+/* A fluid specifying the default conversion handler for newly created
+ ports. Its value should be one of the symbols below. */
+SCM_VARIABLE (default_conversion_strategy_var,
+ "%default-port-conversion-strategy");
+
+/* Whether the above fluid is initialized. */
+static int scm_conversion_strategy_init = 0;
+
+/* The possible conversion strategies. */
+SCM_SYMBOL (sym_error, "error");
+SCM_SYMBOL (sym_substitute, "substitute");
+SCM_SYMBOL (sym_escape, "escape");
+
+/* Return the default failed encoding conversion policy for new created
+ ports. */
+scm_t_string_failed_conversion_handler
+scm_i_default_port_conversion_handler (void)
+{
+ scm_t_string_failed_conversion_handler handler;
+
+ if (!scm_conversion_strategy_init
+ || !scm_is_fluid (SCM_VARIABLE_REF (default_conversion_strategy_var)))
+ handler = SCM_FAILED_CONVERSION_QUESTION_MARK;
+ else
+ {
+ SCM fluid, value;
+
+ fluid = SCM_VARIABLE_REF (default_conversion_strategy_var);
+ value = scm_fluid_ref (fluid);
+
+ if (scm_is_eq (sym_substitute, value))
+ handler = SCM_FAILED_CONVERSION_QUESTION_MARK;
+ else if (scm_is_eq (sym_escape, value))
+ handler = SCM_FAILED_CONVERSION_ESCAPE_SEQUENCE;
+ else
+ /* Default to 'error also when the fluid's value is not one of
+ the valid symbols. */
+ handler = SCM_FAILED_CONVERSION_ERROR;
+ }
+
+ return handler;
+}
+
+/* Use HANDLER as the default conversion strategy for future ports. */
+void
+scm_i_set_default_port_conversion_handler (scm_t_string_failed_conversion_handler
+ handler)
+{
+ SCM strategy;
+
+ if (!scm_conversion_strategy_init
+ || !scm_is_fluid (SCM_VARIABLE_REF (default_conversion_strategy_var)))
+ scm_misc_error (NULL, "tried to set conversion strategy fluid before it is initialized",
+ SCM_EOL);
+
+ switch (handler)
+ {
+ case SCM_FAILED_CONVERSION_ERROR:
+ strategy = sym_error;
+ break;
+
+ case SCM_FAILED_CONVERSION_ESCAPE_SEQUENCE:
+ strategy = sym_escape;
+ break;
+
+ case SCM_FAILED_CONVERSION_QUESTION_MARK:
+ strategy = sym_substitute;
+ break;
+
+ default:
+ abort ();
+ }
+
+ scm_fluid_set_x (SCM_VARIABLE_REF (default_conversion_strategy_var),
+ strategy);
+}
+