mirror of
https://github.com/RetroDECK/Supermodel.git
synced 2024-11-22 22:05:38 +00:00
345 lines
11 KiB
C++
345 lines
11 KiB
C++
/*
|
|
* Config Tree
|
|
* ===========
|
|
*
|
|
* Accessing Hierarchical Nodes
|
|
* ----------------------------
|
|
*
|
|
* A hierarchical data structure supporting arbitrary nesting. Each node
|
|
* (Config::Node) has a key and either a value or children (in fact, it may
|
|
* have both, but this rarely makes semantic sense and so the config tree
|
|
* builders take care not to allow it).
|
|
*
|
|
* Nesting is denoted with the '/' separator. For example:
|
|
*
|
|
* 1. node.ValueAs<int>()
|
|
* 2. node["foo"]
|
|
* 3. node["foo"].ValueAs<int>()
|
|
* 4. node["foo/bar"]
|
|
*
|
|
* [1] accesses the value of the node (more on this below). [2] accesses the
|
|
* a child node with key "foo". [3] accesses the value of the child node "foo".
|
|
* [4] accesses child "bar" of child "foo", and so forth.
|
|
*
|
|
* Similar to map semantics, the operator [] never fails. If the node does not
|
|
* exist, it creates a dummy "missing" node that is retained as a hidden child.
|
|
* This node will have an empty value, which cannot be accessed, except using
|
|
* the ValueAsDefault<> method. This scheme exists to simplify lookup code for
|
|
* keys known at compile time, the logic being that any "missing" key should
|
|
* could just as well have been there in the first place, thus making the added
|
|
* memory usage negligible. For example, it easily allows values with defaults
|
|
* to be expressed as:
|
|
*
|
|
* config["foo/bar"].ValueAsDefault<std::string>("default_value")
|
|
*
|
|
* If the lookups are not known at compile time (e.g., are driven by the
|
|
* program user or external data), it is safer to use Get() and TryGet(), which
|
|
* can throw and return nullptr, respectively, and avoid wasting memory with
|
|
* dummy nodes.
|
|
*
|
|
* Nodes at the same nesting level (siblings) are strung together in a
|
|
* linked list. Parents also maintain pointers to the first and last of their
|
|
* children (for order-preserving iteration) as well as a map for direct
|
|
* lookup by key.
|
|
*
|
|
* Keys may be reused at a given level. Key-value pairs will have their order
|
|
* preserved when iterated but only the most recent key is returned in direct
|
|
* map lookups.
|
|
*
|
|
* Example:
|
|
*
|
|
* <game name="scud">
|
|
* <roms>
|
|
* <crom name="foo.bin" offset=0/>
|
|
* <crom name="bar.bin" offset=2/>
|
|
* </roms>
|
|
*
|
|
* 1. config["game/roms"].ValueAs<std::string>()
|
|
* 2. config["game/roms/crom/offset"].ValueAs<int>()
|
|
* 3. config["game/roms"].begin()
|
|
*
|
|
* [1] will either throw an exception or return an empty string (depending on
|
|
* how the XML was translated to a config tree), [2] will return 2 (the second
|
|
* "crom" tag), and [3] can be used to iterate over both "crom" tags in order.
|
|
*
|
|
* Values
|
|
* ------
|
|
*
|
|
* To check whether or not a value is defined, use the Exists() and Empty()
|
|
* methods.
|
|
*
|
|
* Values are stored in a special container and can be virtually anything.
|
|
* However, it is recommended that only PODs and std::string be used. Arrays
|
|
* and pointers will probably not behave as expected and should be avoided.
|
|
* Trees build from files have all values loaded as std::strings. The types can
|
|
* be changed by subsequent re-assignments or by manually building a tree.
|
|
*
|
|
* To access a value of a given known type, T, use:
|
|
*
|
|
* node.Value<T>()
|
|
*
|
|
* Conversions as supported but are implemented via serialization and de-
|
|
* serialization using sstream. Most "sane" conversions will work as expected.
|
|
* When a conversion to T is desired, or if the stored value type is not
|
|
* precisely known, use:
|
|
*
|
|
* node.ValueAs<T>()
|
|
*
|
|
* These functions will throw an exception if the value is not defined at all
|
|
* or if the node does not exist (i.e., a "missing" node from a failed lookup).
|
|
* An alternative that is guaranteed to succeed is:
|
|
*
|
|
* node.ValueAsDefault<T>(default_value)
|
|
*
|
|
* If the value or node does not exist, default_value is returned, otherwise
|
|
* the stored value is returned with conversion (if needed) to type T.
