/// <summary>
/// Parameter ::= Type Identifier.
/// </summary>
/// <param name="stop"></param>
/// <returns></returns>
private FIELD parseParameter()
{
Token token;
// Parameter ::= Type Identifier.
FIELD result = null;
string name = null;
TYPE parType = parseType();
if ( parType == null ) errors.issue(null,15); // incorrect type
token = lexer.get();
if ( token.code == TokenCode.IDENTIFIER )
{
name = token.image;
lexer.forget();
result = new FIELD(0,name);
result.type = parType;
result.isStatic = false;
}
else
{
errors.issue(token,11,"identifier");
lexer.skipUntil(TokenCode.RPAREN);
result = new FIELD(0,"");
}
result.isParameter = true;
return result;
}
/// <summary>
/// FieldDeclaration ::= [Visibility] ["static"] Type Identifier ";".
///
/// MethodDeclaration ::= [Visibility] ["static"] ("void" | Type) Identifier
/// "("[Parameter {"," Parameter}] ")" Body.
///
/// Visibility ::= "private" | "public" | "private".
///
/// Parameter ::= Type Identifier.
///
/// Body ::= "{" {LocalDeclaration} {Statement} "}".
///
/// LocalDeclaration ::= Type Identifier ";".
/// </summary>
/// <returns></returns>
private DECLARATION parseMethodOrField()
{
int v = 0;
bool s = false;
string name = null;
Token token = lexer.get();
if ( token.code == TokenCode.RBRACE ) // end of class methods
{
lexer.forget();
return null;
}
switch ( token.code )
{
case TokenCode.PUBLIC : v = 0; lexer.forget(); break;
case TokenCode.PRIVATE : v = 1; lexer.forget(); break;
case TokenCode.PROTECTED : v = 2; lexer.forget(); break;
default: v = 0; break;
}
token = lexer.get();
if ( token.code == TokenCode.STATIC ) { s = true; lexer.forget(); }
TYPE type = null;
token = lexer.get();
if ( token.code == TokenCode.VOID )
lexer.forget();
else
type = parseType();
token = lexer.get();
if ( token.code == TokenCode.IDENTIFIER )
{
name = token.image;
lexer.forget();
}
else
errors.issue(token,11,"identifier");
token = lexer.get();
if ( token.code == TokenCode.SEMICOLON )
{
// End of field declaration
lexer.forget();
if ( type == null ) errors.issue(token,14); // void in field declaration
FIELD field = new FIELD(v,name);
field.type = type;
field.isStatic = s;
return field;
}
// Else this is a method declaration.
METHOD method = new METHOD(v, name);
method.isStatic = s;
method.type = type;
if ( name == "Main" )
{
if ( hasMain ) errors.issue(token,32); // multiple Main's
else hasMain =true;
}
// Continue parsing:
// "(" [ Parameter {"," Parameter} ] ")" Body
token = lexer.get();
if ( token.code != TokenCode.LPAREN )
{
errors.issue(token,11,"(");
lexer.skipUntil(TokenCode.RPAREN);
}
else
lexer.forget();
int i = 0;
while ( true ) // parsing method parameters
{
token = lexer.get();
if ( token.code == TokenCode.RPAREN ) { lexer.forget(); break; }
FIELD parameter = parseParameter();
string n = parameter.name;
if ( method.parameters.ContainsKey(n) )
errors.issue(token,12,"parameter",n);
else
{
parameter.number = i;
i++;
method.parameters.Add(n,parameter);
}
token = lexer.get();
if (token.code == TokenCode.COMMA)
{
lexer.forget();
continue;
}
else if (token.code != TokenCode.RPAREN)
{
errors.issue(token,16);
lexer.skipUntil(TokenCode.RPAREN);
lexer.forget();
break;
}
}
// Parsing method body:
//
// Body ::= "{" {LocalDeclaration} {Statement} "}".
