Data update

Task/Dynamic-variable-names/C/dynamic-variable-names.c

@@ -0,0 +1,135 @@
+#include <stdio.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <ctype.h>
+#include <float.h>
+
+static inline uint64_t hash(void const *cp, size_t n) {
+	uint64_t       h = 0;
+	uint64_t const e = UINT64_C(2718281828459045235);  // e * 10**18
+	for(uint8_t const *cb = cp; n > 0; n--) {
+		h = ((h + n) * e) ^ ((*cb++ & 0xFF) * e);
+	}
+	return h;
+}
+
+static void *dup(void const *cp, size_t n) {
+	void *p = malloc(n);
+	return memcpy(p, cp, n);
+}
+
+static void *nodup(void const *cp, size_t n) {
+	return (void*)cp;
+}
+
+#define MAPPED  struct mapped_s
+MAPPED {
+	size_t      n;
+	char const *s;
+};
+#define MAP  struct map_s
+MAP {
+	size_t u;
+	size_t w;
+	size_t m;
+	char   a[];
+};
+
+static MAP *map_alloc(size_t m, size_t z) {
+	const size_t N = (((m * z) + (sizeof(MAP)-1)) / sizeof(MAP)) + 1;
+	MAP *t = calloc(N, sizeof(MAP));
+	t->m = m;
+	t->w = 3 * m / 4;
+	return t;
+}
+
+static void *map(MAP **t, size_t z, char const *s, size_t n, void *(*dup)(void const *, size_t)) {
+	if(!*t) {
+		*t = map_alloc(sizeof(size_t) * CHAR_BIT, z);
+	}
+	MAP        *f = *t;
+	uint64_t const h = hash(s, n);
+	size_t         x = (h / f->m) % f->m;
+	size_t   const k = x + !x;
+	size_t   const l = f->m - k;
+	size_t   const y = h % f->m;
+	x = y;
+	do {
+		MAPPED *p = (MAPPED *)&f->a[x*z];
+		if((p->n == n) && (memcmp(p->s, s, n) == 0)) {
+			return p;
+		}
+		if((p->n == 0) && dup) {
+			if(f->u == f->w) {
+				*t = map_alloc(2 * f->m, z);
+				for(size_t i = 0; f->u < f->w; i++) {
+					MAPPED *q = (MAPPED *)&f->a[i*z];
+					if(q->n > 0) {
+						(void)map(t, z, q->s, q->n, nodup);
+					}
+				}
+				free(f);
+				return map(t, z, s, n, dup);
+			}
+			f->u++;
+			p->n = n;
+			p->s = dup(s, n);
+			return p;
+		}
+		x = (x >= l) ? ((x + 1) % k) : (x + k);
+	} while(x != y)
+		;
+	return NULL;
+}
+
+static double mapf(char const *s, double v, void *(*dup)(void const *, size_t)) {
+	static MAP *t = NULL;
+	struct {
+		MAPPED;
+		double v;
+	} *p = map(&t, sizeof(*p), s, strlen(s), dup);
+	if(p) {
+		if(dup) p->v = v;
+		return p->v;
+	}
+	return NAN;
+}
+
+static inline double assignf(char const *s, double v) {
+	return mapf(s, v, dup);
+}
+
+static inline double valuef(char const *s) {
+	return mapf(s, 0, 0);
+}
+
+static char *enter(char const *prompt) {
+	static char buf[256];
+	fputs(prompt, stdout); fflush(stdout);
+	fgets(buf, sizeof(buf), stdin);
+	char *s = buf;
+	for(; *s && !isgraph(*s); s++)
+		;
+	char *t = s + strlen(s);
+	for(; (t > s) && !isgraph(*(t-1)); t--)
+		;
+	*t = '\0';
+	return s;
+}
+
+int main(int argc, char **argv) {
+	for(;;) {
+		char const *name = enter("Enter: ");
+		if(!*name) break;
+		char *val = strchr(name, '=');
+		if(val) {
+			*val++ = '\0';
+			assignf(name, strtod(val, NULL));
+		} else {
+			printf("%s = %F\n", name, valuef(name));
+		}
+	}
+	return 0;
+}