public SymplEltExpr ParseElt(Lexer lexr)
{
Token token = lexr.GetToken();
if (token != KeywordToken.Elt) {
throw new SymplParseException("Internal: parsing Elt?");
}
var obj = ParseExprAux(lexr);
var indexes = ParseBody(lexr,
"Unexpected EOF in arg list for call to Elt.");
return new SymplEltExpr(obj, indexes);
}
// ParseFile returns an array of top-level expressions parsed in the
// TextReader.
//
public SymplExpr[] ParseFile(TextReader reader) {
if (reader == null) {
throw new ArgumentException("Reader must not be null.");
}
Lexer lexer = new Lexer(reader);
var body = new List<SymplExpr>();
var token = lexer.GetToken();
while (token != SyntaxToken.EOF) {
lexer.PutToken(token);
body.Add(ParseExprAux(lexer));
token = lexer.GetToken();
}
return body.ToArray();
}
// _parseExpr parses an expression from the Lexer passed in.
//
private SymplExpr ParseExprAux(Lexer lexer) {
Token token = lexer.GetToken();
SymplExpr res = null;
if (token == SyntaxToken.EOF) {
throw new SymplParseException(
"Unexpected EOF encountered while parsing expression.");
}
if (token == SyntaxToken.Quote) {
lexer.PutToken(token);
res = ParseQuoteExpr(lexer);
} else if (token == SyntaxToken.Paren) {
lexer.PutToken(token);
res = ParseForm(lexer);
} else if (token is IdOrKeywordToken) {
// If we encounter literal kwd constants, they get turned into ID
// Exprs. Code that accepts Id Exprs, needs to check if the token is
// kwd or not when it matters.
if ((token is KeywordToken) && !(token == KeywordToken.Nil) &&
!(token == KeywordToken.True) && !(token == KeywordToken.False)) {
throw new InvalidCastException("Keyword cannot be an expression");
} else {
res = new SymplIdExpr((IdOrKeywordToken)token);
}
} else if (token is LiteralToken) {
res = new SymplLiteralExpr(((LiteralToken)token).Value);
}
// check for dotted expr
if (res != null) {
Token next = lexer.GetToken();
lexer.PutToken(next);
if (next == SyntaxToken.Dot) {
return ParseDottedExpr(lexer, res);
} else {
return res;
}
}
throw new SymplParseException(
"Unexpected token when expecting " +
"beginning of expression -- " + token.ToString() + " ... " +
lexer.GetToken().ToString() + lexer.GetToken().ToString() +
lexer.GetToken().ToString() + lexer.GetToken().ToString());
}
// This parses a UnaryOp expression.
//
private SymplUnaryExpr ParseExprTreeUnaryOp(Lexer lexr) {
KeywordToken keyword = lexr.GetToken() as KeywordToken;
if (keyword == null) {
throw new SymplParseException(
"Internal error: parsing Unary?");
}
var op = GetOpType(keyword);
var operand = ParseExprAux(lexr);
if (lexr.GetToken() != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Unary expression missing close paren.");
}
return new SymplUnaryExpr(operand, op);
}
// This parses pure list and atom structure. Atoms are IDs, strs, and nums.
// Need quoted form of dotted exprs, quote, etc., if want to have macros one
// day. This is used for Import name parsing, Defun/Lambda params, and quoted
// lists.
//
private SymplListExpr ParseList(Lexer lexer, string errStr) {
var token = lexer.GetToken();
if (token != SyntaxToken.Paren) {
throw new SymplParseException(
"List expression must start with '('.");
}
token = lexer.GetToken();
List<object> res = new List<object>();
while (token != SyntaxToken.EOF && token != SyntaxToken.CloseParen) {
lexer.PutToken(token);
object elt;
if (token == SyntaxToken.Paren) {
elt = ParseList(lexer, errStr);
} else if (token is IdOrKeywordToken || token is LiteralToken) {
elt = token;
lexer.GetToken();
} else if (token == SyntaxToken.Dot) {
throw new SymplParseException(
"Can't have dotted syntax in " + errStr);
} else {
throw new SymplParseException(
"Unexpected token in list -- " + token.ToString());
}
if (elt == null) {
throw new SymplParseException(
"Internal: no next element in list?");
}
res.Add(elt);
token = lexer.GetToken();
}
if (token == SyntaxToken.EOF) {
throw new SymplParseException(
"Unexpected EOF encountered while parsing list.");
}
return new SymplListExpr(res.ToArray());
}
// _parseBreak parses a Break expression, which has an optional value that
// becomes a loop expression's value.
