1 files changed, 394 insertions, 0 deletions

diff --git a/examples/dte/edit.c b/examples/dte/edit.c
new file mode 100644
index 0000000..337a1e9
--- /dev/null
+++ b/examples/dte/edit.c
@@ -0,0 +1,394 @@
+#include <string.h>
+#include "edit.h"
+#include "block.h"
+#include "buffer.h"
+#include "syntax/highlight.h"
+#include "util/debug.h"
+#include "util/list.h"
+#include "util/xmalloc.h"
+
+enum {
+    BLOCK_EDIT_SIZE = 512
+};
+
+static void sanity_check_blocks(const View *view, bool check_newlines)
+{
+#if DEBUG >= 1
+    const Buffer *buffer = view->buffer;
+    BUG_ON(list_empty(&buffer->blocks));
+    BUG_ON(view->cursor.offset > view->cursor.blk->size);
+
+    const Block *blk = BLOCK(buffer->blocks.next);
+    if (blk->size == 0) {
+        // The only time a zero-sized block is valid is when it's the
+        // first and only block
+        BUG_ON(buffer->blocks.next->next != &buffer->blocks);
+        BUG_ON(view->cursor.blk != blk);
+        return;
+    }
+
+    bool cursor_seen = false;
+    block_for_each(blk, &buffer->blocks) {
+        const size_t size = blk->size;
+        BUG_ON(size == 0);
+        BUG_ON(size > blk->alloc);
+        if (blk == view->cursor.blk) {
+            cursor_seen = true;
+        }
+        if (check_newlines) {
+            BUG_ON(blk->data[size - 1] != '\n');
+        }
+        if (DEBUG > 2) {
+            BUG_ON(count_nl(blk->data, size) != blk->nl);
+        }
+    }
+    BUG_ON(!cursor_seen);
+#else
+    // Silence "unused parameter" warnings
+    (void)view;
+    (void)check_newlines;
+#endif
+}
+
+static size_t copy_count_nl(char *dst, const char *src, size_t len)
+{
+    size_t nl = 0;
+    for (size_t i = 0; i < len; i++) {
+        dst[i] = src[i];
+        if (src[i] == '\n') {
+            nl++;
+        }
+    }
+    return nl;
+}
+
+static size_t insert_to_current(BlockIter *cursor, const char *buf, size_t len)
+{
+    Block *blk = cursor->blk;
+    size_t offset = cursor->offset;
+    size_t size = blk->size + len;
+
+    if (size > blk->alloc) {
+        blk->alloc = round_size_to_next_multiple(size, BLOCK_ALLOC_MULTIPLE);
+        xrenew(blk->data, blk->alloc);
+    }
+    memmove(blk->data + offset + len, blk->data + offset, blk->size - offset);
+    size_t nl = copy_count_nl(blk->data + offset, buf, len);
+    blk->nl += nl;
+    blk->size = size;
+    return nl;
+}
+
+/*
+ * Combine current block and new data into smaller blocks:
+ *   - Block _must_ contain whole lines
+ *   - Block _must_ contain at least one line
+ *   - Preferred maximum size of block is BLOCK_EDIT_SIZE
+ *   - Size of any block can be larger than BLOCK_EDIT_SIZE
+ *     only if there's a very long line
+ */
+static size_t split_and_insert(BlockIter *cursor, const char *buf, size_t len)
+{
+    Block *blk = cursor->blk;
+    ListHead *prev_node = blk->node.prev;
+    const char *buf1 = blk->data;
+    const char *buf2 = buf;
+    const char *buf3 = blk->data + cursor->offset;
+    size_t size1 = cursor->offset;
+    size_t size2 = len;
+    size_t size3 = blk->size - size1;
+    size_t total = size1 + size2 + size3;
+    size_t start = 0; // Beginning of new block
+    size_t size = 0; // Size of new block
+    size_t pos = 0; // Current position
+    size_t nl_added = 0;
+
+    while (start < total) {
+        // Size of new block if next line would be added
+        size_t new_size = 0;
+        size_t copied = 0;
+
+        if (pos < size1) {
+            const char *nl = memchr(buf1 + pos, '\n', size1 - pos);
+            if (nl) {
+                new_size = nl - buf1 + 1 - start;
+            }
+        }
+
+        if (!new_size && pos < size1 + size2) {
+            size_t offset = 0;
+            if (pos > size1) {
+                offset = pos - size1;
+            }
+
+            const char *nl = memchr(buf2 + offset, '\n', size2 - offset);
+            if (nl) {
+                new_size = size1 + nl - buf2 + 1 - start;
+            }
+        }
+
+        if (!new_size && pos < total) {
+            size_t offset = 0;
