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package com.jantuomi.interpreter.main.core.parser;
import com.jantuomi.interpreter.main.core.parser.ast.*;
import com.jantuomi.interpreter.main.core.tokenizer.token.Token;
import com.jantuomi.interpreter.main.utils.Counter;
import java.util.ArrayList;
import java.util.List;
/**
* Created by jan on 11.6.2016.
*/
public class Parser {
private static final Parser instance = new Parser();
private List<Token> tokens;
private List<ASTNode> statementSequence;
public static Parser getInstance() {
return instance;
}
private Parser() {
}
public List<ASTNode> parse(List<Token> tokens) {
this.tokens = tokens;
this.statementSequence = new ArrayList<>();
Counter c = new Counter();
while (c.getValue() < tokens.size()) {
AssignmentNode asn = expectAssignmentRoutine(c);
if (asn != null) {
statementSequence.add(asn);
continue;
}
AdditionNode adn = expectAdditionRoutine(c);
if (adn != null) {
statementSequence.add(adn);
continue;
}
}
return statementSequence;
}
public AssignmentNode expectAssignmentRoutine(Counter c) {
Counter d = c.clone();
SymbolNode lhs = expectLHS(d);
if (lhs == null) {
return null;
}
boolean isAssign = expectAssignmentAndAdvance(d);
if (!isAssign) {
return null;
}
ExpressionNode rhs = expectRHS(d);
if (rhs == null) {
return null;
}
AssignmentNode an = new AssignmentNode(lhs, rhs);
c.setValue(d.getValue());
return an;
}
public SymbolNode expectLHS(Counter c) {
SymbolNode sn = parseSymbolAndAdvance(c);
if (sn != null) {
return sn;
}
return null;
}
public ExpressionNode expectRHS(Counter c) {
ExpressionNode en = expectExpression(c);
if (en != null) {
return en;
}
return null;
}
private ExpressionNode expectExpression(Counter c) {
Counter d = c.clone();
AdditionNode an = expectAdditionRoutine(d);
if (an != null) {
c.setValue(d.getValue());
return an;
}
IntegerLiteralNode in = parseIntegerLiteralAndAdvance(d);
if (in != null) {
c.setValue(d.getValue());
return in;
}
SymbolNode sn = parseSymbolAndAdvance(d);
if (sn != null) {
c.setValue(d.getValue());
return sn;
}
return null;
}
private AdditionNode expectAdditionRoutine(Counter c) {
Counter d = c.clone();
ExpressionNode lhs = expectLHS(d);
if (lhs == null) {
return null;
}
boolean isAddition = expectAdditionAndAdvance(d);
if (!isAddition) {
return null;
}
ExpressionNode rhs = expectRHS(d);
if (rhs == null) {
return null;
}
AdditionNode an = new AdditionNode(lhs, rhs);
c.setValue(d.getValue());
return an;
}
private boolean expectAdditionAndAdvance(Counter c) {
if (tokens.get(c.getValue()).is(Token.Type.AdditionToken)) {
c.advance();
return true;
} else {
return false;
}
}
private IntegerLiteralNode parseIntegerLiteralAndAdvance(Counter c) {
if (tokens.get(c.getValue()).is(Token.Type.IntegerLiteralToken)) {
IntegerLiteralNode in = new IntegerLiteralNode(tokens.get(c.getValue()));
c.advance();
return in;
} else {
return null;
}
}
public boolean expectAssignmentAndAdvance(Counter c) {
if (tokens.get(c.getValue()).is(Token.Type.AssignmentToken)) {
c.advance();
return true;
} else {
return false;
}
}
public SymbolNode parseSymbolAndAdvance(Counter c) {
if (tokens.get(c.getValue()).is(Token.Type.SymbolToken)) {
SymbolNode sn = new SymbolNode(tokens.get(c.getValue()));
c.advance();
return sn;
} else {
return null;
}
}
public void printTree(ASTNode e) {
System.out.println("### Tree begin ###");
e.print(0);
System.out.println("### Tree end ###");
}
}
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