Merge branch 'main' into zs/web-ui-improvements

1 files changed, 0 insertions, 2183 deletions

diff --git a/thirdparty/ryml/src/c4/yml/tree.cpp b/thirdparty/ryml/src/c4/yml/tree.cpp
deleted file mode 100644
index b16ff8f5d..000000000
--- a/thirdparty/ryml/src/c4/yml/tree.cpp
+++ /dev/null
@@ -1,2183 +0,0 @@
-#include "c4/yml/tree.hpp"
-#include "c4/yml/detail/parser_dbg.hpp"
-#include "c4/yml/node.hpp"
-#include "c4/yml/detail/stack.hpp"
-
-
-C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wtype-limits")
-C4_SUPPRESS_WARNING_MSVC_WITH_PUSH(4296/*expression is always 'boolean_value'*/)
-
-namespace c4 {
-namespace yml {
-
-
-csubstr normalize_tag(csubstr tag)
-{
-    YamlTag_e t = to_tag(tag);
-    if(t != TAG_NONE)
-        return from_tag(t);
-    if(tag.begins_with("!<"))
-        tag = tag.sub(1);
-    if(tag.begins_with("<!"))
-        return tag;
-    return tag;
-}
-
-csubstr normalize_tag_long(csubstr tag)
-{
-    YamlTag_e t = to_tag(tag);
-    if(t != TAG_NONE)
-        return from_tag_long(t);
-    if(tag.begins_with("!<"))
-        tag = tag.sub(1);
-    if(tag.begins_with("<!"))
-        return tag;
-    return tag;
-}
-
-YamlTag_e to_tag(csubstr tag)
-{
-    if(tag.begins_with("!<"))
-        tag = tag.sub(1);
-    if(tag.begins_with("!!"))
-        tag = tag.sub(2);
-    else if(tag.begins_with('!'))
-        return TAG_NONE;
-    else if(tag.begins_with("tag:yaml.org,2002:"))
-    {
-        RYML_ASSERT(csubstr("tag:yaml.org,2002:").len == 18);
-        tag = tag.sub(18);
-    }
-    else if(tag.begins_with("<tag:yaml.org,2002:"))
-    {
-        RYML_ASSERT(csubstr("<tag:yaml.org,2002:").len == 19);
-        tag = tag.sub(19);
-        if(!tag.len)
-            return TAG_NONE;
-        tag = tag.offs(0, 1);
-    }
-
-    if(tag == "map")
-        return TAG_MAP;
-    else if(tag == "omap")
-        return TAG_OMAP;
-    else if(tag == "pairs")
-        return TAG_PAIRS;
-    else if(tag == "set")
-        return TAG_SET;
-    else if(tag == "seq")
-        return TAG_SEQ;
-    else if(tag == "binary")
-        return TAG_BINARY;
-    else if(tag == "bool")
-        return TAG_BOOL;
-    else if(tag == "float")
-        return TAG_FLOAT;
-    else if(tag == "int")
-        return TAG_INT;
-    else if(tag == "merge")
-        return TAG_MERGE;
-    else if(tag == "null")
-        return TAG_NULL;
-    else if(tag == "str")
-        return TAG_STR;
-    else if(tag == "timestamp")
-        return TAG_TIMESTAMP;
-    else if(tag == "value")
-        return TAG_VALUE;
-
-    return TAG_NONE;
-}
-
-csubstr from_tag_long(YamlTag_e tag)
-{
-    switch(tag)
-    {
-    case TAG_MAP:
-        return {"<tag:yaml.org,2002:map>"};
-    case TAG_OMAP:
-        return {"<tag:yaml.org,2002:omap>"};
-    case TAG_PAIRS:
-        return {"<tag:yaml.org,2002:pairs>"};
-    case TAG_SET:
-        return {"<tag:yaml.org,2002:set>"};
-    case TAG_SEQ:
-        return {"<tag:yaml.org,2002:seq>"};
-    case TAG_BINARY:
-        return {"<tag:yaml.org,2002:binary>"};
-    case TAG_BOOL:
-        return {"<tag:yaml.org,2002:bool>"};
-    case TAG_FLOAT:
-        return {"<tag:yaml.org,2002:float>"};
-    case TAG_INT:
-        return {"<tag:yaml.org,2002:int>"};
-    case TAG_MERGE:
-        return {"<tag:yaml.org,2002:merge>"};
-    case TAG_NULL:
-        return {"<tag:yaml.org,2002:null>"};
-    case TAG_STR:
-        return {"<tag:yaml.org,2002:str>"};
-    case TAG_TIMESTAMP:
-        return {"<tag:yaml.org,2002:timestamp>"};
-    case TAG_VALUE:
-        return {"<tag:yaml.org,2002:value>"};
-    case TAG_YAML:
-        return {"<tag:yaml.org,2002:yaml>"};
-    case TAG_NONE:
-        return {""};
-    }
-    return {""};
-}
-
-csubstr from_tag(YamlTag_e tag)
-{
-    switch(tag)
-    {
-    case TAG_MAP:
-        return {"!!map"};
-    case TAG_OMAP:
-        return {"!!omap"};
-    case TAG_PAIRS:
-        return {"!!pairs"};
-    case TAG_SET:
-        return {"!!set"};
-    case TAG_SEQ:
-        return {"!!seq"};
-    case TAG_BINARY:
-        return {"!!binary"};
-    case TAG_BOOL:
-        return {"!!bool"};
-    case TAG_FLOAT:
-        return {"!!float"};
-    case TAG_INT:
-        return {"!!int"};
-    case TAG_MERGE:
-        return {"!!merge"};
-    case TAG_NULL:
-        return {"!!null"};
-    case TAG_STR:
-        return {"!!str"};
-    case TAG_TIMESTAMP:
-        return {"!!timestamp"};
-    case TAG_VALUE:
-        return {"!!value"};
-    case TAG_YAML:
-        return {"!!yaml"};
-    case TAG_NONE:
-        return {""};
-    }
-    return {""};
-}
-
-
-//-----------------------------------------------------------------------------
-//-----------------------------------------------------------------------------
-//-----------------------------------------------------------------------------
-
-const char* NodeType::type_str(NodeType_e ty)
-{
-    switch(ty & _TYMASK)
-    {
-    case KEYVAL:
-        return "KEYVAL";
-    case KEY:
-        return "KEY";
-    case VAL:
-        return "VAL";
-    case MAP:
-        return "MAP";
-    case SEQ:
-        return "SEQ";
-    case KEYMAP:
-        return "KEYMAP";
-    case KEYSEQ:
-        return "KEYSEQ";
-    case DOCSEQ:
-        return "DOCSEQ";
-    case DOCMAP:
-        return "DOCMAP";
-    case DOCVAL:
-        return "DOCVAL";
-    case DOC:
-        return "DOC";
-    case STREAM:
-        return "STREAM";
-    case NOTYPE:
-        return "NOTYPE";
-    default:
-        if((ty & KEYVAL) == KEYVAL)
-            return "KEYVAL***";
-        if((ty & KEYMAP) == KEYMAP)
-            return "KEYMAP***";
-        if((ty & KEYSEQ) == KEYSEQ)
-            return "KEYSEQ***";
-        if((ty & DOCSEQ) == DOCSEQ)
-            return "DOCSEQ***";
-        if((ty & DOCMAP) == DOCMAP)
-            return "DOCMAP***";
-        if((ty & DOCVAL) == DOCVAL)
-            return "DOCVAL***";
-        if(ty & KEY)
-            return "KEY***";
-        if(ty & VAL)
-            return "VAL***";
-        if(ty & MAP)
-            return "MAP***";
-        if(ty & SEQ)
-            return "SEQ***";
-        if(ty & DOC)
-            return "DOC***";
-        return "(unk)";
-    }
-}
-
-
-//-----------------------------------------------------------------------------
-//-----------------------------------------------------------------------------
-//-----------------------------------------------------------------------------
-
-NodeRef Tree::rootref()
-{
-    return NodeRef(this, root_id());
-}
-ConstNodeRef Tree::rootref() const
-{
-    return ConstNodeRef(this, root_id());
-}
-
-ConstNodeRef Tree::crootref()
-{
-    return ConstNodeRef(this, root_id());
-}
-ConstNodeRef Tree::crootref() const
-{
-    return ConstNodeRef(this, root_id());
-}
-
-NodeRef Tree::ref(size_t id)
-{
-    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
-    return NodeRef(this, id);
-}
-ConstNodeRef Tree::ref(size_t id) const
-{
-    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
-    return ConstNodeRef(this, id);
-}
-
-ConstNodeRef Tree::cref(size_t id)
-{
-    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
-    return ConstNodeRef(this, id);
-}
-ConstNodeRef Tree::cref(size_t id) const
-{
-    _RYML_CB_ASSERT(m_callbacks, id != NONE && id >= 0 && id < m_size);
-    return ConstNodeRef(this, id);
-}
-
-NodeRef Tree::operator[] (csubstr key)
-{
-    return rootref()[key];
-}
-ConstNodeRef Tree::operator[] (csubstr key) const
-{
-    return rootref()[key];
-}
-
-NodeRef Tree::operator[] (size_t i)
-{
-    return rootref()[i];
-}
-ConstNodeRef Tree::operator[] (size_t i) const
-{
-    return rootref()[i];
-}
-
-NodeRef Tree::docref(size_t i)
-{
-    return ref(doc(i));
-}
-ConstNodeRef Tree::docref(size_t i) const
-{
-    return cref(doc(i));
-}
-
-
-//-----------------------------------------------------------------------------
