From 4dcb672b728ad8bbee1cb87d1c49b39d87a7dc82 Mon Sep 17 00:00:00 2001
From: James Roseborough <james.roseborough@luaj.org>
Date: Tue, 28 Aug 2012 16:56:56 +0000
Subject: [PATCH] Sample code to use LuaParser and extract line and column
 info.

---
 examples/jse/SampleParser.java | 75 ++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)
 create mode 100644 examples/jse/SampleParser.java

diff --git a/examples/jse/SampleParser.java b/examples/jse/SampleParser.java
new file mode 100644
index 00000000..c1ba8c10
--- /dev/null
+++ b/examples/jse/SampleParser.java
@@ -0,0 +1,75 @@
+/** 
+ * Sample luaj program that uses the LuaParser class for parsing, and intercepts the 
+ * generated ParseExceptions and fills in the file, line and column information where 
+ * the exception occurred.
+ */
+import java.io.*;
+
+import org.luaj.vm2.*;
+import org.luaj.vm2.ast.*;
+import org.luaj.vm2.parser.*;
+
+
+public class SampleParser {
+	static LuaValue NIL = LuaValue.NIL;  // Workaround needed to ensure classes load in right order.
+	
+	// Sample ParseException subclass that stores the file, line, and column info.
+	static public class FileLineColumnParseException extends ParseException {
+		private static final long serialVersionUID = 1L;
+		public final String file;
+		public final int line;
+		public final int column;
+		public FileLineColumnParseException(String file, int line, int column, String message) {
+			super(message);
+			this.file = file;
+			this.line = line;
+			this.column = column;
+		}
+	}
+	
+	static public void main(String[] args) {
+		if (args.length == 0) {
+			System.out.println("usage: SampleParser luafile");
+			return;
+		}
+		try {
+			final String file = args[0];
+			
+			// Create a custom LuaParser subclass that intercepts parse exceptions and 
+			// extracts the line and column number information from the parse token.
+			LuaParser parser = new LuaParser(new FileInputStream(file)) {
+				  /** Generate ParseException. */
+				  public ParseException generateParseException() {
+				    Token errortok = token.next;
+				    int line = errortok.beginLine;
+				    int column = errortok.beginColumn;
+				    String mess = (errortok.kind == 0) ? tokenImage[0] : errortok.image;
+				    return new FileLineColumnParseException(file, line, column, mess);
+				  }
+			};
+			
+			// Perform the parsing.
+			Chunk chunk = parser.Chunk();
+			
+			// Optionally recurse over the parse tree with a custom Visitor instance.
+			chunk.accept( new Visitor() {
+				// TODO: override Visitor methods here to perform actions on the parse tree.
+			} );
+			
+		} catch ( FileLineColumnParseException e ) {
+			System.out.println( "Parse failed at identified line, column: "+e );
+			System.out.println( "File: "+e.file );
+			System.out.println( "Line: "+e.line );
+			System.out.println( "Column: "+e.column );
+			System.out.println( "Message: "+e.getMessage() );
+			
+		} catch ( ParseException e ) {
+			System.out.println( "Parse failed at unknown location: "+e );
+			e.printStackTrace();
+			
+		} catch ( IOException e ) {
+			System.out.println( "IOException occurred: "+e );
+			e.printStackTrace();
+		}
+	}
+}
\ No newline at end of file