//
private SymplBreakExpr ParseBreak (Lexer lexr) {
if (lexr.GetToken() != KeywordToken.Break) {
throw new SymplParseException("Internal error: parsing Break?");
}
var token = lexr.GetToken();
SymplExpr value;
if (token == SyntaxToken.CloseParen) {
value = null;
} else {
lexr.PutToken(token);
value = ParseExprAux(lexr);
token = lexr.GetToken();
if (token != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Break expression missing close paren.");
}
}
return new SymplBreakExpr(value);
}
private SymplIfExpr ParseIf (Lexer lexr) {
var token = lexr.GetToken();
if (token != KeywordToken.If) {
throw new SymplParseException("Internal: parsing If?");
}
var args = ParseBody(lexr, "Unexpected EOF in If form.");
int argslen = args.Length;
if (argslen == 2) {
return new SymplIfExpr(args[0], args[1], null);
} else if (argslen == 3) {
return new SymplIfExpr(args[0], args[1], args[2]);
} else {
throw new SymplParseException(
"IF must be (if <test> <consequent> [<alternative>]).");
}
}
// _parseBinaryRuntimeCall parses two exprs and a close paren, returning the
// two exprs.
//
private void ParseBinaryRuntimeCall(Lexer lexr, out SymplExpr left,
out SymplExpr right) {
left = ParseExprAux(lexr);
right = ParseExprAux(lexr);
if (lexr.GetToken() != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Expected close paren for Eq call.");
}
}
// This parses a quoted list, ID/keyword, or literal.
//
private SymplQuoteExpr ParseQuoteExpr(Lexer lexer) {
var token = lexer.GetToken();
if (token != SyntaxToken.Quote) {
throw new SymplParseException("Internal: parsing Quote?.");
}
token = lexer.GetToken();
object expr;
if (token == SyntaxToken.Paren) {
lexer.PutToken(token);
expr = ParseList(lexer, "quoted list.");
} else if (token is IdOrKeywordToken ||
token is LiteralToken) {
expr = token;
} else {
throw new SymplParseException(
"Quoted expression can only be list, ID/Symbol, or literal.");
}
return new SymplQuoteExpr(expr);
}
// _parseBody parses sequence of expressions as for Defun, Let, etc., and
// always returns a list, even if empty. It gobbles the close paren too.
//
private SymplExpr[] ParseBody(Lexer lexer, string error) {
Token token = lexer.GetToken();
List<SymplExpr> body = new List<SymplExpr>();
while (token != SyntaxToken.EOF && token != SyntaxToken.CloseParen) {
lexer.PutToken(token);
body.Add(ParseExprAux(lexer));
token = lexer.GetToken();
}
if (token == SyntaxToken.EOF) {
throw new SymplParseException(error);
}
return body.ToArray();
}
// _parseParams parses sequence of vars for Defuns and Lambdas, and always
// returns a list of IdTokens.