-Tree::Tree(Callbacks const& cb)
-    : m_buf(nullptr)
-    , m_cap(0)
-    , m_size(0)
-    , m_free_head(NONE)
-    , m_free_tail(NONE)
-    , m_arena()
-    , m_arena_pos(0)
-    , m_callbacks(cb)
-{
-}
-
-Tree::Tree(size_t node_capacity, size_t arena_capacity, Callbacks const& cb)
-    : Tree(cb)
-{
-    reserve(node_capacity);
-    reserve_arena(arena_capacity);
-}
-
-Tree::~Tree()
-{
-    _free();
-}
-
-
-Tree::Tree(Tree const& that) noexcept : Tree(that.m_callbacks)
-{
-    _copy(that);
-}
-
-Tree& Tree::operator= (Tree const& that) noexcept
-{
-    _free();
-    m_callbacks = that.m_callbacks;
-    _copy(that);
-    return *this;
-}
-
-Tree::Tree(Tree && that) noexcept : Tree(that.m_callbacks)
-{
-    _move(that);
-}
-
-Tree& Tree::operator= (Tree && that) noexcept
-{
-    _free();
-    m_callbacks = that.m_callbacks;
-    _move(that);
-    return *this;
-}
-
-void Tree::_free()
-{
-    if(m_buf)
-    {
-        _RYML_CB_ASSERT(m_callbacks, m_cap > 0);
-        _RYML_CB_FREE(m_callbacks, m_buf, NodeData, m_cap);
-    }
-    if(m_arena.str)
-    {
-        _RYML_CB_ASSERT(m_callbacks, m_arena.len > 0);
-        _RYML_CB_FREE(m_callbacks, m_arena.str, char, m_arena.len);
-    }
-    _clear();
-}
-
-
-C4_SUPPRESS_WARNING_GCC_PUSH
-#if defined(__GNUC__) && __GNUC__>= 8
-    C4_SUPPRESS_WARNING_GCC_WITH_PUSH("-Wclass-memaccess") // error: ‘void* memset(void*, int, size_t)’ clearing an object of type ‘class c4::yml::Tree’ with no trivial copy-assignment; use assignment or value-initialization instead
-#endif
-
-void Tree::_clear()
-{
-    m_buf = nullptr;
-    m_cap = 0;
-    m_size = 0;
-    m_free_head = 0;
-    m_free_tail = 0;
-    m_arena = {};
-    m_arena_pos = 0;
-    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
-        m_tag_directives[i] = {};
-}
-
-void Tree::_copy(Tree const& that)
-{
-    _RYML_CB_ASSERT(m_callbacks, m_buf == nullptr);
-    _RYML_CB_ASSERT(m_callbacks, m_arena.str == nullptr);
-    _RYML_CB_ASSERT(m_callbacks, m_arena.len == 0);
-    m_buf = _RYML_CB_ALLOC_HINT(m_callbacks, NodeData, that.m_cap, that.m_buf);
-    memcpy(m_buf, that.m_buf, that.m_cap * sizeof(NodeData));
-    m_cap = that.m_cap;
-    m_size = that.m_size;
-    m_free_head = that.m_free_head;
-    m_free_tail = that.m_free_tail;
-    m_arena_pos = that.m_arena_pos;
-    m_arena = that.m_arena;
-    if(that.m_arena.str)
-    {
-        _RYML_CB_ASSERT(m_callbacks, that.m_arena.len > 0);
-        substr arena;
-        arena.str = _RYML_CB_ALLOC_HINT(m_callbacks, char, that.m_arena.len, that.m_arena.str);
-        arena.len = that.m_arena.len;
-        _relocate(arena); // does a memcpy of the arena and updates nodes using the old arena
-        m_arena = arena;
-    }
-    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
-        m_tag_directives[i] = that.m_tag_directives[i];
-}
-
-void Tree::_move(Tree & that)
-{
-    _RYML_CB_ASSERT(m_callbacks, m_buf == nullptr);
-    _RYML_CB_ASSERT(m_callbacks, m_arena.str == nullptr);
-    _RYML_CB_ASSERT(m_callbacks, m_arena.len == 0);
-    m_buf = that.m_buf;
-    m_cap = that.m_cap;
-    m_size = that.m_size;
-    m_free_head = that.m_free_head;
-    m_free_tail = that.m_free_tail;
-    m_arena = that.m_arena;
-    m_arena_pos = that.m_arena_pos;
-    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
-        m_tag_directives[i] = that.m_tag_directives[i];
-    that._clear();
-}
-
-void Tree::_relocate(substr next_arena)
-{
-    _RYML_CB_ASSERT(m_callbacks, next_arena.not_empty());
-    _RYML_CB_ASSERT(m_callbacks, next_arena.len >= m_arena.len);
-    memcpy(next_arena.str, m_arena.str, m_arena_pos);
-    for(NodeData *C4_RESTRICT n = m_buf, *e = m_buf + m_cap; n != e; ++n)
-    {
-        if(in_arena(n->m_key.scalar))
-            n->m_key.scalar = _relocated(n->m_key.scalar, next_arena);
-        if(in_arena(n->m_key.tag))
-            n->m_key.tag = _relocated(n->m_key.tag, next_arena);
-        if(in_arena(n->m_key.anchor))
-            n->m_key.anchor = _relocated(n->m_key.anchor, next_arena);
-        if(in_arena(n->m_val.scalar))
-            n->m_val.scalar = _relocated(n->m_val.scalar, next_arena);
-        if(in_arena(n->m_val.tag))
-            n->m_val.tag = _relocated(n->m_val.tag, next_arena);
-        if(in_arena(n->m_val.anchor))
-            n->m_val.anchor = _relocated(n->m_val.anchor, next_arena);
-    }
-    for(TagDirective &C4_RESTRICT td : m_tag_directives)
-    {
-        if(in_arena(td.prefix))
-            td.prefix = _relocated(td.prefix, next_arena);
-        if(in_arena(td.handle))
-            td.handle = _relocated(td.handle, next_arena);
-    }
-}
-
-
-//-----------------------------------------------------------------------------
-void Tree::reserve(size_t cap)
-{
-    if(cap > m_cap)
-    {
-        NodeData *buf = _RYML_CB_ALLOC_HINT(m_callbacks, NodeData, cap, m_buf);
-        if(m_buf)
-        {
-            memcpy(buf, m_buf, m_cap * sizeof(NodeData));
-            _RYML_CB_FREE(m_callbacks, m_buf, NodeData, m_cap);
-        }
-        size_t first = m_cap, del = cap - m_cap;
-        m_cap = cap;
-        m_buf = buf;
-        _clear_range(first, del);
-        if(m_free_head != NONE)
-        {
-            _RYML_CB_ASSERT(m_callbacks, m_buf != nullptr);
-            _RYML_CB_ASSERT(m_callbacks, m_free_tail != NONE);
-            m_buf[m_free_tail].m_next_sibling = first;
-            m_buf[first].m_prev_sibling = m_free_tail;
-            m_free_tail = cap-1;
-        }
-        else
-        {
-            _RYML_CB_ASSERT(m_callbacks, m_free_tail == NONE);
-            m_free_head = first;
-            m_free_tail = cap-1;
-        }
-        _RYML_CB_ASSERT(m_callbacks, m_free_head == NONE || (m_free_head >= 0 && m_free_head < cap));
-        _RYML_CB_ASSERT(m_callbacks, m_free_tail == NONE || (m_free_tail >= 0 && m_free_tail < cap));
-
-        if( ! m_size)
-            _claim_root();
-    }
-}
-
-
-//-----------------------------------------------------------------------------
-void Tree::clear()
-{
-    _clear_range(0, m_cap);
-    m_size = 0;
-    if(m_buf)
-    {
-        _RYML_CB_ASSERT(m_callbacks, m_cap >= 0);
-        m_free_head = 0;
-        m_free_tail = m_cap-1;
-        _claim_root();
-    }
-    else
-    {
-        m_free_head = NONE;
-        m_free_tail = NONE;
-    }
-    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
-        m_tag_directives[i] = {};
-}
-
-void Tree::_claim_root()
-{
-    size_t r = _claim();
-    _RYML_CB_ASSERT(m_callbacks, r == 0);
-    _set_hierarchy(r, NONE, NONE);
-}
-
-
-//-----------------------------------------------------------------------------
-void Tree::_clear_range(size_t first, size_t num)
-{
-    if(num == 0)
-        return; // prevent overflow when subtracting
-    _RYML_CB_ASSERT(m_callbacks, first >= 0 && first + num <= m_cap);
-    memset(m_buf + first, 0, num * sizeof(NodeData)); // TODO we should not need this
-    for(size_t i = first, e = first + num; i < e; ++i)
-    {
-        _clear(i);
-        NodeData *n = m_buf + i;
-        n->m_prev_sibling = i - 1;
-        n->m_next_sibling = i + 1;
-    }
-    m_buf[first + num - 1].m_next_sibling = NONE;
-}
-
-C4_SUPPRESS_WARNING_GCC_POP
-
-
-//-----------------------------------------------------------------------------
-void Tree::_release(size_t i)
-{
-    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);
-
-    _rem_hierarchy(i);
-    _free_list_add(i);
-    _clear(i);
-
-    --m_size;
-}
-
-//-----------------------------------------------------------------------------
-// add to the front of the free list
-void Tree::_free_list_add(size_t i)
-{
-    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);
-    NodeData &C4_RESTRICT w = m_buf[i];
-
-    w.m_parent = NONE;
-    w.m_next_sibling = m_free_head;
