private Tree ParseStatement()
{
if (curToken.type == TokenType.Keyword)
{
Token keyword = curToken;
nextToken();
if (keyword.value == "var" || keyword.value == "global")
{
bool isLocal = keyword.value == "var";
string varName = curToken.value;
nextToken();
Tree expression = null;
if (accept(equals).valid)
{
expression = ParseExpression();
}
Scope last = scopes[scopes.Count - 1];
if (isLocal)
{
last.localVariables.Add(varName, last.localCount);
last.localCount++;
last.maxLocalCount = Math.Max(last.localCount, last.maxLocalCount);
return(new LocalAssignmentTree(last.localCount - 1, expression));
}
else
{
last.globalVariables.Add(varName, true);
return(new GlobalAssignmentTree(varName, expression));
}
}
else if (keyword.value == "function")
{
string name = expect(Token.Identifier).value;
scopes[scopes.Count - 1].globalVariables.Add(name, true);
CreateClosureTree funcTree = ParseFunctionDeclaration();
GlobalAssignmentTree tree = new GlobalAssignmentTree(name, funcTree);
return(tree);
}
else if (keyword.value == "if")
{
IfTree tree = new IfTree();
expect(lParen);
tree.condition = ParseExpression();
expect(rParen);
tree.ifBody = ParseBlockOrStatement(ScopeType.If);
if (accept(kElse).valid)
{
tree.hasElse = true;
tree.elseBody = ParseBlockOrStatement(ScopeType.If);
}
return(tree);
}
else if (keyword.value == "while")
{
WhileTree tree = new WhileTree();
expect(lParen);
tree.condition = ParseExpression();
expect(rParen);
tree.body = ParseBlockOrStatement(ScopeType.While);
return(tree);
}
else if (keyword.value == "return")
{
ReturnTree tree = new ReturnTree();
if (curToken.type != TokenType.Punctuation)
{
tree.value = ParseExpression();
}
return(tree);
}
}
else if (curToken.type == TokenType.Identifier || curToken.compare(lParen))
{
Tree thing = ParseIndexOrCall();
if (thing.type == TreeType.FunctionCall)
{
return(thing);
}
else
{
// assignment
if (thing.type == TreeType.GlobalValue)
{
expect(equals);
Tree value = ParseExpression();
return(new GlobalAssignmentTree((thing as GlobalValueTree).name, value));
}
else if (thing.type == TreeType.LocalValue)
{
expect(equals);
Tree value = ParseExpression();
return(new LocalAssignmentTree((thing as LocalValueTree).index, value));
}
else if (thing.type == TreeType.ObjectIndexValue)
{
expect(equals);
Tree value = ParseExpression();
ObjectIndexValueTree OIVTree = thing as ObjectIndexValueTree;
return(new ObjectIndexAssignmentTree(OIVTree.Object, OIVTree.Index, value));
}
}
}
throw new SyntaxErrorException(curToken.line, "Did not expect " + curToken + " here");
}
//==========
private Tree ParseIndexOrCall(Tree theObject = null)
{
if (theObject == null)
{
if (curToken.type == TokenType.Identifier)
{
theObject = GetVariableFromName(curToken.value);
if (theObject == null)
{
throw new ReferenceErrorException(curToken.line, $"'{curToken.value}' is not defined");
}
if (theObject.type == TreeType.LocalValue)
{
if ((theObject as LocalValueTree).functionId != scopes[scopes.Count - 1].functionId)
{
throw new SyntaxErrorException(curToken.line, "upvalues are not supported");
}
}
nextToken();
}
else if (accept(lParen).valid)
{
theObject = ParseExpression();
expect(rParen);
}
else
{
throw new SyntaxErrorException(curToken.line, "Did not expect " + curToken + " here");
}
}
if (theObject.type == TreeType.FunctionCall)
{
(theObject as FunctionCallTree).isExpression = true;
}
if (accept(dot).valid)
{
//index using identifier
theObject = new ObjectIndexValueTree(theObject, new StringTree(expect(Token.Identifier).value));
return(ParseIndexOrCall(theObject));
}
else if (accept(lSquare).valid)
{
//index using expression
Tree index = ParseExpression();
expect(rSquare);
theObject = new ObjectIndexValueTree(theObject, index);
return(ParseIndexOrCall(theObject));
}
else if (accept(lParen).valid)
{
//function call
FunctionCallTree tree = new FunctionCallTree(theObject);
if (!accept(rParen).valid)
{
do
{
tree.AddArgument(ParseExpression());
} while (accept(comma).valid);
expect(rParen);
}
return(ParseIndexOrCall(tree));
}
if (theObject.type == TreeType.FunctionCall)
{
(theObject as FunctionCallTree).isExpression = false;
}
return(theObject);
}