Prefix all namelist group and option names for MPAS dycore in CAM/CAM-SIMA

When MPAS is used as a dynamical core in a host model (e.g., CAM/CAM-SIMA),
the following transformations are performed for each namelist group and
option name:

1. Leading "config_" is removed recursively from the name. Case-insensitive.
2. Leading "mpas_" is removed recursively from the name. Case-insensitive.
3. Prepend "mpas_" to the name.

By doing so, it is now easier to distinguish MPAS namelist groups and options
from host model ones. Additionally, the possibility of name collisions with
host model ones is also resolved once and for all.

Note that only namelist I/O is affected. Internally, MPAS still refers to its
namelist options by their original names due to compatibility reasons.

For stand-alone MPAS, its namelist groups and options keep their original names
as in the registry.

Author: kuanchihwang

src/tools/registry/gen_inc.c

@@ -15,6 +15,10 @@
 #include "fortprintf.h"
 #include "utility.h"
 
+#ifdef MPAS_CAM_DYCORE
+#include <ctype.h>
+#endif
+
 void process_core_macro(const char *macro, const char *val, va_list ap);
 void process_domain_macro(const char *macro, const char *val, va_list ap);
 
@@ -696,8 +700,12 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 	ezxml_t nmlrecs_xml, nmlopt_xml;
 
 	const char *const_core;
-	const char *nmlrecname, *nmlrecindef, *nmlrecinsub;
-	const char *nmloptname, *nmlopttype, *nmloptval, *nmloptunits, *nmloptdesc, *nmloptposvals, *nmloptindef;
+	const char *original_nmlrecname, *nmlrecindef, *nmlrecinsub;
+	const char *original_nmloptname, *nmlopttype, *nmloptval, *nmloptunits, *nmloptdesc, *nmloptposvals, *nmloptindef;
+
+	// Fortran variable names have a length limit of 63 characters. + 1 for the terminating null character.
+	char nmlrecname[64];
+	char nmloptname[64];
 
 	char pool_name[1024];
 	char core_string[1024];
@@ -743,7 +751,9 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 
 	// Parse Namelist Records
 	for (nmlrecs_xml = ezxml_child(registry, "nml_record"); nmlrecs_xml; nmlrecs_xml = nmlrecs_xml->next){
-		nmlrecname = ezxml_attr(nmlrecs_xml, "name");
+		original_nmlrecname = ezxml_attr(nmlrecs_xml, "name");
+		mangle_name(nmlrecname, sizeof(nmlrecname), original_nmlrecname);
+
 		nmlrecindef = ezxml_attr(nmlrecs_xml, "in_defaults");
 		nmlrecinsub = ezxml_attr(nmlrecs_xml, "in_subpool");
 
@@ -777,7 +787,9 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 
 		// Define variable definitions prior to reading the namelist in.
 		for (nmlopt_xml = ezxml_child(nmlrecs_xml, "nml_option"); nmlopt_xml; nmlopt_xml = nmlopt_xml->next){
-			nmloptname = ezxml_attr(nmlopt_xml, "name");
+			original_nmloptname = ezxml_attr(nmlopt_xml, "name");
+			mangle_name(nmloptname, sizeof(nmloptname), original_nmloptname);
+
 			nmlopttype = ezxml_attr(nmlopt_xml, "type");
 			nmloptval = ezxml_attr(nmlopt_xml, "default_value");
 			nmloptunits = ezxml_attr(nmlopt_xml, "units");
@@ -809,7 +821,9 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 		// Define the namelist block, to read the namelist record in.
 		fortprintf(fd, "      namelist /%s/ &\n", nmlrecname);
 		for (nmlopt_xml = ezxml_child(nmlrecs_xml, "nml_option"); nmlopt_xml; nmlopt_xml = nmlopt_xml->next){
-			nmloptname = ezxml_attr(nmlopt_xml, "name");
+			original_nmloptname = ezxml_attr(nmlopt_xml, "name");
+			mangle_name(nmloptname, sizeof(nmloptname), original_nmloptname);
+
 			if(nmlopt_xml->next){
 				fortprintf(fd, "         %s, &\n", nmloptname);
 			} else {
@@ -840,7 +854,9 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 		// Define broadcast calls for namelist values.
 		fortprintf(fd, "      if (ierr <= 0) then\n");
 		for (nmlopt_xml = ezxml_child(nmlrecs_xml, "nml_option"); nmlopt_xml; nmlopt_xml = nmlopt_xml->next){
-			nmloptname = ezxml_attr(nmlopt_xml, "name");
+			original_nmloptname = ezxml_attr(nmlopt_xml, "name");
+			mangle_name(nmloptname, sizeof(nmloptname), original_nmloptname);
+
 			nmlopttype = ezxml_attr(nmlopt_xml, "type");
 