-    w.m_prev_sibling = NONE;
-    if(m_free_head != NONE)
-        m_buf[m_free_head].m_prev_sibling = i;
-    m_free_head = i;
-    if(m_free_tail == NONE)
-        m_free_tail = m_free_head;
-}
-
-void Tree::_free_list_rem(size_t i)
-{
-    if(m_free_head == i)
-        m_free_head = _p(i)->m_next_sibling;
-    _rem_hierarchy(i);
-}
-
-//-----------------------------------------------------------------------------
-size_t Tree::_claim()
-{
-    if(m_free_head == NONE || m_buf == nullptr)
-    {
-        size_t sz = 2 * m_cap;
-        sz = sz ? sz : 16;
-        reserve(sz);
-        _RYML_CB_ASSERT(m_callbacks, m_free_head != NONE);
-    }
-
-    _RYML_CB_ASSERT(m_callbacks, m_size < m_cap);
-    _RYML_CB_ASSERT(m_callbacks, m_free_head >= 0 && m_free_head < m_cap);
-
-    size_t ichild = m_free_head;
-    NodeData *child = m_buf + ichild;
-
-    ++m_size;
-    m_free_head = child->m_next_sibling;
-    if(m_free_head == NONE)
-    {
-        m_free_tail = NONE;
-        _RYML_CB_ASSERT(m_callbacks, m_size == m_cap);
-    }
-
-    _clear(ichild);
-
-    return ichild;
-}
-
-//-----------------------------------------------------------------------------
-
-C4_SUPPRESS_WARNING_GCC_PUSH
-C4_SUPPRESS_WARNING_CLANG_PUSH
-C4_SUPPRESS_WARNING_CLANG("-Wnull-dereference")
-#if defined(__GNUC__) && (__GNUC__ >= 6)
-C4_SUPPRESS_WARNING_GCC("-Wnull-dereference")
-#endif
-
-void Tree::_set_hierarchy(size_t ichild, size_t iparent, size_t iprev_sibling)
-{
-    _RYML_CB_ASSERT(m_callbacks, iparent == NONE || (iparent >= 0 && iparent < m_cap));
-    _RYML_CB_ASSERT(m_callbacks, iprev_sibling == NONE || (iprev_sibling >= 0 && iprev_sibling < m_cap));
-
-    NodeData *C4_RESTRICT child = get(ichild);
-
-    child->m_parent = iparent;
-    child->m_prev_sibling = NONE;
-    child->m_next_sibling = NONE;
-
-    if(iparent == NONE)
-    {
-        _RYML_CB_ASSERT(m_callbacks, ichild == 0);
-        _RYML_CB_ASSERT(m_callbacks, iprev_sibling == NONE);
-    }
-
-    if(iparent == NONE)
-        return;
-
-    size_t inext_sibling = iprev_sibling != NONE ? next_sibling(iprev_sibling) : first_child(iparent);
-    NodeData *C4_RESTRICT parent = get(iparent);
-    NodeData *C4_RESTRICT psib   = get(iprev_sibling);
-    NodeData *C4_RESTRICT nsib   = get(inext_sibling);
-
-    if(psib)
-    {
-        _RYML_CB_ASSERT(m_callbacks, next_sibling(iprev_sibling) == id(nsib));
-        child->m_prev_sibling = id(psib);
-        psib->m_next_sibling = id(child);
-        _RYML_CB_ASSERT(m_callbacks, psib->m_prev_sibling != psib->m_next_sibling || psib->m_prev_sibling == NONE);
-    }
-
-    if(nsib)
-    {
-        _RYML_CB_ASSERT(m_callbacks, prev_sibling(inext_sibling) == id(psib));
-        child->m_next_sibling = id(nsib);
-        nsib->m_prev_sibling = id(child);
-        _RYML_CB_ASSERT(m_callbacks, nsib->m_prev_sibling != nsib->m_next_sibling || nsib->m_prev_sibling == NONE);
-    }
-
-    if(parent->m_first_child == NONE)
-    {
-        _RYML_CB_ASSERT(m_callbacks, parent->m_last_child == NONE);
-        parent->m_first_child = id(child);
-        parent->m_last_child = id(child);
-    }
-    else
-    {
-        if(child->m_next_sibling == parent->m_first_child)
-            parent->m_first_child = id(child);
-
-        if(child->m_prev_sibling == parent->m_last_child)
-            parent->m_last_child = id(child);
-    }
-}
-
-C4_SUPPRESS_WARNING_GCC_POP
-C4_SUPPRESS_WARNING_CLANG_POP
-
-
-//-----------------------------------------------------------------------------
-void Tree::_rem_hierarchy(size_t i)
-{
-    _RYML_CB_ASSERT(m_callbacks, i >= 0 && i < m_cap);
-
-    NodeData &C4_RESTRICT w = m_buf[i];
-
-    // remove from the parent
-    if(w.m_parent != NONE)
-    {
-        NodeData &C4_RESTRICT p = m_buf[w.m_parent];
-        if(p.m_first_child == i)
-        {
-            p.m_first_child = w.m_next_sibling;
-        }
-        if(p.m_last_child == i)
-        {
-            p.m_last_child = w.m_prev_sibling;
-        }
-    }
-
-    // remove from the used list
-    if(w.m_prev_sibling != NONE)
-    {
-        NodeData *C4_RESTRICT prev = get(w.m_prev_sibling);
-        prev->m_next_sibling = w.m_next_sibling;
-    }
-    if(w.m_next_sibling != NONE)
-    {
-        NodeData *C4_RESTRICT next = get(w.m_next_sibling);
-        next->m_prev_sibling = w.m_prev_sibling;
-    }
-}
-
-//-----------------------------------------------------------------------------
-void Tree::reorder()
-{
-    size_t r = root_id();
-    _do_reorder(&r, 0);
-}
-
-//-----------------------------------------------------------------------------
-size_t Tree::_do_reorder(size_t *node, size_t count)
-{
-    // swap this node if it's not in place
-    if(*node != count)
-    {
-        _swap(*node, count);
-        *node = count;
-    }
-    ++count; // bump the count from this node
-
-    // now descend in the hierarchy
-    for(size_t i = first_child(*node); i != NONE; i = next_sibling(i))
-    {
-        // this child may have been relocated to a different index,
-        // so get an updated version
-        count = _do_reorder(&i, count);
-    }
-    return count;
-}
-
-//-----------------------------------------------------------------------------
-void Tree::_swap(size_t n_, size_t m_)
-{
-    _RYML_CB_ASSERT(m_callbacks, (parent(n_) != NONE) || type(n_) == NOTYPE);
-    _RYML_CB_ASSERT(m_callbacks, (parent(m_) != NONE) || type(m_) == NOTYPE);
-    NodeType tn = type(n_);
-    NodeType tm = type(m_);
-    if(tn != NOTYPE && tm != NOTYPE)
-    {
-        _swap_props(n_, m_);
-        _swap_hierarchy(n_, m_);
-    }
-    else if(tn == NOTYPE && tm != NOTYPE)
-    {
-        _copy_props(n_, m_);
-        _free_list_rem(n_);
-        _copy_hierarchy(n_, m_);
-        _clear(m_);
-        _free_list_add(m_);
-    }
-    else if(tn != NOTYPE && tm == NOTYPE)
-    {
-        _copy_props(m_, n_);
-        _free_list_rem(m_);
-        _copy_hierarchy(m_, n_);
-        _clear(n_);
-        _free_list_add(n_);
-    }
-    else
-    {
-        C4_NEVER_REACH();
-    }
-}
-
-//-----------------------------------------------------------------------------
-void Tree::_swap_hierarchy(size_t ia, size_t ib)
-{
-    if(ia == ib) return;
-
-    for(size_t i = first_child(ia); i != NONE; i = next_sibling(i))
-    {
-        if(i == ib || i == ia)
-            continue;
-        _p(i)->m_parent = ib;
-    }
-
-    for(size_t i = first_child(ib); i != NONE; i = next_sibling(i))
-    {
-        if(i == ib || i == ia)
-            continue;
-        _p(i)->m_parent = ia;
-    }
-
-    auto & C4_RESTRICT a  = *_p(ia);
-    auto & C4_RESTRICT b  = *_p(ib);
-    auto & C4_RESTRICT pa = *_p(a.m_parent);
-    auto & C4_RESTRICT pb = *_p(b.m_parent);
-
-    if(&pa == &pb)
-    {
-        if((pa.m_first_child == ib && pa.m_last_child == ia)
-            ||
-           (pa.m_first_child == ia && pa.m_last_child == ib))
-        {
-            std::swap(pa.m_first_child, pa.m_last_child);
-        }
-        else
-        {
-            bool changed = false;
-            if(pa.m_first_child == ia)
-            {
-                pa.m_first_child = ib;
-                changed = true;
-            }
-            if(pa.m_last_child  == ia)
-            {
-                pa.m_last_child = ib;
-                changed = true;
-            }
-            if(pb.m_first_child == ib && !changed)
-            {
-                pb.m_first_child = ia;
-            }
-            if(pb.m_last_child  == ib && !changed)
-            {
-                pb.m_last_child  = ia;
-            }
-        }
-    }
-    else
-    {
-        if(pa.m_first_child == ia)
-            pa.m_first_child = ib;
-        if(pa.m_last_child  == ia)
-            pa.m_last_child  = ib;
-        if(pb.m_first_child == ib)
-            pb.m_first_child = ia;
