1 files changed, 146 insertions, 0 deletions

diff --git a/examples/dte/history.c b/examples/dte/history.c
new file mode 100644
index 0000000..d03a6c2
--- /dev/null
+++ b/examples/dte/history.c
@@ -0,0 +1,146 @@
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "history.h"
+#include "error.h"
+#include "util/debug.h"
+#include "util/readfile.h"
+#include "util/str-util.h"
+#include "util/xmalloc.h"
+#include "util/xstdio.h"
+
+void history_add(History *history, const char *text)
+{
+    BUG_ON(history->max_entries < 2);
+    if (text[0] == '\0') {
+        return;
+    }
+
+    HashMap *map = &history->entries;
+    HistoryEntry *e = hashmap_get(map, text);
+
+    if (e) {
+        if (e == history->last) {
+            // Existing entry already at end of list; nothing more to do
+            return;
+        }
+        // Remove existing entry from list
+        e->next->prev = e->prev;
+        if (unlikely(e == history->first)) {
+            history->first = e->next;
+        } else {
+            e->prev->next = e->next;
+        }
+    } else {
+        if (map->count == history->max_entries) {
+            // History is full; recycle oldest entry
+            HistoryEntry *old_first = history->first;
+            HistoryEntry *new_first = old_first->next;
+            new_first->prev = NULL;
+            history->first = new_first;
+            e = hashmap_remove(map, old_first->text);
+            BUG_ON(e != old_first);
+        } else {
+            e = xnew(HistoryEntry, 1);
+        }
+        e->text = xstrdup(text);
+        hashmap_insert(map, e->text, e);
+    }
+
+    // Insert entry at end of list
+    HistoryEntry *old_last = history->last;
+    e->next = NULL;
+    e->prev = old_last;
+    history->last = e;
+    if (likely(old_last)) {
+        old_last->next = e;
+    } else {
+        history->first = e;
+    }
+}
+
+bool history_search_forward (
+    const History *history,
+    const HistoryEntry **pos,
+    const char *text
+) {
+    const HistoryEntry *start = *pos ? (*pos)->prev : history->last;
+    for (const HistoryEntry *e = start; e; e = e->prev) {
+        if (str_has_prefix(e->text, text)) {
+            *pos = e;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool history_search_backward (
+    const History *history,
+    const HistoryEntry **pos,
+    const char *text
+) {
+    const HistoryEntry *start = *pos ? (*pos)->next : history->first;
+    for (const HistoryEntry *e = start; e; e = e->next) {
+        if (str_has_prefix(e->text, text)) {
+            *pos = e;
+            return true;
+        }
+    }
+    return false;
+}
+
+void history_load(History *history, char *filename)
+{
+    BUG_ON(!history);
+    BUG_ON(!filename);
+    BUG_ON(history->filename);
+    BUG_ON(history->max_entries < 2);
+
+    hashmap_init(&history->entries, history->max_entries);
+    history->filename = filename;
+
+    char *buf;
+    const ssize_t ssize = read_file(filename, &buf);
+    if (ssize < 0) {
+        if (errno != ENOENT) {
+            error_msg("Error reading %s: %s", filename, strerror(errno));
+        }
+        return;
+    }
+
+    for (size_t pos = 0, size = ssize; pos < size; ) {
+        history_add(history, buf_next_line(buf, &pos, size));
+    }
+
+    free(buf);
+}
+
+void history_save(const History *history)
+{
+    const char *filename = history->filename;
+    if (!filename) {
+        return;
+    }
+
+    FILE *f = xfopen(filename, "w", O_CLOEXEC, 0666);
+    if (!f) {
+        error_msg("Error creating %s: %s", filename, strerror(errno));
+        return;
+    }
+
+    for (const HistoryEntry *e = history->first; e; e = e->next) {
+        xfputs(e->text, f);
+        xfputc('\n', f);
+    }
+
+    fclose(f);
+}
+
+void history_free(History *history)
+{
+    hashmap_free(&history->entries, free);
+    free(history->filename);
+    history->filename = NULL;
+    history->first = NULL;
+    history->last = NULL;
+}