RNA: support automatically mapping string property to char pointer

The goal of this patch is to remove the boilerplate code required to get
a string property that maps to an allocated char pointer in dna.
Previously, one to to provide three callbacks, all of which are not necessary
anymore for a simple string property.

Currently, when an empty string is assigned, the `set` function will always
allocate it as well, instead of assigning `NULL` to the pointer. Some structs
might support `NULL` while others don't, so this is the safer option for now.

Differential Revision: https://developer.blender.org/D10773

2 files changed, 51 insertions, 67 deletions

diff --git a/source/blender/makesrna/intern/makesrna.c b/source/blender/makesrna/intern/makesrna.c
index 6940e475f39..b20d9218316 100644
--- a/source/blender/makesrna/intern/makesrna.c
+++ b/source/blender/makesrna/intern/makesrna.c
@@ -705,26 +705,34 @@ static char *rna_def_property_get_func(
 
         rna_print_data_get(f, dp);
 
-        if (!(prop->flag & PROP_NEVER_NULL)) {
+        if (dp->dnapointerlevel == 1) {
+          /* Handle allocated char pointer properties. */
           fprintf(f, "    if (data->%s == NULL) {\n", dp->dnaname);
           fprintf(f, "        *value = '\\0';\n");
           fprintf(f, "        return;\n");
           fprintf(f, "    }\n");
-        }
-
-        if (sprop->maxlength) {
           fprintf(f,
-                  "    %s(value, data->%s, %d);\n",
+                  "    %s(value, data->%s, strlen(data->%s) + 1);\n",
                   string_copy_func,
                   dp->dnaname,
-                  sprop->maxlength);
+                  dp->dnaname);
         }
         else {
-          fprintf(f,
-                  "    %s(value, data->%s, sizeof(data->%s));\n",
-                  string_copy_func,
-                  dp->dnaname,
-                  dp->dnaname);
+          /* Handle char array properties. */
+          if (sprop->maxlength) {
+            fprintf(f,
+                    "    %s(value, data->%s, %d);\n",
+                    string_copy_func,
+                    dp->dnaname,
+                    sprop->maxlength);
+          }
+          else {
+            fprintf(f,
+                    "    %s(value, data->%s, sizeof(data->%s));\n",
+                    string_copy_func,
+                    dp->dnaname,
+                    dp->dnaname);
+          }
         }
       }
       fprintf(f, "}\n\n");
@@ -1046,25 +1054,30 @@ static char *rna_def_property_set_func(
 
         rna_print_data_get(f, dp);
 
-        if (!(prop->flag & PROP_NEVER_NULL)) {
-          fprintf(f, "    if (data->%s == NULL) {\n", dp->dnaname);
-          fprintf(f, "        return;\n");
-          fprintf(f, "    }\n");
-        }
-
-        if (sprop->maxlength) {
-          fprintf(f,
-                  "    %s(data->%s, value, %d);\n",
-                  string_copy_func,
-                  dp->dnaname,
-                  sprop->maxlength);
+        if (dp->dnapointerlevel == 1) {
+          /* Handle allocated char pointer properties. */
+          fprintf(
+              f, "    if (data->%s != NULL) { MEM_freeN(data->%s); }\n", dp->dnaname, dp->dnaname);
+          fprintf(f, "    const int length = strlen(value);\n");
+          fprintf(f, "    data->%s = MEM_mallocN(length + 1, __func__);\n", dp->dnaname);
+          fprintf(f, "    %s(data->%s, value, length + 1);\n", string_copy_func, dp->dnaname);
         }
         else {
-          fprintf(f,
-                  "    %s(data->%s, value, sizeof(data->%s));\n",
-                  string_copy_func,
-                  dp->dnaname,
-                  dp->dnaname);
+          /* Handle char array properties. */
+          if (sprop->maxlength) {
+            fprintf(f,
+                    "    %s(data->%s, value, %d);\n",
+                    string_copy_func,
+                    dp->dnaname,
+                    sprop->maxlength);
+          }
+          else {
+            fprintf(f,
+                    "    %s(data->%s, value, sizeof(data->%s));\n",
+                    string_copy_func,
+                    dp->dnaname,
+                    dp->dnaname);
+          }
         }
       }
       fprintf(f, "}\n\n");
@@ -1285,10 +1298,17 @@ static char *rna_def_property_length_func(
     }
     else {
       rna_print_data_get(f, dp);
-      if (!(prop->flag & PROP_NEVER_NULL)) {
-        fprintf(f, "    if (data->%s == NULL) { return 0; }\n", dp->dnaname);
+      if (dp->dnapointerlevel == 1) {
+        /* Handle allocated char pointer properties. */
+        fprintf(f,
+                "    return (data->%s == NULL) ? 0 : strlen(data->%s);\n",
+                dp->dnaname,
+                dp->dnaname);
+      }
+      else {
+        /* Handle char array properties. */
+        fprintf(f, "    return strlen(data->%s);\n", dp->dnaname);
       }
-      fprintf(f, "    return strlen(data->%s);\n", dp->dnaname);
     }
     fprintf(f, "}\n\n");
   }
diff --git a/source/blender/makesrna/intern/rna_nodetree.c b/source/blender/makesrna/intern/rna_nodetree.c
index 3aba3e51217..d69a1e3dd06 100644
--- a/source/blender/makesrna/intern/rna_nodetree.c
+++ b/source/blender/makesrna/intern/rna_nodetree.c
@@ -4290,38 +4290,6 @@ void rna_ShaderNodePointDensity_density_minmax(bNode *self,
   RE_point_density_minmax(depsgraph, pd, r_min, r_max);
 }
 
-static void rna_NodeInputString_string_get(PointerRNA *ptr, char *value)
-{
-  bNode *node = (bNode *)ptr->data;
-  NodeInputString *storage = node->storage;
-
-  strcpy(value, (storage->string) ? storage->string : "");
-}
-
-static int rna_NodeInputString_string_length(PointerRNA *ptr)
-{
-  bNode *node = (bNode *)ptr->data;
-  NodeInputString *storage = node->storage;
-
-  return (storage->string) ? strlen(storage->string) : 0;
-}
-
-static void rna_NodeInputString_string_set(PointerRNA *ptr, const char *value)
-{
-  bNode *node = (bNode *)ptr->data;
-  NodeInputString *storage = node->storage;
-
-  if (storage->string) {
-    MEM_freeN(storage->string);
-  }
-
-  if (value && value[0]) {
-    storage->string = BLI_strdup(value);
-  }
-  else {
-    storage->string = NULL;
-  }
-}
 #else
 
 static const EnumPropertyItem prop_image_layer_items[] = {
@@ -4744,10 +4712,6 @@ static void def_fn_input_string(StructRNA *srna)
   RNA_def_struct_sdna_from(srna, "NodeInputString", "storage");
 
   prop = RNA_def_property(srna, "string", PROP_STRING, PROP_NONE);
-  RNA_def_property_string_funcs(prop,
-                                "rna_NodeInputString_string_get",
-                                "rna_NodeInputString_string_length",
-                                "rna_NodeInputString_string_set");
   RNA_def_property_ui_text(prop, "String", "");
   RNA_def_property_update(prop, NC_NODE | NA_EDITED, "rna_Node_update");
 }