private void StringParse()
{
while (Peek() != '"' && !isAtEnd())
{
if (Peek() == '\n')
{
line++;
}
Advance();
}
// Unterminated string.
if (isAtEnd())
{
ElizScriptCompiler.Error(line, "Unterminated string.");
return;
}
// The closing ".
Advance();
// Trim the surrounding quotes.
string value = source.Substring(start + 1, current - start - 2);
AddToken(TokenType.STRING, value);
}
public Void VisitThisExpr(Expr.This expr)
{
if (currentClass == ClassType.NONE)
{
ElizScriptCompiler.Error(expr.keyword,
"Cannot use 'this' outside of a class.");
return(null);
}
ResolveLocal(expr, expr.keyword);
return(null);
}
public Void VisitClassStmt(Stmt.Class stmt)
{
ClassType enclosingClass = currentClass;
currentClass = ClassType.CLASS;
Declare(stmt.name);
Define(stmt.name);
if (stmt.baseclass != null && stmt.name.Lexeme.Equals(stmt.baseclass.name.Lexeme))
{
ElizScriptCompiler.Error(stmt.baseclass.name, "A class cannot inherit from itself.");
}
if (stmt.baseclass != null)
{
currentClass = ClassType.SUBCLASS;
Resolve(stmt.baseclass);
}
if (stmt.baseclass != null)
{
BeginScope();
scopes.Last()["base"] = true;
}
BeginScope();
scopes.Last()["this"] = true;
foreach (Stmt.Function method in stmt.methods)
{
FunctionType declaration = FunctionType.METHOD;
if (method.name.Lexeme.Equals("init"))
{
declaration = FunctionType.INITIALIZER;
}
ResolveFunction(method, declaration);
}
EndScope();
if (stmt.baseclass != null)
{
EndScope();
}
currentClass = enclosingClass;
return(null);
}
public Void VisitBaseExpr(Expr.Base expr)
{
if (currentClass == ClassType.NONE)
{
ElizScriptCompiler.Error(expr.keyword, "Cannot use 'base' outside of a class.");
}
else if (currentClass != ClassType.SUBCLASS)
{
ElizScriptCompiler.Error(expr.keyword, "Cannot use 'base' in a class with no baseclass.");
}
ResolveLocal(expr, expr.keyword);
return(null);
}
public void Interpret(List <Stmt> statements)
{
try
{
foreach (Stmt statement in statements)
{
Execute(statement);
}
}
catch (RuntimeError error)
{
ElizScriptCompiler.RuntimeError(error);
}
}
public Void VisitVariableExpr(Expr.Variable expr)
{
try
{
if (scopes.Count > 0 && scopes.Last()[expr.name.Lexeme] == false)
{
ElizScriptCompiler.Error(expr.name,
"Cannot read local variable in its own initializer.");
}
}
catch { }
ResolveLocal(expr, expr.name);
return(null);
}
void Declare(Token name)
{
if (scopes.Count == 0)
{
return;
}
Dictionary <string, bool> scope = scopes.Last(); /*Peek()*/
if (scope.ContainsKey(name.Lexeme))
{
ElizScriptCompiler.Error(name,
"Variable with this name already declared in this scope.");
}
scope[name.Lexeme] = false;
}
public Void VisitReturnStmt(Stmt.Return stmt)
{
if (currentFunction == FunctionType.NONE)
{
ElizScriptCompiler.Error(stmt.keyword, "Cannot return from top-level code.");
}
if (stmt.value != null)
{
if (currentFunction == FunctionType.INITIALIZER)
{
ElizScriptCompiler.Error(stmt.keyword,
"Cannot return a value from an initializer.");
}
Resolve(stmt.value);
}
return(null);
}
private ParseError Error(Token token, String message)
{
ElizScriptCompiler.Error(token, message);
return(new ParseError());
}
private void ScanToken()
{
char c = Advance();
switch (c)
{
case '(': AddToken(TokenType.LEFT_PAREN); break;
case ')': AddToken(TokenType.RIGHT_PAREN); break;
case '{': AddToken(TokenType.LEFT_BRACE); break;
case '}': AddToken(TokenType.RIGHT_BRACE); break;
case ',': AddToken(TokenType.COMMA); break;
case '.': AddToken(TokenType.DOT); break;
case '-': AddToken(TokenType.MINUS); break;
case '+': AddToken(TokenType.PLUS); break;
case ';': AddToken(TokenType.SEMICOLON); break;
case '*': AddToken(TokenType.STAR); break;
case '/':
if (Match('/'))
{
// A comment goes until the end of the line.
while (Peek() != '\n' && !isAtEnd())
{
Advance();
}
}
else
{
AddToken(TokenType.SLASH);
}
break;
case '!': AddToken(Match('=') ? TokenType.BANG_EQUAL : TokenType.BANG); break;
case '=': AddToken(Match('=') ? TokenType.EQUAL_EQUAL : TokenType.EQUAL); break;
case '<': AddToken(Match('=') ? TokenType.LESS_EQUAL : TokenType.LESS); break;
case '>': AddToken(Match('=') ? TokenType.GREATER_EQUAL : TokenType.GREATER); break;
case ' ':
case '\r':
case '\t':
// Ignore whitespace.
break;
case '\n':
line++;
break;
case '"': StringParse(); break;
default:
if (IsDigit(c))
{
NumberParse();
}
else if (IsAlpha(c))
{
IdentifierParse();
}
else
{
ElizScriptCompiler.Error(line, "Unexpected character.");
}
break;
}
}
