1 files changed, 153 insertions, 0 deletions
diff --git a/examples/dte/file-history.c b/examples/dte/file-history.c
new file mode 100644
index 0000000..8066b94
--- /dev/null
+++ b/examples/dte/file-history.c
@@ -0,0 +1,153 @@
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include "file-history.h"
+#include "error.h"
+#include "util/debug.h"
+#include "util/readfile.h"
+#include "util/str-util.h"
+#include "util/string-view.h"
+#include "util/strtonum.h"
+#include "util/xmalloc.h"
+#include "util/xstdio.h"
+
+enum {
+    MAX_ENTRIES = 512
+};
+
+void file_history_add(FileHistory *history, unsigned long row, unsigned long col, const char *filename)
+{
+    BUG_ON(row == 0);
+    BUG_ON(col == 0);
+    HashMap *map = &history->entries;
+    FileHistoryEntry *e = hashmap_get(map, filename);
+
+    if (e) {
+        if (e == history->last) {
+            e->row = row;
+            e->col = col;
+            return;
+        }
+        e->next->prev = e->prev;
+        if (unlikely(e == history->first)) {
+            history->first = e->next;
+        } else {
+            e->prev->next = e->next;
+        }
+    } else {
+        if (map->count == MAX_ENTRIES) {
+            // History is full; recycle the oldest entry
+            FileHistoryEntry *old_first = history->first;
+            FileHistoryEntry *new_first = old_first->next;
+            new_first->prev = NULL;
+            history->first = new_first;
+            e = hashmap_remove(map, old_first->filename);
+            BUG_ON(e != old_first);
+        } else {
+            e = xnew(FileHistoryEntry, 1);
+        }
+        e->filename = xstrdup(filename);
+        hashmap_insert(map, e->filename, e);
+    }
+
+    // Insert the entry at the end of the list
+    FileHistoryEntry *old_last = history->last;
+    e->next = NULL;
+    e->prev = old_last;
+    e->row = row;
+    e->col = col;
+    history->last = e;
+    if (likely(old_last)) {
+        old_last->next = e;
+    } else {
+        history->first = e;
+    }
+}
+
+static bool parse_ulong_field(StringView *sv, unsigned long *valp)
+{
+    size_t n = buf_parse_ulong(sv->data, sv->length, valp);
+    if (n == 0 || *valp == 0 || sv->data[n] != ' ') {
+        return false;
+    }
+    strview_remove_prefix(sv, n + 1);
+    return true;
+}
+
+void file_history_load(FileHistory *history, char *filename)
+{
+    BUG_ON(!history);
+    BUG_ON(!filename);
+    BUG_ON(history->filename);
+
+    hashmap_init(&history->entries, 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; ) {
+        unsigned long row, col;
+        StringView line = buf_slice_next_line(buf, &pos, size);
+        if (unlikely(
+            !parse_ulong_field(&line, &row)
+            || !parse_ulong_field(&line, &col)
+            || line.length < 2
+            || line.data[0] != '/'
+            || buf[pos - 1] != '\n'
+        )) {
+            continue;
+        }
+        buf[pos - 1] = '\0'; // null-terminate line, by replacing '\n' with '\0'
+        file_history_add(history, row, col, line.data);
+    }
+
+    free(buf);
+}
+
+void file_history_save(const FileHistory *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 FileHistoryEntry *e = history->first; e; e = e->next) {
+        xfprintf(f, "%lu %lu %s\n", e->row, e->col, e->filename);
+    }
+
+    fclose(f);
+}
+
+bool file_history_find(const FileHistory *history, const char *filename, unsigned long *row, unsigned long *col)
+{
+    const FileHistoryEntry *e = hashmap_get(&history->entries, filename);
+    if (!e) {
+        return false;
+    }
+    *row = e->row;
+    *col = e->col;
+    return true;
+}
+
+void file_history_free(FileHistory *history)
+{
+    hashmap_free(&history->entries, free);
+    free(history->filename);
+    history->filename = NULL;
+    history->first = NULL;
+    history->last = NULL;
+}