From 7221289477ba80bfbb9c2c37e43a9d6b1d0e6d17 Mon Sep 17 00:00:00 2001
From: Thomas Schmucker <ts@its1.de>
Date: Sun, 10 Apr 2022 09:01:17 +0200
Subject: feat: rename files

---
 src/hash-table.c | 220 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 220 insertions(+)
 create mode 100644 src/hash-table.c

(limited to 'src/hash-table.c')

diff --git a/src/hash-table.c b/src/hash-table.c
new file mode 100644
index 0000000..256fac9
--- /dev/null
+++ b/src/hash-table.c
@@ -0,0 +1,220 @@
+#include <ctype.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "util.h"
+
+/* --8<-- hash_type */
+typedef int T;
+
+struct hash_item {
+	struct hash_item *next;
+	char *            key;
+	T                 data;
+};
+
+struct hash_tab {
+	struct hash_item *table[251]; // fit for your needs...
+};
+/* -->8-- */
+
+/* --8<-- hash_key */
+static unsigned long
+hash_key(const unsigned char *str)
+{
+	unsigned long hash = 5381;
+	unsigned int  c;
+
+	while ( (c = *str++) != '\0' )
+		hash = ((hash << 5) + hash) + c; /* hash * 33 + c */
+
+	return hash;
+}
+/* -->8-- */
+
+/* --8<-- hash_init */
+void
+hash_init(struct hash_tab *ht)
+{
+	for ( size_t i = 0; i != NELEM(ht->table); ++i )
+		ht->table[i] = NULL;
+}
+/* -->8-- */
+
+/* --8<-- hash_add */
+static struct hash_item *
+hash_add(struct hash_item *next, const char *key, T data)
+{
+	struct hash_item *new_item;
+	char *            new_key;
+
+	new_key  = strdup(key); // strdup: not standard but commonly used...
+	new_item = malloc(sizeof *new_item);
+
+	if ( new_key == NULL || new_item == NULL ) {
+		free(new_key);
+		free(new_item);
+		ERROR("out of memory");
+		return NULL;
+	}
+
+	new_item->next = next;
+	new_item->key  = new_key;
+	new_item->data = data;
+
+	return new_item;
+}
+/* -->8-- */
+
+/* --8<-- hash_lookup */
+T *
+hash_lookup(struct hash_tab *ht, const char *key, T data, int create)
+{
+	unsigned long     h;
+	struct hash_item *item;
+
+	h = hash_key((const unsigned char *) key) % NELEM(ht->table);
+	for ( item = ht->table[h]; item; item = item->next )
+		if ( strcmp(key, item->key) == 0 )
+			return &item->data;
+
+	// not found! create?
+	if ( create ) {
+		item = hash_add(ht->table[h], key, data);
+		if ( item )
+			ht->table[h] = item;
+		else
+			ERROR("can't create item");
+	}
+
+	return item ? &item->data : NULL;
+}
+/* -->8-- */
+
+/* --8<-- hash_delete */
+bool
+hash_delete(struct hash_tab *ht, const char *key)
+{
+	unsigned long     h;
+	struct hash_item *prev, *p;
+
+	h    = hash_key((const unsigned char *) key) % NELEM(ht->table);
+	prev = NULL;
+	for ( p = ht->table[h]; p; p = p->next ) {
+		if ( strcmp(key, p->key) == 0 ) {
+			if ( prev == NULL )
+				ht->table[h] = p->next;
+			else
+				prev->next = p->next;
+
+			free(p->key);
+			free(p);
+
+			return true; // successfully removed!
+		}
+		prev = p;
+	}
+
+	return false;
+}
+/* -->8-- */
+
+/* --8<-- hash_apply */
+void
+hash_apply(struct hash_tab *ht, void (*visit)(const char *key, T data, void *cl), void *cl)
+{
+	struct hash_item *item;
+
+	for ( size_t i = 0; i != NELEM(ht->table); ++i )
+		for ( item = ht->table[i]; item; item = item->next )
+			visit(item->key, item->data, cl);
+}
+/* -->8-- */
+
+/* --8<-- hash_free */
+void
+hash_free(struct hash_tab *ht)
+{
+	struct hash_item *p, *next;
+
+	for ( size_t i = 0; i != NELEM(ht->table); ++i ) {
+		for ( p = ht->table[i]; p; p = next ) {
+			next = p->next;
+			free(p->key);
+			free(p);
+		}
+		ht->table[i] = NULL;
+	}
+}
+/* -->8-- */
+
+static int
+getword(FILE *fp, char *buf, size_t size, int first(int), int rest(int))
+{
+	size_t i = 0;
+	int    c;
+
+	c = getc(fp);
+	for ( ; c != EOF; c = getc(fp) )
+		if ( first(c) ) {
+			if ( i < size - 1 )
+				buf[i++] = c;
+			c = getc(fp);
+			break;
+		}
+
+	for ( ; c != EOF && rest(c); c = getc(fp) )
+		if ( i < size - 1 )
+			buf[i++] = c;
+
+	if ( i < size )
+		buf[i] = 0;
+	else
+		buf[size - 1] = 0;
+
+	if ( c != EOF )
+		ungetc(c, fp);
+
+	return c > 0;
+}
+
+static int
+first(int c)
+{
+	return isalpha(c);
+}
+
+static int
+rest(int c)
+{
+	return isalpha(c) || c == '_';
+}
+
+static void
+print(const char *key, T data, void *cl)
+{
+	fprintf(cl, "%s: %d\n", key, data);
+}
+
+int
+main()
+{
+	struct hash_tab ht[1];
+	char            word[100];
+
+	hash_init(ht);
+
+	while ( getword(stdin, word, sizeof word, first, rest) ) {
+		T *p = hash_lookup(ht, word, 0, 1);
+		if ( p )
+			++(*p);
+	}
+
+	hash_delete(ht, "new_item");
+
+	hash_apply(ht, print, stdout);
+
+	hash_free(ht);
+}
-- 
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