-        if(pb.m_last_child  == ib)
-            pb.m_last_child  = ia;
-    }
-    std::swap(a.m_first_child , b.m_first_child);
-    std::swap(a.m_last_child  , b.m_last_child);
-
-    if(a.m_prev_sibling != ib && b.m_prev_sibling != ia &&
-       a.m_next_sibling != ib && b.m_next_sibling != ia)
-    {
-        if(a.m_prev_sibling != NONE && a.m_prev_sibling != ib)
-            _p(a.m_prev_sibling)->m_next_sibling = ib;
-        if(a.m_next_sibling != NONE && a.m_next_sibling != ib)
-            _p(a.m_next_sibling)->m_prev_sibling = ib;
-        if(b.m_prev_sibling != NONE && b.m_prev_sibling != ia)
-            _p(b.m_prev_sibling)->m_next_sibling = ia;
-        if(b.m_next_sibling != NONE && b.m_next_sibling != ia)
-            _p(b.m_next_sibling)->m_prev_sibling = ia;
-        std::swap(a.m_prev_sibling, b.m_prev_sibling);
-        std::swap(a.m_next_sibling, b.m_next_sibling);
-    }
-    else
-    {
-        if(a.m_next_sibling == ib) // n will go after m
-        {
-            _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling == ia);
-            if(a.m_prev_sibling != NONE)
-            {
-                _RYML_CB_ASSERT(m_callbacks, a.m_prev_sibling != ib);
-                _p(a.m_prev_sibling)->m_next_sibling = ib;
-            }
-            if(b.m_next_sibling != NONE)
-            {
-                _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling != ia);
-                _p(b.m_next_sibling)->m_prev_sibling = ia;
-            }
-            size_t ns = b.m_next_sibling;
-            b.m_prev_sibling = a.m_prev_sibling;
-            b.m_next_sibling = ia;
-            a.m_prev_sibling = ib;
-            a.m_next_sibling = ns;
-        }
-        else if(a.m_prev_sibling == ib) // m will go after n
-        {
-            _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling == ia);
-            if(b.m_prev_sibling != NONE)
-            {
-                _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling != ia);
-                _p(b.m_prev_sibling)->m_next_sibling = ia;
-            }
-            if(a.m_next_sibling != NONE)
-            {
-                _RYML_CB_ASSERT(m_callbacks, a.m_next_sibling != ib);
-                _p(a.m_next_sibling)->m_prev_sibling = ib;
-            }
-            size_t ns = b.m_prev_sibling;
-            a.m_prev_sibling = b.m_prev_sibling;
-            a.m_next_sibling = ib;
-            b.m_prev_sibling = ia;
-            b.m_next_sibling = ns;
-        }
-        else
-        {
-            C4_NEVER_REACH();
-        }
-    }
-    _RYML_CB_ASSERT(m_callbacks, a.m_next_sibling != ia);
-    _RYML_CB_ASSERT(m_callbacks, a.m_prev_sibling != ia);
-    _RYML_CB_ASSERT(m_callbacks, b.m_next_sibling != ib);
-    _RYML_CB_ASSERT(m_callbacks, b.m_prev_sibling != ib);
-
-    if(a.m_parent != ib && b.m_parent != ia)
-    {
-        std::swap(a.m_parent, b.m_parent);
-    }
-    else
-    {
-        if(a.m_parent == ib && b.m_parent != ia)
-        {
-            a.m_parent = b.m_parent;
-            b.m_parent = ia;
-        }
-        else if(a.m_parent != ib && b.m_parent == ia)
-        {
-            b.m_parent = a.m_parent;
-            a.m_parent = ib;
-        }
-        else
-        {
-            C4_NEVER_REACH();
-        }
-    }
-}
-
-//-----------------------------------------------------------------------------
-void Tree::_copy_hierarchy(size_t dst_, size_t src_)
-{
-    auto const& C4_RESTRICT src = *_p(src_);
-    auto      & C4_RESTRICT dst = *_p(dst_);
-    auto      & C4_RESTRICT prt = *_p(src.m_parent);
-    for(size_t i = src.m_first_child; i != NONE; i = next_sibling(i))
-    {
-        _p(i)->m_parent = dst_;
-    }
-    if(src.m_prev_sibling != NONE)
-    {
-        _p(src.m_prev_sibling)->m_next_sibling = dst_;
-    }
-    if(src.m_next_sibling != NONE)
-    {
-        _p(src.m_next_sibling)->m_prev_sibling = dst_;
-    }
-    if(prt.m_first_child == src_)
-    {
-        prt.m_first_child = dst_;
-    }
-    if(prt.m_last_child  == src_)
-    {
-        prt.m_last_child  = dst_;
-    }
-    dst.m_parent       = src.m_parent;
-    dst.m_first_child  = src.m_first_child;
-    dst.m_last_child   = src.m_last_child;
-    dst.m_prev_sibling = src.m_prev_sibling;
-    dst.m_next_sibling = src.m_next_sibling;
-}
-
-//-----------------------------------------------------------------------------
-void Tree::_swap_props(size_t n_, size_t m_)
-{
-    NodeData &C4_RESTRICT n = *_p(n_);
-    NodeData &C4_RESTRICT m = *_p(m_);
-    std::swap(n.m_type, m.m_type);
-    std::swap(n.m_key, m.m_key);
-    std::swap(n.m_val, m.m_val);
-}
-
-//-----------------------------------------------------------------------------
-void Tree::move(size_t node, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, node != after);
-    _RYML_CB_ASSERT(m_callbacks,  ! is_root(node));
-    _RYML_CB_ASSERT(m_callbacks, (after == NONE) || (has_sibling(node, after) && has_sibling(after, node)));
-
-    _rem_hierarchy(node);
-    _set_hierarchy(node, parent(node), after);
-}
-
-//-----------------------------------------------------------------------------
-
-void Tree::move(size_t node, size_t new_parent, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, node != after);
-    _RYML_CB_ASSERT(m_callbacks, new_parent != NONE);
-    _RYML_CB_ASSERT(m_callbacks, new_parent != node);
-    _RYML_CB_ASSERT(m_callbacks, new_parent != after);
-    _RYML_CB_ASSERT(m_callbacks,  ! is_root(node));
-
-    _rem_hierarchy(node);
-    _set_hierarchy(node, new_parent, after);
-}
-
-size_t Tree::move(Tree *src, size_t node, size_t new_parent, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, new_parent != NONE);
-    _RYML_CB_ASSERT(m_callbacks, new_parent != after);
-
-    size_t dup = duplicate(src, node, new_parent, after);
-    src->remove(node);
-    return dup;
-}
-
-void Tree::set_root_as_stream()
-{
-    size_t root = root_id();
-    if(is_stream(root))
-        return;
-    // don't use _add_flags() because it's checked and will fail
-    if(!has_children(root))
-    {
-        if(is_val(root))
-        {
-            _p(root)->m_type.add(SEQ);
-            size_t next_doc = append_child(root);
-            _copy_props_wo_key(next_doc, root);
-            _p(next_doc)->m_type.add(DOC);
-            _p(next_doc)->m_type.rem(SEQ);
-        }
-        _p(root)->m_type = STREAM;
-        return;
-    }
-    _RYML_CB_ASSERT(m_callbacks, !has_key(root));
-    size_t next_doc = append_child(root);
-    _copy_props_wo_key(next_doc, root);
-    _add_flags(next_doc, DOC);
-    for(size_t prev = NONE, ch = first_child(root), next = next_sibling(ch); ch != NONE; )
-    {
-        if(ch == next_doc)
-            break;
-        move(ch, next_doc, prev);
-        prev = ch;
-        ch = next;
-        next = next_sibling(next);
-    }
-    _p(root)->m_type = STREAM;
-}
-
-
-//-----------------------------------------------------------------------------
-void Tree::remove_children(size_t node)
-{
-    _RYML_CB_ASSERT(m_callbacks, get(node) != nullptr);
-    size_t ich = get(node)->m_first_child;
-    while(ich != NONE)
-    {
-        remove_children(ich);
-        _RYML_CB_ASSERT(m_callbacks, get(ich) != nullptr);
-        size_t next = get(ich)->m_next_sibling;
-        _release(ich);
-        if(ich == get(node)->m_last_child)
-            break;
-        ich = next;
-    }
-}
-
-bool Tree::change_type(size_t node, NodeType type)
-{
-    _RYML_CB_ASSERT(m_callbacks, type.is_val() || type.is_map() || type.is_seq());
-    _RYML_CB_ASSERT(m_callbacks, type.is_val() + type.is_map() + type.is_seq() == 1);
-    _RYML_CB_ASSERT(m_callbacks, type.has_key() == has_key(node) || (has_key(node) && !type.has_key()));
-    NodeData *d = _p(node);
-    if(type.is_map() && is_map(node))
-        return false;
