Rearrange code and cleanup

include/editor/folds.h

@@ -0,0 +1,150 @@
+#ifndef EDITOR_FOLDS_H
+#define EDITOR_FOLDS_H
+
+#include "editor/editor.h"
+
+inline std::vector<Fold>::iterator find_fold_iter(Editor *editor,
+                                                  uint32_t line) {
+  auto &folds = editor->folds;
+  auto it = std::lower_bound(
+      folds.begin(), folds.end(), line,
+      [](const Fold &fold, uint32_t value) { return fold.start < value; });
+  if (it != folds.end() && it->start == line)
+    return it;
+  if (it != folds.begin()) {
+    --it;
+    if (it->contains(line))
+      return it;
+  }
+  return folds.end();
+}
+
+inline bool add_fold(Editor *editor, uint32_t start, uint32_t end) {
+  if (!editor || !editor->root)
+    return false;
+  if (start > end)
+    std::swap(start, end);
+  if (start >= editor->root->line_count)
+    return false;
+  end = std::min(end, editor->root->line_count - 1);
+  if (start == end)
+    return false;
+  Fold new_fold{start, end};
+  auto &folds = editor->folds;
+  auto it = std::lower_bound(
+      folds.begin(), folds.end(), new_fold.start,
+      [](const Fold &fold, uint32_t value) { return fold.start < value; });
+  if (it != folds.begin()) {
+    auto prev = std::prev(it);
+    if (prev->end + 1 >= new_fold.start) {
+      new_fold.start = std::min(new_fold.start, prev->start);
+      new_fold.end = std::max(new_fold.end, prev->end);
+      it = folds.erase(prev);
+    }
+  }
+  while (it != folds.end() && it->start <= new_fold.end + 1) {
+    new_fold.end = std::max(new_fold.end, it->end);
+    it = folds.erase(it);
+  }
+  folds.insert(it, new_fold);
+  return true;
+}
+
+inline bool remove_fold(Editor *editor, uint32_t line) {
+  auto it = find_fold_iter(editor, line);
+  if (it == editor->folds.end())
+    return false;
+  editor->folds.erase(it);
+  return true;
+}
+
+inline void apply_line_insertion(Editor *editor, uint32_t line, uint32_t rows) {
+  for (auto it = editor->folds.begin(); it != editor->folds.end();) {
+    if (line <= it->start) {
+      it->start += rows;
+      it->end += rows;
+      ++it;
+    } else if (line <= it->end) {
+      it = editor->folds.erase(it);
+    } else {
+      ++it;
+    }
+  }
+}
+
+inline void apply_line_deletion(Editor *editor, uint32_t removal_start,
+                                uint32_t removal_end) {
+  if (removal_start > removal_end)
+    return;
+  uint32_t rows_removed = removal_end - removal_start + 1;
+  std::vector<Fold> updated;
+  updated.reserve(editor->folds.size());
+  for (auto fold : editor->folds) {
+    if (removal_end < fold.start) {
+      fold.start -= rows_removed;
+      fold.end -= rows_removed;
+      updated.push_back(fold);
+      continue;
+    }
+    if (removal_start > fold.end) {
+      updated.push_back(fold);
+      continue;
+    }
+  }
+  editor->folds.swap(updated);
+}
+
+inline const Fold *fold_for_line(const std::vector<Fold> &folds,
+                                 uint32_t line) {
+  auto it = std::lower_bound(
+      folds.begin(), folds.end(), line,
+      [](const Fold &fold, uint32_t value) { return fold.start < value; });
+  if (it != folds.end() && it->start == line)
+    return &(*it);
+  if (it != folds.begin()) {
+    --it;
+    if (it->contains(line))
+      return &(*it);
+  }
+  return nullptr;
+}
+
+inline Fold *fold_for_line(std::vector<Fold> &folds, uint32_t line) {
+  const auto *fold =
+      fold_for_line(static_cast<const std::vector<Fold> &>(folds), line);
+  return const_cast<Fold *>(fold);
+}
+
+inline bool line_is_fold_start(const std::vector<Fold> &folds, uint32_t line) {
+  const Fold *fold = fold_for_line(folds, line);
+  return fold && fold->start == line;
+}
+
+inline bool line_is_folded(const std::vector<Fold> &folds, uint32_t line) {
+  return fold_for_line(folds, line) != nullptr;
+}
+
+inline uint32_t next_unfolded_row(const Editor *editor, uint32_t row) {
+  uint32_t limit = editor && editor->root ? editor->root->line_count : 0;
+  while (row < limit) {
+    const Fold *fold = fold_for_line(editor->folds, row);
+    if (!fold)
+      return row;
+    row = fold->end + 1;
+  }
+  return limit;
+}
+
+inline uint32_t prev_unfolded_row(const Editor *editor, uint32_t row) {
+  while (row > 0) {
+    const Fold *fold = fold_for_line(editor->folds, row);
+    if (!fold)
+      return row;
+    if (fold->start == 0)
+      return 0;
+    row = fold->start - 1;
+  }
+  return 0;
+}
+
+#endif