modules: simplify module lookup by name.

* m4/m4private.h (m4:namemap): New field for hash table to lookup
module structures by name string.
* m4/m4.c (hashfn): Hash function for plain strings.
(m4_create): Initialise namemap field to a hash table using hashfn
for inserting and looking up keys.
* m4/module.c (m4__module_find): Replace the fussy libltdl
twiddling with a hash lookup in m4:namemap.
Add a new context parameter. Adjust all callers.

Signed-off-by: Gary V. Vaughan <gary@gnu.org>

4 files changed, 24 insertions, 16 deletions

diff --git a/m4/m4.c b/m4/m4.c
index 04977995..d9166655 100644
--- a/m4/m4.c
+++ b/m4/m4.c
@@ -20,9 +20,21 @@
 
 #include <config.h>
 
+#include "bitrotate.h"
 #include "m4private.h"
 
 #define DEFAULT_NESTING_LIMIT	1024
+#define DEFAULT_NAMEMAP_SIZE    61
+
+static size_t
+hashfn (const void *ptr)
+{
+  const char *s = (const char *) ptr;
+  size_t val = DEFAULT_NAMEMAP_SIZE;
+  while (*s)
+    val = rotl_sz (val, 7) + to_uchar (*s++);
+  return val;
+}
 
 
 m4 *
@@ -33,6 +45,9 @@ m4_create (void)
   context->symtab = m4_symtab_create (0);
   context->syntax = m4_syntax_create ();
 
+  context->namemap =
+    m4_hash_new (DEFAULT_NAMEMAP_SIZE, hashfn, (m4_hash_cmp_func *) strcmp);
+
   context->debug_file	 = stderr;
   obstack_init (&context->trace_messages);
 
diff --git a/m4/m4private.h b/m4/m4private.h
index dbda70ca..926df58f 100644
--- a/m4/m4private.h
+++ b/m4/m4private.h
@@ -60,6 +60,7 @@ struct m4 {
   m4_symbol_table *     symtab;
   m4_syntax_table *     syntax;
   m4_module *           modules;
+  m4_hash *             namemap;
 
   const char *          current_file;   /* Current input file.  */
   int                   current_line;   /* Current input line.  */
@@ -190,7 +191,7 @@ struct m4_module
 extern void         m4__module_init (m4 *context);
 extern m4_module *  m4__module_open (m4 *context, const char *name,
                                      m4_obstack *obs);
-extern m4_module *  m4__module_find (const char *name);
+extern m4_module *  m4__module_find (m4 *context, const char *name);
 
 
 /* --- SYMBOL TABLE MANAGEMENT --- */
diff --git a/m4/module.c b/m4/module.c
index dce0f5bf..05b7bdef 100644
--- a/m4/module.c
+++ b/m4/module.c
@@ -87,7 +87,7 @@ void *
 m4_module_import (m4 *context, const char *module_name,
                   const char *symbol_name, m4_obstack *obs)
 {
-  m4_module *   module          = m4__module_find (module_name);
+  m4_module *   module          = m4__module_find (context, module_name);
   void *        symbol_address  = NULL;
 
   /* Try to load the module if it is not yet available (errors are
@@ -256,19 +256,10 @@ m4_module_next (m4 *context, m4_module *module)
 /* Return the first loaded module that passes the registered interface test
    and is called NAME.  */
 m4_module *
-m4__module_find (const char *name)
+m4__module_find (m4 *context, const char *name)
 {
-  lt_dlhandle handle;
-  m4_module *module;
-  assert (iface_id);
-
-  handle = lt_dlhandle_fetch (iface_id, name);
-  if (!handle)
-    return NULL;
-  module = (m4_module *) lt_dlcaller_get_data (iface_id, handle);
-  if (module)
-    assert (module->handle == handle);
-  return module;
+  m4_module **pmodule = (m4_module **) m4_hash_lookup (context->namemap, name);
+  return pmodule ? *pmodule : NULL;
 }
 
 
@@ -402,6 +393,7 @@ m4__module_open (m4 *context, const char *name, m4_obstack *obs)
 	  module->next   = context->modules;
 
 	  context->modules = module;
+	  m4_hash_insert (context->namemap, xstrdup (name), module);
 
           /* clear out any stale errors, since we have to use
              lt_dlerror to distinguish between success and
diff --git a/src/freeze.c b/src/freeze.c
index d2e9ea62..3b1fdd95 100644
--- a/src/freeze.c
+++ b/src/freeze.c
@@ -711,7 +711,7 @@ ill-formed frozen file, invalid builtin %s encountered"),
 ill-formed frozen file, invalid module %s encountered"),
                             quotearg_style_mem (locale_quoting_style,
                                                 string[2], number[2]));
-                module = m4__module_find (string[2]);
+                module = m4__module_find (context, string[2]);
               }
             token = m4_builtin_find_by_name (context, module, string[1]);
 
@@ -966,7 +966,7 @@ ill-formed frozen file, version 2 directive `%c' encountered"), 'T');
 ill-formed frozen file, invalid module %s encountered"),
                             quotearg_style_mem (locale_quoting_style,
                                                 string[2], number[2]));
-                module = m4__module_find (string[2]);
+                module = m4__module_find (context, string[2]);
               }
 
             m4_set_symbol_value_text (token, xmemdup0 (string[1], number[1]),