Fixed macro plugin loading and duplicate initialization.

compiler/macro-master.stanza

@@ -7,6 +7,7 @@ defpackage stz/macro-master :
   import stz/sexp-serializer
   import stz/sexp-checker
   import stz/params
+  import stz/verbose
 
 ;============================================================
 ;========================= API ==============================
@@ -33,18 +34,11 @@ public defmulti filename (p:MacroPlugin) -> String
 ;  macro contains a superset of the expected packages.
 public defn load-macro-plugin (filename:String,
                                expected-packages:Maybe<Tuple<Symbol>>) -> MacroPlugin :
+  ;Report macro plugin.
+  vprintln("Load macro plugin %~." % [filename])
+
   ;Load the macro dynamic library.
-  val lib =
-    try :
-      dynamic-library-open(ensure-slash(filename))
-    catch (e:Exception) :
-      throw(ErrorLoadingMacroPlugin(filename, e))
-
-  ;Test that it's a valid macro plugin
-  test-validity(lib)
-
-  ;Call its main function for initialization.
-  call-main(lib)
+  val lib = load-macro-dylib(filename)
 
   ;Create the interface for communicating with it.
   val interface = PluginInterface(SExpIO())
@@ -58,10 +52,9 @@ public defn load-macro-plugin (filename:String,
 
   ;Check that the plugin supports the expected packages.
   if not empty?(expected-packages) :
-    if not subset?(value!(expected-packages), supported-packages) :
-      throw(UnexpectedPackagesInPlugin(filename,
-                                       supported-packages,
-                                       value!(expected-packages)))
+    val missing = difference(value!(expected-packages), supported-packages)
+    if not empty?(missing) :
+      throw(UnexpectedPackagesInPlugin(filename, missing))
 
   ;Create the plugin
   new MacroPlugin :
@@ -73,10 +66,47 @@ public defn load-macro-plugin (filename:String,
     defmethod filename (this) :
       filename
 
-;Helper: Return true if xs is a subset of ys.
-defn subset? (xs:Seqable<Symbol>, ys:Seqable<Symbol>) -> True|False :
+;Helper: Return all items in 'xs' that does not exist in 'ys'.
+defn difference (xs:Seqable<Symbol>, ys:Seqable<Symbol>) -> Tuple<Symbol> :
   val ys-set = to-hashset<Symbol>(ys)
-  for x in xs all? : ys-set[x]
+  to-tuple $ for x in xs filter : not ys-set[x]
+
+;============================================================
+;================== Already Loaded Set ======================
+;============================================================
+
+;Each entry, PATH => LIB, means that the resolved path PATH
+;has already been loaded and we retrieved and initialized
+;library LIB.
+val LOADED-LIBRARIES = HashTable<String,DynamicLibrary>()
+
+;Load and initialize the given dynamic library.
+defn load-macro-dylib (filename:String) -> DynamicLibrary :
+  try :
+    ;Resolve the full path first.
+    val path = resolve-path!(ensure-slash(filename))
+
+    ;Test whether the library has already been loaded.
+    match(get?(LOADED-LIBRARIES, path)) :
+      ;Case: If the library has already been loaded, then
+      ;just return it directly.
+      (dylib:DynamicLibrary) :
+        dylib
+      ;Case: The library hasn't been loaded, so load and
+      ;initialize it.
+      (f:False) :
+        ;Load the library.
+        val dylib = dynamic-library-open(path)
+        ;Ensure it is a macro plugin by running a simple
+        ;handshake function.
+        test-validity(dylib)
+        ;Initialize the macro.
+        call-main(dylib)
+        ;And store it into the table.
+        LOADED-LIBRARIES[path] = dylib
+        dylib        
+  catch (e:Exception) :
+    throw(ErrorLoadingMacroPlugin(filename, e))
 
 ;============================================================
 ;===================== Ensure Slash =========================
@@ -148,13 +178,11 @@ defmethod print (o:OutputStream, e:InvalidMacroPlugin) :
 ;packages.
 public defstruct UnexpectedPackagesInPlugin <: MacroPluginError :
   filename:String
-  supported-packages:Tuple<Symbol>
-  expected-packages:Tuple<Symbol>
+  missing:Tuple<Symbol>
 
 defmethod print (o:OutputStream, e:UnexpectedPackagesInPlugin) :
-  print(o, "Unexpected packages supported by macro plugin %~. The plugin \
-            supports packages %_, but it was expected to support %_." % [
-           filename(e), quotes(supported-packages(e)), quotes(expected-packages(e))])
+  print(o, "The macro plugin %~ is missing syntax packages. It is stated to contain the \
+            %_ syntax packages but does not." % [filename(e), quotes(missing(e))])
 