//
private IdOrKeywordToken[] ParseParams(Lexer lexer, string definer) {
Token token = lexer.GetToken();
if (token != SyntaxToken.Paren) {
throw new SymplParseException(
definer + " must have param list following name.");
}
lexer.PutToken(token);
return EnsureListOfIds(ParseList(lexer, "param list.").Elements, false,
definer + " params must be valid IDs.");
}
private SymplExpr ParseLambda(Lexer lexer) {
Token token = lexer.GetToken();
if (token != KeywordToken.Lambda) {
throw new SymplParseException("Internal: parsing Lambda?");
}
var parms = ParseParams(lexer, "Lambda");
var body = ParseBody(lexer, "Hit EOF in function body");
return new SymplLambdaExpr(parms, body);
}
private SymplExpr ParseDefun(Lexer lexer) {
Token token = lexer.GetToken();
if (token != KeywordToken.Defun) {
throw new SymplParseException("Internal: parsing Defun?");
}
IdOrKeywordToken name = lexer.GetToken() as IdOrKeywordToken;
if (name == null || name.IsKeywordToken) {
throw new SymplParseException(
"Defun must have an ID for name -- " + name.ToString());
}
var parms = ParseParams(lexer, "Defun");
var body = ParseBody(lexer, "Hit EOF in function body" +
name.Name);
return new SymplDefunExpr(name.Name, parms, body);
}
// _parseKeywordForm parses parenthetic built in forms such as defun, if,
// loop, etc.
//
private SymplExpr ParseKeywordForm(Lexer lexer) {
Token name = lexer.GetToken();
if (!(name is KeywordToken)) {
throw new SymplParseException(
"Internal error: parsing keyword form?");
}
lexer.PutToken(name);
if (name == KeywordToken.Import) {
return ParseImport(lexer);
} else if (name == KeywordToken.Defun) {
return ParseDefun(lexer);
} else if (name == KeywordToken.Lambda) {
return ParseLambda(lexer);
} else if (name == KeywordToken.Set) {
return ParseSet(lexer);
} else if (name == KeywordToken.LetStar) {
return ParseLetStar(lexer);
} else if (name == KeywordToken.Block) {
return ParseBlock(lexer);
} else if (name == KeywordToken.Eq) {
return ParseEq(lexer);
} else if (name == KeywordToken.Cons) {
return ParseCons(lexer);
} else if (name == KeywordToken.List) {
return ParseListCall(lexer);
} else if (name == KeywordToken.If) {
return ParseIf(lexer);
} else if (name == KeywordToken.New) {
return ParseNew(lexer);
} else if (name == KeywordToken.Loop) {
return ParseLoop(lexer);
} else if (name == KeywordToken.Break) {
return ParseBreak(lexer);
} else if (name == KeywordToken.Elt) {
return ParseElt(lexer);
} else if (name == KeywordToken.Add ||
name == KeywordToken.Substract ||
name == KeywordToken.Muliply ||
name == KeywordToken.Divide ||
name == KeywordToken.Equal ||
name == KeywordToken.NotEqual ||
name == KeywordToken.GreaterThan ||
name == KeywordToken.LessThan ||
name == KeywordToken.And ||
name == KeywordToken.Or) {
return ParseExprTreeBinaryOp(lexer);
} else if (name == KeywordToken.Not) {
return ParseExprTreeUnaryOp(lexer);
}
throw new SymplParseException(
"Internal: unrecognized keyword form?");
}
// first sub form must be expr resulting in callable, but if it is dotted expr,
// then eval the first N-1 dotted exprs and use invoke member or get member
// on last of dotted exprs so that the 2..N sub forms are the arguments to
// the invoke member. It's as if the call breaks into a block of a temp
// assigned to the N-1 dotted exprs followed by an invoke member (or a get
// member and call, which the runtime binder decides). The non-dotted expr
// simply evals to an object that better be callable with the supplied args,
// which may be none.
//
private SymplFunCallExpr ParseFunctionCall(Lexer lexer) {
// First sub expr is callable object or invoke member expr.
var fun = ParseExprAux(lexer);
if (fun is SymplDottedExpr) {
SymplDottedExpr dottedExpr = (SymplDottedExpr)fun;
// Keywords ok as members.
if (!(dottedExpr.Exprs.Last() is SymplIdExpr)) {
throw new SymplParseException(
"Function call with dotted expression for function must " +
"end with ID Expr, not member invoke." +
dottedExpr.Exprs.Last().ToString());
}
}
// Tail exprs are args.
