JsonFormat

How a node's JSON is laid out when it's read (SearchHit.writeJsonTo, SelectedNode.writeJsonTo and their readJsonAsString). COMPACT, the default, is the exact output form of SPEC.md §5, with no whitespace. Any other format writes the same tokens with whitespace between them (SPEC.md §5.1), so removing the whitespace outside strings gives the compact text back byte for byte, unless maxLevels cuts nested containers out. Formatting is applied as the node is read; it's never stored.

A formatted container is written on one line — [1, 2, 3], {"id": 7, "tags": ["a", "b"]} — when that line fits lineWidth and the container passes maxInlineElements and maxInlineDepth; otherwise each of its elements starts a line of its own, indented one step deeper than the container, and the closing bracket goes on a line of its own at the container's indentation. With JsonFormat(lineWidth = 32):

{
  "name": "ada",
  "tags": ["math", "engines"],
  "scores": [
    {"round": 1, "points": 40},
    {"round": 2, "points": 44}
  ]
}

• indent: one indentation step, empty or up to MAX_INDENT_SPACES spaces, or one tab.

• lineWidth: the columns a line with a container on it may take: its indentation, the key before the container, the container and the comma after it. A column is a code point, and a tab counts as TAB_COLUMNS. 0 puts no non-empty container on one line — the layout of kotlinx.serialization's prettyPrint. At most MAX_LINE_WIDTH.

• maxInlineElements: a container with more elements (members, or array elements) never goes on one line.

• maxInlineDepth: a container that holds a non-empty container nested deeper than this never goes on one line; 0 puts only containers of scalars on one line.

• maxLevels: how many levels of nested containers are written in full. A non-empty container nested deeper than this below the node is written as {...} or [...] and laid out like a scalar, so 0 writes only the node's own elements: {"name": "ada", "tags": [...], "address": {...}}. Text cut this way isn't JSON.

Empty containers are always {} and []. A key is followed by ": ", the elements of a one-line container are separated by ", ", lines end with \n, and the text doesn't end with one. Scalars are never broken, so a long string makes a line longer than lineWidth.

Memory stays independent of the node's size: the writer holds at most one line's worth of the node while it decides. Formats are values: two instances with the same settings are equal.