+            if (pos > size1 + size2) {
+                offset = pos - size1 - size2;
+            }
+
+            const char *nl = memchr(buf3 + offset, '\n', size3 - offset);
+            if (nl) {
+                new_size = size1 + size2 + nl - buf3 + 1 - start;
+            } else {
+                new_size = total - start;
+            }
+        }
+
+        if (new_size <= BLOCK_EDIT_SIZE) {
+            // Fits
+            size = new_size;
+            pos = start + new_size;
+            if (pos < total) {
+                continue;
+            }
+        } else {
+            // Does not fit
+            if (!size) {
+                // One block containing one very long line
+                size = new_size;
+                pos = start + new_size;
+            }
+        }
+
+        BUG_ON(!size);
+        Block *new = block_new(size);
+        if (start < size1) {
+            size_t avail = size1 - start;
+            size_t count = MIN(size, avail);
+            new->nl += copy_count_nl(new->data, buf1 + start, count);
+            copied += count;
+            start += count;
+        }
+        if (start >= size1 && start < size1 + size2) {
+            size_t offset = start - size1;
+            size_t avail = size2 - offset;
+            size_t count = MIN(size - copied, avail);
+            new->nl += copy_count_nl(new->data + copied, buf2 + offset, count);
+            copied += count;
+            start += count;
+        }
+        if (start >= size1 + size2) {
+            size_t offset = start - size1 - size2;
+            size_t avail = size3 - offset;
+            size_t count = size - copied;
+            BUG_ON(count > avail);
+            new->nl += copy_count_nl(new->data + copied, buf3 + offset, count);
+            copied += count;
+            start += count;
+        }
+
+        new->size = size;
+        BUG_ON(copied != size);
+        list_add_before(&new->node, &blk->node);
+
+        nl_added += new->nl;
+        size = 0;
+    }
+
+    cursor->blk = BLOCK(prev_node->next);
+    while (cursor->offset > cursor->blk->size) {
+        cursor->offset -= cursor->blk->size;
+        cursor->blk = BLOCK(cursor->blk->node.next);
+    }
+
+    nl_added -= blk->nl;
+    block_free(blk);
+    return nl_added;
+}
+
+static size_t insert_bytes(BlockIter *cursor, const char *buf, size_t len)
+{
+    // Blocks must contain whole lines.
+    // Last char of buf might not be newline.
+    block_iter_normalize(cursor);
+
+    Block *blk = cursor->blk;
+    size_t new_size = blk->size + len;
+    if (new_size <= blk->alloc || new_size <= BLOCK_EDIT_SIZE) {
+        return insert_to_current(cursor, buf, len);
+    }
+
+    if (blk->nl <= 1 && !memchr(buf, '\n', len)) {
+        // Can't split this possibly very long line.
+        // insert_to_current() is much faster than split_and_insert().
+        return insert_to_current(cursor, buf, len);
+    }
+    return split_and_insert(cursor, buf, len);
+}
+
+void do_insert(View *view, const char *buf, size_t len)
+{
+    Buffer *buffer = view->buffer;
+    size_t nl = insert_bytes(&view->cursor, buf, len);
+    buffer->nl += nl;
+    sanity_check_blocks(view, true);
+
+    view_update_cursor_y(view);
+    buffer_mark_lines_changed(buffer, view->cy, nl ? LONG_MAX : view->cy);
+    if (buffer->syn) {
+        hl_insert(buffer, view->cy, nl);
+    }
+}
+
+static bool only_block(const Buffer *buffer, const Block *blk)
+{
+    return blk->node.prev == &buffer->blocks && blk->node.next == &buffer->blocks;
+}
+
+char *do_delete(View *view, size_t len, bool sanity_check_newlines)
+{
+    ListHead *saved_prev_node = NULL;
+    Block *blk = view->cursor.blk;
+    size_t offset = view->cursor.offset;
+    size_t pos = 0;
+    size_t deleted_nl = 0;
+
+    if (!len) {
+        return NULL;
+    }
+
+    if (!offset) {
+        // The block where cursor is can become empty and thereby may be deleted
+        saved_prev_node = blk->node.prev;
+    }
+
+    Buffer *buffer = view->buffer;
