Add history support, and fix parsing system.

src/internal/syntax/parser_state.cc

@@ -0,0 +1,195 @@
+#include "internal/syntax/parser.h"
+
+namespace bed::internal::syntax {
+void ParseState::retain(ParseState *n) {
+  if (n)
+    n->refs++;
+};
+
+void ParseState::release(Language &lang, ParseState *n) {
+  if (!n || --n->refs > 0)
+    return;
+  if (n->is_branch()) {
+    auto *branch = (ParseStateBranch *)n;
+    release(lang, branch->left);
+    release(lang, branch->right);
+    delete branch;
+  } else {
+    auto *leaf = (ParseStateLeaf *)n;
+    if (leaf->state)
+      lang.destroy(leaf->state);
+    if (leaf->blocks)
+      free(leaf->blocks);
+    delete leaf;
+  }
+}
+
+int height(ParseState *n) {
+  return n ? n->height : 0;
+}
+
+int balance_factor(ParseState *n) {
+  ParseStateBranch *b = (ParseStateBranch *)n;
+  return height(b->left) - height(b->right);
+}
+
+ParseState *rotate_right(Language &lang, ParseStateBranch *z) {
+  ParseStateBranch *y = (ParseStateBranch *)z->left;
+  ParseState *middle = new ParseStateBranch(y->right, z->right);
+  ParseState *out = new ParseStateBranch(y->left, middle);
+  ParseState::release(lang, middle);
+  ParseState::release(lang, z);
+  return out;
+}
+
+ParseState *rotate_left(Language &lang, ParseStateBranch *z) {
+  ParseStateBranch *y = (ParseStateBranch *)z->right;
+  ParseState *middle = new ParseStateBranch(z->left, y->left);
+  ParseState *out = new ParseStateBranch(middle, y->right);
+  ParseState::release(lang, middle);
+  ParseState::release(lang, z);
+  return out;
+}
+
+ParseState *balance(Language &lang, ParseState *node) {
+  if (!node || !node->is_branch())
+    return node;
+  ParseStateBranch *b = (ParseStateBranch *)node;
+  int bf = balance_factor(node);
+  if (bf > 1) {
+    ParseStateBranch *left = (ParseStateBranch *)b->left;
+    if (balance_factor(left) < 0) {
+      ParseState::retain(left);
+      auto new_left = rotate_left(lang, left);
+      auto rebuilt = new ParseStateBranch(new_left, b->right);
+      auto result = rotate_right(lang, (ParseStateBranch *)rebuilt);
+      ParseState::release(lang, new_left);
+      ParseState::release(lang, b);
+      return result;
+    }
+    return rotate_right(lang, b);
+  }
+  if (bf < -1) {
+    ParseStateBranch *right = (ParseStateBranch *)b->right;
+    if (balance_factor(right) > 0) {
+      ParseState::retain(right);
+      auto new_right = rotate_right(lang, right);
+      auto rebuilt = new ParseStateBranch(b->left, new_right);
+      auto result = rotate_left(lang, (ParseStateBranch *)rebuilt);
+      ParseState::release(lang, new_right);
+      ParseState::release(lang, b);
+      return result;
+    }
+    return rotate_left(lang, b);
+  }
+  return node;
+}
+
+ParseState *ParseState::build(Language &lang, ParseState **pieces, uint64_t lo, uint64_t hi) {
+  if (hi - lo == 1)
+    return pieces[lo];
+  uint64_t mid = lo + (hi - lo) / 2;
+  ParseState *left = build(lang, pieces, lo, mid);
+  ParseState *right = build(lang, pieces, mid, hi);
+  ParseState *node = concat(lang, left, right);
+  release(lang, left);
+  release(lang, right);
+  return node;
+}
+
+ParseState *ParseState::splice(
+  Language &lang, ParseState *root, vase::Shard *vase,
+  uint64_t line, uint64_t original, uint64_t final
+) {
+  if (!vase)
+    return nullptr;
+  if (!root || (line == 0 && root->lines() == original)) {
+    vase::Iterator it(vase, 0, Direction::Forward);
+    void *state = lang.none_state();
+    std::vector<Token> tokens;
+    std::vector<ParseEvent> events;
+    ParsePieceBuilder builder(lang, 0);
+    for (uint64_t at = 0; at < final; ++at) {
+      it.next();
+      tokens.clear();
+      events.clear();
+      lang.parse(&state, it.line, at == 0, &tokens, &events);
+      builder.add(state, at, events);
+    }
+    lang.destroy(state);
+    return builder.finish();
+  }
+  uint64_t at;
+  void *state;
+  ParseState *prefix;
+  {
+    uint64_t offset;
+    TreeCursor c = TreeCursor(lang, root, line, &offset);
+    prefix = c.prefix();
+    at = line - offset;
+    state = lang.copy(c.leaf->state);
+  }
+  vase::Iterator it(vase, at, Direction::Forward);
+  std::vector<Token> tokens;
+  std::vector<ParseEvent> events;
+  uint64_t end_in_tree = line + original;
+  uint64_t end_extra;
+  TreeCursor c = TreeCursor(lang, root, end_in_tree, &end_extra);
+  uint64_t end_in_vase = line + final;
+  ParsePieceBuilder builder(lang, at);
+  while (at < end_in_vase + end_extra) {
+    it.next();
+    tokens.clear();
+    events.clear();
+    lang.parse(&state, it.line, at == 0, &tokens, &events);
+    builder.add(state, at, events);
+    ++at;
+  }
+  c.next();
+  while (c.leaf) {
+    if (lang.equal(state, c.leaf->state))
+      break;
+    for (uint64_t i = 0; i < c.leaf->lines(); ++i) {
+      it.next();
+      tokens.clear();
+      events.clear();
+      lang.parse(&state, it.line, at == 0, &tokens, &events);
+      builder.add(state, at, events);
+      ++at;
+    }
+    c.next();
+  }
+  lang.destroy(state);
+  ParseState *suffix = c.suffix();
+  ParseState *new_stuff = builder.finish();
+  auto a = concat(lang, prefix, new_stuff);
+  release(lang, prefix);
+  release(lang, new_stuff);
+  auto result = concat(lang, a, suffix);
+  release(lang, a);
+  release(lang, suffix);
+  return result;
+}
+
+ParseState *ParseState::concat(Language &lang, ParseState *a, ParseState *b) {
+  if (!a)
+    return (retain(b), b);
+  if (!b)
+    return (retain(a), a);
+  if (a->height > b->height + 1) {
+    ParseStateBranch *ba = (ParseStateBranch *)a;
+    ParseState *r = concat(lang, ba->right, b);
+    ParseState *out = balance(lang, new ParseStateBranch(ba->left, r));
+    release(lang, r);
+    return out;
+  }
+  if (b->height > a->height + 1) {
+    ParseStateBranch *bb = (ParseStateBranch *)b;
+    ParseState *l = concat(lang, a, bb->left);
+    ParseState *out = balance(lang, new ParseStateBranch(l, bb->right));
+    release(lang, l);
+    return out;
+  }
+  return balance(lang, new ParseStateBranch(a, b));
+}
+} // namespace bed::internal::syntax