1 files changed, 147 insertions, 0 deletions
diff --git a/examples/dte/shift.c b/examples/dte/shift.c
new file mode 100644
index 0000000..6276d3c
--- /dev/null
+++ b/examples/dte/shift.c
@@ -0,0 +1,147 @@
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+#include "shift.h"
+#include "block-iter.h"
+#include "buffer.h"
+#include "change.h"
+#include "indent.h"
+#include "move.h"
+#include "options.h"
+#include "selection.h"
+#include "util/debug.h"
+#include "util/macros.h"
+#include "util/xmalloc.h"
+
+static char *alloc_indent(const LocalOptions *options, size_t count, size_t *sizep)
+{
+    bool use_spaces = use_spaces_for_indent(options);
+    size_t size = use_spaces ? count * options->indent_width : count;
+    *sizep = size;
+    return memset(xmalloc(size), use_spaces ? ' ' : '\t', size);
+}
+
+static void shift_right(View *view, size_t nr_lines, size_t count)
+{
+    const LocalOptions *options = &view->buffer->options;
+    size_t indent_size;
+    char *indent = alloc_indent(options, count, &indent_size);
+
+    for (size_t i = 0; true; ) {
+        StringView line;
+        fetch_this_line(&view->cursor, &line);
+        IndentInfo info = get_indent_info(options, &line);
+        if (info.wsonly) {
+            if (info.bytes) {
+                // Remove indentation
+                buffer_delete_bytes(view, info.bytes);
+            }
+        } else if (info.sane) {
+            // Insert whitespace
+            buffer_insert_bytes(view, indent, indent_size);
+        } else {
+            // Replace whole indentation with sane one
+            size_t size;
+            char *buf = alloc_indent(options, info.level + count, &size);
+            buffer_replace_bytes(view, info.bytes, buf, size);
+            free(buf);
+        }
+        if (++i == nr_lines) {
+            break;
+        }
+        block_iter_eat_line(&view->cursor);
+    }
+
+    free(indent);
+}
+
+static void shift_left(View *view, size_t nr_lines, size_t count)
+{
+    const LocalOptions *options = &view->buffer->options;
+    const size_t indent_width = options->indent_width;
+    const bool space_indent = use_spaces_for_indent(options);
+
+    for (size_t i = 0; true; ) {
+        StringView line;
+        fetch_this_line(&view->cursor, &line);
+        IndentInfo info = get_indent_info(options, &line);
+        if (info.wsonly) {
+            if (info.bytes) {
+                // Remove indentation
+                buffer_delete_bytes(view, info.bytes);
+            }
+        } else if (info.level && info.sane) {
+            size_t n = MIN(count, info.level);
+            if (space_indent) {
+                n *= indent_width;
+            }
+            buffer_delete_bytes(view, n);
+        } else if (info.bytes) {
+            // Replace whole indentation with sane one
+            if (info.level > count) {
+                size_t size;
+                char *buf = alloc_indent(options, info.level - count, &size);
+                buffer_replace_bytes(view, info.bytes, buf, size);
+                free(buf);
+            } else {
+                buffer_delete_bytes(view, info.bytes);
+            }
+        }
+        if (++i == nr_lines) {
+            break;
+        }
+        block_iter_eat_line(&view->cursor);
+    }
+}
+
+static void do_shift_lines(View *view, int count, size_t nr_lines)
+{
+    begin_change_chain();
+    block_iter_bol(&view->cursor);
+    if (count > 0) {
+        shift_right(view, nr_lines, count);
+    } else {
+        shift_left(view, nr_lines, -count);
+    }
+    end_change_chain(view);
+}
+
+void shift_lines(View *view, int count)
+{
+    unsigned int width = view->buffer->options.indent_width;
+    BUG_ON(width > INDENT_WIDTH_MAX);
+    BUG_ON(count == 0);
+
+    long x = view_get_preferred_x(view) + (count * width);
+    x = MAX(x, 0);
+
+    if (view->selection == SELECT_NONE) {
+        do_shift_lines(view, count, 1);
+        goto out;
+    }
+
+    SelectionInfo info;
+    view->selection = SELECT_LINES;
+    init_selection(view, &info);
+    view->cursor = info.si;
+    size_t nr_lines = get_nr_selected_lines(&info);
+    do_shift_lines(view, count, nr_lines);
+    if (info.swapped) {
+        // Cursor should be at beginning of selection
+        block_iter_bol(&view->cursor);
+        view->sel_so = block_iter_get_offset(&view->cursor);
+        while (--nr_lines) {
+            block_iter_prev_line(&view->cursor);
+        }
+    } else {
+        BlockIter save = view->cursor;
+        while (--nr_lines) {
+            block_iter_prev_line(&view->cursor);
+        }
+        view->sel_so = block_iter_get_offset(&view->cursor);
+        view->cursor = save;
+    }
+
+out:
+    move_to_preferred_x(view, x);
+}