libmisc: Invent fmt.h to replace printf

1 files changed, 156 insertions, 0 deletions

diff --git a/libmisc/include/libmisc/fmt.h b/libmisc/include/libmisc/fmt.h
new file mode 100644
index 0000000..c29c085
--- /dev/null
+++ b/libmisc/include/libmisc/fmt.h
@@ -0,0 +1,156 @@
+/* libmisc/fmt.h - Write formatted text
+ *
+ * Copyright (C) 2025  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBMISC_FMT_H_
+#define _LIBMISC_FMT_H_
+
+#include <stddef.h> /* for size_t */
+#include <stdint.h> /* for (u)int{n}_t */
+
+#include <libmisc/macro.h>
+#include <libmisc/obj.h>
+
+/* destination interface ******************************************************/
+
+#define fmt_dest_LO_IFACE \
+	LO_FUNC(void  , putb, uint8_t b) \
+	LO_FUNC(size_t, tell)
+LO_INTERFACE(fmt_dest);
+
+/* type-specific fmt_print_() functions ***************************************/
+
+/* Simple bytes.  */
+void fmt_print_byte(lo_interface fmt_dest w, uint8_t b);
+
+/* These are `static inline` so that the compiler can unroll the loops.  */
+static inline void fmt_print_mem(lo_interface fmt_dest w, const void *_str, size_t size) {
+	const uint8_t *str = _str;
+	while (size--)
+		fmt_print_byte(w, *(str++));
+}
+static inline void fmt_print_str(lo_interface fmt_dest w, const char *str) {
+	while (*str)
+		fmt_print_byte(w, *(str++));
+}
+static inline void fmt_print_strn(lo_interface fmt_dest w, const char *str, size_t size) {
+	while (size-- && *str)
+		fmt_print_byte(w, *(str++));
+}
+
+/* Quoted bytes.  */
+void fmt_print_qbyte(lo_interface fmt_dest w, uint8_t b);
+void fmt_print_qmem(lo_interface fmt_dest w, const void *str, size_t size);
+void fmt_print_qstr(lo_interface fmt_dest w, const char *str);
+void fmt_print_qstrn(lo_interface fmt_dest w, const char *str, size_t size);
+
+/* Integers.  */
+#define _fmt_declare_base(base)                                                  \
+	void _fmt_print_base##base##_u8(lo_interface fmt_dest w, uint8_t val);   \
+	void _fmt_print_base##base##_u16(lo_interface fmt_dest w, uint16_t val); \
+	void _fmt_print_base##base##_u32(lo_interface fmt_dest w, uint32_t val); \
+	void _fmt_print_base##base##_u64(lo_interface fmt_dest w, uint64_t val); \
+	void _fmt_print_base##base##_s8(lo_interface fmt_dest w, int8_t val);    \
+	void _fmt_print_base##base##_s16(lo_interface fmt_dest w, int16_t val);  \
+	void _fmt_print_base##base##_s32(lo_interface fmt_dest w, int32_t val);  \
+	void _fmt_print_base##base##_s64(lo_interface fmt_dest w, int64_t val);  \
+	LM_FORCE_SEMICOLON
+_fmt_declare_base(2);
+_fmt_declare_base(8);
+_fmt_declare_base(10);
+_fmt_declare_base(16);
+#undef _fmt_declare_base
+
+#define _fmt_intswitch(val, prefix) _Generic((val)                    , \
+	unsigned char      : LM_CAT3_(prefix, u, __SCHAR_WIDTH__)     , \
+	unsigned short     : LM_CAT3_(prefix, u, __SHRT_WIDTH__)      , \
+	unsigned int       : LM_CAT3_(prefix, u, __INT_WIDTH__)       , \
+	unsigned long      : LM_CAT3_(prefix, u, __LONG_WIDTH__)      , \
+	unsigned long long : LM_CAT3_(prefix, u, __LONG_LONG_WIDTH__) , \
+	signed char        : LM_CAT3_(prefix, s, __SCHAR_WIDTH__)     , \
+	signed short       : LM_CAT3_(prefix, s, __SHRT_WIDTH__)      , \
+	signed int         : LM_CAT3_(prefix, s, __INT_WIDTH__)       , \
+	signed long        : LM_CAT3_(prefix, s, __LONG_WIDTH__)      , \
+	signed long long   : LM_CAT3_(prefix, s, __LONG_LONG_WIDTH__) )
+#define fmt_print_base2(w, val)  (_fmt_intswitch((val), _fmt_print_base2_)((w), (val)))
+#define fmt_print_base8(w, val)  (_fmt_intswitch((val), _fmt_print_base8_)((w), (val)))
+#define fmt_print_base10(w, val) (_fmt_intswitch((val), _fmt_print_base10_)((w), (val)))
+#define fmt_print_base16(w, val) (_fmt_intswitch((val), _fmt_print_base16_)((w), (val)))
+
+/* Booleans.  */
+void fmt_print_bool(lo_interface fmt_dest w, bool b);