var args = ParseBody(lexer, "Unexpected EOF in arg list for " +
fun.ToString());
return new SymplFunCallExpr(fun, args);
}
// (import id[.id]* [{id | (id [id]*)} [{id | (id [id]*)}]] )
// (import file-or-dotted-Ids name-or-list-of-members reanme-or-list-of)
//
private SymplExpr ParseImport(Lexer lexer) {
if (lexer.GetToken() != KeywordToken.Import) {
throw new SymplParseException(
"Internal: parsing Import call?");
}
IdOrKeywordToken[] ns_or_module = ParseImportNameOrModule(lexer);
IdOrKeywordToken[] members = ParseImportNames(lexer, "member names", true);
IdOrKeywordToken[] as_names = ParseImportNames(lexer, "renames", false);
if (members.Length != as_names.Length && as_names.Length != 0) {
throw new SymplParseException(
"Import as-names must be same form as member names.");
}
if (lexer.GetToken() != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Import must end with closing paren.");
}
return new SymplImportExpr(ns_or_module, members, as_names);
}
// Parses dotted namespaces or Sympl.Globals members to import.
//
private IdOrKeywordToken[] ParseImportNameOrModule(Lexer lexer) {
Token token = lexer.GetToken();
if (!(token is IdOrKeywordToken)) { // Keywords are ok here.
throw new SymplParseException(
"Id must follow Import symbol");
}
Token dot = lexer.GetToken();
List<IdOrKeywordToken> ns_or_module = new List<IdOrKeywordToken>();
if (dot == SyntaxToken.Dot) {
lexer.PutToken(dot);
var tmp = ParseDottedExpr(
lexer, new SymplIdExpr((IdOrKeywordToken)token));
foreach (var e in tmp.Exprs) {
if (!(e is SymplIdExpr)) { // Keywords are ok here.
throw new SymplParseException(
"Import targets must be dotted identifiers." +
e.ToString() + ns_or_module.ToString());
}
ns_or_module.Add(((SymplIdExpr)e).IdToken);
}
token = lexer.GetToken();
} else {
ns_or_module.Add((IdOrKeywordToken)token);
token = dot;
}
lexer.PutToken(token);
return ns_or_module.ToArray();
}
private SymplConsExpr ParseCons (Lexer lexr) {
var token = lexr.GetToken();
if (token != KeywordToken.Cons) {
throw new SymplParseException("Internal: parsing Cons?");
}
SymplExpr left, right;
ParseBinaryRuntimeCall(lexr, out left, out right);
return new SymplConsExpr(left, right);
}
// Parses list of member names to import from the object represented in the
// result of _parseImportNameOrModule, which will be a file module or object
// from Sympl.Globals. This is also used to parse the list of renames for
// these same members.
//
private IdOrKeywordToken[] ParseImportNames(Lexer lexer, string nameKinds,
bool allowKeywords) {
Token token = lexer.GetToken();
List<IdOrKeywordToken> names = new List<IdOrKeywordToken>();
if (token is IdOrKeywordToken) {
IdOrKeywordToken idToken = (IdOrKeywordToken)token;
if (!idToken.IsKeywordToken) {
names.Add(idToken);
}
} else if (token == SyntaxToken.Paren) {
lexer.PutToken(token);
object[] memberTokens = ParseList(lexer, "Import " + nameKinds + ".")
.Elements;
IdOrKeywordToken[] memberIdTokens =
EnsureListOfIds(memberTokens, allowKeywords,
"Import " + nameKinds + " must be valid IDs.");
} else if (token == SyntaxToken.CloseParen) {
lexer.PutToken(token);
} else {
throw new SymplParseException(
"Import takes dotted names, then member vars.");
}
return names.ToArray();
}
// _parseListCall parses a call to the List built-in keyword form that takes
// any number of arguments.
//
private SymplListCallExpr ParseListCall (Lexer lexr) {
Token token = lexr.GetToken();
if (token != KeywordToken.List) {
throw new SymplParseException("Internal: parsing List call?");
}
var args = ParseBody(lexr, "Unexpected EOF in arg list for call to List.");
return new SymplListCallExpr(args);
}
// _parseDottedExpr gathers infix dotted member access expressions. The
// object expression can be anything and is passed in via expr. Successive
// member accesses must be dotted identifier expressions or member invokes --
// a.b.(c 3).d. The member invokes cannot have dotted expressions for the
// member name such as a.(b.c 3).
