Eolian: Support default return values from .eo file.

Now, it is possible to assign a default return value for a
method/property.
It will be used in case the function invocation makes issues, e.g eo_do
failing to find the function...

src/bin/eolian/legacy_generator.c

@@ -298,8 +298,11 @@ _eapi_func_generate(const char *classname, Eolian_Function funcid, Eolian_Functi
      {
         if (eina_strbuf_length_get(eoparam)) eina_strbuf_append(eoparam, ", ");
         Eina_Bool had_star = !!strchr(rettype, '*');
-        sprintf (tmpstr, "   %s%s%s%s = 0;\n",
-              ret_const?"const ":"", rettype, had_star?"":" ", retname);
+        const char *dflt_ret_val =
+           eolian_function_return_dflt_value_get(funcid, ftype);
+        sprintf (tmpstr, "   %s%s%s%s = %s;\n",
+              ret_const?"const ":"", rettype, had_star?"":" ", retname,
+              dflt_ret_val?dflt_ret_val:"0");
         eina_strbuf_append_printf(eoparam, "&%s", retname);
      }
 

src/lib/eolian/Eolian.h

@@ -464,6 +464,22 @@ EAPI Eina_Bool eolian_parameter_is_own(Eolian_Function_Parameter param_desc);
  */
 EAPI const char *eolian_function_return_type_get(Eolian_Function function_id, Eolian_Function_Type ftype);
 
+/*
+ * @brief Get the return default value of a function.
+ *
+ * @param[in] function_id id of the function
+ * @param[in] ftype type of the function
+ * @return the return default value of the function
+ *
+ * The return default value is needed to return an appropriate
+ * value if an error occurs (eo_do failure...).
+ * The default value is not mandatory, so NULL can be returned.
+ *
+ * @ingroup Eolian
+ */
+EAPI const char *
+eolian_function_return_dflt_value_get(Eolian_Function foo_id, Eolian_Function_Type ftype);
+
 /*
  * @brief Get the return comment of a function.
  *

src/lib/eolian/eo_definitions.c

@@ -8,6 +8,7 @@ eo_definitions_ret_free(Eo_Ret_Def *ret)
 {
    if (ret->type) eina_stringshare_del(ret->type);
    if (ret->comment) eina_stringshare_del(ret->comment);
+   if (ret->dflt_ret_val) free(ret->dflt_ret_val);
    free(ret);
 }
 

src/lib/eolian/eo_definitions.h

@@ -10,6 +10,7 @@ typedef struct _eo_ret_def
 {
    const char *type;
    const char *comment;
+   const char *dflt_ret_val;
    Eina_Bool warn_unused:1;
    Eina_Bool own:1;
 } Eo_Ret_Def;

src/lib/eolian/eo_lexer.rl

@@ -263,6 +263,24 @@ _eo_tokenizer_return_get(Eo_Tokenizer *toknz, char *p)
         ret->own = EINA_TRUE;
         memset(s, ' ', 4);
      }
+   s = strchr(toknz->saved.tok, '(');
+   if (s)
+     {
+        char *end = strchr(s, ')');
+        if (!end)
+           ABORT(toknz, "wrong syntax (missing ')'): %s",
+                 _eo_tokenizer_token_get(toknz, p));
+        /* Current values in s and end have to be changed to ' ' to not disturb the next steps (type extraction) */
+        *s++ = ' ';
+        while (*s == ' ') s++;
+        *end-- = ' ';
+        while (end > s && *end == ' ') end--;
+        if (end < s)
+           ABORT(toknz, "empty default return value: %s",
+                 _eo_tokenizer_token_get(toknz, p));
+        ret->dflt_ret_val = strndup(s, end - s + 1);
+        memset(s, ' ', end - s + 1);
+     }
    *p = ';';
    s = p - 1; /* Don't look at the character ';' */
    /* Remove any space between the param name and ';'
@@ -400,6 +418,8 @@ _eo_tokenizer_implement_get(Eo_Tokenizer *toknz, char *p)
    list_separator    = ',';
    colon             = ':';
 
+   # chars allowed on the return line.
+   return_char       = (alnum_u | '*' | ws | '@' | '(' | ')' | '.' | '-');
 }%%
 
 %%{
@@ -462,7 +482,7 @@ _eo_tokenizer_implement_get(Eo_Tokenizer *toknz, char *p)
    }
 
    rettype_comment = ws* eo_comment %end_accessor_rettype_comment;
-   rettype = 'return' ws+ alpha+ >save_fpc (alnum_u | '*' | ws | '@')+ %end_accessor_return end_statement rettype_comment?;
+   rettype = 'return' ws+ alpha+ >save_fpc return_char+ %end_accessor_return end_statement rettype_comment?;
 
    legacy = 'legacy' ws+ ident %end_accessor_legacy end_statement;
 
