# DFHack Lua API

Contents

- DF structure wrapper
  - Typed object references
    - Primitive references
    - Struct references
    - Container references
    - Bitfield references
  - Named types
  - Global functions
  - Recursive table assignment
- DFHack utilities
  - Persistent configuration storage
  - Material info lookup
  - C++ function wrappers
    - Gui module
    - Job module
    - Units module
    - Items module
    - Maps module

# DF structure wrapper

DF structures described by the xml files in library/xml are exported to lua code as a tree of objects and functions under the `df` global, which broadly maps to the `df` namespace in C++.

WARNING: The wrapper provides almost raw access to the memory of the game, so mistakes in manipulating objects are as likely to crash the game as equivalent plain C++ code would be. E.g. NULL pointer access is safely detected, but dangling pointers aren't.

Objects managed by the wrapper can be broadly classified into the following groups:

1. Typed object pointers (references).

   References represent objects in DF memory with a known type.

   In addition to fields and methods defined by the wrapped type, every reference has some built-in properties and methods.

2. Untyped pointers

   Represented as lightuserdata.

   In assignment to a pointer NULL can be represented either as `nil`, or a NULL lightuserdata; reading a NULL pointer field returns `nil`.

3. Named types

   Objects in the `df` tree that represent identity of struct, class, enum and bitfield types. They host nested named types, static methods, builtin properties & methods, and, for enums and bitfields, the bi-directional mapping between key names and values.

4. The `global` object

   `df.global` corresponds to the `df::global` namespace, and behaves as a mix between a named type and a reference, containing both nested types and fields corresponding to global symbols.

In addition to the `global` object and top-level types the `df` global also contains a few global builtin utility functions.

## Typed object references

The underlying primitive lua object is userdata with a metatable. Every structured field access produces a new userdata instance.

All typed objects have the following built-in features:

- `ref1 == ref2`, `tostring(ref)`

  References implement equality by type & pointer value, and string conversion.

- `pairs(ref)`

  Returns an iterator for the sequence of actual C++ field names and values. Fields are enumerated in memory order. Methods and lua wrapper properties are not included in the iteration.

  WARNING: a few of the data structures (like ui_look_list) contain unions with pointers to different types with vtables. Using pairs on such structs is an almost sure way to crash with an access violation.

- `ref._kind`

  Returns one of: `primitive`, `struct`, `container`, or `bitfield`, as appropriate for the referenced object.

- `ref._type`

  Returns the named type object or a string that represents the referenced object type.

- `ref:sizeof()`

  Returns size, address

- `ref:new()`

  Allocates a new instance of the same type, and copies data from the current object.

- `ref:delete()`

  Destroys the object with the C++ `delete` operator. If destructor is not available, returns false.

  WARNING: the lua reference object remains as a dangling pointer, like a raw C++ pointer would.

- `ref:assign(object)`

  Assigns data from object to ref. Object must either be another ref of a compatible type, or a lua table; in the latter case special recursive assignment rules are applied.

- `ref:_displace(index[,step])`

  Returns a new reference with the pointer adjusted by index*step. Step defaults to the natural object size.

### Primitive references

References of the _kind `'primitive'` are used for objects that don't fit any of the other reference types. Such references can only appear as a value of a pointer field, or as a result of calling the `_field()` method.

They behave as structs with one field `value` of the right type.

### Struct references

Struct references are used for class and struct objects.

They implement the following features:

- `ref.field`, `ref.field = value`

  Valid fields of the structure may be accessed by subscript.

  Primitive typed fields, i.e. numbers & strings, are converted to/from matching lua values. The value of a pointer is a reference to the target, or nil/NULL. Complex types are represented by a reference to the field within the structure; unless recursive lua table assignment is used, such fields can only be read.

  NOTE: In case of inheritance, superclass fields have precedence over the subclass, but fields shadowed in this way can still be accessed as `ref['subclasstype.field']`. This shadowing order is necessary because vtable-based classes are automatically exposed in their exact type, and the reverse rule would make access to superclass fields unreliable.

- `ref._field(field)`

  Returns a reference to a valid field. That is, unlike regular subscript, it returns a reference to the field within the structure even for primitive typed fields and pointers.

