//-------------------------------------------------------------------
// 8. statement = BEGIN block END
// | lvalue ASSIGN expr
// | READ LPAREN idList RPAREN
// | WRITE LPAREN exprList RPAREN
// | IF expr THEN statement (ELSE statement)?
// | WHILE expr DO statement
// | EXIT
//-------------------------------------------------------------------
public static void statement() {
//statement = BEGIN block END
if (token.type.name().equals("beginTK")) {
token = next();
block();
if (token.type.name().equals("endTK")) {
token = next();
} else {
error("END keyword expected after block");
}
// statement = lvalue ASSIGN expr // lvalue = ID args
} else if (token.type.name().equals("identifierTK")) {
lvalue();
if (token.type.name().equals("assignTK")) {
token = next();
expr();
} else {
error("Assignment operator expected after lvalue");
}
// statement = READ LPAREN idList RPAREN
} else if (token.type.name().equals("readTK")) {
token = next();
if (token.type.name().equals("lparenTK")) {
token = next();
idList();
if (token.type.name().equals("rparenTK")) {
token = next();
} else {
error("Right parenthesis expected after idList in READ statement");
}
} else {
error("Left parenthesis expected before idList in READ statement");
}
// statement = WRITE LPAREN exprList RPAREN
} else if (token.type.name().equals("writeTK")) {
token = next();
if (token.type.name().equals("lparenTK")) {
token = next();
exprList();
if (token.type.name().equals("rparenTK")) {
token = next();
} else {
error("Right parenthesis expected after exprList in WRITE statement");
}
} else {
error("Left parenthesis expected before exprList in WRITE statement");
}
//statement = IF expr THEN statement (ELSE statement)?
} else if (token.type.name().equals("ifTK")) {
token = next();
expr();
if (token.type.name().equals("thenTK")) {
token = next();
statement();
if (token.type.name().equals("elseTK")) {
token = next();
statement();
}
} else {
error("THEN keyword expected after IF expression");
}
//statement = WHILE expr DO statement
} else if (token.type.name().equals("whileTK")) {
token = next();
expr();
if (token.type.name().equals("doTK")) {
token = next();
statement();
} else {
error("DO keyword expected after WHILE expression");
}
//statement = EXIT
} else if (token.type.name().equals("exitTK")) {
token = next();
}
}

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