Merge pull request #69 from defold/editor-scrips

Add editor scripts manual

docs/en/en.json

@@ -549,6 +549,15 @@
                         "name": "Debugging on iOS"
                     }
                 ]
+            },
+            {
+                "name": "EDITOR EXTENSIONS",
+                "items": [
+                    {
+                        "path": "/manuals/editor-scripts",
+                        "name": "Editor scripts"
+                    }
+                ]
             }
         ]
     }

docs/en/manuals/editor-scripts.md

@@ -0,0 +1,188 @@
+---
+title: Editor scripts
+brief: This manual explains how to extend editor using Lua
+---
+
+# Editor scripts
+
+You can create custom menu items and editor lifecycle hooks using Lua files with special extension: `.editor_script`. Using this system, you can tweak editor to enhance your development workflow.
+
+## Editor script runtime
+
+Editor scripts run inside an editor, in a Lua VM emulated by Java VM. All scripts share the same single environment, which means they can interact with each other. You can require Lua modules, just as with `.script` files, but Lua version that is running inside the editor is different, so make sure your shared code is compatible. Editor uses Lua version 5.2.x, more specifically [luaj](https://github.com/luaj/luaj) runtime, which is currently the only viable solution to run Lua on JVM. Besides that, there are some restrictions:
+- there is no `debug` and `coroutine` packages;
+- there is no `os.execute` — we provide a more user-friendly and secure way to execute shell scripts in [actions](#_actions) section;
+- there is no `os.tmpname` and `io.tmpfile` — currently editor scripts can access files only inside the project directory;
+- there is currently no `os.rename` and `os.remove`, although we want to add them;
+- there is no `os.exit` and `os.setlocale`.
+
+All editor extensions defined in editor scripts are loaded when you open a project. When you fetch libraries, extensions are reloaded, since there might be new editor scripts in a libraries you depend on. During this reload, no changes in your own editor scripts are picked up, since you might be in the middle of changing them. To reload them as well, you should run Project → Reload Extensions command.
+
+## Anatomy of `.editor_script`
+
+Every editor script should return a module, like that:
+```lua
+local M = {}
+
+function M.get_commands() 
+  -- TODO
+end
+
+return M
+```
+Editor then collects all editor scripts defined in project and libraries, loads them into single Lua VM and calls into them when needed (more on that in [commands](#_commands) and [lifecycle hooks](#_lifecycle_hooks) sections).
+
+## Editor API
+
+You can interact with the editor using `editor` package that defines this API:
+- `editor.platform` — a string, either `"x86_64-win32"` for Windows, `"x86_64-darwin"` for macOS or `"x86_64-linux"` for Linux.
+- `editor.get(node_id, property)` - get a value of some node inside the editor. Nodes in the editor are various entities, such as script or collection files, game objects inside collections, json files loaded as resources, etc. `node_id` is a userdata that is passed to the editor script by the editor. `property` is a string. Currently these properties are supported:
+  - `"path"` — file path from the project folder for *resources* — entities that exist as files. Example of returned value: `"/main/game.script"`
+  - `"text"` — text content of a resource editable as text (such as script files or json). Example of returned value: `"function init(self)\nend"`. Please note that this is not the same as reading file with `io.open()`, because you can edit a file without saving it, and these edits are available only when accessing `"text"` property.
+
+## Commands
+
+If editor script module defines function `get_commands`, it will be called on extension reload, and returned commands will be available for use inside the editor in menu bar or in context menus in Assets and Outline panes. Example:
+```lua
+local M = {}
+
+function M.get_commands()
+  return {
+    {
+      label = "Remove Comments",
+      locations = {"Edit", "Assets"},
+      query = {
+        selection = {type = "resource", cardinality = "one"}
+      },
+      active = function(opts)
+        local path = editor.get(opts.selection, "path")
+        return ends_with(path, ".lua") or ends_with(path, ".script")
+      end,
+      run = function(opts)
+        local text = editor.get(opts.selection, "text")
+        return {
+          {
+            action = "set", 
+            node_id = opts.selection, 
+            property = "text", 
+            value = strip_comments(text)
+          }
+        }
+      end 
+    },
+    {
+      label = "Minify JSON"
+      locations = {"Assets"},
+      query = {
+        selection = {type = "resource", cardinality = "one"}
+      },
+      active = function(opts)
+        return ends_with(editor.get(opts.selection, "path"), ".json")
+      end,
+      run = function(opts)
+        local path = editor.get(opts.selection, "path")
+        return {
+          {
+            action = "shell", 
+            command = {"./scripts/minify-json.sh", path:sub(2)}
+          }
+        }
+      end
+    }
+  }
+end
+
+return M
+```
+Editor expects `get_commands()` to return an array of tables, each describing a separate command. Command description consists of:
+
+- `label` (required) — text on a menu item that will be displayed to the user
+- `locations` (required) — an array of either `"Edit"`, `"View"`, `"Assets"` or `"Outline"`, describes a place where this command should be available. `"Edit"` and `"View"` mean menu bar at the top, `"Assets"` means context menu in Assets pane, and `"Outline"` means context menu in Outline pane.
+- `query` — a way for command to ask editor for relevant information and define what data it operates on. For every key in `query` table there will be corresponding key in `opts` table that `active` and `run` callbacks receive as argument. Supported keys:
+  - `selection` means this command is valid when there is something selected, and it operates on this selection.
+    - `type` is a type of selected nodes command is interested in, currently only `"resource"` is allowed. In Assets and Outline, resource is selected item. In menu bar (Edit or View), resource is a currently open file;
