Update based on review comments

Signed-off-by: Barry Xu <barry.xu@sony.com>

Author: Barry-Xu-2018

rcl_yaml_param_parser/src/parse.c

@@ -88,12 +88,15 @@ void * get_value(
   RCUTILS_CHECK_ALLOCATOR_WITH_MSG(
     &allocator, "allocator is invalid", return NULL);
 
-  bool str_tag_enabled = tag != NULL && strcmp(YAML_STR_TAG, (char *)tag) == 0;
+  /// Check for yaml string tag
+  if (tag != NULL && strcmp(YAML_STR_TAG, (char *)tag) == 0) {
+    *val_type = DATA_TYPE_STRING;
+    return rcutils_strdup(value, allocator);
+  }
 
   /// Check if it is bool
   if (style != YAML_SINGLE_QUOTED_SCALAR_STYLE &&
-    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE &&
-    !str_tag_enabled)
+    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE)
   {
     if ((0 == strcmp(value, "Y")) ||
       (0 == strcmp(value, "y")) ||
@@ -140,8 +143,7 @@ void * get_value(
 
   /// Check for int
   if (style != YAML_SINGLE_QUOTED_SCALAR_STYLE &&
-    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE &&
-    !str_tag_enabled)
+    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE)
   {
     errno = 0;
     ival = strtol(value, &endptr, 0);
@@ -162,8 +164,7 @@ void * get_value(
 
   /// Check for float
   if (style != YAML_SINGLE_QUOTED_SCALAR_STYLE &&
-    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE &&
-    !str_tag_enabled)
+    style != YAML_DOUBLE_QUOTED_SCALAR_STYLE)
   {
     errno = 0;
     endptr = NULL;

rcl_yaml_param_parser/test/correct_config.yaml

@@ -53,4 +53,4 @@ string_tag:
   ros__parameters:
     string_bool: !!str yes
     string_int: !!str 1234
-    string_double: !!str 12.34
+    string_double: !!str 12.34