final int analyzeFirstCharacter()

in src/org/apache/xerces/impl/xpath/regex/Token.java [385:490]
87 lines of code
40 McCabe index (conditional complexity)

    final int analyzeFirstCharacter(RangeToken result, int options) {
        switch (this.type) {
          case CONCAT:
            int ret = FC_CONTINUE;
            for (int i = 0;  i < this.size();  i ++)
                if ((ret = this.getChild(i).analyzeFirstCharacter(result, options)) != FC_CONTINUE)
                    break;
            return ret;

          case UNION:
            if (this.size() == 0)
                return FC_CONTINUE;
            /*
             *  a|b|c -> FC_TERMINAL
             *  a|.|c -> FC_ANY
             *  a|b|  -> FC_CONTINUE
             */
            int ret2 = FC_CONTINUE;
            boolean hasEmpty = false;
            for (int i = 0;  i < this.size();  i ++) {
                ret2 = this.getChild(i).analyzeFirstCharacter(result, options);
                if (ret2 == FC_ANY)
                    break;
                else if (ret2 == FC_CONTINUE)
                    hasEmpty = true;
            }
            return hasEmpty ? FC_CONTINUE : ret2;

          case CONDITION:
            int ret3 = this.getChild(0).analyzeFirstCharacter(result, options);
            if (this.size() == 1)  return FC_CONTINUE;
            if (ret3 == FC_ANY)  return ret3;
            int ret4 = this.getChild(1).analyzeFirstCharacter(result, options);
            if (ret4 == FC_ANY)  return ret4;
            return ret3 == FC_CONTINUE || ret4 == FC_CONTINUE ? FC_CONTINUE : FC_TERMINAL;

          case CLOSURE:
          case NONGREEDYCLOSURE:
            this.getChild(0).analyzeFirstCharacter(result, options);
            return FC_CONTINUE;

          case EMPTY:
          case ANCHOR:
            return FC_CONTINUE;

          case CHAR:
            int ch = this.getChar();
            result.addRange(ch, ch);
            if (ch < 0x10000 && isSet(options, RegularExpression.IGNORE_CASE)) {
                ch = Character.toUpperCase((char)ch);
                result.addRange(ch, ch);
                ch = Character.toLowerCase((char)ch);
                result.addRange(ch, ch);
            }
            return FC_TERMINAL;

          case DOT:
              return FC_ANY;

          case RANGE:
            result.mergeRanges(this);
            return FC_TERMINAL;

          case NRANGE:                          // ****
            result.mergeRanges(Token.complementRanges(this));
            return FC_TERMINAL;

          case INDEPENDENT:
          case PAREN:
            return this.getChild(0).analyzeFirstCharacter(result, options);

          case MODIFIERGROUP:
            options |= ((ModifierToken)this).getOptions();
            options &= ~((ModifierToken)this).getOptionsMask();
            return this.getChild(0).analyzeFirstCharacter(result, options);

          case BACKREFERENCE:
            result.addRange(0, UTF16_MAX);  // **** We can not optimize.
            return FC_ANY;

          case STRING:
            int cha = this.getString().charAt(0);
            int ch2;
            if (REUtil.isHighSurrogate(cha)
                && this.getString().length() >= 2
                && REUtil.isLowSurrogate((ch2 = this.getString().charAt(1))))
                cha = REUtil.composeFromSurrogates(cha, ch2);
            result.addRange(cha, cha);
            if (cha < 0x10000 && isSet(options, RegularExpression.IGNORE_CASE)) {
                cha = Character.toUpperCase((char)cha);
                result.addRange(cha, cha);
                cha = Character.toLowerCase((char)cha);
                result.addRange(cha, cha);
            }
            return FC_TERMINAL;

          case LOOKAHEAD:
          case NEGATIVELOOKAHEAD:
          case LOOKBEHIND:
          case NEGATIVELOOKBEHIND:
            return FC_CONTINUE;

          default:
            throw new RuntimeException("Token#analyzeHeadCharacter(): Invalid Type: "+this.type);
        }
    }