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recompile.javaAPI DocJava SE 5 API6633Fri Aug 26 14:55:28 BST 2005com.sun.org.apache.regexp.internal

recompile

public class recompile extends Object
'recompile' is a command line tool that pre-compiles one or more regular expressions for use with the regular expression matcher class 'RE'. For example, the command "java recompile a*b" produces output like this: 

// Pre-compiled regular expression "a*b"
char[] re1Instructions =
{
0x007c, 0x0000, 0x001a, 0x007c, 0x0000, 0x000d, 0x0041,
0x0001, 0x0004, 0x0061, 0x007c, 0x0000, 0x0003, 0x0047,
0x0000, 0xfff6, 0x007c, 0x0000, 0x0003, 0x004e, 0x0000,
0x0003, 0x0041, 0x0001, 0x0004, 0x0062, 0x0045, 0x0000,
0x0000,
};

REProgram re1 = new REProgram(re1Instructions);
By pasting this output into your code, you can construct a regular expression matcher (RE) object directly from the pre-compiled data (the character array re1), thus avoiding the overhead of compiling the expression at runtime. For example: 

RE r = new RE(re1);
see
RE
see
RECompiler
author
Jonathan Locke
version
$Id: recompile.java,v 1.1 2000/04/27 01:22:33 jon Exp $

Fields Summary
Constructors Summary
Methods Summary
public static void_main(java.lang.String[] arg)
Main application entrypoint.

param
arg Command line arguments

        // Create a compiler object
        RECompiler r = new RECompiler();

        // Print usage if arguments are incorrect
        if (arg.length <= 0 || arg.length % 2 != 0)
        {
            System.out.println("Usage: recompile <patternname> <pattern>");
            System.exit(0);
        }

        // Loop through arguments, compiling each
        for (int i = 0; i < arg.length; i += 2)
        {
            try
            {
                // Compile regular expression
                String name         = arg[i];
                String pattern      = arg[i+1];
                String instructions = name + "PatternInstructions";

                // Output program as a nice, formatted character array
                System.out.print("\n    // Pre-compiled regular expression '" + pattern + "'\n" 
                                 + "    private static char[] " + instructions + " = \n    {");

                // Compile program for pattern
                REProgram program = r.compile(pattern);

                // Number of columns in output
                int numColumns = 7;

                // Loop through program
                char[] p = program.getInstructions();
                for (int j = 0; j < p.length; j++)
                {
                    // End of column?
                    if ((j % numColumns) == 0)
                    {
                        System.out.print("\n        ");
                    }

                    // Print character as padded hex number
                    String hex = Integer.toHexString(p[j]);
                    while (hex.length() < 4)
                    {
                        hex = "0" + hex;
                    }
                    System.out.print("0x" + hex + ", ");
                }

                // End of program block
                System.out.println("\n    };");
                System.out.println("\n    private static RE " + name + "Pattern = new RE(new REProgram(" + instructions + "));");
            }
            catch (RESyntaxException e)
            {
                System.out.println("Syntax error in expression \"" + arg[i] + "\": " + e.toString());
            }
            catch (Exception e)
            {
                System.out.println("Unexpected exception: " + e.toString());
            }
            catch (Error e)
            {
                System.out.println("Internal error: " + e.toString());
            }
        }