- `ref:vmethod(args...)`

  Named virtual methods are also exposed, subject to the same shadowing rules.

- `pairs(ref)`

  Enumerates all real fields (but not methods) in memory (= declaration) order.

### Container references

Containers represent vectors and arrays, possibly resizable.

A container field can associate an enum to the container reference, which allows accessing elements using string keys instead of numerical indices.

Implemented features:

- `ref._enum`

  If the container has an associated enum, returns the matching named type object.

- `#ref`

  Returns the length of the container.

- `ref[index]`

  Accesses the container element, using either a 0-based numerical index, or, if an enum is associated, a valid enum key string.

  Accessing an invalid index is an error, but some container types may return a default value, or auto-resize instead for convenience. Currently this relaxed mode is implemented by df-flagarray aka BitArray.

- `ref._field(index)`

  Like with structs, returns a pointer to the array element, if possible. Flag and bit arrays cannot return such pointer, so it fails with an error.

- `pairs(ref)`, `ipairs(ref)`

  If the container has no associated enum, both behave identically, iterating over numerical indices in order. Otherwise, ipairs still uses numbers, while pairs tries to substitute enum keys whenever possible.

- `ref:resize(new_size)`

  Resizes the container if supported, or fails with an error.

- `ref:insert(index,item)`

  Inserts a new item at the specified index. To add at the end, use `#ref` as index.

- `ref:erase(index)`

  Removes the element at the given valid index.

### Bitfield references

Bitfields behave like special fixed-size containers. The `_enum` property points to the bitfield type.

Numerical indices correspond to the shift value, and if a subfield occupies multiple bits, the `ipairs` order would have a gap.

## Named types

Named types are exposed in the `df` tree with names identical to the C++ version, except for the `::` vs `.` difference.

All types and the global object have the following features:

- `type._kind`

  Evaluates to one of `struct-type`, `class-type`, `enum-type`, `bitfield-type` or `global`.

- `type._identity`

  Contains a lightuserdata pointing to the underlying DFHack::type_instance object.

Types excluding the global object also support:

- `type:sizeof()`

  Returns the size of an object of the type.

- `type:new()`

  Creates a new instance of an object of the type.

- `type:is_instance(object)`

  Returns true if object is same or subclass type, or a reference to an object of same or subclass type. It is permissible to pass nil, NULL or non-wrapper value as object; in this case the method returns nil.

In addition to this, enum and bitfield types contain a bi-directional mapping between key strings and values, and also map `_first_item` and `_last_item` to the min and max values.

Struct and class types with instance-vector attribute in the xml have a `type.find(key)` function that wraps the find method provided in C++.

## Global functions

The `df` table itself contains the following functions and values:

- `NULL`, `df.NULL`

  Contains the NULL lightuserdata.

- `df.isnull(obj)`

  Evaluates to true if obj is nil or NULL; false otherwise.

- `df.isvalid(obj[,allow_null])`

  For supported objects returns one of `type`, `voidptr`, `ref`.

  If allow_null is true, and obj is nil or NULL, returns `null`.

  Otherwise returns nil.

- `df.sizeof(obj)`

  For types and refs identical to `obj:sizeof()`. For lightuserdata returns nil, address

- `df.new(obj)`, `df.delete(obj)`, `df.assign(obj, obj2)`

  Equivalent to using the matching methods of obj.

- `df._displace(obj,index[,step])`

  For refs equivalent to the method, but also works with lightuserdata (step is mandatory then).

- `df.is_instance(type,obj)`

  Equivalent to the method, but also allows a reference as proxy for its type.

## Recursive table assignment

Recursive assignment is invoked when a lua table is assigned to a C++ object or field, i.e. one of:

- `ref:assign{...}`
- `ref.field = {...}`

The general mode of operation is that all fields of the table are assigned to the fields of the target structure, roughly emulating the following code:

    function rec_assign(ref,table)
        for key,value in pairs(table) do
            ref[key] = value
        end
    end

Since assigning a table to a field using = invokes the same process, it is recursive.

There are however some variations to this process depending on the type of the field being assigned to:

1. If the table contains an `assign` field, it is applied first, using the `ref:assign(value)` method. It is never assigned as a usual field.

2. When a table is assigned to a non-NULL pointer field using the `ref.field = {...}` syntax, it is applied to the target of the pointer instead.