//
private SymplDottedExpr ParseDottedExpr(Lexer lexer, SymplExpr objExpr) {
Token token = lexer.GetToken();
if (token != SyntaxToken.Dot) {
throw new SymplParseException(
"Internal: parsing dotted expressions?");
}
List<SymplExpr> exprs = new List<SymplExpr>();
token = lexer.GetToken();
while (token is IdOrKeywordToken || token == SyntaxToken.Paren) {
// Needs to be fun call or IDs
SymplExpr expr;
if (token is IdOrKeywordToken) {
// Keywords are ok as member names.
expr = new SymplIdExpr((IdOrKeywordToken)token);
} else {
lexer.PutToken(token);
expr = ParseForm(lexer);
SymplFunCallExpr funCall = expr as SymplFunCallExpr;
if (funCall != null || !(funCall.Function is SymplIdExpr)) {
throw new SymplParseException(
"Dotted expressions must be identifiers or " +
"function calls with identiers as the function " +
"value -- " + expr.ToString());
}
}
exprs.Add(expr);
token = lexer.GetToken();
if (token != SyntaxToken.Dot) {
break;
}
token = lexer.GetToken();
}
lexer.PutToken(token);
return new SymplDottedExpr(objExpr, exprs.ToArray());
}
// This parses pure list and atom structure. Atoms are IDs, strs, and nums.
// _parseLoop parses a loop expression, a sequence of exprs to
// execute in order, forever. See Break for returning expression's value.
//
private SymplLoopExpr ParseLoop (Lexer lexr) {
if (lexr.GetToken() != KeywordToken.Loop) {
throw new SymplParseException("Internal error: parsing Loop?");
}
var body = ParseBody(lexr, "Unexpected EOF in Loop.");
return new SymplLoopExpr(body);
}
// _parseSet parses a LHS expression and value expression. All analysis on
// the LHS is in etgen.py.
//
private SymplAssignExpr ParseSet(Lexer lexer) {
if (lexer.GetToken() != KeywordToken.Set) {
throw new SymplParseException("Internal error: parsing Set?");
}
var lhs = ParseExprAux(lexer);
var val = ParseExprAux(lexer);
if (lexer.GetToken() != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Expected close paren for Set expression.");
}
return new SymplAssignExpr(lhs, val);
}
// Parse a New form for creating instances of types. Second sub expr (one
// after kwd New) evals to a type.
//
// Consider adding a new kwd form generic-type-args that could be the third
// sub expr and take any number of sub exprs that eval to types. These could
// be used to specific concrete generic type instances. Without this support
// SymPL programmers need to open code this as the examples show.
//
private SymplNewExpr ParseNew(Lexer lexr) {
Token token = lexr.GetToken();
if (token != KeywordToken.New) {
throw new SymplParseException("Internal: parsing New?");
}
var type = ParseExprAux(lexr);
var args = ParseBody(lexr, "Unexpected EOF in arg list for call to New.");
return new SymplNewExpr(type, args);
}
// _parseLetStar parses (let* ((<var> <expr>)*) <body>).
//
private SymplLetStarExpr ParseLetStar(Lexer lexer) {
if (lexer.GetToken() != KeywordToken.LetStar) {
throw new SymplParseException("Internal error: parsing Let?");
}
var token = lexer.GetToken();
if (token != SyntaxToken.Paren) {
throw new SymplParseException(
"Let expression has no bindings? Missing '('.");
}
// Get bindings
List<LetBinding> bindings = new List<LetBinding>();
token = lexer.GetToken();
while (token == SyntaxToken.Paren) {
var e = ParseExprAux(lexer);
var id = e as SymplIdExpr;
if (id == null || id.IdToken.IsKeywordToken) {
throw new SymplParseException(
"Let binding must be (<ID> <expr>) -- ");
}
var init = ParseExprAux(lexer);
bindings.Add(new LetBinding(id.IdToken, init));
token = lexer.GetToken();
if (token != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Let binding missing close paren -- ");
}
token = lexer.GetToken();
}
if (token != SyntaxToken.CloseParen) {
throw new SymplParseException(
"Let bindings missing close paren.");
}
var body = ParseBody(lexer, "Unexpected EOF in Let.");
return new SymplLetStarExpr(bindings.ToArray(), body);
}
// This parses a BinaryOp expression.