 ;Helper: Add quotes and commas around names.
 defn quotes (ss:Seqable<Symbol>) -> ? :

compiler/macroexpander.stanza

@@ -7,6 +7,7 @@ defpackage stz/macroexpander :
   import stz/core-macros
   import stz/proj-manager
   import stz/proj-ir
+  import stz/verbose
 
 ;============================================================
 ;====================== API =================================
@@ -116,9 +117,10 @@ public defn StanzaMacroexpander (sys:MacroSystem,
     ;Helper: Find a macro plugin using the proj file.
     defn find-using-proj () -> MacroPlugin|False :
       match(proj-manager:ProjManager) :
-        val filename = find-syntax-packages(proj-manager, packages)
-        match(filename:String) :
-          plugin(load-macro-from-file(LoadedFromProj, filename, One(packages)))
+        val plugin-details = find-syntax-packages(proj-manager, packages)
+        if not empty?(plugin-details) :
+          val [filename, stated-packages] = value!(plugin-details)
+          plugin(load-macro-from-file(LoadedFromProj, filename, One(stated-packages)))
 
     ;Helper: Return true if the root expander
     ;supports the given packages.

compiler/params.stanza

@@ -18,7 +18,7 @@ public defn compiler-flags () :
   to-tuple(COMPILE-FLAGS)
 
 ;========= Stanza Configuration ========
-public val STANZA-VERSION = [0 18 87]
+public val STANZA-VERSION = [0 18 88]
 public var STANZA-INSTALL-DIR:String = ""
 public var OUTPUT-PLATFORM:Symbol = `platform
 public var STANZA-PKG-DIRS:List<String> = List()

compiler/proj-manager.stanza

@@ -67,8 +67,11 @@ public defmulti find-package (l:ProjManager, name:Symbol) -> PkgLocation|False
 public defmulti conditional-imports (l:ProjManager, packages:Seqable<Symbol>) -> Tuple<Symbol>
 
 ;Given the set of syntax packages we need, find the name of the plugin
-;that supports all of them. Returns false if none could be found.
-public defmulti find-syntax-packages (l:ProjManager, names:Tuple<Symbol>) -> String|False
+;that supports all of them. If a plugin is found, then we return
+;[filename, stated-packages] where:
+;- filename: The filename of the macro plugin that supports the requested packages.
+;- stated-packages: The syntax packages that the macro plugin is stated to support.
+public defmulti find-syntax-packages (l:ProjManager, names:Tuple<Symbol>) -> Maybe<[String,Tuple<Symbol>]>
 
 ;Returns the list of all syntax-package groups listed in the
 ;.proj files.
@@ -201,7 +204,7 @@ public defn ProjManager (proj:ProjFile, params:ProjParams, auxfile:AuxFile) :
       PkgLocation(name, src-path, pkg-file, read-pkg?)
 
   ;Find a set of syntax packages
-  defn find-syntax-packages (names:Tuple<Symbol>) -> String|False :
+  defn find-syntax-packages (names:Tuple<Symbol>) -> Maybe<[String,Tuple<Symbol>]> :
     ;Returns true if names is a superset of xs.
     defn superset-of-names? (xs:Seqable<Symbol>) -> True|False :
       val xs-set = to-hashset<Symbol>(xs)
@@ -214,9 +217,9 @@ public defn ProjManager (proj:ProjFile, params:ProjParams, auxfile:AuxFile) :
     ;Note: We implicitly add `core and `tests to the supported packages.
     ;These are implicitly supported by all plugins even if not
     ;listed by the user.
-    value? $ for stmt in syntax-packages first :
+    for stmt in syntax-packages first :
       val added-packages = cat(`(core tests), packages(stmt))
-      if superset-of-names?(added-packages) : One(filename(stmt))
+      if superset-of-names?(added-packages) : One([filename(stmt), packages(stmt)])
       else : None()
 
   ;Retrieve conditional imports