|
|
*
|
|
* INI Semantics
|
|
* -------------
|
|
*
|
|
* INI files are linear in nature and divided into sections. Config trees built
|
|
* to represent INI files must adhere to the following rules:
|
|
*
|
|
* - Section nodes have their key set to the section name and value empty.
|
|
* They are the only nodes that can have children (i.e., IsLeaf() == false,
|
|
* HasChildren() == true).
|
|
* - Top-level node in the tree is the global section, and its key is
|
|
* "Global".
|
|
* - Only the global section (top-level section) may have child nodes that are
|
|
* sections. The config tree can therefore only be up to 2 levels deep: the
|
|
* first, top-most level consists of global parameters, and section nodes
|
|
* provide one more level of nesting.
|
|
*
|
|
* INI files contain zero or more sections followed by zero or more settings
|
|
* each.
|
|
*
|
|
* Setting0 = 100
|
|
* [ Global ]
|
|
* Setting1 = 200
|
|
* [ Section1 ]
|
|
* SettingA = 1 ; this is a comment
|
|
* SettingB = foo
|
|
* [ Section2 ]
|
|
* SettingX = bar
|
|
* SettingZ = "baz" ; quotes are optional and are stripped off during parsing
|
|
*
|
|
* Any setting not explicitly part of a section is assigned to the "Global"
|
|
* section. For example, Setting0 and Setting1 above are both part of "Global".
|
|
*
|
|
* Multiple sections can be specified like so:
|
|
*
|
|
* [ Section1, Section2, Section3 ]
|
|
* SettingX = foo
|
|
* [ Section4, , Section5 ]
|
|
* SettingX = bar
|
|
*
|
|
* In this example, SettingX will be set to "foo" in Section1, Section2, and
|
|
* Section3. It will be set to "bar" in Section4, Section5, and the "Global"
|
|
* section because of the unnamed element.
|
|
*
|
|
* TODO
|
|
* ----
|
|
* - TryGet() can be made quicker by attempting a direct lookup first. We never
|
|
* add keys with '/' in them (they are split up into nested nodes). Most
|
|
* lookups are likely to be leaf level, so a direct lookup should be possible
|
|
* first and, if it fails, the key can be retried as a nested path.
|
|
* - Define our own exceptions?
|
|
*/
|
|
|
|
#include "Util/NewConfig.h"
|
|
|
|
namespace Util
|
|
{
|
|
namespace Config
|
|
{
|
|
void Node::CheckEmptyOrMissing() const
|
|
{
|
|
if (m_missing)
|
|
throw std::range_error(Util::Format() << "Node \"" << m_key << "\" does not exist");
|
|
if (Empty())
|
|
throw std::logic_error(Util::Format() << "Node \"" << m_key << "\" has no value" );
|
|
}
|
|
|
|
const Node &Node::MissingNode(const std::string &key) const
|
|
{
|
|
auto it = m_missing_nodes.find(key);
|
|
if (it == m_missing_nodes.end())
|
|
{
|
|
auto result = m_missing_nodes.emplace(key, key);
|
|
result.first->second.m_missing = true; // mark this node as missing
|
|
return result.first->second;
|
|
}
|
|
return it->second;
|
|
}
|
|
|
|
const Node &Node::operator[](const std::string &path) const
|
|
{
|
|
const Node *e = this;
|
|
std::vector<std::string> keys = Util::Format(path).Split('/');
|
|
for (auto &key: keys)
|
|
{
|
|
auto it = e->m_children.find(key);
|
|
if (it == e->m_children.end())
|
|
return e->MissingNode(key);
|
|
e = it->second.get();
|
|
}
|
|
return *e;
|
|
}
|
|
|
|
Node &Node::Get(const std::string &path)
|
|
{
|
|
Node *node = TryGet(path);
|
|
if (!node)
|
|
throw std::range_error(Util::Format() << "Node \"" << path << "\" does not exist");
|
|
return *node;
|
|
}
|
|
|
|
const Node &Node::Get(const std::string &path) const
|
|
{
|
|
const Node *node = TryGet(path);
|
|
if (!node)
|
|
throw std::range_error(Util::Format() << "Node \"" << path << "\" does not exist");
|
|
return *node;
|
|
}
|