token = lexer.get();
if ( token.code == TokenCode.LBRACE ) lexer.forget();
else lexer.skipUntil(TokenCode.RBRACE);
int j = 0;
while ( true )
{
token = lexer.get();
if ( token.code == TokenCode.RBRACE ) { lexer.forget(); break; }
ENTITY bodyElement = parseBodyElement();
if ( bodyElement == null ) // and error was detected
continue;
else if ( bodyElement is FIELD )
{
(bodyElement as FIELD).isLocal = true;
string n = (bodyElement as FIELD).name;
if ( method.locals.ContainsKey(n) )
errors.issue(token,12,"local",n);
else
{
(bodyElement as FIELD).number = j;
j++;
method.locals.Add(n,bodyElement as FIELD);
}
}
else if ( bodyElement is STATEMENT )
method.statements.Add(bodyElement as STATEMENT);
}
return method;
}
/// <summary>
/// Body ::= "{" {LocalDeclaration} {Statement} "}".
///
/// Statement ::= Assignment
/// | IfStatement
/// | WhileStatement
/// | ReturnStatement
/// | CallStatement
/// | PrintStatement
/// | Block
/// </summary>
/// <returns></returns>
private ENTITY parseBodyElement()
{
Token token = lexer.get();
switch ( token.code )
{
case TokenCode.IF :
{
// IfStatement ::= "if" "(" Relation ")" Statement ["else" Statement].
IF ifStmt = new IF();
lexer.forget();
token = lexer.get();
if ( token.code != TokenCode.LPAREN )
lexer.skipUntil(TokenCode.RPAREN);
else
{
lexer.forget();
ifStmt.relation = parseRelation();
}
token = lexer.get();
if ( token.code == TokenCode.RPAREN ) lexer.forget();
else lexer.skipUntil(TokenCode.RPAREN);
ifStmt.thenPart = parseBodyElement() as STATEMENT;
token = lexer.get();
if ( token.code == TokenCode.ELSE )
{
lexer.forget();
ifStmt.elsePart = parseBodyElement() as STATEMENT;
}
return ifStmt;
}
case TokenCode.WHILE:
{
// WhileStatement ::= "while" "(" Relation ")" Statement .
WHILE whileStmt = new WHILE();
lexer.forget();
token = lexer.get();
if ( token.code != TokenCode.LPAREN )
{
errors.issue(token,20);
lexer.skipUntil(TokenCode.RPAREN);
}
else
{
lexer.forget();
whileStmt.relation = parseRelation();
}
token = lexer.get();
if ( token.code == TokenCode.RPAREN ) lexer.forget();
else lexer.skipUntil(TokenCode.RPAREN);
whileStmt.body = parseBodyElement() as STATEMENT;
return whileStmt;
}
case TokenCode.RETURN:
{
// ReturnStatement ::= "return" [Expression] ";"
RETURN returnStmt = new RETURN();
lexer.forget();
token = lexer.get();
if ( token.code == TokenCode.SEMICOLON )
lexer.forget();
else
{
returnStmt.result = parseExpression();
token = lexer.get();
if ( token.code != TokenCode.SEMICOLON )
lexer.skipUntil(TokenCode.SEMICOLON);
lexer.forget();
}
return returnStmt;
}
case TokenCode.PRINT:
{
// PrintStatement ::= "print" "(" Expression ")" ";".
PRINT print = new PRINT();
lexer.forget();
token = lexer.get();
if ( token.code != TokenCode.LPAREN ) goto Error;
lexer.forget();
print.value = parseExpression();
token = lexer.get();
if ( token.code != TokenCode.RPAREN ) goto Error;
lexer.forget();
token = lexer.get();
if ( token.code != TokenCode.SEMICOLON ) goto Error;
lexer.forget();
return print;
Error:
errors.issue(token,19);
lexer.skipUntil(TokenCode.SEMICOLON);
lexer.forget();
return null;
}
case TokenCode.LBRACE:
{
// Block ::= "{" {Statement} "}".
