private static PathExpr parse()

in parquet-cli/src/main/java/org/apache/parquet/cli/util/Expressions.java [114:182]
69 lines of code
15 McCabe index (conditional complexity)

  private static PathExpr parse(String path) {
    PathExpr expr = null;
    PathExpr last = null;
    boolean inDeref = false;
    boolean afterDeref = false;
    int valueStart = 0;
    for (int i = 0; i < path.length(); i += 1) {
      switch (path.charAt(i)) {
        case '.':
          Preconditions.checkState(valueStart != i || afterDeref, "Empty reference: ''");
          if (!inDeref) {
            if (valueStart != i) {
              PathExpr current = PathExpr.field(path.substring(valueStart, i));
              if (last != null) {
                last.children.add(current);
              } else {
                expr = current;
              }
              last = current;
            }
            valueStart = i + 1;
            afterDeref = false;
          }
          break;
        case '[':
          Preconditions.checkState(!inDeref, "Cannot nest [ within []");
          Preconditions.checkState(valueStart != i || afterDeref, "Empty reference: ''");
          if (valueStart != i) {
            PathExpr current = PathExpr.field(path.substring(valueStart, i));
            if (last != null) {
              last.children.add(current);
            } else {
              expr = current;
            }
            last = current;
          }
          valueStart = i + 1;
          inDeref = true;
          afterDeref = false;
          break;
        case ']':
          Preconditions.checkState(inDeref, "Cannot use ] without a starting [");
          Preconditions.checkState(valueStart != i, "Empty reference: ''");
          PathExpr current = PathExpr.deref(path.substring(valueStart, i));
          if (last != null) {
            last.children.add(current);
          } else {
            expr = current;
          }
          last = current;
          valueStart = i + 1;
          inDeref = false;
          afterDeref = true;
          break;
        default:
          Preconditions.checkState(!afterDeref, "Fields after [] must start with .");
      }
    }
    Preconditions.checkState(!inDeref, "Fields after [ must end with ]");
    if (valueStart < path.length()) {
      PathExpr current = PathExpr.field(path.substring(valueStart, path.length()));
      if (last != null) {
        last.children.add(current);
      } else {
        expr = current;
      }
    }
    return expr;
  }