:sig
DTree

:desc
Dynamic tree/container type used throughout UCE for structured data.

:Overview
`DTree` is UCE's general-purpose structured value type.

This is the runtime's default container for nested data such as configuration trees, call payloads, decoded JSON, connection state, and metadata returned by runtime helpers.

:Value Kinds
- `DTree` can hold:
- `String`
- `f64`
- `bool`
- pointer
- nested map of child `DTree` values (map-shaped `DTree` values can be used to represent list-like data when the keys are numeric strings in sequence)

:Used in
`context.var`
`context.cfg`
`context.call`
`context.connection`
`json_decode()` results
`unit_call()` return values
`unit_info()`

:Reading Values
`["key"]` accesses or creates a child node.
`.has("key")` checks whether a child exists without creating it.
`.key("key")` returns a child pointer when it already exists.
`.get_or_create("key")` returns a child pointer and creates it when missing.
`.get_by_path("a/b/c")` traverses nested children without creating missing keys.
`.to_string()` reads scalar content as text.
`.to_s64()`, `.to_u64()`, and `.to_f64()` perform best-effort numeric conversion.
`.to_bool()` performs best-effort boolean conversion.
`.to_stringmap()` converts a map-shaped tree into `StringMap`.

`operator[]` creates missing entries, just like `std::map`.
`.has()` and `.key()` are the non-mutating lookup helpers.
`.get_by_path()` is the non-creating traversal helper.
`.json_decode()` currently stores JSON numbers as string-valued `DTree` nodes, so typed numeric conversion is the normal way to consume those values.
References are dereferenced automatically in most normal reads.

:Conversion Rules
Scalar-looking strings are trimmed before numeric and boolean parsing.
`.to_bool()` understands common textual forms such as `true`, `false`, `yes`, `no`, `1`, and `0`.
`bool` values convert numerically to `1` / `0`.
Pointer values convert numerically when read as numbers.
Single-value maps can act as scalar wrappers for numeric and boolean conversion.
Invalid numeric input falls back to `0`.
`.to_stringmap()` converts map children key-by-key using each child's `to_string()`.

:Writing Values
`.set(String)`
`.set(f64)`
`.set_bool(bool)`
`.set(StringMap)`
`.set_array()`
`.push(...)`
`.pop()`
`.remove(key)`
`.clear()`

Use `.set_array()` when you want list-style behavior with `push()` / `pop()`.

:Inspection Helpers
`.has(key)`
`.key(key)`
`.get_or_create(key)`
`.get_type_name()`
`.is_array()`
`.is_list()`
`.to_json()`

:each()
`each(std::function<void (DTree t, String key)> f)` iterates over the current tree value.

For map-shaped `DTree` values, the callback is invoked once for each child entry and receives:
`t` as the child value
`key` as the child key

For non-map values, `each()` still invokes the callback once:
`t` is the current value
`key` is an empty string

Typical usage:
`context.var["items"].each([&](DTree item, String key) { print(key, ": ", item.to_string(), "\n"); });`

:Examples
`String theme = context.cfg.get_by_path("theme/key").to_string()`

`u64 compiled_mtime = unit_info("test/hello.uce")["compiled_mtime"].to_u64()`

`bool dark_mode = context.call["dark_mode"].to_bool()`

`if(DTree* user = payload.key("user")) { print(user->to_json()); }`

`payload.get_or_create("headers")->get_or_create("Content-Type")->set("text/plain")`

`StringMap headers = payload["headers"].to_stringmap()`

:related
**PHP:** Nested associative arrays, `stdClass`, decoded JSON trees, and helper accessors for deep array paths.
**JavaScript / Node.js:** Plain objects, arrays, `Map`, and JSON-shaped data passed between handlers.

:see
>types
get_by_path
json_decode