLib.java	Tue Dec 25 03:42:42 2012 +0000
@@ -0,0 +1,210 @@
+package luan.lib;
+
+import java.util.regex.Pattern;
+import java.util.regex.Matcher;
+import luan.Lua;
+import luan.LuaState;
+import luan.LuaTable;
+import luan.LuaFunction;
+import luan.LuaJavaFunction;
+import luan.LuaNumber;
+import luan.LuaElement;
+import luan.LuaException;
+
+
+public final class StringLib {
+
+	public static void register(LuaState lua) {
+		LuaTable module = new LuaTable();
+		LuaTable global = lua.global();
+		global.put("string",module);
+		try {
+			module.put( "byte", new LuaJavaFunction(StringLib.class.getMethod("byte_",String.class,Integer.class,Integer.class),null) );
+			module.put( "char", new LuaJavaFunction(StringLib.class.getMethod("char_",new byte[0].getClass()),null) );
+			add( module, "find", String.class, String.class, Integer.class, Boolean.class );
+			add( module, "gmatch", String.class, String.class );
+			add( module, "gsub", LuaState.class, String.class, String.class, Object.class, Integer.class );
+			add( module, "len", String.class );
+			add( module, "lower", String.class );
+			add( module, "match", String.class, String.class, Integer.class );
+			add( module, "rep", String.class, Integer.TYPE, String.class );
+			add( module, "reverse", String.class );
+			add( module, "sub", String.class, Integer.TYPE, Integer.class );
+			add( module, "upper", String.class );
+		} catch(NoSuchMethodException e) {
+			throw new RuntimeException(e);
+		}
+	}
+
+	private static void add(LuaTable t,String method,Class<?>... parameterTypes) throws NoSuchMethodException {
+		t.put( method, new LuaJavaFunction(StringLib.class.getMethod(method,parameterTypes),null) );
+	}
+
+	static int start(String s,int i) {
+		return i==0 ? 0 : i > 0 ? i - 1 : s.length() + i;
+	}
+
+	static int start(String s,Integer i,int dflt) {
+		return i==null ? dflt : start(s,i);
+	}
+
+	static int end(String s,int i) {
+		return i==0 ? 0 : i > 0 ? i : s.length() + i + 1;
+	}
+
+	static int end(String s,Integer i,int dflt) {
+		return i==null ? dflt : end(s,i);
+	}
+
+	public static byte[] byte_(String s,Integer i,Integer j) {
+		int start = start(s,i,0);
+		int end = end(s,j,start+1);
+		return s.substring(start,end).getBytes();
+	}
+
+	public static String char_(byte... bytes) {
+		return new String(bytes);
+	}
+
+	// format is hard because String.format() is too stupid to convert ints to floats.
+
+	public static int len(String s) {
+		return s.length();
+	}
+
+	public static String lower(String s) {
+		return s.toLowerCase();
+	}
+
+	public static String upper(String s) {
+		return s.toUpperCase();
+	}
+
+	public static String reverse(String s) {
+		return new StringBuilder(s).reverse().toString();
+	}
+
+	public static String rep(String s,int n,String sep) {
+		if( n < 1 )
+			return "";
+		StringBuilder buf = new StringBuilder(s);
+		while( --n > 0 ) {
+			if( sep != null )
+				buf.append(sep);
+			buf.append(s);
+		}
+		return buf.toString();
+	}
+
+	public static String sub(String s,int i,Integer j) {
+		int start = start(s,i);
+		int end = end(s,j,s.length());
+		return s.substring(start,end);
+	}
+
+	public static int[] find(String s,String pattern,Integer init,Boolean plain) {
+		int start = start(s,init,0);
+		if( Boolean.TRUE.equals(plain) ) {
+			int i = s.indexOf(pattern,start);
+			return i == -1 ? null : new int[]{i+1,i+pattern.length()};
+		}
+		Matcher m = Pattern.compile(pattern).matcher(s);
+		return m.find(start) ? new int[]{m.start()+1,m.end()} : null;
+	}
+
+	public static String[] match(String s,String pattern,Integer init) {
+		int start = start(s,init,0);
+		Matcher m = Pattern.compile(pattern).matcher(s);
+		if( !m.find(start) )
+			return null;
+		final int n = m.groupCount();
+		if( n == 0 )
+			return new String[]{m.group()};
+		String[] rtn = new String[n];
+		for( int i=0; i<n; i++ ) {
+			rtn[i] = m.group(i);
+		}
+		return rtn;
+	}
+
+	public static LuaFunction gmatch(String s,String pattern) {
+		final Matcher m = Pattern.compile(pattern).matcher(s);
+		return new LuaFunction() {
+			public Object[] call(LuaState lua,Object[] args) {
+				if( !m.find() )
+					return LuaFunction.EMPTY_RTN;
+				final int n = m.groupCount();
+				if( n == 0 )
+					return new String[]{m.group()};
+				String[] rtn = new String[n];
+				for( int i=0; i<n; i++ ) {
+					rtn[i] = m.group(i);
+				}
+				return rtn;
+			}
+		};
+	}
+
+	public static Object[] gsub(LuaState lua,String s,String pattern,Object repl,Integer n) throws LuaException {
+		int max = n==null ? Integer.MAX_VALUE : n;
+		final Matcher m = Pattern.compile(pattern).matcher(s);
+		if( repl instanceof String ) {
+			String replacement = (String)repl;
+			int i = 0;
+			StringBuffer sb = new StringBuffer();
+			while( i<max && m.find() ) {
+				m.appendReplacement(sb,replacement);
+				i++;
+			}
+			m.appendTail(sb);
+			return new Object[]{ sb.toString(), new LuaNumber(i) };
+		}
+		if( repl instanceof LuaTable ) {
+			LuaTable t = (LuaTable)repl;
+			int i = 0;
+			StringBuffer sb = new StringBuffer();
+			while( i<max && m.find() ) {
+				String match = m.groupCount()==0 ? m.group() : m.group(0);
+				Object val = t.get(match);
+				if( Lua.toBoolean(val) ) {
+					String replacement = Lua.asString(val);
+					if( replacement==null )
+						throw new LuaException( lua, LuaElement.JAVA, "invalid replacement value (a "+Lua.type(val)+")" );
+					m.appendReplacement(sb,replacement);
+				}
+				i++;
+			}
+			m.appendTail(sb);
+			return new Object[]{ sb.toString(), new LuaNumber(i) };
+		}
+		if( repl instanceof LuaFunction ) {
+			LuaFunction fn = (LuaFunction)repl;
+			int i = 0;
+			StringBuffer sb = new StringBuffer();
+			while( i<max && m.find() ) {
+				Object[] args;
+				final int count = m.groupCount();
+				if( count == 0 ) {
+					args = new Object[]{m.group()};
+				} else {
+					args = new Object[count];
+					for( int j=0; j<count; j++ ) {
+						args[j] = m.group(j);
+					}
+				}
+				Object val = Lua.first( lua.call(fn,LuaElement.JAVA,"repl-arg",args) );
+				if( Lua.toBoolean(val) ) {
+					String replacement = Lua.asString(val);
+					if( replacement==null )
+						throw new LuaException( lua, LuaElement.JAVA, "invalid replacement value (a "+Lua.type(val)+")" );
+					m.appendReplacement(sb,replacement);
+				}
+				i++;
+			}
+			m.appendTail(sb);
+			return new Object[]{ sb.toString(), new LuaNumber(i) };
+		}
+		throw new LuaException( lua, LuaElement.JAVA, "bad argument #3 to 'gsub' (string/function/table expected)" );
+	}
+
+}