public IWasmicSyntaxTreeExpression GetExpression()
{
IWasmicSyntaxTreeExpression lhs;
switch (_lexer.Next.TokenType)
{
case TokenType.Identifier:
var name = _lexer.Next.Value;
_lexer.Advance();
while (_lexer.Next.TokenType == TokenType.Period)
{
_lexer.Advance();
_lexer.AssertNext(TokenType.Identifier);
name += $".{_lexer.Next.Value}";
_lexer.Advance();
}
int?arrayOffset = null;
if (_lexer.Next.TokenType == TokenType.L_Bracket)
{
_lexer.Advance(); // eat [
_lexer.AssertNext(TokenType.Int32);
arrayOffset = int.Parse(_lexer.Next.Value) * 4;
_lexer.Advance(); // eat offset
_lexer.AssertNext(TokenType.R_Bracket);
_lexer.Advance(); // eat ]
}
switch (_lexer.Next.TokenType)
{
case TokenType.Equal:
_lexer.Advance(); // eat =
lhs = arrayOffset.HasValue
? (IWasmicSyntaxTreeExpression)GetSetArrayLocalVariable(name, arrayOffset.Value)
: GetSetLocalVariable(name, null, false);
break;
case TokenType.PlusEqual:
_lexer.Advance(); // eat +=
var valueExpression = GetExpression();
var getExpr = GetGetLocalVariable(name);
var expression = new BinopExpresison(valueExpression, getExpr, Operation.Add);
lhs = GetSetLocalVariable(name, expression);
break;
case TokenType.L_Paren:
lhs = _functionCallParser.Parse(_lexer, _functionMap, this, name);
break;
default:
lhs = arrayOffset.HasValue
? (IWasmicSyntaxTreeExpression)GetGetArrayLocalVariable(name, arrayOffset.Value)
: GetGetLocalVariable(name);
break;
}
break;
case TokenType.Int32:
var i32 = _lexer.Next.Value;
_lexer.Advance();
lhs = new Literal("i32", i32);
break;
case TokenType.Int64:
var i64 = _lexer.Next.Value;
_lexer.Advance();
lhs = new Literal("i64", i64);
break;
case TokenType.String:
var result = _lexer.Next.Value;
_lexer.Advance();
(int offset, string label) = _heap.AllocateOrGetString(result);
lhs = new WasmicString(label, offset, result.Length);
break;
case TokenType.If:
lhs = GetIf();
break;
default:
throw new NotImplementedException(_lexer.Next.TokenType.ToString());
}
switch (_lexer.Next.TokenType)
{
case TokenType.Plus:
case TokenType.Minus:
case TokenType.Star:
case TokenType.Slash:
return(_binopExpressionParser.Parse(_lexer, this, lhs));
case TokenType.EqualComparer:
case TokenType.GrThanComparer:
case TokenType.GrThanOrEqComparer:
case TokenType.LsThanComparer:
case TokenType.LsThanOrEqComparer:
return(_comparisonParser.Parse(_lexer, this, lhs));
}
return(lhs);
}