add PIC_USE_FILE and PIC_USE_READ flags

lib/include/picconf.h

@@ -5,12 +5,11 @@
 /** enable libc */
 /* #define PIC_USE_LIBC 1 */
 
-/** enable stdio */
-/* #define PIC_USE_STDIO 1 */
-
 /** enable specific features */
+/* #define PIC_USE_READ 1 */
 /* #define PIC_USE_WRITE 1 */
 /* #define PIC_USE_EVAL 1 */
+/* #define PIC_USE_FILE 1 */
 
 /** essential external functions */
 /* #define PIC_JMPBUF jmp_buf */

lib/include/picrin/extra.h

@@ -15,8 +15,6 @@ void *pic_default_allocf(void *, void *, size_t);
 pic_value pic_fopen(pic_state *, FILE *, const char *mode);
 #endif
 
-pic_value pic_read(pic_state *, pic_value port);
-
 /* for debug */
 
 #if PIC_USE_WRITE

lib/include/picrin/setup.h

@@ -8,8 +8,8 @@
 # define PIC_USE_LIBC 1
 #endif
 
-#ifndef PIC_USE_STDIO
-# define PIC_USE_STDIO 1
+#ifndef PIC_USE_READ
+# define PIC_USE_READ 1
 #endif
 
 #ifndef PIC_USE_WRITE
@@ -20,6 +20,17 @@
 # define PIC_USE_EVAL 1
 #endif
 
+#ifndef PIC_USE_FILE
+# define PIC_USE_FILE 1
+#endif
+
+#if !PIC_USE_READ && PIC_USE_EVAL
+# error PIC_USE_EVAL requires PIC_USE_READ
+#endif
+#if !PIC_USE_LIBC && PIC_USE_FILE
+# error PIC_USE_FILE requires PIC_USE_LIBC
+#endif
+
 #ifndef PIC_JMPBUF
 # include <setjmp.h>
 # define PIC_JMPBUF jmp_buf
@@ -383,8 +394,11 @@ pic_atod(const char *str)
   return atof(str);
 }
 
-#if PIC_USE_STDIO
+#if PIC_USE_FILE
 # include <stdio.h>
+#endif
+
+#if PIC_USE_LIBC
 
 PIC_STATIC_INLINE void
 pic_dtoa(double dval, char *buf)