requires: {#Set}.
provides: {#FileModule. #Module}.

globals modules: (globals modules as: ExtensibleSequence).
"Overrides the interpreter's type for this global."
_@lobby enterModule: name
"Overrides the interpreter's hook of the same signature."
[
  globals modules include: name.
  currentModule: name
].

globals addSlot: #Modules valued: Namespace clone.
"TODO: make it a collection?"

prototypes addSlot: #Module valued: Cloneable derive.
"Modules are a collection of objects and methods, which together provide
certain features, and require other modules' features to function."
Module addSlot: #requirements valued: Set newEmpty.
"Requirements are the set of modules that the given one requires before it can
be loaded."
Module addSlot: #imports valued: Set newEmpty.
"Imports are objects and features referenced by the module's code."
Module addSlot: #exports valued: Set newEmpty.
"Exports are objects and features provided by the module's code."
Module addSlot: #objects valued: Set newEmpty.
"These are the non-method objects that the module defines and installs."
Module addSlot: #methods valued: Set newEmpty.
"These are the closures that the module defines and installs, whether named or
dispatched or anonymous."

m@(Module traits) initialize
"Reset all of the module's attributes."
[
  m requirements: m requirements newEmpty.
  m imports: m imports newEmpty.
  m exports: m exports newEmpty.
  m objects: m objects newEmpty.
  m methods: m methods newEmpty.
  m
].

m@(Module traits) newEmpty
[
  m clone initialize
].

m@(Module traits) newForFileNamed: filename
[
  FileModule newForFileNamed: filename
].

m@(Module traits) copy
[| newM |
  newM: m clone.
  newM requirements: m requirements copy.
  newM imports: m imports copy.
  newM exports: m exports copy.
  newM objects: m objects copy.
  newM methods: m methods copy.
  newM
].

m@(Module traits) newBasedOn: moduleSet
[| newM |
  newM: m clone initialize.
  newM requirements: (moduleSet select: [| :each | each is: Module]).
  newM
].

m@(Module traits) provide: obj
[
  "TODO: include some check here to avoid arbitrary provision."
  m exports include: obj
].

m@(Module traits) provides: obj
[
  "TODO: do modules automatically export their imports?"
  m exports includes: obj
].

m@(Module traits) import: obj from: prereq
[
  (prereq provides: obj)
    ifTrue: [m requirements include: prereq. m imports include: obj].
  m
].

m@(Module traits) importAll: c from: prereq
[
  c do: [| :each | (prereq provides: each)
    ifFalse: [^ (prereq error:
		   prereq name ; ' does not provide ' ; each print)]].
  m requirements include: prereq.
  c do: [| :each | m imports include: each].
  m
].

prototypes addSlot: #FileModule valued: Module derive.
"FileModules are Modules which are drastically simplified for the purposes of
bootstrapping. Requirements and provisions are symbols, and other features are
ignored."
FileModule addSlot: #filename valued: ''.

m@(FileModule traits) newForFileNamed: filename
[| newM |
  newM: m newEmpty.
  newM filename: filename.
  newM
].

m@(FileModule traits) readDefinitions
"Reads in a file, building the module's collections while evaluating the
contents."
"TODO: implement it!"
[| input |
  input: (FileStream newForInputNamed: m filename).
  input close.
  m
].

m@(FileModule traits) metaInfoFilename
[| basename |
  basename: (m filename sliceFrom: 0 to: (m filename indexOfSubSeq: '.slate')).
  basename ; '.module'
].

m@(FileModule traits) writeOutInfo
"Writes out a source definition of the Module object described by the given
filename."
"TODO: implement it!"
[| output |
  output: (FileStream newForOuputNamed: m metaInfoFilename).
  output ; '[| m |\n'.
  output ; 'm: Module newForFileNamed: ' ; m filename ; '.\n'.
  output ; 'm imports: '.
  m imports printOn: output.
  output ; '.\n'.
  output ; 'm exports: '.
  m exports printOn: output.
  output ; '.\n'.
  output ; 'modules include: m.\n'.
  output ; 'm] value.\n'.
  output close.
  m
].

"SourceWriter print: ([| M |
  M: Module newForFileNamed: (m filename) `unquote.
  M imports: (m imports) `unquote.
  M exports: (m exports) `unquote.
  modules include: M.
  M] value.
) `quote on: output."

m@(FileModule traits) readInInfo
"Reads from a source definition of the Module object described by the given
filename."
"TODO: implement it!"
[| input |
  input: (FileStream newForInputNamed: m metaInfoFilename).
  input close.
  m
].