//
private SymplBinaryExpr ParseExprTreeBinaryOp(Lexer lexr) {
KeywordToken keyword = lexr.GetToken() as KeywordToken;
if (keyword == null) {
throw new SymplParseException(
"Internal error: parsing Binary?");
}
SymplExpr left, right;
ParseBinaryRuntimeCall(lexr, out left, out right);
var op = GetOpType(keyword);
return new SymplBinaryExpr(left, right, op);
}
// _parseBlock parses a block expression, a sequence of exprs to
// execute in order, returning the last expression's value.
//
private SymplBlockExpr ParseBlock(Lexer lexer) {
if (lexer.GetToken() != KeywordToken.Block) {
throw new SymplParseException(
"Internal error: parsing Block?");
}
var body = ParseBody(lexer, "Unexpected EOF in Block.");
return new SymplBlockExpr(body);
}
// _parseForm parses a parenthetic form. If the first token after the paren
// is a keyword, then it something like defun, loop, if, try, etc. If the
// first sub expr is another parenthetic form, then it must be an expression
// that returns a callable object.
//
private SymplExpr ParseForm(Lexer lexer) {
Token token = lexer.GetToken();
if (token != SyntaxToken.Paren) {
throw new SymplParseException(
"List expression must start with '('.");
}
token = lexer.GetToken();
if (token is IdOrKeywordToken) {
lexer.PutToken(token);
if (token is KeywordToken) {
// Defun, Let*, Set, Import, ...
return ParseKeywordForm(lexer);
} else {
return ParseFunctionCall(lexer);
}
} else {
lexer.PutToken(token);
return ParseFunctionCall(lexer);
}
}
// _parseKeywordForm parses parenthetic built in forms such as defun, if,
// loop, etc.
//
private SymplExpr ParseKeywordForm(Lexer lexer)
{
Token name = lexer.GetToken();
if (!(name is KeywordToken))
{
throw new SymplParseException(
"Internal error: parsing keyword form?");
}
lexer.PutToken(name);
if (name == KeywordToken.Import)
{
return(ParseImport(lexer));
}
else if (name == KeywordToken.Defun)
{
return(ParseDefun(lexer));
}
else if (name == KeywordToken.Lambda)
{
return(ParseLambda(lexer));
}
else if (name == KeywordToken.Set)
{
return(ParseSet(lexer));
}
else if (name == KeywordToken.LetStar)
{
return(ParseLetStar(lexer));
}
else if (name == KeywordToken.Block)
{
return(ParseBlock(lexer));
}
else if (name == KeywordToken.Eq)
{
return(ParseEq(lexer));
}
else if (name == KeywordToken.Cons)
{
return(ParseCons(lexer));
}
else if (name == KeywordToken.List)
{
return(ParseListCall(lexer));
}
else if (name == KeywordToken.If)
{
return(ParseIf(lexer));
}
else if (name == KeywordToken.New)
{
return(ParseNew(lexer));
}
else if (name == KeywordToken.Loop)
{
return(ParseLoop(lexer));
}
else if (name == KeywordToken.Break)
{
return(ParseBreak(lexer));
}
else if (name == KeywordToken.Elt)
{
return(ParseElt(lexer));
}
else if (name == KeywordToken.Add ||
name == KeywordToken.Substract ||
name == KeywordToken.Muliply ||
name == KeywordToken.Divide ||
name == KeywordToken.Equal ||
name == KeywordToken.NotEqual ||
name == KeywordToken.GreaterThan ||
name == KeywordToken.LessThan ||
name == KeywordToken.And ||
name == KeywordToken.Or)
{
return(ParseExprTreeBinaryOp(lexer));
}
else if (name == KeywordToken.Not)
{
return(ParseExprTreeUnaryOp(lexer));
}
throw new SymplParseException(
"Internal: unrecognized keyword form?");
}