+
+/* The high-level fmt_print() interface ***************************************/
+
+#define fmt_print(w, ...) do { LM_FOREACH_PARAM_(_fmt_param, (w), __VA_ARGS__) } while (0)
+#define _fmt_param(w, arg)                                   \
+	LM_IF(LM_IS_TUPLE(arg))(                             \
+		_fmt_param_tuple LM_EAT() (w, LM_EXPAND arg) \
+	)(                                                   \
+		_fmt_param_nontuple(w, arg)                  \
+	);
+#define _fmt_param_tuple(w, fn, ...) fmt_print_##fn(w __VA_OPT__(,) __VA_ARGS__)
+#define _fmt_param_nontuple(w, val) _Generic((val), \
+	unsigned char      : LM_CAT2_(_fmt_print_base10_u, __SCHAR_WIDTH__)     , \
+	unsigned short     : LM_CAT2_(_fmt_print_base10_u, __SHRT_WIDTH__)      , \
+	unsigned int       : LM_CAT2_(_fmt_print_base10_u, __INT_WIDTH__)       , \
+	unsigned long      : LM_CAT2_(_fmt_print_base10_u, __LONG_WIDTH__)      , \
+	unsigned long long : LM_CAT2_(_fmt_print_base10_u, __LONG_LONG_WIDTH__) , \
+	signed char        : LM_CAT2_(_fmt_print_base10_s, __SCHAR_WIDTH__)     , \
+	signed short       : LM_CAT2_(_fmt_print_base10_s, __SHRT_WIDTH__)      , \
+	signed int         : LM_CAT2_(_fmt_print_base10_s, __INT_WIDTH__)       , \
+	signed long        : LM_CAT2_(_fmt_print_base10_s, __LONG_WIDTH__)      , \
+	signed long long   : LM_CAT2_(_fmt_print_base10_s, __LONG_LONG_WIDTH__) , \
+	char *             : fmt_print_str                                      , \
+	const char *       : fmt_print_str                                      , \
+	bool               : fmt_print_bool                                     )(w, val)
+
+/* print-to-memory ************************************************************/
+
+struct fmt_buf {
+	void    *dat;
+	size_t   len, cap;
+};
+LO_IMPLEMENTATION_H(fmt_dest, struct fmt_buf, fmt_buf);
+
+#define fmt_snprint(buf, n, ...) ({                                \
+	struct fmt_buf _w = { .dat = buf, .cap = n };              \
+	lo_interface fmt_dest w = lo_box_fmt_buf_as_fmt_dest(&_w); \
+	fmt_print(w, __VA_ARGS__);                                 \
+	if (_w.len < _w.cap)                                       \
+		((char *)_w.dat)[_w.len] = '\0';                   \
+	_w.len;                                                    \
+})
+
+/* justify ********************************************************************/
+
+/* *grubles about not being allowed to nest things* */
+#define _fmt_param_indirect() _fmt_param
+#define _fmt_print2(w, ...) do { LM_FOREACH_PARAM2_(_fmt_param2, (w), __VA_ARGS__) } while (0)
+#define _fmt_param2(...) _LM_DEFER2(_fmt_param_indirect)()(__VA_ARGS__)
+
+#define fmt_print_ljust(w, width, fillchar, ...) do { \
+	size_t beg = LO_CALL(w, tell);                \
+	_fmt_print2(w, __VA_ARGS__);                  \
+	while ((LO_CALL(w, tell) - beg) < width)      \
+		fmt_print_byte(w, fillchar);          \
+} while (0)
+
+#define fmt_print_rjust(w, width, fillchar, ...) do {                          \
+	struct fmt_buf _discard = {};                                          \
+	lo_interface fmt_dest discard = lo_box_fmt_buf_as_fmt_dest(&_discard); \
+	_fmt_print2(discard, __VA_ARGS__);                                     \
+	while (_discard.len++ < width)                                         \
+		fmt_print_byte(w, fillchar);                                   \
+	_fmt_print2(w, __VA_ARGS__);                                           \
+} while (0)
+
+void fmt_print_base16_u8_(lo_interface fmt_dest w, uint8_t x);
+void fmt_print_base16_u16_(lo_interface fmt_dest w, uint16_t x);
+void fmt_print_base16_u32_(lo_interface fmt_dest w, uint32_t x);
+void fmt_print_base16_u64_(lo_interface fmt_dest w, uint64_t x);
+void fmt_print_ptr(lo_interface fmt_dest w, void *ptr);
+
+#endif /* _LIBMISC_FMT_H_ */