lexer.forget();
BLOCK block = new BLOCK();
while ( true )
{
STATEMENT statement = parseBodyElement() as STATEMENT;
if ( statement == null ) break;
block.statements.Add(statement);
}
token = lexer.get();
if ( token.code != TokenCode.RBRACE ) lexer.skipUntil(TokenCode.RBRACE);
lexer.forget();
return block;
}
case TokenCode.INT:
{
// int x;
// int[] x;
bool isArray = false;
lexer.forget();
token = lexer.get();
if ( token.code == TokenCode.LBRACKET )
{
isArray = true;
lexer.forget();
token = lexer.get();
if ( token.code != TokenCode.RBRACKET )
{
errors.issue(token,17);
lexer.skipUntil(TokenCode.SEMICOLON);
return null;
}
else
lexer.forget();
}
string fname = "";
token = lexer.get();
if ( token.code != TokenCode.IDENTIFIER )
{
errors.issue(token,17);
lexer.skipUntil(TokenCode.SEMICOLON);
return null;
}
else
{
fname = token.image;
lexer.forget();
}
token = lexer.get();
if ( token.code != TokenCode.SEMICOLON ) lexer.skipUntil(TokenCode.SEMICOLON);
lexer.forget();
TYPE type = new TYPE();
type.classRef = null;
type.className = "int";
type.isArray = isArray;
FIELD local = new FIELD(0,fname);
local.type = type;
local.isLocal = true;
return local;
}
case TokenCode.IDENTIFIER:
{
// Assignment ::= Identifier ["." Identifier | "[" Expression "]" ] "=" Expression ";"
//
// CallStatement ::= Identifier ["." Identifier] "(" [Expression {"," Expression}]")" ";".
//
// LocalDeclaration ::= Type Identifier ";".
ENTITY result = null;
NAME name = parseName();
if ( name == null ) // An error was detected
{
lexer.skipUntil(TokenCode.SEMICOLON);
return null;
}
// After that goes either assignment of left parenthesis.
token = lexer.get();
if ( token.code == TokenCode.ASSIGN )
{
lexer.forget();
EXPRESSION rightSide = parseExpression();
ASSIGNMENT assignment = new ASSIGNMENT();
assignment.name = name;
assignment.expression = rightSide;
result = assignment;
}
else if ( token.code == TokenCode.LPAREN )
{
lexer.forget();
CALL call = new CALL();
call.name = name;
while ( true )
{
token = lexer.get();
if ( token.code == TokenCode.RPAREN ) { lexer.forget(); break; }
call.arguments.Add(parseExpression());
token = lexer.get();
if ( token.code == TokenCode.COMMA )
{
lexer.forget();
continue;
}
else if ( token.code != TokenCode.RPAREN )
{
errors.issue(token,18);
lexer.skipUntil(TokenCode.SEMICOLON);
return null;
}
}
result = call;
}
else if ( token.code == TokenCode.IDENTIFIER )
{
// Dont't forget()
// A local declaration?
// -- Converting NAME to TYPE
TYPE type = new TYPE();
type.className = name.name;
type.isArray = name is ARRAY_ELEM;
FIELD local = new FIELD(0,token.image);
local.type = type;
result = local;
lexer.forget();
}
token = lexer.get();
if ( token.code != TokenCode.SEMICOLON )
{
errors.issue(token,19);
lexer.skipUntil(TokenCode.SEMICOLON);
}
lexer.forget();
return result;
}
case TokenCode.RBRACE :
// End of method body
// Don't forget().
return null;
default :
errors.issue(token,17);
lexer.skipUntil(TokenCode.SEMICOLON);
lexer.forget();
return null;
}
}
private void generateLocal( ILGenerator il, FIELD field )
{
TYPE t = field.type;
Type type = null;
if ( t.classRef == null )
{
if ( t.isArray ) type = typeof(int[]); else type = typeof(int);
}
else
{
type = classes[t.className].typeBuilder;
if ( t.isArray ) type = type.MakeArrayType();
}
LocalBuilder local = il.DeclareLocal(type);
if ( t.classRef == null )
{
if ( t.isArray ) il.Emit(OpCodes.Ldnull);
else il.Emit(OpCodes.Ldc_I4_0);
}
else
il.Emit(OpCodes.Ldnull);
il.Emit(OpCodes.Stloc,local);
}
