Class Compiler

classpath/java/util/regex/Compiler.java:21–533

Compiles regular expressions into PikeVMs. @author Johannes Schindelin

 * @author Johannes Schindelin
 */
class Compiler implements PikeVMOpcodes {
  private final static CharacterMatcher regularCharacter =
      CharacterMatcher.parse("[^\\\\.*+?|\\[\\]{}()^$]");

  private static class Output {
    private int[] program;
    private int offset;
    private int groupCount = -1;
    private int findPreambleSize;
    private ArrayList<CharacterMatcher> classes;
    private ArrayList<PikeVM> lookarounds;

    public Output(Expression expr) {
      // try-run to determine the code size
      expr.writeCode(this);
      program = new int[offset];
      offset = 0;
      groupCount = -1;
      classes = new ArrayList<CharacterMatcher>();
      lookarounds = new ArrayList<PikeVM>();
      // write it out!
      expr.writeCode(this);
    }

    public void add(int opcode) {
      if (program != null) {
        program[offset] = opcode;
      }
      offset++;
    }

    public int markJump() {
      return offset++;
    }

    public void setJump(int mark) {
      if (program != null) {
        program[mark] = offset;
      }
    }

    public void markFindPreambleEnd() {
      findPreambleSize = offset;
    }

    public PikeVM toVM() {
      CharacterMatcher[] classes = new CharacterMatcher[this.classes.size()];
      this.classes.toArray(classes);
      PikeVM[] lookarounds = new PikeVM[this.lookarounds.size()];
      this.lookarounds.toArray(lookarounds);
      return new PikeVM(program, findPreambleSize, groupCount, classes,
        lookarounds);
    }

    public int addClass(CharacterMatcher characterClass) {
      if (program == null) {
        return -1;
      }