Index: load_cache/load_cache.c
===================================================================
--- load_cache/load_cache.c	(revision 759)
+++ load_cache/load_cache.c	(revision 760)
@@ -2,8 +2,15 @@
 #include <genht/htsp.h>
 #include <genht/hash.h>
 #include <genvector/vtp0.h>
+
+/* These are required for stat() and are C89. */
+#include <sys/types.h>
+#include <sys/stat.h>
+
 #include "load_cache.h"
 
+static void ldch_free_file_low(ldch_ctx_t *ctx, ldch_file_t *file);
+
 char *ldch_strdup(const char *s)
 {
 	int l = strlen(s);
@@ -11,6 +18,15 @@
 	return memcpy(o, s, l+1);
 }
 
+double ldch_file_mtime(const char *path)
+{
+	struct stat st;
+	if (stat(path, &st) != 0)
+		return -1;
+	return st.st_mtime;
+}
+
+
 void ldch_init(ldch_ctx_t *ctx)
 {
 	memset(ctx, 0, sizeof(ldch_ctx_t));
@@ -65,17 +81,27 @@
 	ldch_file_t *file = htsp_get(&ctx->files, filename);
 	void **d;
 	ldch_data_t *data;
+	double fmd = ldch_file_mtime(filename);
 
+	if (fmd < 0)
+		return NULL;
+
 	/* get low level */
 	if (file == NULL) {
-		file = low->parse(low, low_call_ctx, filename);
+		file = low->parse_alloc(low, low_call_ctx, filename);
 		if (file == NULL)
 			return NULL;
-		
+		if (low->parse(low, low_call_ctx, file, filename) != 0)
+			ldch_unload(ctx, file);
+		file->last_low_parsed = fmd;
 	}
 	else {
 		if (low->uid != file->low_parser->uid)
 			return NULL; /* can't parse the same file twice, with different low level */
+		if (fmd > file->last_low_parsed) { /* changed on disk */
+			ldch_free_file_low(ctx, file);
+			low->parse(low, low_call_ctx, file, filename);
+		}
 	}
 
 	/* get high level parsing donw */
@@ -120,7 +146,7 @@
 	free(data);
 }
 
-static void ldch_free_file(ldch_ctx_t *ctx, ldch_file_t *file)
+static void ldch_free_file_low(ldch_ctx_t *ctx, ldch_file_t *file)
 {
 	long n;
 
@@ -131,7 +157,11 @@
 
 	if (file->low_parser->free_payload != NULL)
 		file->low_parser->free_payload(file);
+}
 
+static void ldch_free_file(ldch_ctx_t *ctx, ldch_file_t *file)
+{
+	ldch_free_file_low(ctx, file);
 	free(file->name);
 	free(file);
 }
Index: load_cache/load_cache.h
===================================================================
--- load_cache/load_cache.h	(revision 759)
+++ load_cache/load_cache.h	(revision 760)
@@ -11,8 +11,9 @@
 struct ldch_low_parser_s {
 	char *name;
 	ldch_uid_t uid;
-	ldch_file_t *(*parse)(ldch_low_parser_t *parser, void *call_ctx, const char *fn);
-	void (*free_payload)(ldch_file_t *file);
+	ldch_file_t *(*parse_alloc)(ldch_low_parser_t *parser, void *call_ctx, const char *fn); /* called when the file is first loaded; should allocate (ldch_file_t *) */
+	int (*parse)(ldch_low_parser_t *parser, void *call_ctx, ldch_file_t *file, const char *fn); /* called after parse_alloc() on initial load or after free_payload() on reload */
+	void (*free_payload)(ldch_file_t *file); /* should free the in-memory document/parse-tree; a call to parse() may follow when reloading */
 	void (*unreg)(ldch_ctx_t *ctx, ldch_low_parser_t *low);
 	void *used_data;
 };
@@ -38,6 +39,7 @@
 	vtp0_t data;          /* -> (ldch_data_t *), indexed by high_parser uid */
 	void *user_data;
 	ldch_low_parser_t *low_parser;
+	double last_low_parsed; /* time stamp the file was last low-level parsed */
 	size_t low_payload_size;
 	char low_payload[1];  /* real size: low_payload_size (caches low level parsed data) */
 };