-    else if(type.is_seq() && is_seq(node))
-        return false;
-    else if(type.is_val() && is_val(node))
-        return false;
-    d->m_type = (d->m_type & (~(MAP|SEQ|VAL))) | type;
-    remove_children(node);
-    return true;
-}
-
-
-//-----------------------------------------------------------------------------
-size_t Tree::duplicate(size_t node, size_t parent, size_t after)
-{
-    return duplicate(this, node, parent, after);
-}
-
-size_t Tree::duplicate(Tree const* src, size_t node, size_t parent, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
-    _RYML_CB_ASSERT(m_callbacks,  ! src->is_root(node));
-
-    size_t copy = _claim();
-
-    _copy_props(copy, src, node);
-    _set_hierarchy(copy, parent, after);
-    duplicate_children(src, node, copy, NONE);
-
-    return copy;
-}
-
-//-----------------------------------------------------------------------------
-size_t Tree::duplicate_children(size_t node, size_t parent, size_t after)
-{
-    return duplicate_children(this, node, parent, after);
-}
-
-size_t Tree::duplicate_children(Tree const* src, size_t node, size_t parent, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
-    _RYML_CB_ASSERT(m_callbacks, after == NONE || has_child(parent, after));
-
-    size_t prev = after;
-    for(size_t i = src->first_child(node); i != NONE; i = src->next_sibling(i))
-    {
-        prev = duplicate(src, i, parent, prev);
-    }
-
-    return prev;
-}
-
-//-----------------------------------------------------------------------------
-void Tree::duplicate_contents(size_t node, size_t where)
-{
-    duplicate_contents(this, node, where);
-}
-
-void Tree::duplicate_contents(Tree const *src, size_t node, size_t where)
-{
-    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, where != NONE);
-    _copy_props_wo_key(where, src, node);
-    duplicate_children(src, node, where, last_child(where));
-}
-
-//-----------------------------------------------------------------------------
-size_t Tree::duplicate_children_no_rep(size_t node, size_t parent, size_t after)
-{
-    return duplicate_children_no_rep(this, node, parent, after);
-}
-
-size_t Tree::duplicate_children_no_rep(Tree const *src, size_t node, size_t parent, size_t after)
-{
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, parent != NONE);
-    _RYML_CB_ASSERT(m_callbacks, after == NONE || has_child(parent, after));
-
-    // don't loop using pointers as there may be a relocation
-
-    // find the position where "after" is
-    size_t after_pos = NONE;
-    if(after != NONE)
-    {
-        for(size_t i = first_child(parent), icount = 0; i != NONE; ++icount, i = next_sibling(i))
-        {
-            if(i == after)
-            {
-                after_pos = icount;
-                break;
-            }
-        }
-        _RYML_CB_ASSERT(m_callbacks, after_pos != NONE);
-    }
-
-    // for each child to be duplicated...
-    size_t prev = after;
-    for(size_t i = src->first_child(node), icount = 0; i != NONE; ++icount, i = src->next_sibling(i))
-    {
-        if(is_seq(parent))
-        {
-            prev = duplicate(i, parent, prev);
-        }
-        else
-        {
-            _RYML_CB_ASSERT(m_callbacks, is_map(parent));
-            // does the parent already have a node with key equal to that of the current duplicate?
-            size_t rep = NONE, rep_pos = NONE;
-            for(size_t j = first_child(parent), jcount = 0; j != NONE; ++jcount, j = next_sibling(j))
-            {
-                if(key(j) == key(i))
-                {
-                    rep = j;
-                    rep_pos = jcount;
-                    break;
-                }
-            }
-            if(rep == NONE) // there is no repetition; just duplicate
-            {
-                prev = duplicate(src, i, parent, prev);
-            }
-            else  // yes, there is a repetition
-            {
-                if(after_pos != NONE && rep_pos < after_pos)
-                {
-                    // rep is located before the node which will be inserted,
-                    // and will be overridden by the duplicate. So replace it.
-                    remove(rep);
-                    prev = duplicate(src, i, parent, prev);
-                }
-                else if(prev == NONE)
-                {
-                    // first iteration with prev = after = NONE and repetition
-                    prev = rep;
-                }
-                else if(rep != prev)
-                {
-                    // rep is located after the node which will be inserted
-                    // and overrides it. So move the rep into this node's place.
-                    move(rep, prev);
-                    prev = rep;
-                }
-            } // there's a repetition
-        }
-    }
-
-    return prev;
-}
-
-
-//-----------------------------------------------------------------------------
-
-void Tree::merge_with(Tree const *src, size_t src_node, size_t dst_node)
-{
-    _RYML_CB_ASSERT(m_callbacks, src != nullptr);
-    if(src_node == NONE)
-        src_node = src->root_id();
-    if(dst_node == NONE)
-        dst_node = root_id();
-    _RYML_CB_ASSERT(m_callbacks, src->has_val(src_node) || src->is_seq(src_node) || src->is_map(src_node));
-
-    if(src->has_val(src_node))
-    {
-        if( ! has_val(dst_node))
-        {
-            if(has_children(dst_node))
-                remove_children(dst_node);
-        }
-        if(src->is_keyval(src_node))
-            _copy_props(dst_node, src, src_node);
-        else if(src->is_val(src_node))
-            _copy_props_wo_key(dst_node, src, src_node);
-        else
-            C4_NEVER_REACH();
-    }
-    else if(src->is_seq(src_node))
-    {
-        if( ! is_seq(dst_node))
-        {
-            if(has_children(dst_node))
-                remove_children(dst_node);
-            _clear_type(dst_node);
-            if(src->has_key(src_node))
-                to_seq(dst_node, src->key(src_node));
-            else
-                to_seq(dst_node);
-        }
-        for(size_t sch = src->first_child(src_node); sch != NONE; sch = src->next_sibling(sch))
-        {
-            size_t dch = append_child(dst_node);
-            _copy_props_wo_key(dch, src, sch);
-            merge_with(src, sch, dch);
-        }
-    }
-    else if(src->is_map(src_node))
-    {
-        if( ! is_map(dst_node))
-        {
-            if(has_children(dst_node))
-                remove_children(dst_node);
-            _clear_type(dst_node);
-            if(src->has_key(src_node))
-                to_map(dst_node, src->key(src_node));
-            else
-                to_map(dst_node);
-        }
-        for(size_t sch = src->first_child(src_node); sch != NONE; sch = src->next_sibling(sch))
-        {
-            size_t dch = find_child(dst_node, src->key(sch));
-            if(dch == NONE)
-            {
-                dch = append_child(dst_node);
-                _copy_props(dch, src, sch);
-            }
-            merge_with(src, sch, dch);
-        }
-    }
-    else
-    {
-        C4_NEVER_REACH();
-    }
-}
-
-
-//-----------------------------------------------------------------------------
-
-namespace detail {
-/** @todo make this part of the public API, refactoring as appropriate
- * to be able to use the same resolver to handle multiple trees (one
- * at a time) */
-struct ReferenceResolver
-{
-    struct refdata
-    {
-        NodeType type;
-        size_t node;
-        size_t prev_anchor;
-        size_t target;
-        size_t parent_ref;
-        size_t parent_ref_sibling;
-    };
-
-    Tree *t;
-    /** from the specs: "an alias node refers to the most recent
-     * node in the serialization having the specified anchor". So
-     * we need to start looking upward from ref nodes.
