406 lines
9.1 KiB
C++
406 lines
9.1 KiB
C++
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// LuaJson.cpp
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// Implements the Json exposure bindings to Lua
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#include "Globals.h"
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#include <sstream>
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#include "LuaJson.h"
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#include "LuaState.h"
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#include "tolua++/include/tolua++.h"
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#include "json/json.h"
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#include "../JsonUtils.h"
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// fwd:
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static void PushJsonValue(const Json::Value & a_Value, cLuaState & a_LuaState);
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static Json::Value JsonSerializeValue(cLuaState & a_LuaState);
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/** Exception thrown when the input cannot be serialized.
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Keeps track of the error message and the problematic value's path in the table.
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*/
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class CannotSerializeException:
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public std::runtime_error
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{
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using Super = std::runtime_error;
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public:
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/** Constructs a new instance of the exception based on the provided values directly. */
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explicit CannotSerializeException(const AString & a_ValueName, const char * a_ErrorMsg):
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Super(a_ErrorMsg),
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m_ValueName(a_ValueName)
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{
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}
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/** Constructs a new instance of the exception based on the provided values directly. */
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explicit CannotSerializeException(int a_ValueIndex, const char * a_ErrorMsg):
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Super(a_ErrorMsg),
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m_ValueName(Printf("%d", a_ValueIndex))
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{
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}
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/** Constructs a new instance of the exception that takes the error message and value name from the parent, and prefix the value name with the specified prefix.
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Used for prefixing the value name's path along the call stack that lead to the main exception. */
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explicit CannotSerializeException(const CannotSerializeException & a_Parent, const AString & a_ValueNamePrefix):
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Super(a_Parent.what()),
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m_ValueName(a_ValueNamePrefix + "." + a_Parent.m_ValueName)
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{
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}
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/** Constructs a new instance of the exception that takes the error message and value name from the parent, and prefix the value name with the specified prefix.
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Used for prefixing the value name's path along the call stack that lead to the main exception. */
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explicit CannotSerializeException(const CannotSerializeException & a_Parent, int a_ValueNamePrefixIndex):
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Super(a_Parent.what()),
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m_ValueName(Printf("%d", a_ValueNamePrefixIndex) + "." + a_Parent.m_ValueName)
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{
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}
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const AString & GetValueName() const { return m_ValueName; }
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protected:
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AString m_ValueName;
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};
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/** Pushes the specified Json array as a table on top of the specified Lua state.
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Assumes that a_Value is an array. */
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static void PushJsonArray(const Json::Value & a_Value, cLuaState & a_LuaState)
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{
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// Create the appropriately-sized Lua table:
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lua_createtable(a_LuaState, static_cast<int>(a_Value.size()), 0);
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// Insert each value to the appropriate index (1-based):
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int idx = 1;
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for (const auto & v: a_Value)
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{
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// Include Json null values in the array - it will have holes, but indices will stay the same
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PushJsonValue(v, a_LuaState);
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lua_rawseti(a_LuaState, -2, idx);
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idx += 1;
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} // for v: a_Value[]
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}
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/** Pushes the specified Json object as a table on top of the specified Lua state.
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Assumes that a_Value is an object. */
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static void PushJsonObject(const Json::Value & a_Value, cLuaState & a_LuaState)
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{
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// Create the appropriately-sized Lua table:
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lua_createtable(a_LuaState, 0, static_cast<int>(a_Value.size()));
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// Json::Value has no means of iterating over children with their names included.
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// We need to iterate over names and "find" them in the object again:
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auto names = a_Value.getMemberNames();
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for (const auto & n: names)
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{
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auto v = a_Value[n];
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if (v.isNull())
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{
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// Skip null values
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continue;
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}
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// Set the value in Lua's table:
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a_LuaState.Push(n);
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PushJsonValue(v, a_LuaState);
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lua_rawset(a_LuaState, -3);
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} // for itr - a_Value[]
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}
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/** Pushes the specified Json value as an appropriate type on top of the specified Lua state. */
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void PushJsonValue(const Json::Value & a_Value, cLuaState & a_LuaState)
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{
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switch (a_Value.type())
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{
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case Json::nullValue:
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{
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a_LuaState.Push(cLuaState::Nil);
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break;
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}
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case Json::intValue:
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case Json::uintValue:
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case Json::realValue:
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{
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a_LuaState.Push(static_cast<lua_Number>(a_Value.asDouble()));
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break;
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}
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case Json::booleanValue:
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{
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a_LuaState.Push(a_Value.asBool());
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break;
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}
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case Json::stringValue:
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{
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a_LuaState.Push(a_Value.asString());
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break;
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}
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case Json::arrayValue:
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{
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PushJsonArray(a_Value, a_LuaState);
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break;
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}
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case Json::objectValue:
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{
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PushJsonObject(a_Value, a_LuaState);
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break;
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}
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} // switch (v.type())
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}
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/** Serializes the Lua table at the top of the specified Lua state's stack into a Json value.