 			if(strncmp(nmlopttype, "real", 1024) == 0){
@@ -858,7 +874,9 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 		fortprintf(fd, "            call mpas_log_write('    The following values will be used for variables in this record:')\n");
 		fortprintf(fd, "            call mpas_log_write(' ')\n");
 		for (nmlopt_xml = ezxml_child(nmlrecs_xml, "nml_option"); nmlopt_xml; nmlopt_xml = nmlopt_xml->next){
-			nmloptname = ezxml_attr(nmlopt_xml, "name");
+			original_nmloptname = ezxml_attr(nmlopt_xml, "name");
+			mangle_name(nmloptname, sizeof(nmloptname), original_nmloptname);
+
 			nmlopttype = ezxml_attr(nmlopt_xml, "type");
 
 			if (strncmp(nmlopttype, "character", 1024) == 0) {
@@ -885,10 +903,12 @@ int parse_namelist_records_from_registry(ezxml_t registry)/*{{{*/
 		fortprintf(fd, "\n");
 
 		for (nmlopt_xml = ezxml_child(nmlrecs_xml, "nml_option"); nmlopt_xml; nmlopt_xml = nmlopt_xml->next){
-			nmloptname = ezxml_attr(nmlopt_xml, "name");
+			original_nmloptname = ezxml_attr(nmlopt_xml, "name");
+			mangle_name(nmloptname, sizeof(nmloptname), original_nmloptname);
 
-			fortprintf(fd, "      call mpas_pool_add_config(%s, '%s', %s)\n", pool_name, nmloptname, nmloptname);
-			fortprintf(fcg, "      call mpas_pool_get_config(configPool, '%s', %s)\n", nmloptname, nmloptname);
+			// Always keep namelist options to their original names in MPAS pools for compatibility reasons.
+			fortprintf(fd, "      call mpas_pool_add_config(%s, '%s', %s)\n", pool_name, original_nmloptname, nmloptname);
+			fortprintf(fcg, "      call mpas_pool_get_config(configPool, '%s', %s)\n", original_nmloptname, nmloptname);
 		}
 		fortprintf(fd, "\n");
 		fortprintf(fcg, "\n");
@@ -2532,3 +2552,54 @@ int parse_structs_from_registry(ezxml_t registry)/*{{{*/
 
 	return 0;
 }/*}}}*/
+
+
+/**
+ * mangle_name
+ *
+ * Perform name mangling for MPAS namelist groups and options, as appropriate, depending on the containing
+ * host model.
+ *
+ * When MPAS is used as a dynamical core in a host model (e.g., CAM/CAM-SIMA), it needs to share
+ * the namelist file with other model components. As a result, MPAS namelist groups and options may not
+ * be easily recognizable at first sight. With the `MPAS_CAM_DYCORE` macro being defined, this function
+ * adds a unique identifier to each MPAS namelist group and option name by performing the following
+ * transformations:
+ *
+ * 1. Leading "config_" is removed recursively from the name. Case-insensitive.
+ * 2. Leading "mpas_" is removed recursively from the name. Case-insensitive.
+ * 3. Prepend "mpas_" to the name.
+ *
+ * By doing so, it is now easier to distinguish MPAS namelist groups and options from host model ones.
+ * The possibility of name collisions with host model ones is also resolved once and for all.
+ *
+ * For stand-alone MPAS, where the `MPAS_CAM_DYCORE` macro is not defined, this function just returns
+ * the name as is.
+ */
+void mangle_name(char *new_name, const size_t new_name_size, const char *old_name)
+{
+    if (!new_name || !old_name || new_name_size == 0) return;
+
+#ifdef MPAS_CAM_DYCORE
+    const char *const new_prefix = "mpas_";
+    const char *const old_prefix = "config_";
+
+    // Remove all leading whitespaces by moving pointer forward.
+    while (*old_name != '\0' && isspace((unsigned char) *old_name)) old_name++;
+
+    // Remove all leading "config_" by moving pointer forward.
+    while (strncasecmp(old_name, old_prefix, strlen(old_prefix)) == 0) old_name += strlen(old_prefix);
+
+    // Remove all leading "mpas_" by moving pointer forward.
+    while (strncasecmp(old_name, new_prefix, strlen(new_prefix)) == 0) old_name += strlen(new_prefix);
+
+    *new_name = '\0';
+    snprintf(new_name, new_name_size, "%s%s", new_prefix, old_name);
+
+    // Remove all trailing whitespaces by zeroing (nulling) out.
+    new_name += strlen(new_name) - 1;
+    while (*new_name != '\0' && isspace((unsigned char) *new_name)) *new_name-- = '\0';
+#else
+    snprintf(new_name, new_name_size, "%s", old_name);
+#endif
+}

src/tools/registry/gen_inc.h

@@ -38,3 +38,4 @@ int push_attributes(ezxml_t currentPosition);
 int merge_structs_and_var_arrays(ezxml_t currentPosition);
 int merge_streams(ezxml_t registry);
 int parse_structs_from_registry(ezxml_t registry);
+void mangle_name(char *new_name, const size_t new_name_size, const char *old_name);