--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/luan/interp/ParseException.java	Sun Jun 22 04:10:59 2014 +0000
@@ -0,0 +1,55 @@
+package luan.interp;
+
+import luan.LuanSource;
+
+
+public final class ParseException extends Exception {
+	public final LuanSource src;
+	public final int iCurrent;
+	public final int iHigh;
+
+	ParseException(String msg,LuanSource src,int iCurrent,int iHigh) {
+		super(msg);
+		this.src = src;
+		this.iCurrent = iCurrent;
+		this.iHigh = iHigh;
+//System.out.println("iCurrent = "+iCurrent);
+//System.out.println("iHigh = "+iHigh);
+	}
+
+	private class Location {
+		final int line;
+		final int pos;
+
+		Location(int index) {
+			int line = 0;
+			int i = -1;
+			while(true) {
+				int j = src.text.indexOf('\n',i+1);
+				if( j == -1 || j >= index )
+					break;
+				i = j;
+				line++;
+			}
+			this.line = line;
+			this.pos = index - i - 1;
+		}
+	}
+
+	private String[] lines() {
+		return src.text.split("\n",-1);
+	}
+
+	public String getFancyMessage() {
+		Location loc = new Location(iCurrent);
+		String line = lines()[loc.line];
+		String msg = getMessage() +  " (line " + (loc.line+1) + ", pos " + (loc.pos+1) + ") in " + src.name + "\n";
+		StringBuilder sb = new StringBuilder(msg);
+		sb.append( line + "\n" );
+		for( int i=0; i<loc.pos; i++ ) {
+			sb.append( line.charAt(i)=='\t' ? '\t' : ' ' );
+		}
+		sb.append("^\n");
+		return sb.toString();
+	}
+}