File	Doc	Category	Size	Date	Package
REProgram.java	API Doc	Java SE 5 API	7438	Fri Aug 26 14:55:28 BST 2005	com.sun.org.apache.regexp.internal

REProgram

• java.lang.Object

Fields Summary
static final int	OPT_HASBACKREFS
char[]	instruction
int	lenInstruction
char[]	prefix
int	flags

Constructors Summary
public REProgram(char[] instruction) Constructs a program object from a character array param instruction Character array with RE opcode instructions in it // Optimization flags (REProgram.OPT_*) this(instruction, instruction.length);
public REProgram(char[] instruction, int lenInstruction) Constructs a program object from a character array param instruction Character array with RE opcode instructions in it param lenInstruction Amount of instruction array in use setInstructions(instruction, lenInstruction);

Methods Summary
public char[]	getInstructions() Returns a copy of the current regular expression program in a character array that is exactly the right length to hold the program. If there is no program compiled yet, getInstructions() will return null. return A copy of the current compiled RE program // Ensure program has been compiled! if (lenInstruction != 0) { // Return copy of program char[] ret = new char[lenInstruction]; System.arraycopy(instruction, 0, ret, 0, lenInstruction); return ret; } return null;
public void	setInstructions(char[] instruction, int lenInstruction) Sets a new regular expression program to run. It is this method which performs any special compile-time search optimizations. Currently only two optimizations are in place - one which checks for backreferences (so that they can be lazily allocated) and another which attempts to find an prefix anchor string so that substantial amounts of input can potentially be skipped without running the actual program. param instruction Program instruction buffer param lenInstruction Length of instruction buffer in use // Save reference to instruction array this.instruction = instruction; this.lenInstruction = lenInstruction; // Initialize other program-related variables flags = 0; prefix = null; // Try various compile-time optimizations if there's a program if (instruction != null && lenInstruction != 0) { // If the first node is a branch if (lenInstruction >= RE.nodeSize && instruction[0 + RE.offsetOpcode] == RE.OP_BRANCH) { // to the end node int next = instruction[0 + RE.offsetNext]; if (instruction[next + RE.offsetOpcode] == RE.OP_END) { // and the branch starts with an atom if (lenInstruction >= (RE.nodeSize * 2) && instruction[RE.nodeSize + RE.offsetOpcode] == RE.OP_ATOM) { // then get that atom as an prefix because there's no other choice int lenAtom = instruction[RE.nodeSize + RE.offsetOpdata]; prefix = new char[lenAtom]; System.arraycopy(instruction, RE.nodeSize * 2, prefix, 0, lenAtom); } } } BackrefScanLoop: // Check for backreferences for (int i = 0; i < lenInstruction; i += RE.nodeSize) { switch (instruction[i + RE.offsetOpcode]) { case RE.OP_ANYOF: i += (instruction[i + RE.offsetOpdata] * 2); break; case RE.OP_ATOM: i += instruction[i + RE.offsetOpdata]; break; case RE.OP_BACKREF: flags |= OPT_HASBACKREFS; break BackrefScanLoop; } } }