-     *
-     * @see http://yaml.org/spec/1.2/spec.html#id2765878 */
-    stack<refdata> refs;
-
-    ReferenceResolver(Tree *t_) : t(t_), refs(t_->callbacks())
-    {
-        resolve();
-    }
-
-    void store_anchors_and_refs()
-    {
-        // minimize (re-)allocations by counting first
-        size_t num_anchors_and_refs = count_anchors_and_refs(t->root_id());
-        if(!num_anchors_and_refs)
-            return;
-        refs.reserve(num_anchors_and_refs);
-
-        // now descend through the hierarchy
-        _store_anchors_and_refs(t->root_id());
-
-        // finally connect the reference list
-        size_t prev_anchor = npos;
-        size_t count = 0;
-        for(auto &rd : refs)
-        {
-            rd.prev_anchor = prev_anchor;
-            if(rd.type.is_anchor())
-                prev_anchor = count;
-            ++count;
-        }
-    }
-
-    size_t count_anchors_and_refs(size_t n)
-    {
-        size_t c = 0;
-        c += t->has_key_anchor(n);
-        c += t->has_val_anchor(n);
-        c += t->is_key_ref(n);
-        c += t->is_val_ref(n);
-        for(size_t ch = t->first_child(n); ch != NONE; ch = t->next_sibling(ch))
-            c += count_anchors_and_refs(ch);
-        return c;
-    }
-
-    void _store_anchors_and_refs(size_t n)
-    {
-        if(t->is_key_ref(n) || t->is_val_ref(n) || (t->has_key(n) && t->key(n) == "<<"))
-        {
-            if(t->is_seq(n))
-            {
-                // for merging multiple inheritance targets
-                //   <<: [ *CENTER, *BIG ]
-                for(size_t ich = t->first_child(n); ich != NONE; ich = t->next_sibling(ich))
-                {
-                    RYML_ASSERT(t->num_children(ich) == 0);
-                    refs.push({VALREF, ich, npos, npos, n, t->next_sibling(n)});
-                }
-                return;
-            }
-            if(t->is_key_ref(n) && t->key(n) != "<<") // insert key refs BEFORE inserting val refs
-            {
-                RYML_CHECK((!t->has_key(n)) || t->key(n).ends_with(t->key_ref(n)));
-                refs.push({KEYREF, n, npos, npos, NONE, NONE});
-            }
-            if(t->is_val_ref(n))
-            {
-                RYML_CHECK((!t->has_val(n)) || t->val(n).ends_with(t->val_ref(n)));
-                refs.push({VALREF, n, npos, npos, NONE, NONE});
-            }
-        }
-        if(t->has_key_anchor(n))
-        {
-            RYML_CHECK(t->has_key(n));
-            refs.push({KEYANCH, n, npos, npos, NONE, NONE});
-        }
-        if(t->has_val_anchor(n))
-        {
-            RYML_CHECK(t->has_val(n) || t->is_container(n));
-            refs.push({VALANCH, n, npos, npos, NONE, NONE});
-        }
-        for(size_t ch = t->first_child(n); ch != NONE; ch = t->next_sibling(ch))
-        {
-            _store_anchors_and_refs(ch);
-        }
-    }
-
-    size_t lookup_(refdata *C4_RESTRICT ra)
-    {
-        RYML_ASSERT(ra->type.is_key_ref() || ra->type.is_val_ref());
-        RYML_ASSERT(ra->type.is_key_ref() != ra->type.is_val_ref());
-        csubstr refname;
-        if(ra->type.is_val_ref())
-        {
-            refname = t->val_ref(ra->node);
-        }
-        else
-        {
-            RYML_ASSERT(ra->type.is_key_ref());
-            refname = t->key_ref(ra->node);
-        }
-        while(ra->prev_anchor != npos)
-        {
-            ra = &refs[ra->prev_anchor];
-            if(t->has_anchor(ra->node, refname))
-                return ra->node;
-        }
-
-        #ifndef RYML_ERRMSG_SIZE
-          #define RYML_ERRMSG_SIZE 1024
-        #endif
-
-        char errmsg[RYML_ERRMSG_SIZE];
-        snprintf(errmsg, RYML_ERRMSG_SIZE, "anchor does not exist: '%.*s'",
-                 static_cast<int>(refname.size()), refname.data());
-        c4::yml::error(errmsg);
-        return NONE;
-    }
-
-    void resolve()
-    {
-        store_anchors_and_refs();
-        if(refs.empty())
-            return;
-
-        /* from the specs: "an alias node refers to the most recent
-         * node in the serialization having the specified anchor". So
-         * we need to start looking upward from ref nodes.
-         *
-         * @see http://yaml.org/spec/1.2/spec.html#id2765878 */
-        for(size_t i = 0, e = refs.size(); i < e; ++i)
-        {
-            auto &C4_RESTRICT rd = refs.top(i);
-            if( ! rd.type.is_ref())
-                continue;
-            rd.target = lookup_(&rd);
-        }
-    }
-
-}; // ReferenceResolver
-} // namespace detail
-
-void Tree::resolve()
-{
-    if(m_size == 0)
-        return;
-
-    detail::ReferenceResolver rr(this);
-
-    // insert the resolved references
-    size_t prev_parent_ref = NONE;
-    size_t prev_parent_ref_after = NONE;
-    for(auto const& C4_RESTRICT rd : rr.refs)
-    {
-        if( ! rd.type.is_ref())
-            continue;
-        if(rd.parent_ref != NONE)
-        {
-            _RYML_CB_ASSERT(m_callbacks, is_seq(rd.parent_ref));
-            size_t after, p = parent(rd.parent_ref);
-            if(prev_parent_ref != rd.parent_ref)
-            {
-                after = rd.parent_ref;//prev_sibling(rd.parent_ref_sibling);
-                prev_parent_ref_after = after;
-            }
-            else
-            {
-                after = prev_parent_ref_after;
-            }
-            prev_parent_ref = rd.parent_ref;
-            prev_parent_ref_after = duplicate_children_no_rep(rd.target, p, after);
-            remove(rd.node);
-        }
-        else
-        {
-            if(has_key(rd.node) && is_key_ref(rd.node) && key(rd.node) == "<<")
-            {
-                _RYML_CB_ASSERT(m_callbacks, is_keyval(rd.node));
-                size_t p = parent(rd.node);
-                size_t after = prev_sibling(rd.node);
-                duplicate_children_no_rep(rd.target, p, after);
-                remove(rd.node);
-            }
-            else if(rd.type.is_key_ref())
-            {
-                _RYML_CB_ASSERT(m_callbacks, is_key_ref(rd.node));
-                _RYML_CB_ASSERT(m_callbacks, has_key_anchor(rd.target) || has_val_anchor(rd.target));
-                if(has_val_anchor(rd.target) && val_anchor(rd.target) == key_ref(rd.node))
-                {
-                    _RYML_CB_CHECK(m_callbacks, !is_container(rd.target));
-                    _RYML_CB_CHECK(m_callbacks, has_val(rd.target));
-                    _p(rd.node)->m_key.scalar = val(rd.target);
-                    _add_flags(rd.node, KEY);
-                }
-                else
-                {
-                    _RYML_CB_CHECK(m_callbacks, key_anchor(rd.target) == key_ref(rd.node));
-                    _p(rd.node)->m_key.scalar = key(rd.target);
-                    _add_flags(rd.node, VAL);
-                }
-            }
-            else
-            {
-                _RYML_CB_ASSERT(m_callbacks, rd.type.is_val_ref());
-                if(has_key_anchor(rd.target) && key_anchor(rd.target) == val_ref(rd.node))
-                {
-                    _RYML_CB_CHECK(m_callbacks, !is_container(rd.target));
-                    _RYML_CB_CHECK(m_callbacks, has_val(rd.target));
-                    _p(rd.node)->m_val.scalar = key(rd.target);
-                    _add_flags(rd.node, VAL);
-                }
-                else
-                {
-                    duplicate_contents(rd.target, rd.node);
-                }
-            }
-        }
-    }
-
-    // clear anchors and refs
-    for(auto const& C4_RESTRICT ar : rr.refs)
-    {
-        rem_anchor_ref(ar.node);
-        if(ar.parent_ref != NONE)
-            if(type(ar.parent_ref) != NOTYPE)
-                remove(ar.parent_ref);
-    }
-
-}
-
-//-----------------------------------------------------------------------------
-
-size_t Tree::num_children(size_t node) const
-{
-    size_t count = 0;
-    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
-        ++count;
-    return count;
-}
-
-size_t Tree::child(size_t node, size_t pos) const
-{
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    size_t count = 0;
-    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
-    {
-        if(count++ == pos)
-            return i;
-    }
-    return NONE;
-}
-
-size_t Tree::child_pos(size_t node, size_t ch) const
-{
-    size_t count = 0;
-    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
-    {
-        if(i == ch)
-            return count;
-        ++count;
-    }
-    return npos;
-}
-
-#if defined(__clang__)
-#   pragma clang diagnostic push
-#   pragma GCC diagnostic ignored "-Wnull-dereference"
-#elif defined(__GNUC__)
-#   pragma GCC diagnostic push
-#   if __GNUC__ >= 6
-#       pragma GCC diagnostic ignored "-Wnull-dereference"
-#   endif
-#endif
-
-size_t Tree::find_child(size_t node, csubstr const& name) const
-{
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    _RYML_CB_ASSERT(m_callbacks, is_map(node));
-    if(get(node)->m_first_child == NONE)
-    {
-        _RYML_CB_ASSERT(m_callbacks, _p(node)->m_last_child == NONE);
-        return NONE;
-    }
-    else
-    {
-        _RYML_CB_ASSERT(m_callbacks, _p(node)->m_last_child != NONE);
-    }
-    for(size_t i = first_child(node); i != NONE; i = next_sibling(i))
