Improvements to API of nimscriptsupport module.

* setCommand "nop" no longer needed.
* Recursive setCommand supported.
* Explicit execTask procedure which executes the task explicitly instead of setting global compiler variables.

src/nimble.nim

@@ -10,7 +10,7 @@ import nimblepkg/packageinfo, nimblepkg/version, nimblepkg/tools,
        nimblepkg/download, nimblepkg/config, nimblepkg/nimbletypes,
        nimblepkg/publish
 
-import compiler/options as compiler_options
+import nimblepkg/nimscriptsupport
 
 when not defined(windows):
   from posix import getpid
@@ -223,7 +223,7 @@ proc parseCmdLine(): Options =
     case kind
     of cmdArgument:
       if result.action.typ == actionNil:
-        compiler_options.command = key
+        setNimScriptCommand(key)
         result.action.typ = parseActionType(key)
         initAction(result, key)
       else:
@@ -1017,14 +1017,9 @@ proc doAction(options: Options) =
   if not existsDir(options.getPkgsDir):
     createDir(options.getPkgsDir)
 
-  # The nimscript file may use `setCommand` to set the command so we need to
-  # re-read it from the compiler.
-  # TODO: It doesn't appear that this actually happens, can we just remove this?
-  var command = compiler_options.command.parseActionType()
-  var doLoop = true
-  while doLoop:
-    doLoop = false
-    let cmd = compiler_options.command.normalize
+  var command = getNimScriptCommand().parseActionType()
+  # The loop is necessary to support tasks using `setCommand`.
+  while true:
     case command
     of actionUpdate:
       update(options)
@@ -1050,11 +1045,22 @@ proc doAction(options: Options) =
       publish(pkgInfo)
     of actionDump:
       dump(options)
-    of actionNil: discard "assuming nimscript 'nop' command here"
+    of actionNil:
+      assert false
     of actionCustom:
-      # calls Nimscript as a side effect :-/
-      discard getPkgInfo(getCurrentDir())
-      doLoop = cmd != compiler_options.command.normalize
+      # Custom command. Attempt to call a NimScript task.
+      let (isNimScript, nimbleFile) = findNimbleFile(getCurrentDir(), true)
+      if not isNimScript:
+        writeHelp()
+      let oldCmd = getNimScriptCommand()
+      if not execTask(nimbleFile, oldCmd):
+        echo("FAILURE: Could not find task ", oldCmd, " in ", nimbleFile)
+        writeHelp()
+      if getNimScriptCommand().normalize == "nop":
+        echo("WARNING: Using `setCommand 'nop'` is not necessary.")
+        break
+      command = getNimScriptCommand().parseActionType()
+      if not hasTaskRequestedCommand(): break
 
 when isMainModule:
   when defined(release):

src/nimblepkg/nimscriptsupport.nim

@@ -11,10 +11,15 @@ import
   compiler/msgs, compiler/magicsys, compiler/lists
 
 from compiler/scriptconfig import setupVM
+from compiler/idents import getIdent
+from compiler/astalgo import strTableGet, `$`
 
 import nimbletypes, version
 import os, strutils
 
+const
+  internalCmd = "NimbleInternal"
+
 proc raiseVariableError(ident, typ: string) {.noinline.} =
   raise newException(NimbleError,
     "NimScript's variable '" & ident & "' needs a value of type '" & typ & "'.")
@@ -53,7 +58,10 @@ proc extractRequires(result: var seq[PkgTuple]) =
   else:
     raiseVariableError("requiresData", "seq[(string, VersionReq)]")
 
-proc readPackageInfoFromNims*(scriptName: string; result: var PackageInfo) =
+proc execScript(scriptName: string) =
+  ## Executes the specified script.
+  ##
+  ## No clean up is performed and must be done manually!
   setDefaultLibpath()
   passes.gIncludeFile = includeModule
   passes.gImportModule = importModule
@@ -74,6 +82,21 @@ proc readPackageInfoFromNims*(scriptName: string; result: var PackageInfo) =
   compileSystemModule()
   processModule(m, llStreamOpen(scriptName, fmRead), nil)
 
+proc cleanup() =
+  # ensure everything can be called again:
+  resetAllModulesHard()
+  clearPasses()
+  vm.globalCtx = nil
+  initDefines()
+
+proc readPackageInfoFromNims*(scriptName: string; result: var PackageInfo) =
+  ## Executes the `scriptName` nimscript file. Reads the package information
+  ## that it populates.
+
+  # Execute the nimscript file.
+  execScript(scriptName)
+
+  # Extract all the necessary fields populated by the nimscript file.
   template trivialField(field) =
     result.field = getGlobal(astToStr field)
 
@@ -111,7 +134,32 @@ proc readPackageInfoFromNims*(scriptName: string; result: var PackageInfo) =
   else:
     result.backend = backend.toLower()
 
-  # ensure everything can be called again:
-  resetAllModulesHard()
-  vm.globalCtx = nil
-  initDefines()
+  cleanup()
+
+proc execTask*(scriptName, taskName: string): bool =
+  ## Executes the specified task in the specified script.
+  ##
+  ## `scriptName` should be a filename pointing to the nimscript file.
+  result = true
+  options.command = internalCmd
+  echo("Executing task ", taskName, " in ", scriptName)
+
+  execScript(scriptName)
+  # Explicitly execute the task procedure, instead of relying on hack.
+  assert vm.globalCtx.module.kind == skModule
+  let prc = vm.globalCtx.module.tab.strTableGet(getIdent(taskName & "Task"))
+  if prc.isNil:
+    # Procedure not defined in the NimScript module.
+    return false
+  discard vm.globalCtx.execProc(prc, [])
+  cleanup()
+
+proc getNimScriptCommand*(): string =
+  options.command
+
+proc setNimScriptCommand*(command: string) =
+  options.command = command
+
+proc hasTaskRequestedCommand*(): bool =
+  ## Determines whether the last executed task used ``setCommand``
+  return getNimScriptCommand() != internalCmd