// constructor -> '{' [ field { sep field } [sep] ] '}'
// sep -> ',' | ';'
private void Constructor( ExpDesc t )
{
var fs = CurFunc;
int line = Lexer.LineNumber;
int pc = Coder.CodeABC( fs, OpCode.OP_NEWTABLE, 0, 0, 0 );
var cc = new ConstructorControl();
cc.ExpTable = t;
InitExp( t, ExpKind.VRELOCABLE, pc );
InitExp( cc.ExpLastItem, ExpKind.VVOID, 0); // no value (yet)
Coder.Exp2NextReg( fs, t );
CheckNext( (int)'{' );
do {
Utl.Assert( cc.ExpLastItem.Kind == ExpKind.VVOID ||
cc.NumToStore > 0 );
if( Lexer.Token.TokenType == (int)'}' )
break;
CloseListField( fs, cc );
Field( cc );
} while( TestNext( (int)',' ) || TestNext( (int)';' ) );
CheckMatch( (int)'}', (int)'{', line );
LastListField( fs, cc );
// set initial array size and table size
// 因为没有实现 OP_NEWTABLE 对 ARG_B 和 ARG_C 的处理, 所以这里也暂不实现
// 不影响逻辑, 只是效率差别
// var ins = fs.Proto.Code[pc];
// ins.SETARG_B( 0 );
// ins.SETARG_C( 0 );
// 算了, 还是实现吧, 方便检查生成的 bytecode 是否跟 luac 一样
var ins = fs.Proto.Code[pc];
ins.SETARG_B( Integer2FloatingPointByte( (uint)cc.NumArray ) );
ins.SETARG_C( Integer2FloatingPointByte( (uint)cc.NumRecord) );
fs.Proto.Code[pc] = ins; // Instruction 是值类型的 唉
}
// field -> listfield | recfield
private void Field( ConstructorControl cc )
{
switch( Lexer.Token.TokenType )
{
// may be 'listfield' or 'recfield'
case (int)TK.NAME: {
// expression?
if( Lexer.GetLookAhead().TokenType != (int)'=' )
ListField( cc );
else
RecField( cc );
break;
}
case (int)'[': {
RecField( cc );
break;
}
default: {
ListField( cc );
break;
}
}
}
// listfield -> exp
private void ListField( ConstructorControl cc )
{
Expr( cc.ExpLastItem );
CheckLimit( CurFunc, cc.NumArray, LuaLimits.MAX_INT,
"items in a constructor" );
cc.NumArray++;
cc.NumToStore++;
}
private void LastListField( FuncState fs, ConstructorControl cc )
{
if( cc.NumToStore == 0 )
return;
if( HasMultiRet( cc.ExpLastItem.Kind ) )
{
Coder.SetMultiRet( fs, cc.ExpLastItem );
Coder.SetList( fs, cc.ExpTable.Info, cc.NumArray, LuaDef.LUA_MULTRET );
// do not count last expression (unknown number of elements)
cc.NumArray--;
}
else
{
if( cc.ExpLastItem.Kind != ExpKind.VVOID )
Coder.Exp2NextReg( fs, cc.ExpLastItem );
Coder.SetList( fs, cc.ExpTable.Info, cc.NumArray, cc.NumToStore );
}
}
private void CloseListField( FuncState fs, ConstructorControl cc )
{
// there is no list item
if( cc.ExpLastItem.Kind == ExpKind.VVOID )
return;
Coder.Exp2NextReg( fs, cc.ExpLastItem );
cc.ExpLastItem.Kind = ExpKind.VVOID;
if( cc.NumToStore == LuaDef.LFIELDS_PER_FLUSH )
{
// flush
Coder.SetList( fs, cc.ExpTable.Info, cc.NumArray, cc.NumToStore );
// no more item pending
cc.NumToStore = 0;
}
}
// recfield -> (NAME | '[' exp1 ']') = exp1
private void RecField( ConstructorControl cc )
{
var fs = CurFunc;
int reg = fs.FreeReg;
var key = new ExpDesc();
var val = new ExpDesc();
if( Lexer.Token.TokenType == (int)TK.NAME )
{
CheckLimit( fs, cc.NumRecord, LuaLimits.MAX_INT,
"items in a constructor" );
CodeString( key, CheckName() );
}
// ls->t.token == '['
else
{
YIndex( key );
}
cc.NumRecord++;
CheckNext( (int)'=' );
int rkkey = Coder.Exp2RK( fs, key );
Expr( val );
Coder.CodeABC( fs, OpCode.OP_SETTABLE, cc.ExpTable.Info, rkkey,
Coder.Exp2RK( fs, val ) );
fs.FreeReg = reg; // free registers
}