-    {
-        if(_p(i)->m_key.scalar == name)
-        {
-            return i;
-        }
-    }
-    return NONE;
-}
-
-#if defined(__clang__)
-#   pragma clang diagnostic pop
-#elif defined(__GNUC__)
-#   pragma GCC diagnostic pop
-#endif
-
-
-//-----------------------------------------------------------------------------
-
-void Tree::to_val(size_t node, csubstr val, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || ! parent_is_map(node));
-    _set_flags(node, VAL|more_flags);
-    _p(node)->m_key.clear();
-    _p(node)->m_val = val;
-}
-
-void Tree::to_keyval(size_t node, csubstr key, csubstr val, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
-    _set_flags(node, KEYVAL|more_flags);
-    _p(node)->m_key = key;
-    _p(node)->m_val = val;
-}
-
-void Tree::to_map(size_t node, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || ! parent_is_map(node)); // parent must not have children with keys
-    _set_flags(node, MAP|more_flags);
-    _p(node)->m_key.clear();
-    _p(node)->m_val.clear();
-}
-
-void Tree::to_map(size_t node, csubstr key, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
-    _set_flags(node, KEY|MAP|more_flags);
-    _p(node)->m_key = key;
-    _p(node)->m_val.clear();
-}
-
-void Tree::to_seq(size_t node, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_seq(node));
-    _set_flags(node, SEQ|more_flags);
-    _p(node)->m_key.clear();
-    _p(node)->m_val.clear();
-}
-
-void Tree::to_seq(size_t node, csubstr key, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _RYML_CB_ASSERT(m_callbacks, parent(node) == NONE || parent_is_map(node));
-    _set_flags(node, KEY|SEQ|more_flags);
-    _p(node)->m_key = key;
-    _p(node)->m_val.clear();
-}
-
-void Tree::to_doc(size_t node, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _set_flags(node, DOC|more_flags);
-    _p(node)->m_key.clear();
-    _p(node)->m_val.clear();
-}
-
-void Tree::to_stream(size_t node, type_bits more_flags)
-{
-    _RYML_CB_ASSERT(m_callbacks,  ! has_children(node));
-    _set_flags(node, STREAM|more_flags);
-    _p(node)->m_key.clear();
-    _p(node)->m_val.clear();
-}
-
-
-//-----------------------------------------------------------------------------
-size_t Tree::num_tag_directives() const
-{
-    // this assumes we have a very small number of tag directives
-    for(size_t i = 0; i < RYML_MAX_TAG_DIRECTIVES; ++i)
-        if(m_tag_directives[i].handle.empty())
-            return i;
-    return RYML_MAX_TAG_DIRECTIVES;
-}
-
-void Tree::clear_tag_directives()
-{
-    for(TagDirective &td : m_tag_directives)
-        td = {};
-}
-
-size_t Tree::add_tag_directive(TagDirective const& td)
-{
-    _RYML_CB_CHECK(m_callbacks, !td.handle.empty());
-    _RYML_CB_CHECK(m_callbacks, !td.prefix.empty());
-    _RYML_CB_ASSERT(m_callbacks, td.handle.begins_with('!'));
-    _RYML_CB_ASSERT(m_callbacks, td.handle.ends_with('!'));
-    // https://yaml.org/spec/1.2.2/#rule-ns-word-char
-    _RYML_CB_ASSERT(m_callbacks, td.handle == '!' || td.handle == "!!" || td.handle.trim('!').first_not_of("01234567890abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-") == npos);
-    size_t pos = num_tag_directives();
-    _RYML_CB_CHECK(m_callbacks, pos < RYML_MAX_TAG_DIRECTIVES);
-    m_tag_directives[pos] = td;
-    return pos;
-}
-
-size_t Tree::resolve_tag(substr output, csubstr tag, size_t node_id) const
-{
-    // lookup from the end. We want to find the first directive that
-    // matches the tag and has a target node id leq than the given
-    // node_id.
-    for(size_t i = RYML_MAX_TAG_DIRECTIVES-1; i != (size_t)-1; --i)
-    {
-        auto const& td = m_tag_directives[i];
-        if(td.handle.empty())
-            continue;
-        if(tag.begins_with(td.handle) && td.next_node_id <= node_id)
-        {
-            _RYML_CB_ASSERT(m_callbacks, tag.len >= td.handle.len);
-            csubstr rest = tag.sub(td.handle.len);
-            size_t len = 1u + td.prefix.len + rest.len + 1u;
-            size_t numpc = rest.count('%');
-            if(numpc == 0)
-            {
-                if(len <= output.len)
-                {
-                    output.str[0] = '<';
-                    memcpy(1u + output.str, td.prefix.str, td.prefix.len);
-                    memcpy(1u + output.str + td.prefix.len, rest.str, rest.len);
-                    output.str[1u + td.prefix.len + rest.len] = '>';
-                }
-            }
-            else
-            {
-                // need to decode URI % sequences
-                size_t pos = rest.find('%');
-                _RYML_CB_ASSERT(m_callbacks, pos != npos);
-                do {
-                    size_t next = rest.first_not_of("0123456789abcdefABCDEF", pos+1);
-                    if(next == npos)
-                        next = rest.len;
-                    _RYML_CB_CHECK(m_callbacks, pos+1 < next);
-                    _RYML_CB_CHECK(m_callbacks, pos+1 + 2 <= next);
-                    size_t delta = next - (pos+1);
-                    len -= delta;
-                    pos = rest.find('%', pos+1);
-                } while(pos != npos);
-                if(len <= output.len)
-                {
-                    size_t prev = 0, wpos = 0;
-                    auto appendstr = [&](csubstr s) { memcpy(output.str + wpos, s.str, s.len); wpos += s.len; };
-                    auto appendchar = [&](char c) { output.str[wpos++] = c; };
-                    appendchar('<');
-                    appendstr(td.prefix);
-                    pos = rest.find('%');
-                    _RYML_CB_ASSERT(m_callbacks, pos != npos);
-                    do {
-                        size_t next = rest.first_not_of("0123456789abcdefABCDEF", pos+1);
-                        if(next == npos)
-                            next = rest.len;
-                        _RYML_CB_CHECK(m_callbacks, pos+1 < next);
-                        _RYML_CB_CHECK(m_callbacks, pos+1 + 2 <= next);
-                        uint8_t val;
-                        if(C4_UNLIKELY(!read_hex(rest.range(pos+1, next), &val) || val > 127))
-                            _RYML_CB_ERR(m_callbacks, "invalid URI character");
-                        appendstr(rest.range(prev, pos));
-                        appendchar((char)val);
-                        prev = next;
-                        pos = rest.find('%', pos+1);
-                    } while(pos != npos);
-                    _RYML_CB_ASSERT(m_callbacks, pos == npos);
-                    _RYML_CB_ASSERT(m_callbacks, prev > 0);
-                    _RYML_CB_ASSERT(m_callbacks, rest.len >= prev);
-                    appendstr(rest.sub(prev));
-                    appendchar('>');
-                    _RYML_CB_ASSERT(m_callbacks, wpos == len);
-                }
-            }
-            return len;
-        }
-    }
-    return 0; // return 0 to signal that the tag is local and cannot be resolved
-}
-
-namespace {
-csubstr _transform_tag(Tree *t, csubstr tag, size_t node)
-{
-    size_t required_size = t->resolve_tag(substr{}, tag, node);
-    if(!required_size)
-        return tag;
-    const char *prev_arena = t->arena().str;
-    substr buf = t->alloc_arena(required_size);
-    _RYML_CB_ASSERT(t->m_callbacks, t->arena().str == prev_arena);
-    size_t actual_size = t->resolve_tag(buf, tag, node);
-    _RYML_CB_ASSERT(t->m_callbacks, actual_size <= required_size);
-    return buf.first(actual_size);
-}
-void _resolve_tags(Tree *t, size_t node)
-{
-    for(size_t child = t->first_child(node); child != NONE; child = t->next_sibling(child))
-    {
-        if(t->has_key(child) && t->has_key_tag(child))
-            t->set_key_tag(child, _transform_tag(t, t->key_tag(child), child));
-        if(t->has_val(child) && t->has_val_tag(child))
-            t->set_val_tag(child, _transform_tag(t, t->val_tag(child), child));
-        _resolve_tags(t, child);
-    }
-}
-size_t _count_resolved_tags_size(Tree const* t, size_t node)
-{
-    size_t sz = 0;
-    for(size_t child = t->first_child(node); child != NONE; child = t->next_sibling(child))
-    {
-        if(t->has_key(child) && t->has_key_tag(child))
-            sz += t->resolve_tag(substr{}, t->key_tag(child), child);
-        if(t->has_val(child) && t->has_val_tag(child))
-            sz += t->resolve_tag(substr{}, t->val_tag(child), child);
-        sz += _count_resolved_tags_size(t, child);
-    }
-    return sz;
-}
-} // namespace
-
-void Tree::resolve_tags()
-{
-    if(empty())
-        return;
-    if(num_tag_directives() == 0)
-        return;
-    size_t needed_size = _count_resolved_tags_size(this, root_id());
-    if(needed_size)
-        reserve_arena(arena_size() + needed_size);
-    _resolve_tags(this, root_id());
-}
-
-
-//-----------------------------------------------------------------------------
-
-csubstr Tree::lookup_result::resolved() const
-{
-    csubstr p = path.first(path_pos);
-    if(p.ends_with('.'))
-        p = p.first(p.len-1);
-    return p;
-}
-
-csubstr Tree::lookup_result::unresolved() const
-{
-    return path.sub(path_pos);
-}
-
-void Tree::_advance(lookup_result *r, size_t more) const
-{
-    r->path_pos += more;
-    if(r->path.sub(r->path_pos).begins_with('.'))