@@ -687,7 +707,7 @@ _eo_tokenizer_implement_get(Eo_Tokenizer *toknz, char *p)
    meth_legacy = 'legacy' ws+ ident %end_method_legacy end_statement;
 
    meth_rettype_comment = ws* eo_comment %end_method_rettype_comment;
-   meth_rettype = 'return' ws+ alpha+ >save_fpc (alnum_u | '*' | ws | '@')+ %end_method_rettype end_statement meth_rettype_comment?;
+   meth_rettype = 'return' ws+ alpha+ >save_fpc return_char+ %end_method_rettype end_statement meth_rettype_comment?;
 
    meth_obj_const = 'const' %end_method_obj_const end_statement;
 
@@ -1366,6 +1386,8 @@ eo_tokenizer_database_fill(const char *filename)
                              accessor->type == SETTER?SET:GET, accessor->ret->warn_unused);
                        database_function_return_flag_set_own(foo_id,
                              accessor->type == SETTER?SET:GET, accessor->ret->own);
+                       database_function_return_dflt_val_set(foo_id,
+                             accessor->type == SETTER?SET:GET, accessor->ret->dflt_ret_val);
                     }
                   if (accessor->legacy)
                     {
@@ -1407,8 +1429,11 @@ eo_tokenizer_database_fill(const char *filename)
                {
                   database_function_data_set(foo_id, EOLIAN_METHOD_RETURN_TYPE, meth->ret->type);
                   database_function_description_set(foo_id, EOLIAN_RETURN_COMMENT, meth->ret->comment);
-                  database_function_return_flag_set_as_warn_unused(foo_id, METHOD_FUNC, meth->ret->warn_unused);
+                  database_function_return_flag_set_as_warn_unused(foo_id,
+                        METHOD_FUNC, meth->ret->warn_unused);
                   database_function_return_flag_set_own(foo_id, METHOD_FUNC, meth->ret->own);
+                  database_function_return_dflt_val_set(foo_id,
+                        METHOD_FUNC, meth->ret->dflt_ret_val);
                }
              database_function_description_set(foo_id, EOLIAN_COMMENT, meth->comment);
              database_function_data_set(foo_id, EOLIAN_LEGACY, meth->legacy);

src/lib/eolian/eolian_database.c

@@ -1,6 +1,10 @@
 #include <Eina.h>
 #include "eolian_database.h"
 
+#define PROP_GET_RETURN_DFLT_VAL "property_get_return_dflt_val"
+#define PROP_SET_RETURN_DFLT_VAL "property_set_return_dflt_val"
+#define METHOD_RETURN_DFLT_VAL "method_return_dflt_val"
+
 static Eina_Hash *_classes = NULL;
 static int _database_init_count = 0;
 
@@ -851,6 +855,33 @@ eolian_function_return_type_get(Eolian_Function foo_id, Eolian_Function_Type fty
    return ret;
 }
 
+void database_function_return_dflt_val_set(Eolian_Function foo_id, Eolian_Function_Type ftype, const char *ret_dflt_value)
+{
+   const char *key = NULL;
+   switch (ftype)
+     {
+      case SET: key = PROP_SET_RETURN_DFLT_VAL; break;
+      case GET: key = PROP_GET_RETURN_DFLT_VAL; break;
+      case METHOD_FUNC: key = METHOD_RETURN_DFLT_VAL; break;
+      default: return;
+     }
+   database_function_data_set(foo_id, key, ret_dflt_value);
+}
+
+EAPI const char *
+eolian_function_return_dflt_value_get(Eolian_Function foo_id, Eolian_Function_Type ftype)
+{
+   const char *key = NULL;
+   switch (ftype)
+     {
+      case SET: key = PROP_SET_RETURN_DFLT_VAL; break;
+      case GET: key = PROP_GET_RETURN_DFLT_VAL; break;
+      case UNRESOLVED: case METHOD_FUNC: key = METHOD_RETURN_DFLT_VAL; break;
+      default: return NULL;
+     }
+   return eolian_function_data_get(foo_id, key);
+}
+
 EAPI const char *
 eolian_function_return_comment_get(Eolian_Function foo_id, Eolian_Function_Type ftype)
 {

src/lib/eolian/eolian_database.h

@@ -94,6 +94,8 @@ void database_parameter_own_set(Eolian_Function_Parameter, Eina_Bool own);
 
 void database_function_return_type_set(Eolian_Function foo_id, Eolian_Function_Type ftype, const char *ret_type);
 
+void database_function_return_dflt_val_set(Eolian_Function foo_id, Eolian_Function_Type ftype, const char *ret_dflt_value);
+
 void database_function_return_flag_set_as_warn_unused(Eolian_Function foo_id,
       Eolian_Function_Type ftype, Eina_Bool warn_unused);