   If the pointer is NULL, the table is checked for a `new` field:

   1. If it is nil or false, assignment fails with an error.
   2. If it is true, the pointer is initialized with a newly allocated object of the declared target type of the pointer.
   3. Otherwise, `table.new` must be a named type, or an object of a type compatible with the pointer. The pointer is initialized with the result of calling `table.new:new()`.

   After this auto-vivification process, assignment proceeds as if the pointer wasn't NULL.

   Obviously, the `new` field inside the table is always skipped during the actual per-field assignment processing.

3. If the target of the assignment is a container, a separate rule set is used:

   1. If the table contains neither `assign` nor `resize` fields, it is interpreted as an ordinary 1-based lua array. The container is resized to the #-size of the table, and elements are assigned in numeric order:

          ref:resize(#table);
          for i=1,#table do ref[i-1] = table[i] end

   2. Otherwise, `resize` must be true, false, or an explicit number. If it is not false, the container is resized. After that the usual struct-like 'pairs' assignment is performed.

      In case `resize` is true, the size is computed by scanning the table for the largest numeric key.

   This means that in order to reassign only one element of a container using this system, it is necessary to use:

       { resize=false, [idx]=value }

Since nil inside a table is indistinguishable from missing key, it is necessary to use `df.NULL` as a null pointer value.

This system is intended as a way to define a nested object tree using pure lua data structures, and then materialize it in C++ memory in one go. Note that if pointer auto-vivification is used, an error in the middle of the recursive walk would not destroy any objects allocated in this way, so the user should be prepared to catch the error and do the necessary cleanup.

# DFHack utilities

DFHack utility functions are placed in the `dfhack` global tree.

Currently it defines the following features:

- `dfhack.print(args...)`

  Output tab-separated args as standard lua print would do, but without a newline.

- `print(args...)`, `dfhack.println(args...)`

  A replacement of the standard library print function that works with DFHack output infrastructure.

- `dfhack.printerr(args...)`

  Same as println; intended for errors. Uses red color and logs to stderr.log.

- `dfhack.color([color])`

  Sets the current output color. If color is nil or -1, resets to default.

- `dfhack.is_interactive()`

  Checks if the thread can access the interactive console and returns true or false.

- `dfhack.lineedit([prompt[,history_filename]])`

  If the thread owns the interactive console, shows a prompt and returns the entered string. Otherwise returns nil, error.

- `dfhack.interpreter([prompt[,env[,history_filename]]])`

  Starts an interactive lua interpreter, using the specified prompt string, global environment and command-line history file.

  If the interactive console is not accessible, returns nil, error.

- `dfhack.pcall(f[,args...])`

  Invokes f via xpcall, using an error function that attaches a stack trace to the error. The same function is used by SafeCall in C++, and dfhack.safecall.

  The returned error is a table with separate `message` and `stacktrace` string fields; it implements `__tostring`.

- `safecall(f[,args...])`, `dfhack.safecall(f[,args...])`

  Just like pcall, but also prints the error using printerr before returning. Intended as a convenience function.

- `dfhack.with_suspend(f[,args...])`

  Calls `f` with arguments after grabbing the DF core suspend lock. Suspending is necessary for accessing a consistent state of DF memory.

  Returned values and errors are propagated through after releasing the lock. It is safe to nest suspends.

  Every thread is allowed only one suspend per DF frame, so it is best to group operations together in one big critical section. A plugin can choose to run all lua code inside a C++-side suspend lock.

- `dfhack.call_with_finalizer(num_cleanup_args,always,cleanup_fn[,cleanup_args...],fn[,args...])`

  Invokes `fn` with `args`, and after it returns or throws an error calls `cleanup_fn` with `cleanup_args`. Any return values from `fn` are propagated, and errors are re-thrown.

  The `num_cleanup_args` integer specifies the number of `cleanup_args`, and the `always` boolean specifies if cleanup should be called in any case, or only in case of an error.

- `dfhack.with_finalize(cleanup_fn,fn[,args...])`

  Calls `fn` with arguments, then finalizes with `cleanup_fn`. Implemented using `call_with_finalizer(0,true,...)`.

