/// <summary>
/// Visits the function call expression tree
/// </summary>
/// <param name="exp"></param>
public object VisitIndex(IndexExpr exp)
{
_callBackOnNodeStart(exp);
_callBackOnNodeStart(exp.VarExp);
_callBackOnNodeStart(exp.IndexExp);
return null;
}
/// <summary>
/// Creates an index expression from the parameters supplied.
/// </summary>
/// <param name="varExp"></param>
/// <param name="indexExp"></param>
/// <param name="isAssignment"></param>
/// <param name="token"></param>
/// <returns></returns>
public static Expr Index(Expr varExp, Expr indexExp, bool isAssignment, TokenData token)
{
var exp = new IndexExpr();
exp.IsAssignment = isAssignment;
exp.VarExp = varExp;
exp.IndexExp = indexExp;
SetupContext(exp, token);
return exp;
}
/// <summary>
/// Evaluate object[index]
/// </summary>
/// <returns></returns>
public static object EvalIndexAccess(IndexExpr expr)
{
var ndxVal = expr.IndexExp.Evaluate();
var listObject = expr.VariableExp.Evaluate();
// Check for empty objects.
ExceptionHelper.NotNull(expr, listObject, "indexing");
ExceptionHelper.NotNull(expr, ndxVal, "indexing");
var lobj = (LObject)listObject;
// CASE 1. Access
// e.g. Array: users[0]
// e.g. Map: users['total']
if (!expr.IsAssignment)
{
var result = EvalHelper.AccessIndex(Ctx.Methods, expr, lobj, (LObject)ndxVal);
return result;
}
// CASE 2. Assignment
// e.g. Array: users[0] = 'john'
// e.g. Map: users['total'] = 200
// NOTE: In this case of assignment, return back a MemberAccess object descripting what is assign
var indexAccess = new IndexAccess();
indexAccess.Instance = lobj;
indexAccess.MemberName = (LObject)ndxVal;
return indexAccess;
}
/// <summary>
/// Parses an Id based expression:
/// 1. user : variable
/// 2. getUser() : function call
/// 3. users[ : index expression
/// 4. user.name : member access
///
/// ASSIGNMENT: EXPRESSION:
/// result = 2; result -> variableexpression
/// items[0] = 'kishore'; items[0] -> indexexpression( variableexpression | name)
/// getuser(); getuser() -> functionexpression()
/// user.age = 30; user.age -> memberexpression( variableexpression | name/member )
/// items[0].name = 'kishore'; items[0].name -> memberexpression( indexexpression( variableexpression ) )
/// getuser()[0] = 0; getuser()[0] -> indexexpression( functionexpression )
/// user.name.last = 'kishore'; user.name.last -> memberexpression( memberexpression )
/// </summary>
/// <param name="name"></param>
/// <param name="existing"></param>
/// <param name="isCurrentTokenAMember">Whether or not the current token is a '[', '(' or a '.'</param>
/// <returns></returns>
public Expr ParseIdExpression(string name = null, Expr existing = null, bool isCurrentTokenAMember = false)
{
Expr exp = existing;
var aheadToken = isCurrentTokenAMember ? _tokenIt.NextToken : _tokenIt.Peek();
var currentName = "";
if (existing == null)
{
currentName = string.IsNullOrEmpty(name) ? _tokenIt.NextToken.Token.Text : name;
exp = this.ToIdentExpr(currentName, _tokenIt.NextToken);
}
if(!isCurrentTokenAMember)
_tokenIt.Advance();
int memberAccess = 0;
bool isFunction = (exp.IsNodeType(NodeTypes.SysVariable) && _context.Symbols.IsFunc(((VariableExpr)exp).Name));
// CASE 1: function call without out parenthesis.
if (isFunction && aheadToken.Token != Tokens.LeftParenthesis)
{
exp = ParseFuncExpression(exp, null);
exp.Ctx = _context;
return exp;
}
// CASE 2: Simple variable expression - e.g. result + 2
bool isMemberAccessAhead = ( aheadToken.Token == Tokens.LeftParenthesis || aheadToken.Token == Tokens.LeftBracket || aheadToken.Token == Tokens.Dot );
if( !isFunction && !isMemberAccessAhead )
{
exp.Ctx = _context;
return exp;
}
// CASE 3: Member access of some sort using either "." | "[]" | "()"
// 1. result.total : Dot access
// 2. result[0] : Array access
// 3. add( 2, 3 ) : Function access/call
var tokenData = _tokenIt.NextToken;
var token = _tokenIt.NextToken.Token;
var members = new List<string>();
members.Add(exp.ToQualifiedName());
while (token == Tokens.LeftParenthesis || token == Tokens.LeftBracket || token == Tokens.Dot)
{
// Case 2: "("- function call
if (token == Tokens.LeftParenthesis)
{
exp = ParseFuncExpression(exp, members);
}
// Case 3: "[" - indexing
else if (token == Tokens.LeftBracket)
{
_tokenIt.Advance();
_state.IndexExp++;
// Get index exp ( n+1 ) or n, etc.
var index = ParseExpression(Terminators.ExpBracketEnd);
_tokenIt.Expect(Tokens.RightBracket);
_state.IndexExp--;
// Note: if = sign then property access should return a property info.
// otherwise get the value of the property.
bool isAssignment = _tokenIt.NextToken.Token == Tokens.Assignment;
exp = new IndexExpr(exp, index, isAssignment);
}
// Case 4: "." - member access
else if (_tokenIt.NextToken.Token == Tokens.Dot)
{
_tokenIt.Advance();
var member = _tokenIt.ExpectId();
// Keep list of each member name.
members.Add(member);
// Note: if = sign then property access should return a property info.
// otherwise get the value of the property.
bool isAssignment = _tokenIt.NextToken.Token == Tokens.Assignment;
exp = new MemberAccessExpr(exp, member, isAssignment);
}
this.SetupContext(exp, tokenData);
memberAccess++;
// Check limit.
_context.Limits.CheckParserMemberAccess(exp, memberAccess);
tokenData = _tokenIt.NextToken;
token = tokenData.Token;
}
return exp;
}