+    char *deleted = xmalloc(len);
+    while (pos < len) {
+        ListHead *next = blk->node.next;
+        size_t avail = blk->size - offset;
+        size_t count = MIN(len - pos, avail);
+        size_t nl = copy_count_nl(deleted + pos, blk->data + offset, count);
+        if (count < avail) {
+            memmove (
+                blk->data + offset,
+                blk->data + offset + count,
+                avail - count
+            );
+        }
+
+        deleted_nl += nl;
+        buffer->nl -= nl;
+        blk->nl -= nl;
+        blk->size -= count;
+        if (!blk->size && !only_block(buffer, blk)) {
+            block_free(blk);
+        }
+
+        offset = 0;
+        pos += count;
+        blk = BLOCK(next);
+
+        BUG_ON(pos < len && next == &buffer->blocks);
+    }
+
+    if (saved_prev_node) {
+        // Cursor was at beginning of a block that was possibly deleted
+        if (saved_prev_node->next == &buffer->blocks) {
+            view->cursor.blk = BLOCK(saved_prev_node);
+            view->cursor.offset = view->cursor.blk->size;
+        } else {
+            view->cursor.blk = BLOCK(saved_prev_node->next);
+        }
+    }
+
+    blk = view->cursor.blk;
+    if (
+        blk->size
+        && blk->data[blk->size - 1] != '\n'
+        && blk->node.next != &buffer->blocks
+    ) {
+        Block *next = BLOCK(blk->node.next);
+        size_t size = blk->size + next->size;
+
+        if (size > blk->alloc) {
+            blk->alloc = round_size_to_next_multiple(size, BLOCK_ALLOC_MULTIPLE);
+            xrenew(blk->data, blk->alloc);
+        }
+        memcpy(blk->data + blk->size, next->data, next->size);
+        blk->size = size;
+        blk->nl += next->nl;
+        block_free(next);
+    }
+
+    sanity_check_blocks(view, sanity_check_newlines);
+
+    view_update_cursor_y(view);
+    buffer_mark_lines_changed(buffer, view->cy, deleted_nl ? LONG_MAX : view->cy);
+    if (buffer->syn) {
+        hl_delete(buffer, view->cy, deleted_nl);
+    }
+    return deleted;
+}
+
+char *do_replace(View *view, size_t del, const char *buf, size_t ins)
+{
+    block_iter_normalize(&view->cursor);
+    Block *blk = view->cursor.blk;
+    size_t offset = view->cursor.offset;
+
+    size_t avail = blk->size - offset;
+    if (del >= avail) {
+        goto slow;
+    }
+
+    size_t new_size = blk->size + ins - del;
+    if (new_size > BLOCK_EDIT_SIZE) {
+        // Should split
+        if (blk->nl > 1 || memchr(buf, '\n', ins)) {
+            // Most likely can be split
+            goto slow;
+        }
+    }
+
+    if (new_size > blk->alloc) {
+        blk->alloc = round_size_to_next_multiple(new_size, BLOCK_ALLOC_MULTIPLE);
+        xrenew(blk->data, blk->alloc);
+    }
+
+    // Modification is limited to one block
+    Buffer *buffer = view->buffer;
+    char *ptr = blk->data + offset;
+    char *deleted = xmalloc(del);
+    size_t del_nl = copy_count_nl(deleted, ptr, del);
+    blk->nl -= del_nl;
+    buffer->nl -= del_nl;
+
+    if (del != ins) {
+        memmove(ptr + ins, ptr + del, avail - del);
+    }
+
+    size_t ins_nl = copy_count_nl(ptr, buf, ins);
+    blk->nl += ins_nl;
+    buffer->nl += ins_nl;
+    blk->size = new_size;
+    sanity_check_blocks(view, true);
+    view_update_cursor_y(view);
+
+    // If the number of inserted and removed bytes are the same, some
+    // line(s) changed but the lines after them didn't move up or down
+    long max = (del_nl == ins_nl) ? view->cy + del_nl : LONG_MAX;
+    buffer_mark_lines_changed(buffer, view->cy, max);
+
+    if (buffer->syn) {
+        hl_delete(buffer, view->cy, del_nl);
+        hl_insert(buffer, view->cy, ins_nl);
+    }
+
+    return deleted;
+
+slow:
+    // The "sanity_check_newlines" argument of do_delete() is false here
+    // because it may be removing a terminating newline that do_insert()
+    // is going to insert again at a different position:
+    deleted = do_delete(view, del, false);
+    do_insert(view, buf, ins);
+    return deleted;
+}