- `dfhack.with_onerror(cleanup_fn,fn[,args...])`

  Calls `fn` with arguments, then finalizes with `cleanup_fn` on any thrown error. Implemented using `call_with_finalizer(0,false,...)`.

- `dfhack.with_temp_object(obj,fn[,args...])`

  Calls `fn(obj,args...)`, then finalizes with `obj:delete()`.

## Persistent configuration storage

This api is intended for storing configuration options in the world itself. It probably should be restricted to data that is world-dependent.

Entries are identified by a string `key`, but it is also possible to manage multiple entries with the same key; their identity is determined by `entry_id`. Every entry has a mutable string `value`, and an array of 7 mutable `ints`.

- `dfhack.persistent.get(key)`, `entry:get()`

  Retrieves a persistent config record with the given string key, or refreshes an already retrieved entry. If there are multiple entries with the same key, it is undefined which one is retrieved by the first version of the call.

  Returns entry, or nil if not found.

- `dfhack.persistent.delete(key)`, `entry:delete()`

  Removes an existing entry. Returns true if succeeded.

- `dfhack.persistent.get_all(key[,match_prefix])`

  Retrieves all entries with the same key, or starting with key..'/'. Calling `get_all('',true)` will match all entries.

  If none found, returns nil; otherwise returns an array of entries.

- `dfhack.persistent.save({key=str1, ...}[,new])`, `entry:save([new])`

  Saves changes in an entry, or creates a new one. Passing true as new forces creation of a new entry even if one already exists; otherwise the existing one is simply updated. Returns entry, did_create_new

Since the data is hidden in data structures owned by the DF world, and automatically stored in the save game, these save and retrieval functions can just copy values in memory without doing any actual I/O. However, currently every entry has a 180+-byte dead-weight overhead.

## Material info lookup

A material info record has fields:

- `type`, `index`, `material`

  DF material code pair, and a reference to the material object.

- `mode`

  One of `'builtin'`, `'inorganic'`, `'plant'`, `'creature'`.

- `inorganic`, `plant`, `creature`

  If the material is of the matching type, contains a reference to the raw object.

- `figure`

  For a specific creature material contains a ref to the historical figure.

Functions:

- `dfhack.matinfo.decode(type,index)`

  Looks up material info for the given number pair; if not found, returs nil.

- `....decode(matinfo)`, `....decode(item)`, `....decode(obj)`

  Uses `matinfo.type`/`matinfo.index`, item getter vmethods, or `obj.mat_type`/`obj.mat_index` to get the code pair.

- `dfhack.matinfo.find(token[,token...])`

  Looks up material by a token string, or a pre-split string token sequence.

- `dfhack.matinfo.getToken(...)`, `info:getToken()`

  Applies `decode` and constructs a string token.

- `info:toString([temperature[,named]])`

  Returns the human-readable name at the given temperature.

- `info:getCraftClass()`

  Returns the classification used for craft skills.

- `info:matches(obj)`

  Checks if the material matches job_material_category or job_item. Accept dfhack_material_category auto-assign table.

## C++ function wrappers

Thin wrappers around C++ functions, similar to the ones for virtual methods.

- `dfhack.TranslateName(name,in_english,only_last_name)`

  Convert a language_name or only the last name part to string.

### Gui module

- `dfhack.gui.getSelectedWorkshopJob(silent)`

  When a job is selected in 'q' mode, returns the job, else prints error unless silent and returns nil.

- `dfhack.gui.getSelectedJob(silent)`

  Returns the job selected in a workshop or unit/jobs screen.

- `dfhack.gui.getSelectedUnit(silent)`

  Returns the unit selected via 'v', 'k', unit/jobs, or a full-screen item view of a cage or suchlike.

- `dfhack.gui.getSelectedItem(silent)`

  Returns the item selected via 'v' ->inventory, 'k', 't', or a full-screen item view of a container. Note that in the last case, the highlighted contained item is returned, not the container itself.

- `dfhack.gui.showAnnouncement(text,color,is_bright)`

  Adds a regular announcement with given text, color, and brightness. The is_bright boolean actually seems to invert the brightness.

- `dfhack.gui.showPopupAnnouncement(text,color,is_bright)`

  Pops up a titan-style modal announcement window.

### Job module

- `dfhack.job.cloneJobStruct(job)`

  Creates a deep copy of the given job.