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Lets jsoncpp decides whether to serialize into an object or an array. */
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static Json::Value JsonSerializeTable(cLuaState & a_LuaState)
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{
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Json::Value res;
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lua_pushnil(a_LuaState);
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while (lua_next(a_LuaState, -2) != 0)
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{
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if (lua_type(a_LuaState, -2) == LUA_TNUMBER)
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{
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int idx;
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a_LuaState.GetStackValue(-2, idx);
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try
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{
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res[idx - 1] = JsonSerializeValue(a_LuaState);
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}
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catch (const CannotSerializeException & exc)
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{
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throw CannotSerializeException(exc, idx);
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}
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catch (const std::exception & exc) // Cannot catch Json::Exception, because it's not properly defined
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{
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throw CannotSerializeException(idx, exc.what());
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}
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}
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else
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{
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AString name;
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if (a_LuaState.GetStackValue(-2, name))
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{
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try
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{
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res[name] = JsonSerializeValue(a_LuaState);
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}
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catch (const CannotSerializeException & exc)
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{
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throw CannotSerializeException(exc, name);
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}
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catch (const std::exception & exc) // Cannot catch Json::Exception, because it's not properly defined
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{
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throw CannotSerializeException(name, exc.what());
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}
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}
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}
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lua_pop(a_LuaState, 1);
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}
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return res;
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}
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/** Serializes the Lua value at the top of the specified Lua state into a Json value. */
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static Json::Value JsonSerializeValue(cLuaState & a_LuaState)
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{
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switch (lua_type(a_LuaState, -1))
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{
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case LUA_TBOOLEAN:
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{
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bool v;
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a_LuaState.GetStackValue(-1, v);
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return Json::Value(v);
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}
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case LUA_TNIL:
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{
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return Json::Value(Json::nullValue);
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}
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case LUA_TNUMBER:
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{
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lua_Number v;
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a_LuaState.GetStackValue(-1, v);
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return Json::Value(v);
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}
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case LUA_TSTRING:
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{
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AString v;
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a_LuaState.GetStackValue(-1, v);
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return Json::Value(v);
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}
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case LUA_TTABLE:
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{
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return JsonSerializeTable(a_LuaState);
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}
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default:
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{
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LOGD("Attempting to serialize an unhandled Lua value type: %d", lua_type(a_LuaState, -1));
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return Json::Value(Json::nullValue);
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}
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}
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}
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static int tolua_cJson_Parse(lua_State * a_LuaState)
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{
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// Function signature:
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// cJson:Parse("string") -> table
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// Check the param types:
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cLuaState L(a_LuaState);
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if (
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!L.CheckParamUserTable(1, "cJson") ||
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!L.CheckParamString(2) ||
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!L.CheckParamEnd(3)
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)
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{
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return 0;
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}
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// Get the input string:
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AString input;
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if (!L.GetStackValue(2, input))
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{
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LOGWARNING("cJson:Parse(): Cannot read input string");
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L.LogStackTrace();
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return 0;
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}
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// Parse the string:
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Json::Value root;
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AString ParseError;
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if (!JsonUtils::ParseString(input, root, &ParseError))
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{
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L.Push(cLuaState::Nil, Printf("Parsing Json failed: %s", ParseError));
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return 2;
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}
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// Push the Json value onto Lua stack:
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PushJsonValue(root, L);
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return 1;
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}
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static int tolua_cJson_Serialize(lua_State * a_LuaState)
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{
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// Function signature:
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// cJson:Serialize({table}, [{option1 = value1, option2 = value2}]) -> string
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// Check the param types:
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cLuaState L(a_LuaState);
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if (
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!L.CheckParamUserTable(1, "cJson") ||
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!L.CheckParamTable(2) ||
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!L.CheckParamEnd(4)
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)
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{
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return 0;
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}
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// Push the table to the top of the Lua stack, and call the serializing function:
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lua_pushvalue(L, 2);
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Json::Value root;
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try
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{
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root = JsonSerializeValue(L);
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}
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catch (const CannotSerializeException & exc)
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{
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lua_pushnil(L);
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L.Push(Printf("Cannot serialize into Json, value \"%s\" caused an error \"%s\"", exc.GetValueName().c_str(), exc.what()));
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return 2;
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}
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lua_pop(L, 1);
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// Create the writer, with all properties (optional param 3) applied to it:
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Json::StreamWriterBuilder builder;
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if (lua_istable(L, 3))
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{
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lua_pushnil(L);
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while (lua_next(L, -2) != 0)
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{
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if (lua_type(L, -2) == LUA_TSTRING)
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{
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AString propName, propValue;
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if (L.GetStackValues(-2, propName, propValue))
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{
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builder[propName] = propValue;
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}
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}
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lua_pop(L, 1);
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}
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// Check for invalid settings:
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Json::Value invalid;
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if (!builder.validate(&invalid))
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{
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LOGINFO("cJson:Serialize(): detected invalid settings:");
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for (const auto & n: invalid.getMemberNames())
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{
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LOGINFO(" \"%s\" (\"%s\")", n.c_str(), invalid[n].asCString());
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}
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}
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}
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auto writer(builder.newStreamWriter());
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// Serialize the string and push it as the return value:
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std::stringstream ss;
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writer->write(root, &ss);
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L.Push(ss.str());
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return 1;
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}
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void cLuaJson::Bind(cLuaState & a_LuaState)
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{
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tolua_beginmodule(a_LuaState, nullptr);
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// Create the cJson API class:
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tolua_usertype(a_LuaState, "cJson");
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tolua_cclass(a_LuaState, "cJson", "cJson", "", nullptr);
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// Fill in the functions (alpha-sorted):
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tolua_beginmodule(a_LuaState, "cJson");
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tolua_function(a_LuaState, "Parse", tolua_cJson_Parse);
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tolua_function(a_LuaState, "Serialize", tolua_cJson_Serialize);
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tolua_endmodule(a_LuaState);
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tolua_endmodule(a_LuaState);
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}
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