+    - `cardinality` defines how many selected items there should be. If `"one"`, selection passed to command callback will be a single node id. If `"many"`, selection passed to command callback will be an array of one or more node ids.
+- `active` - a callback that is executed to check that command is active, expected to return boolean. If `locations` include `"Assets"` or `"Outline"`, `active` will be called when showing context menu. If locations include `"Edit"` or `"View"`, active will be called on every user interaction, such as typing on keyboard or clicking with mouse, so be sure that `active` is relatively fast.
+- `run` - a callback that is executed when user selects menu item, expected to return an array of [actions](#_actions).
+
+## Actions
+
+Action is a table describing what editor should do. Every action has an `action` key. Actions come in 2 flavors: undoable and non-undoable. 
+
+### Undoable actions
+
+Undoable action can be undone after it is executed. If a command returns multiple undoable actions, they are performed together, and get undone together. You should use undoable actions if you can. Their downside is that they are more limited.
+
+Existing undoable actions:
+- `"set"` — set a property of a node in the editor to some value. Example:
+  ```lua
+  {
+    action = "set",
+    node_id = opts.selection,
+    property = "text",
+    value = "current time is " .. os.date()
+  }
+  ```
+  `"set"` action requires these keys:
+  - `node_id` — node id userdata;
+  - `property` — a property of a node to set, currently only `"text"` is supported;
+  - `value` — new value for a property. For `"text"` property it should be a string.
+
+### Non-undoable actions
+
+Non-undoable action clears undo history, so if you want to undo such action, you will have to use other means, such as version control.
+
+Existing non-undoable actions:
+- `"shell"` — execute a shell script. Example:
+  ```lua
+  {
+    action = "shell",
+    command = {
+      "./scripts/minify-json.sh", 
+      editor.get(opts.selection, "path"):sub(2) -- trim leading "/"
+    }
+  }
+  ```
+  `"shell"` action requires `command` key, which is an array of command and it's arguments. Main difference with `os.execute` is that since this is a potentially dangerous operation, editor will show a confirmation dialog asking user if they want to execute this command. It will remember each command that user already allowed.
+
+### Mixing actions and side effects
+
+You can mix undoable and non-undoable actions. Actions are executed sequentially, hence depending on an order of actions you will end up losing ability to undo parts of that command.
+
+Instead of returning actions from functions that expect them, you can just read and write to files directly using `io.open()`. This will trigger a resource reload that will clear undo history. 
+
+## Lifecycle hooks
+
+There is a specially treated editor script file: `hooks.editor_script`, located in a root of your project, in the same directory as `game.project`. This and only this editor script will receive lifecycle events from the editor. Example of such file:
+```lua
+local M = {}
+
+function M.on_build_started(opts) 
+  local file = io.open("assets/build.json", "w")
+  file:write("{\"build_time\": \"".. os.date() .."\"}")
+end
+
+return M
+```
+We decided to limit lifecycle hooks to single editor script file because order in which build hooks happen is more important than how easy it is to add another build step. Commands are independent from each other, so it does not really matter in what order they are shown in the menu, in the end user executes a particular command they selected. If it was possible to specify build hooks in different editor scripts, it would create a problem: in which order do hooks execute? You probably want to create a checksums of content after you compress it... And having a single file that establishes order of build steps by calling each step function explicitly is a way to solve this problem.
+
+Every lifecycle hook can return actions or write to files in project directory.
+
+Existing lifecycle hooks that `/hooks.editor_script` may specify:
+- `on_build_started(opts)` — executed when game is Built to run locally or on some remote target. Your changes, be it returned actions or updated file contents, will appear in a built game. Raising an error from this hook will abort a build. `opts` is a table that contains following keys:
+  - `platform` — a string in `%arch%-%os%` format describing what platform it's built for, currently always the same value as in `editor.platform`.
+- `on_build_finished(opts)` — executed when build is finished, be at successful or failed. `opts` is a table with following keys:
+  - `platform` — same as in `on_build_started`
+  - `success` — whether build is successful, either `true` or `false`
+- `on_bundle_started(opts)` — executed when you create a bundle or Build HTML5 version of a game. As with `on_build_started`, changes triggered by this hook will appear in a bundle, and errors will abort a bundle. `opts` will have these keys:
+  - `output_directory` — a file path pointing to a directory with bundle output, for example `"/path/to/project/build/default/__htmlLaunchDir"`
+  - `platform` — platform the game is bundled for. See a list of possible platform values in [Bob manual](/manuals/bob).
+- `on_bundle_finished(opts)` — executed when bundle is finished, be it successful or not. `opts` is a table with the same data as `opts` in `on_bundle_started`, plus `success` key indicating whether build is successful.
+- `on_target_launched(opts)` — executed when user launched a game and it successfully started. `opts` contains an `url` key pointing to a launched engine service, for example, `"http://127.0.0.1:35405"`
+- `on_target_terminated(opts)` — executed when launched game is closed, has same opts as `on_target_launched`
+
+Please note that lifecycle hooks currently are an editor-only feature, and they are not executed by Bob when bundling from command line.
+
+## Editor scripts in libraries
+
+You can publish libraries for other people to use that contain commands, and they will be automatically picked up by editor. Hooks, on the other hand, can't be picked up automatically, since they have to be defined in a file that is in a root folder of a project, but libraries expose only subfolders. This is intended to give more control over build process: you still can create lifecycle hooks as simple functions in `.lua` files, so users of your library can require and use them in their `/hooks.editor_script`.