- `dfhack.job.printJobDetails(job)`

  Prints info about the job.

- `dfhack.job.printItemDetails(jobitem,idx)`

  Prints info about the job item.

- `dfhack.job.getHolder(job)`

  Returns the building holding the job.

- `dfhack.job.getWorker(job)`

  Returns the unit performing the job.

- `dfhack.job.is_equal(job1,job2)`

  Compares important fields in the job and nested item structures.

- `dfhack.job.is_item_equal(job_item1,job_item2)`

  Compares important fields in the job item structures.

- `dfhack.job.listNewlyCreated(first_id)`

  Returns the current value of `df.global.job_next_id`, and if there are any jobs with `first_id <= id < job_next_id`, a lua list containing them.

### Units module

- `dfhack.units.getPosition(unit)`

  Returns true x,y,z of the unit; may be not equal to unit.pos if caged.

- `dfhack.units.getContainer(unit)`

  Returns the container (cage) item or nil.

- `dfhack.units.setNickname(unit,nick)`

  Sets the unit's nickname properly.

- `dfhack.units.getVisibleName(unit)`

  Returns the language_name object visible in game, accounting for false identities.

- `dfhack.units.getNemesis(unit)`

  Returns the nemesis record of the unit if it has one, or nil.

- `dfhack.units.isDead(unit)`

  The unit is completely dead and passive.

- `dfhack.units.isAlive(unit)`

  The unit isn't dead or undead.

- `dfhack.units.isSane(unit)`

  The unit is capable of rational action, i.e. not dead, insane or zombie.

- `dfhack.units.clearBurrowMembers(burrow)`

  Removes all units from the burrow.

- `dfhack.units.isInBurrow(unit,burrow)`

  Checks if the unit is in the burrow.

- `dfhack.units.setInBurrow(unit,burrow,enable)`

  Adds or removes the unit from the burrow.

### Items module

- `dfhack.items.getPosition(item)`

  Returns true x,y,z of the item; may be not equal to item.pos if in inventory.

- `dfhack.items.getOwner(item)`

  Returns the owner unit or nil.

- `dfhack.items.setOwner(item,unit)`

  Replaces the owner of the item. If unit is nil, removes ownership. Returns false in case of error.

- `dfhack.items.getContainer(item)`

  Returns the container item or nil.

- `dfhack.items.getContainedItems(item)`

  Returns a list of items contained in this one.

- `dfhack.items.moveToGround(item,pos)`

  Move the item to the ground at position. Returns false if impossible.

- `dfhack.items.moveToContainer(item,container)`

  Move the item to the container. Returns false if impossible.

### Maps module

- `dfhack.maps.getSize()`

  Returns map size in blocks: x, y, z

- `dfhack.maps.getTileSize()`

  Returns map size in tiles: x, y, z

- `dfhack.maps.getBlock(x,y,z)`

  Returns a map block object for given x,y,z in local block coordinates.

- `dfhack.maps.getTileBlock(coords)`

  Returns a map block object for given df::coord in local tile coordinates.

- `dfhack.maps.getRegionBiome(region_coord2d)`

  Returns the biome info struct for the given global map region.

- `dfhack.maps.getGlobalInitFeature(index)`

  Returns the global feature object with the given index.

- `dfhack.maps.getLocalInitFeature(region_coord2d,index)`

  Returns the local feature object with the given region coords and index.

- `dfhack.maps.findBurrowByName(name)`

  Returns the burrow pointer or nil.

- `dfhack.maps.listBurrowBlocks(burrow)`

  Returns a table of map block pointers.

- `dfhack.maps.clearBurrowTiles(burrow)`

  Removes all tiles from the burrow.

- `dfhack.maps.isBurrowTile(burrow,tile_coord)`

  Checks if the tile is in burrow.

- `dfhack.maps.setBurrowTile(burrow,tile_coord,enable)`

  Adds or removes the tile from the burrow. Returns false if invalid coords.

- `dfhack.maps.isBlockBurrowTile(burrow,block,x,y)`

  Checks if the tile within the block is in burrow.

- `dfhack.maps.setBlockBurrowTile(burrow,block,x,y,enable)`

  Adds or removes the tile from the burrow. Returns false if invalid coords.