From d789313bd0a1f596ba73224777a017ac39ecbb3b Mon Sep 17 00:00:00 2001
From: Ekaitz Zarraga <ekaitz@elenq.tech>
Date: Sat, 2 Mar 2024 23:44:28 +0100
Subject: piece-table: index and start with insert

---
 src/piece-table.c | 55 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

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

diff --git a/src/piece-table.c b/src/piece-table.c
index 490950b..be9f1b2 100644
--- a/src/piece-table.c
+++ b/src/piece-table.c
@@ -1,3 +1,4 @@
+#include <assert.h>
 #include "piece-table.h"
 
 static piece *make_piece() {
@@ -39,6 +40,16 @@ bool init_piece_table(piece_table *pt, char *orig) {
     return true;
 }
 
+
+static void free_piece_list(piece *p) {
+    piece *cur, *next;
+    assert(p != NULL);
+    for ( cur = p; cur != p; cur = next ) {
+        next = cur->next;
+        free( cur );
+    }
+}
+
 void free_piece_table(piece_table *pt) {
     free_growable_buffer(&pt->add);
     free_fixed_buffer(&pt->orig);
@@ -49,6 +60,48 @@ void free_piece_table(piece_table *pt) {
     pt->length = 0;
 }
 
-void free_piece_list(piece *pt) {
+
+static void find_piece_by_pos(piece_table *pt, size_t pos) {
+    piece *cur;
+    assert(pos < pt->length);
+    if ( pos >= pt->cached_offset ) {
+        /* Search forward */
+        for ( cur = pt->cached; ; cur = cur->next ) {
+            if ( pt->cached_offset + pt->length > pos ) {
+                pt->cached = cur;
+                assert(pt->cached != pt->sentinel);
+                return;
+            }
+            pt->cached_offset += cur->length;
+        }
+    } else {
+        /* Search backwards */
+        for ( cur = pt->cached->prev; ; cur = cur->prev ) {
+            pt->cached_offset -= cur->length;
+            if ( pt->cached_offset < pos ) {
+                pt->cached = cur;
+                assert(pt->cached != pt->sentinel);
+                return;
+            }
+        }
+    }
+}
+
+char index_piece_table(piece_table *pt, size_t pos) {
+    assert(pos < pt->length);
+    find_piece_by_pos(pt, pos);
+    return pt->cached->start[pos - pt->cached_offset];
+}
+
+void insert_piece_table(piece_table *pt, char val, size_t pos) {
+    /* At the moment inserts only one char */
+    append_growable_buffer(&pt->add, &val, 1);
+
+    find_piece_by_pos(pt, pos);
+
     // TODO
 }
+
+void delete_piece_table(piece_table *pt, size_t pos, size_t len) {
+
+}
-- 
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