-        ++r->path_pos;
-}
-
-Tree::lookup_result Tree::lookup_path(csubstr path, size_t start) const
-{
-    if(start == NONE)
-        start = root_id();
-    lookup_result r(path, start);
-    if(path.empty())
-        return r;
-    _lookup_path(&r);
-    if(r.target == NONE && r.closest == start)
-        r.closest = NONE;
-    return r;
-}
-
-size_t Tree::lookup_path_or_modify(csubstr default_value, csubstr path, size_t start)
-{
-    size_t target = _lookup_path_or_create(path, start);
-    if(parent_is_map(target))
-        to_keyval(target, key(target), default_value);
-    else
-        to_val(target, default_value);
-    return target;
-}
-
-size_t Tree::lookup_path_or_modify(Tree const *src, size_t src_node, csubstr path, size_t start)
-{
-    size_t target = _lookup_path_or_create(path, start);
-    merge_with(src, src_node, target);
-    return target;
-}
-
-size_t Tree::_lookup_path_or_create(csubstr path, size_t start)
-{
-    if(start == NONE)
-        start = root_id();
-    lookup_result r(path, start);
-    _lookup_path(&r);
-    if(r.target != NONE)
-    {
-        C4_ASSERT(r.unresolved().empty());
-        return r.target;
-    }
-    _lookup_path_modify(&r);
-    return r.target;
-}
-
-void Tree::_lookup_path(lookup_result *r) const
-{
-    C4_ASSERT( ! r->unresolved().empty());
-    _lookup_path_token parent{"", type(r->closest)};
-    size_t node;
-    do
-    {
-        node = _next_node(r, &parent);
-        if(node != NONE)
-            r->closest = node;
-        if(r->unresolved().empty())
-        {
-            r->target = node;
-            return;
-        }
-    } while(node != NONE);
-}
-
-void Tree::_lookup_path_modify(lookup_result *r)
-{
-    C4_ASSERT( ! r->unresolved().empty());
-    _lookup_path_token parent{"", type(r->closest)};
-    size_t node;
-    do
-    {
-        node = _next_node_modify(r, &parent);
-        if(node != NONE)
-            r->closest = node;
-        if(r->unresolved().empty())
-        {
-            r->target = node;
-            return;
-        }
-    } while(node != NONE);
-}
-
-size_t Tree::_next_node(lookup_result * r, _lookup_path_token *parent) const
-{
-    _lookup_path_token token = _next_token(r, *parent);
-    if( ! token)
-        return NONE;
-
-    size_t node = NONE;
-    csubstr prev = token.value;
-    if(token.type == MAP || token.type == SEQ)
-    {
-        _RYML_CB_ASSERT(m_callbacks, !token.value.begins_with('['));
-        //_RYML_CB_ASSERT(m_callbacks, is_container(r->closest) || r->closest == NONE);
-        _RYML_CB_ASSERT(m_callbacks, is_map(r->closest));
-        node = find_child(r->closest, token.value);
-    }
-    else if(token.type == KEYVAL)
-    {
-        _RYML_CB_ASSERT(m_callbacks, r->unresolved().empty());
-        if(is_map(r->closest))
-            node = find_child(r->closest, token.value);
-    }
-    else if(token.type == KEY)
-    {
-        _RYML_CB_ASSERT(m_callbacks, token.value.begins_with('[') && token.value.ends_with(']'));
-        token.value = token.value.offs(1, 1).trim(' ');
-        size_t idx = 0;
-        _RYML_CB_CHECK(m_callbacks, from_chars(token.value, &idx));
-        node = child(r->closest, idx);
-    }
-    else
-    {
-        C4_NEVER_REACH();
-    }
-
-    if(node != NONE)
-    {
-        *parent = token;
-    }
-    else
-    {
-        csubstr p = r->path.sub(r->path_pos > 0 ? r->path_pos - 1 : r->path_pos);
-        r->path_pos -= prev.len;
-        if(p.begins_with('.'))
-            r->path_pos -= 1u;
-    }
-
-    return node;
-}
-
-size_t Tree::_next_node_modify(lookup_result * r, _lookup_path_token *parent)
-{
-    _lookup_path_token token = _next_token(r, *parent);
-    if( ! token)
-        return NONE;
-
-    size_t node = NONE;
-    if(token.type == MAP || token.type == SEQ)
-    {
-        _RYML_CB_ASSERT(m_callbacks, !token.value.begins_with('['));
-        //_RYML_CB_ASSERT(m_callbacks, is_container(r->closest) || r->closest == NONE);
-        if( ! is_container(r->closest))
-        {
-            if(has_key(r->closest))
-                to_map(r->closest, key(r->closest));
-            else
-                to_map(r->closest);
-        }
-        else
-        {
-            if(is_map(r->closest))
-                node = find_child(r->closest, token.value);
-            else
-            {
-                size_t pos = NONE;
-                _RYML_CB_CHECK(m_callbacks, c4::atox(token.value, &pos));
-                _RYML_CB_ASSERT(m_callbacks, pos != NONE);
-                node = child(r->closest, pos);
-            }
-        }
-        if(node == NONE)
-        {
-            _RYML_CB_ASSERT(m_callbacks, is_map(r->closest));
-            node = append_child(r->closest);
-            NodeData *n = _p(node);
-            n->m_key.scalar = token.value;
-            n->m_type.add(KEY);
-        }
-    }
-    else if(token.type == KEYVAL)
-    {
-        _RYML_CB_ASSERT(m_callbacks, r->unresolved().empty());
-        if(is_map(r->closest))
-        {
-            node = find_child(r->closest, token.value);
-            if(node == NONE)
-                node = append_child(r->closest);
-        }
-        else
-        {
-            _RYML_CB_ASSERT(m_callbacks, !is_seq(r->closest));
-            _add_flags(r->closest, MAP);
-            node = append_child(r->closest);
-        }
-        NodeData *n = _p(node);
-        n->m_key.scalar = token.value;
-        n->m_val.scalar = "";
-        n->m_type.add(KEYVAL);
-    }
-    else if(token.type == KEY)
-    {
-        _RYML_CB_ASSERT(m_callbacks, token.value.begins_with('[') && token.value.ends_with(']'));
-        token.value = token.value.offs(1, 1).trim(' ');
-        size_t idx;
-        if( ! from_chars(token.value, &idx))
-             return NONE;
-        if( ! is_container(r->closest))
-        {
-            if(has_key(r->closest))
-            {
-                csubstr k = key(r->closest);
-                _clear_type(r->closest);
-                to_seq(r->closest, k);
-            }
-            else
-            {
-                _clear_type(r->closest);
-                to_seq(r->closest);
-            }
-        }
-        _RYML_CB_ASSERT(m_callbacks, is_container(r->closest));
-        node = child(r->closest, idx);
-        if(node == NONE)
-        {
-            _RYML_CB_ASSERT(m_callbacks, num_children(r->closest) <= idx);
-            for(size_t i = num_children(r->closest); i <= idx; ++i)
-            {
-                node = append_child(r->closest);
-                if(i < idx)
-                {
-                    if(is_map(r->closest))
-                        to_keyval(node, /*"~"*/{}, /*"~"*/{});
-                    else if(is_seq(r->closest))
-                        to_val(node, /*"~"*/{});
-                }
-            }
-        }
-    }
-    else
-    {
-        C4_NEVER_REACH();
-    }
-
-    _RYML_CB_ASSERT(m_callbacks, node != NONE);
-    *parent = token;
-    return node;
-}
-
-/** types of tokens:
- * - seeing "map."  ---> "map"/MAP
- * - finishing "scalar" ---> "scalar"/KEYVAL
- * - seeing "seq[n]" ---> "seq"/SEQ (--> "[n]"/KEY)
- * - seeing "[n]" ---> "[n]"/KEY
- */
-Tree::_lookup_path_token Tree::_next_token(lookup_result *r, _lookup_path_token const& parent) const
-{
-    csubstr unres = r->unresolved();
-    if(unres.empty())
-        return {};
-
-    // is it an indexation like [0], [1], etc?
-    if(unres.begins_with('['))
-    {
-        size_t pos = unres.find(']');
-        if(pos == csubstr::npos)
-            return {};
-        csubstr idx = unres.first(pos + 1);
-        _advance(r, pos + 1);
-        return {idx, KEY};
-    }
-
-    // no. so it must be a name
-    size_t pos = unres.first_of(".[");
-    if(pos == csubstr::npos)
-    {
-        _advance(r, unres.len);
-        NodeType t;
-        if(( ! parent) || parent.type.is_seq())
-            return {unres, VAL};
-        return {unres, KEYVAL};
-    }
-
-    // it's either a map or a seq
-    _RYML_CB_ASSERT(m_callbacks, unres[pos] == '.' || unres[pos] == '[');
-    if(unres[pos] == '.')
-    {
-        _RYML_CB_ASSERT(m_callbacks, pos != 0);
-        _advance(r, pos + 1);
-        return {unres.first(pos), MAP};
-    }
-
-    _RYML_CB_ASSERT(m_callbacks, unres[pos] == '[');
-    _advance(r, pos);
-    return {unres.first(pos), SEQ};
-}
-
-
-} // namespace ryml
-} // namespace c4
-
-
-C4_SUPPRESS_WARNING_GCC_POP
-C4_SUPPRESS_WARNING_MSVC_POP