private StmtResult IfStatement() =>
/*
* ifStmt → "if" "(" expression ")" statement
* ( "else" statement )? ;
*/
from lParen in Consume(TokenType.LeftParen, "Expected '(' after 'if'.")
from condition in Expression()
from rParent in Consume(TokenType.RightParen, "Expected ')' after condition.")
from thenBranch in Statement()
from elseBranch in Match(TokenType.Else) ? Statement() : StmtResult.Ok(null)
select new IfStmt(condition, thenBranch, elseBranch) as Stmt;
public override async Task <StmtResult> Eval(EvalContext context)
{
// Debug.Log("block begins");
await base.Eval(context);
foreach (Stmt stmt in Statements)
{
//Debug.Log("block stmt begins");
StmtResult result = await stmt.Eval(context);
//Debug.Log("block stmt ends");
if (result == StmtResult.Break)
{
return(StmtResult.Break);
}
}
return(StmtResult.None);
}
public override async Task <StmtResult> Eval(EvalContext context)
{
//Debug.Log("repeat begins");
await base.Eval(context);
while (true)
{
//Debug.Log("repeatbody begins");
StmtResult result = await Body.Eval(context);
if (result == StmtResult.Break || context.Target.isActiveAndEnabled == false)
{
return(StmtResult.None);
}
Block newbody = (Block)Body;
if (newbody.Statements.Count == 1 && newbody.Statements[0] is If)
{
//임시방편
await new WaitForSeconds(0.2f);
}
}
}
private StmtResult ForStatement()
{
/*
* forStmt → "for" "(" ( varDecl | exprStmt | ";" )
* expression? ";"
* expression? ")" statement ;
*/
StmtResult ForInitializer()
{
if (Match(TokenType.Semicolon))
{
return(StmtResult.Ok(null));
}
if (Match(TokenType.Var))
{
return(VarDeclaration());
}
return(ExpressionStatement());
}
ExprResult ForCondition()
{
if (Check(TokenType.Semicolon))
{
return(ExprResult.Ok(null));
}
return(Expression());
}
ExprResult ForIncrementer()
{
if (Check(TokenType.RightParen))
{
return(ExprResult.Ok(null));
}
return(Expression());
}
Stmt BuildForAst(Stmt initializer, Expr condition, Expr incrementer, Stmt statement)
{
// express `for(var i = 0; i < 10; i++) { statement }` as a while loop;
// var i = 0;
// while(i<10) {
// { statement; }
// i++;
// }
var body = incrementer is null ? statement : new BlockStmt(new List <Stmt>()
{
statement, new ExpressionStmt(incrementer)
});
var cond = condition ?? new LiteralExpr(true);
var loop = new WhileStmt(cond, body);
var block = initializer is null ? loop : new BlockStmt(new List <Stmt>()
{
initializer, loop
}) as Stmt;
return(block);
}
return
(from lParen in Consume(TokenType.LeftParen, "Expected '(' after 'for'.")
from initializer in ForInitializer() //first semi is parsed as part of initializer
from condition in ForCondition()
from semi2 in Consume(TokenType.Semicolon, "Expected ';' after condition.")
from incrementer in ForIncrementer()
from rParen in Consume(TokenType.RightParen, "Expected ')' after increment expression.")
from statement in Statement()
select BuildForAst(initializer, condition, incrementer, statement));
}
