utils.h: Some utility functions and macros

Signed-off-by: Yuxuan Shui <yshuiv7@gmail.com>

src/utils.h

@@ -0,0 +1,80 @@
+#pragma once
+#include <ctype.h>
+#include <stddef.h>
+#include <stdlib.h>
+static inline const char *
+skip_space_const(const char *src) {
+  if (!src)
+    return NULL;
+  while (*src && isspace(*src))
+    src++;
+  return src;
+}
+
+static inline char *
+skip_space_mut(char *src) {
+  if (!src)
+    return NULL;
+  while (*src && isspace(*src))
+    src++;
+  return src;
+}
+
+#define skip_space(x) _Generic((x), \
+  char *: skip_space_mut, \
+  const char *: skip_space_const \
+)(x)
+
+/// RC_TYPE generates a reference counted type from `type`
+///
+/// parameters:
+///   name = the generated type will be called `name`_t.
+///   ctor = the constructor of `type`, will be called when
+///          a value of `type` is created. should take one
+///          argument of `type *`.
+///   dtor = the destructor. will be called when all reference
+///          is gone. has same signature as ctor
+///   Q    = function qualifier. this is the qualifier that
+///          will be put before generated functions
+//
+/// functions generated:
+///   `name`_new:   create a new reference counted object of `type`
+///   `name`_ref:   increment the reference counter, return a
+///                 reference to the object
+///   `name`_unref: decrement the reference counter. take a `type **`
+///                 because it needs to nullify the reference.
+#define RC_TYPE(type, name, ctor, dtor, Q) \
+typedef struct { \
+  type inner; \
+  int ref_count; \
+} name##_internal_t; \
+typedef type name##_t; \
+Q type *name##_new(void) { \
+  name##_internal_t *ret = malloc(sizeof(name##_internal_t)); \
+  ctor((type *)ret); \
+  ret->ref_count = 1; \
+  return (type *)ret; \
+} \
+Q type *name##_ref(type *a) { \
+  __auto_type b = (name##_internal_t *)a; \
+  b->ref_count++; \
+  return a; \
+} \
+Q void name##_unref(type **a) { \
+  __auto_type b = (name##_internal_t *)*a; \
+  if (!b) \
+    return; \
+  b->ref_count--; \
+  if (!b->ref_count) {\
+    dtor((type *)b); \
+    free(b); \
+  } \
+  *a = NULL; \
+}
+
+/// Generate prototypes for functions generated by RC_TYPE
+#define RC_TYPE_PROTO(type, name) \
+typedef type name##_t; \
+type *name##_new(void); \
+void name##_ref(type *a); \
+void name##_unref(type **a);