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Code Issues Releases Wiki Activity

Implement Shunting Yard.

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Danila Fedorin 2017-07-25 13:53:38 -07:00
parent 043d02ead2
commit 3684673362
1 changed files with 85 additions and 0 deletions
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src/org/nwapw/abacus/tree/TreeNode.java Normal file
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package org.nwapw.abacus.tree;
import org.nwapw.abacus.lexing.Lexer;
import org.nwapw.abacus.lexing.pattern.Match;
import java.util.*;
public abstract class TreeNode {
private static Lexer<TokenType> lexer = new Lexer<TokenType>(){{
register(".", TokenType.ANY);
register("\\+|-|\\*|/|^", TokenType.OP);
register("[0-9]+(\\.[0-9]+)?", TokenType.NUM);
register("[a-zA-Z]+", TokenType.WORD);
register("\\(", TokenType.OPEN_PARENTH);
register("\\)", TokenType.CLOSE_PARENTH);
}};
private static HashMap<String, Integer> precedenceMap = new HashMap<String, Integer>(){{
put("+", 0);
put("-", 0);
put("*", 1);
put("/", 1);
put("^", 2);
}};
private static HashMap<String, OperatorAssociativity> associativityMap =
new HashMap<String, OperatorAssociativity>() {{
put("+", OperatorAssociativity.LEFT);
put("-", OperatorAssociativity.LEFT);
put("*", OperatorAssociativity.LEFT);
put("/", OperatorAssociativity.LEFT);
put("^", OperatorAssociativity.RIGHT);
}};
private static Comparator<TokenType> tokenSorter = Comparator.comparingInt(e -> e.priority);
public static ArrayList<Match<TokenType>> tokenize(String string){
return lexer.lexAll(string, 0, tokenSorter);
}
public static ArrayList<Match<TokenType>> intoPostfix(String source, ArrayList<Match<TokenType>> from){
ArrayList<Match<TokenType>> output = new ArrayList<>();
Stack<Match<TokenType>> tokenStack = new Stack<>();
while(!from.isEmpty()){
Match<TokenType> match = from.remove(0);
if(match.getType() == TokenType.NUM) {
output.add(match);
} else if(match.getType() == TokenType.OP){
String tokenString = source.substring(match.getFrom(), match.getTo());
int precedence = precedenceMap.get(tokenString);
OperatorAssociativity associativity = associativityMap.get(tokenString);
while(!tokenStack.empty()) {
Match<TokenType> otherMatch = tokenStack.peek();
if(otherMatch.getType() != TokenType.OP) break;
int otherPrecdence = precedenceMap.get(source.substring(otherMatch.getFrom(), otherMatch.getTo()));
if(otherPrecdence < precedence ||
(associativity == OperatorAssociativity.RIGHT && otherPrecdence == precedence)) {
break;
}
output.add(tokenStack.pop());
}
tokenStack.push(match);
} else if(match.getType() == TokenType.OPEN_PARENTH){
tokenStack.push(match);
} else if(match.getType() == TokenType.CLOSE_PARENTH){
while(!tokenStack.empty() && tokenStack.peek().getType() != TokenType.OPEN_PARENTH){
output.add(tokenStack.pop());
}
if(tokenStack.empty()) return null;
tokenStack.pop();
}
}
while(!tokenStack.empty()){
if(!(tokenStack.peek().getType() == TokenType.OP)) return null;
output.add(tokenStack.pop());
}
return output;
}
public static TreeNode fromString(String string){
return null;
}
}