# tmplpool.icn: Template pool object for webstyler.icn
#--

$ifndef __TMPLPOOL_ICN__
$define __TMPLPOOL_ICN__

$define  TMPL_POOL_REVISION  "$Revision: 1.4 $"
$define  TMPL_POOL_DATE      "$Date: 1996/10/10 18:15:34 $"

#================================================================
# Class TmplPool: An instance of this object is a facility for
# obtaining template objects, given a template's file name.
# Digested templates are cached so that each source file need be
# read only once.
#----------------------------------------------------------------
# tmplPool  :=  Tmpl_Pool_New ( log )
#   [ returns a new template pool object that will use `log'
#     for error logging when templates are read
#   ]
#--
# template  :=  Tmpl_Pool_Lookup ( tmplPool, fileName )
#   [ if fileName is &null and file DEFAULT_TEMPLATE_FILE_NAME
#     is a valid template file ->
#       returns the Template object corresponding to that file
#   | else if fileName points to a valid template file, relative
#     to the starting directory ->
#       returns the Template object representing that file
#   | else ->
#       tmplPool.log  ||:=  error message(s)
#       fail
#   ]   
#----------------------------------------------------------------
  record tmplPoolTag (  # State for a TmplPool object
    log,            # The log object for template scanning errors
    templateMap )   # Table: maps fileName |-> template

#================================================================
# INVARIANTS
#----------------------------------------------------------------
#   .templateMap is a table, with a &null default value, that
#   maps a fileName that names a valid template file  |-> the
#   corresponding template object
#----------------------------------------------------------------

$define  DEFAULT_TEMPLATE_FILE_NAME     "Template"


# - - -    T m p l _ P o o l _ N e w   - - -

procedure Tmpl_Pool_New ( log )
  local tmplPool

  tmplPool              :=  tmplPoolTag ( );
  tmplPool.log          :=  log;
  tmplPool.templateMap  :=  table ( );

  return tmplPool;
end # --- Tmpl_Pool_New ---


# - - -   T m p l _ P o o l _ L o o k u p   - - -

procedure Tmpl_Pool_Lookup ( tmplPool, fileName )
  #-- 1 --
  #-[ template  :=  &null
  #-]
  local template

  #-- 2 --
  #-[ if fileName is &null ->
  #     fileName  :=  DEFAULT_TEMPLATE_FILE_NAME
  #-]
  / fileName  :=  DEFAULT_TEMPLATE_FILE_NAME;

  #-- 3 --
  #-[ if fileName is a key in .templateMap ->
  #     return the corresponding value
  # | else -> I
  #-]
  if  ( template := \ tmplPool.templateMap [ fileName ] )  then
    return template;

  #-- 4 --
  #-[ if fileName names a valid template file ->
  #     template  :=  a Template object representing that file
  # | else ->
  #     tmplPool.log  ||:=  error message(s)
  #     fail
  #-]
  if  not ( template := Template_New ( fileName, tmplPool.log ) )  then
    fail;

  #-- 5 --
  #-[ tmplPool.templateMap  +:=  an entry mapping fileName |-> template
  #   return template
  #-]
  tmplPool.templateMap [ fileName ]  :=  template;
  return template;

end # --- Tmpl_Pool_Lookup ---

$endif