protected ExpressionBase ParseShorthandBody(PositionalTokenizer tokenizer)
{
ExpressionBase.SkipWhitespace(tokenizer);
var expression = ExpressionBase.Parse(tokenizer);
if (expression.Type == ExpressionType.ParseError)
{
return(expression);
}
switch (expression.Type)
{
case ExpressionType.Return:
return(ParseError(tokenizer, "Return statement is implied by =>", ((ReturnExpression)expression).Keyword));
case ExpressionType.For:
return(ParseError(tokenizer, "Shorthand function definition does not support loops.", expression));
case ExpressionType.If:
return(ParseError(tokenizer, "Shorthand function definition does not support branches.", expression));
}
var returnExpression = new ReturnExpression(expression);
Expressions.Add(returnExpression);
Location = new TextRange(Location.Start, expression.Location.End);
return(MakeReadOnly(this));
}
/// <summary>
/// Replaces the variables in the expression with values from <paramref name="scope" />.
/// </summary>
/// <param name="scope">The scope object containing variable values.</param>
/// <param name="result">[out] The new expression containing the replaced variables.</param>
/// <returns>
/// <c>true</c> if substitution was successful, <c>false</c> if something went wrong, in which case <paramref name="result" /> will likely be a <see cref="ParseErrorExpression" />.
/// </returns>
public override bool ReplaceVariables(InterpreterScope scope, out ExpressionBase result)
{
ExpressionBase value;
if (!Value.ReplaceVariables(scope, out value))
{
result = value;
return(false);
}
result = new ReturnExpression(value);
return(true);
}
/// <summary>
/// Parses a function definition.
/// </summary>
/// <remarks>
/// Assumes the 'function' keyword has already been consumed.
/// </remarks>
internal static ExpressionBase Parse(PositionalTokenizer tokenizer, int line = 0, int column = 0)
{
var function = new FunctionDefinitionExpression();
function._keyword = new KeywordExpression("function", line, column);
ExpressionBase.SkipWhitespace(tokenizer);
line = tokenizer.Line;
column = tokenizer.Column;
var functionName = tokenizer.ReadIdentifier();
function.Name = new VariableDefinitionExpression(functionName.ToString(), line, column);
if (functionName.IsEmpty)
{
ExpressionBase.ParseError(tokenizer, "Invalid function name");
return(function);
}
ExpressionBase.SkipWhitespace(tokenizer);
if (tokenizer.NextChar != '(')
{
ExpressionBase.ParseError(tokenizer, "Expected '(' after function name", function.Name);
return(function);
}
tokenizer.Advance();
ExpressionBase.SkipWhitespace(tokenizer);
if (tokenizer.NextChar != ')')
{
do
{
line = tokenizer.Line;
column = tokenizer.Column;
var parameter = tokenizer.ReadIdentifier();
if (parameter.IsEmpty)
{
ExpressionBase.ParseError(tokenizer, "Invalid parameter name", line, column);
return(function);
}
function.Parameters.Add(new VariableDefinitionExpression(parameter.ToString(), line, column));
ExpressionBase.SkipWhitespace(tokenizer);
if (tokenizer.NextChar == ')')
{
break;
}
if (tokenizer.NextChar != ',')
{
ExpressionBase.ParseError(tokenizer, "Expected ',' or ')' after parameter name, found: " + tokenizer.NextChar);
return(function);
}
tokenizer.Advance();
ExpressionBase.SkipWhitespace(tokenizer);
} while (true);
}
tokenizer.Advance(); // closing parenthesis
ExpressionBase.SkipWhitespace(tokenizer);
ExpressionBase expression;
if (tokenizer.Match("=>"))
{
ExpressionBase.SkipWhitespace(tokenizer);
expression = ExpressionBase.Parse(tokenizer);
if (expression.Type == ExpressionType.ParseError)
{
return(expression);
}
if (expression.Type == ExpressionType.Return)
{
return(new ParseErrorExpression("Return statement is implied by =>", ((ReturnExpression)expression).Keyword));
}
var returnExpression = new ReturnExpression(expression);
function.Expressions.Add(returnExpression);
return(function);
}
if (tokenizer.NextChar != '{')
{
ExpressionBase.ParseError(tokenizer, "Expected '{' after function declaration", function.Name);
return(function);
}
line = tokenizer.Line;
column = tokenizer.Column;
tokenizer.Advance();
ExpressionBase.SkipWhitespace(tokenizer);
bool seenReturn = false;
while (tokenizer.NextChar != '}')
{
expression = ExpressionBase.Parse(tokenizer);
if (expression.Type == ExpressionType.ParseError)
{
return(expression);
}
if (expression.Type == ExpressionType.Return)
{
seenReturn = true;
}
else if (seenReturn)
{
ExpressionBase.ParseError(tokenizer, "Expression after return statement", expression);
}
function.Expressions.Add(expression);
ExpressionBase.SkipWhitespace(tokenizer);
}
tokenizer.Advance();
return(function);
}