|
|
|
Node *Node::TryGet(const std::string &path)
|
|
{
|
|
Node *e = this;
|
|
std::vector<std::string> keys = Util::Format(path).Split('/');
|
|
for (auto &key: keys)
|
|
{
|
|
auto it = e->m_children.find(key);
|
|
if (it == e->m_children.end())
|
|
return nullptr;
|
|
e = it->second.get();
|
|
}
|
|
return e;
|
|
}
|
|
|
|
const Node *Node::TryGet(const std::string &path) const
|
|
{
|
|
const Node *e = this;
|
|
std::vector<std::string> keys = Util::Format(path).Split('/');
|
|
for (auto &key: keys)
|
|
{
|
|
auto it = e->m_children.find(key);
|
|
if (it == e->m_children.end())
|
|
return nullptr;
|
|
e = it->second.get();
|
|
}
|
|
return e;
|
|
}
|
|
|
|
void Node::Serialize(std::ostream *os, size_t indent_level) const
|
|
{
|
|
std::fill_n(std::ostream_iterator<char>(*os), 2 * indent_level, ' ');
|
|
*os << m_key << "=\"";
|
|
if (Exists())
|
|
m_value->Serialize(os);
|
|
*os << "\" children={";
|
|
for (auto v: m_children)
|
|
*os << ' ' << v.first;
|
|
*os << " }" << std::endl;
|
|
for (ptr_t child = m_first_child; child; child = child->m_next_sibling)
|
|
child->Serialize(os, indent_level + 1);
|
|
}
|
|
|
|
std::string Node::ToString(size_t indent_level) const
|
|
{
|
|
std::ostringstream os;
|
|
Serialize(&os, indent_level);
|
|
return os.str();
|
|
}
|
|
|
|
// Adds a newly-created node (which, among other things, implies no
|
|
// children) as a child
|
|
void Node::AddChild(Node &parent, ptr_t &node)
|
|
{
|
|
if (!parent.m_last_child)
|
|
{
|
|
parent.m_first_child = node;
|
|
parent.m_last_child = node;
|
|
}
|
|
else
|
|
{
|
|
parent.m_last_child->m_next_sibling = node;
|
|
parent.m_last_child = node;
|
|
}
|
|
parent.m_children[node->m_key] = node;
|
|
}
|
|
|
|
void Node::DeepCopy(const Node &that)
|
|
{
|
|
if (this == &that)
|
|
return;
|
|
Destroy();
|
|
*const_cast<std::string *>(&m_key) = that.m_key;
|
|
if (that.m_value)
|
|
m_value = that.m_value->MakeCopy();
|
|
for (ptr_t child = that.m_first_child; child; child = child->m_next_sibling)
|
|
{
|
|
ptr_t copied_child = std::make_shared<Node>(*child);
|
|
AddChild(*this, copied_child);
|
|
}
|
|
}
|
|
|
|
void Node::Swap(Node &rhs)
|
|
{
|
|
m_next_sibling.swap(rhs.m_next_sibling);
|
|
m_first_child.swap(rhs.m_first_child);
|
|
m_last_child.swap(rhs.m_last_child);
|
|
m_children.swap(rhs.m_children);
|
|
const_cast<std::string *>(&m_key)->swap(*const_cast<std::string *>(&rhs.m_key));
|
|
m_value.swap(rhs.m_value);
|
|
}
|
|
|
|
Node &Node::operator=(const Node &rhs)
|
|
{
|
|
DeepCopy(rhs);
|
|
return *this;
|
|
}
|
|
|
|
Node &Node::operator=(Node &&rhs) noexcept
|
|
{
|
|
Swap(rhs);
|
|
return *this;
|
|
}
|
|
|
|
Node::Node()
|
|
: m_key("config"), // a default key value
|
|
m_value(nullptr) // this node is empty
|
|
{
|
|
//std::cout << "<<< Created " << "<null>" << " (" << this << ")" << std::endl;
|
|
}
|
|
|
|
Node::Node(const std::string &key)
|
|
: m_key(key),
|
|
m_value(nullptr) // this node is empty
|
|
{
|
|
//std::cout << "<<< Created " << key << " (" << this << ")" << std::endl;
|
|
}
|
|
|
|
Node::Node(const std::string &key, const std::string &value)
|
|
: m_key(key),
|
|
m_value(std::make_shared<ValueInstance<std::string>>(value))
|
|
{
|
|
//std::cout << "<<< Created " << key << '=' << value << " (" << this << ")" << std::endl;
|
|
}
|
|
|
|
Node::Node(const Node &that)
|
|
{
|
|
DeepCopy(that);
|
|
}
|
|
|
|
Node::Node(Node &&that) noexcept
|
|
{
|
|
Swap(that);
|
|
}
|
|
|
|
Node::~Node()
|
|
{
|
|
//std::cout << ">>> Destroyed " << m_key << " (" << this << ")" << std::endl;
|
|
}
|
|
} // Config
|
|
} // Util
|