id: no-string-concat-in-loop
valid:
  - |
    StringBuilder result = new StringBuilder();
    for (String item : items) {
      result.append(item);
    }
  - 'String result = prefix + suffix;'
  - |
    int total = 0;
    for (int value : values) {
      total = total + value;
    }
  - |
    double count = 0;
    while (ready()) {
      count += 1;
    }
  # PR #2212 review F1: numeric accumulation whose right-hand side merely
  # contains a string literal, deep inside a call argument. The pre-fix rule
  # searched for a string_literal with `stopBy: end` and fired on both lines.
  - |
    class Counter {
      void run(java.util.Map<String, Integer> counts, java.util.List<String> keys) {
        int total = 0;
        for (String key : keys) {
          total += counts.get("label");
          total = total + counts.getOrDefault("k", 0);
        }
      }
    }
  # A String-named local in a different method must not license numeric
  # accumulation here. This pins the method scoping of the declaration arm.
  - |
    class Scoped {
      String build(java.util.List<String> items) {
        String total = "";
        return total;
      }
      int count(java.util.List<String> items) {
        int total = 0;
        for (String item : items) {
          total += item.length();
        }
        return total;
      }
    }
invalid:
  - |
    String result = "";
    for (String item : items) {
      result += item + " ";
    }
  - |
    while (ready()) {
      result = result + " " ;
    }
  # PR #2212 review F2: the canonical true positive. No string literal appears
  # anywhere in either statement, so the pre-fix rule reported nothing.
  - |
    class Builder {
      String join(java.util.List<String> items) {
        String s = "";
        for (String x : items) {
          s += x;
        }
        return s;
      }
    }
  - |
    class Builder {
      String join(java.util.List<String> items) {
        String t = "";
        for (String x : items) {
          t = t + x;
        }
        return t;
      }
    }
  # The accumulator is a String field, not a local.
  - |
    class Accumulator {
      private String buffer = "";
      void add(java.util.List<String> items) {
        for (String item : items) {
          buffer += item;
        }
      }
    }
  # do-while loops allocate the same way as for and while.
  - |
    class Looper {
      String pump() {
        String out = "";
        do {
          out += next();
        } while (ready());
        return out;
      }
    }