Index: doc/proposals/modules-gen-hdr/cfa-cppp
===================================================================
--- doc/proposals/modules-gen-hdr/cfa-cppp	(revision b28ce93ef6648a426d1fb594f74b51bfeda9976c)
+++ doc/proposals/modules-gen-hdr/cfa-cppp	(revision b28ce93ef6648a426d1fb594f74b51bfeda9976c)
@@ -0,0 +1,177 @@
+#! /usr/bin/python3
+
+import fileinput
+import sys
+import re
+import os
+from enum import Enum
+
+class Section(Enum):
+    PREAMBLE = 1
+    EXP_TYPE = 2
+    EXP_VALUE = 3
+    STATIC = 4
+    UNKNOWN = 5
+
+class ValueSubsection(Enum):
+    FUNCTION = 1
+    VARIABLE = 2
+    NA = 3
+
+outfile = sys.argv[1]
+outfile_local = os.path.basename(outfile)
+parts = re.match(r"(?P<module>.*)\.(?P<mode>[^\.]*)\.[hc]$", outfile_local)
+module = parts.group('module')
+outtype = parts.group('mode')
+
+srcfile = os.path.join(os.path.dirname(outfile), module) + ".src.c"
+circImpVar = "__{mod}_{ty}_IMPORTING__".format(mod=module.upper(), ty=outtype.upper())
+
+sys.stdout = open(outfile, 'w')
+
+# data about the current //#-delimited chunk of file
+section = Section.PREAMBLE
+valueSubsection = ValueSubsection.NA
+lines = []
+
+def declOnly():
+    if valueSubsection == ValueSubsection.VARIABLE:
+        eqpos = lines[0].find('=')
+        lines[0] = lines[0][0:eqpos]
+        print( 'extern', lines[0], ';' )
+    else:
+        if lines[0].endswith("{"):
+            lines[0] = lines[0][0:len(lines[0])-2].rstrip()
+        print( lines[0], ';' )
+
+def fulldump():
+    for line in lines:
+        print(line)
+
+def flush():
+    global lines
+    # print("\t// flush", outtype, section)
+
+    if (section == Section.PREAMBLE):
+        postpreamble()
+    elif (len(lines) == 0):
+        return
+    elif (outtype == 'tdcl') & (section == Section.EXP_TYPE):
+        declOnly()
+    elif (outtype == 'defn') & (section == Section.EXP_TYPE):
+        fulldump()
+    elif (outtype == 'defn') & (section == Section.EXP_VALUE):
+        declOnly()
+    elif (outtype == 'impl') & (section == Section.EXP_VALUE):
+        fulldump()
+    elif (outtype == 'impl') & (section == Section.STATIC):
+        fulldump()
+    else:
+        for line in lines:
+            pass #print("//", line)
+
+    lines = []
+
+class ImportStyle(Enum):
+    NO_EXPORT = 1
+    EXPORT_INCOMPLETE = 2
+    EXPORT_COMPLETE = 3
+
+def emitInclude(imodule, iftype):
+    print('#include "{mod}.{typ}.h"'.format(mod=imodule, typ=iftype))
+
+def import_(cmd):
+    if section == Section.PREAMBLE:
+        if cmd.startswith("auto"):
+            cmd = cmd.replace("auto","").lstrip()
+            if cmd.startswith("&"):
+                cmd = cmd.replace("&","").lstrip()
+                style = ImportStyle.EXPORT_INCOMPLETE
+            else:
+                style = ImportStyle.EXPORT_COMPLETE
+        elif cmd.startswith("static"):
+            cmd = cmd.replace("static","").lstrip()
+            style = ImportStyle.NO_EXPORT
+        else:
+            print("#error import not understood:", cmd)            
+            style = ImportStyle.NO_EXPORT
+        imodule = cmd
+        if( style != ImportStyle.EXPORT_COMPLETE) & (outtype == "impl"):
+            emitInclude(imodule, "defn")
+        if (style == ImportStyle.EXPORT_COMPLETE) & (outtype == "defn"):
+            emitInclude(imodule, "defn")
+        if (style != ImportStyle.NO_EXPORT) & (outtype == "tdcl"):
+            emitInclude(imodule, outtype)
+    else:
+        print("#error illegal place for: import ", cmd)
+
+def beginunit():
+    print("//", outfile_local)
+    if (outtype == "tdcl"):
+        print("#pragma once")
+    elif outtype == "defn":
+        print("#ifdef", circImpVar)
+        print("#error Illegal circularity detected")
+        print("#else")
+        print("#define", circImpVar)
+    if outtype == "defn":
+        emitInclude(module, "tdcl")
+    elif outtype == "impl":
+        emitInclude(module, "defn")
+
+def postpreamble():
+    if outtype == "defn":
+        print("#undef", circImpVar)
+        print("#pragma once")
+
+
+
+def endunit():
+    if outtype == "defn":
+        print("#endif // ", circImpVar)
+
+try:
+    with open(srcfile, "r") as file:
+        beginunit()
+        for line in file:
+            line = line.rstrip()
+            if ( line.startswith("#import") ):
+                line = line.replace("#import", "").lstrip()
+                import_(line)
+            elif ( line.startswith("//#") ):
+                flush()
+                line = line.replace("//#", "").lstrip()
+                if line[0] == '@':
+                    section = Section.EXP_TYPE
+                    valueSubsection = ValueSubsection.NA
+                elif line[0] == '$':
+                    section = Section.EXP_VALUE
+                    valueSubsection = ValueSubsection.NA
+                    # print("\t// object decl:{name}, with deps:{decldeps}".format(
+                    #     name=name, decldeps=decldeps))
+                    line = line[1:]
+                    if line[0] == 'f':
+                        valueSubsection = ValueSubsection.FUNCTION
+                    elif line[0] == 'v':
+                        valueSubsection = ValueSubsection.VARIABLE
+                    else:
+                        print("#error $-subdirective not understood: ", line)
+                        valueSubsection = ValueSubsection.NA
+                elif line[0] == '-':
+                    section = Section.STATIC
+                    valueSubsection = ValueSubsection.NA
+                else:
+                    print("#error directive not understood:", line)
+                    section = Section.UNKNOWN
+                    valueSubsection = ValueSubsection.NA
+                line = line[1:]
+            else:
+                line = line.split("//")[0].rstrip()
+                if (line):
+                    lines.append(line)
+        flush()
+        endunit()
+except FileNotFoundError:
+    print("Error: The file '" + srcfile + "' was not found.")
+
+