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Code Issues Releases Wiki Activity

Move parsing code into TreeBuilder, change lexing and parsing algorithms

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This commit is contained in:
Danila Fedorin
2017-07-27 12:53:58 -07:00
parent 78e2d50f89
commit f931b9f322
6 changed files with 153 additions and 162 deletions
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152
src/org/nwapw/abacus/tree/TreeNode.java
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@@ -11,158 +11,6 @@ import java.util.*;
*/
public abstract class TreeNode {
/**
* The lexer used to lex tokens.
*/
protected static Lexer<TokenType> lexer = new Lexer<TokenType>(){{
register(",", TokenType.COMMA);
register("\\+|-|\\*|/", TokenType.OP);
register("[0-9]+(\\.[0-9]+)?", TokenType.NUM);
register("[a-zA-Z]+", TokenType.WORD);
register("\\(", TokenType.OPEN_PARENTH);
register("\\)", TokenType.CLOSE_PARENTH);
}};
/**
* A map that maps operations to their precedence.
*/
protected static HashMap<String, Integer> precedenceMap = new HashMap<String, Integer>(){{
put("+", 0);
put("-", 0);
put("*", 1);
put("/", 1);
}};
/**
* A map that maps operations to their associativity.
*/
protected static HashMap<String, OperatorAssociativity> associativityMap =
new HashMap<String, OperatorAssociativity>() {{
put("+", OperatorAssociativity.LEFT);
put("-", OperatorAssociativity.LEFT);
put("*", OperatorAssociativity.LEFT);
put("/", OperatorAssociativity.LEFT);
}};
/**
* Comparator used to sort token types.
*/
protected static Comparator<TokenType> tokenSorter = Comparator.comparingInt(e -> e.priority);
/**
* Tokenizes a string, converting it into matches
* @param string the string to tokenize.
* @return the list of tokens produced.
*/
public static ArrayList<Match<TokenType>> tokenize(String string){
return lexer.lexAll(string, 0, tokenSorter);
}
/**
* Rearranges tokens into a postfix list, using Shunting Yard.
* @param source the source string.
* @param from the tokens to be rearranged.
* @return the resulting list of rearranged tokens.
*/
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);
TokenType matchType = match.getType();
if(matchType == TokenType.NUM || matchType == TokenType.WORD) {
output.add(match);
} else if(matchType == 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(matchType == TokenType.OPEN_PARENTH){
if(!output.isEmpty() && output.get(output.size() - 1).getType() == TokenType.WORD){
tokenStack.push(output.remove(output.size() - 1));
output.add(new Match<>(0, 0, TokenType.INTERNAL_FUNCTION_END));
}
tokenStack.push(match);
} else if(matchType == TokenType.CLOSE_PARENTH || matchType == TokenType.COMMA){
while(!tokenStack.empty() && tokenStack.peek().getType() != TokenType.OPEN_PARENTH){
output.add(tokenStack.pop());
}
if(tokenStack.empty()) return null;
if(matchType == TokenType.CLOSE_PARENTH){
tokenStack.pop();
if(!tokenStack.empty() && tokenStack.peek().getType() == TokenType.WORD) {
output.add(tokenStack.pop());
output.add(new Match<>(0, 0, TokenType.INTERNAL_FUNCTION_START));
}
}
}
}
while(!tokenStack.empty()){
if(!(tokenStack.peek().getType() == TokenType.OP)) return null;
output.add(tokenStack.pop());
}
return output;
}
/**
* Constructs a tree recursively from a list of tokens.
* @param source the source string.
* @param matches the list of tokens from the source string.
* @return the construct tree expression.
*/
public static TreeNode fromStringRecursive(String source, ArrayList<Match<TokenType>> matches){
if(matches.size() == 0) return null;
Match<TokenType> match = matches.remove(0);
TokenType matchType = match.getType();
if(matchType == TokenType.OP){
TreeNode right = fromStringRecursive(source, matches);
TreeNode left = fromStringRecursive(source, matches);
if(left == null || right == null) return null;
else return new OpNode(source.substring(match.getFrom(), match.getTo()), left, right);
} else if(matchType == TokenType.NUM){
return new NumberNode(Double.parseDouble(source.substring(match.getFrom(), match.getTo())));
} else if(matchType == TokenType.INTERNAL_FUNCTION_START){
if(matches.isEmpty() || matches.get(0).getType() != TokenType.WORD) return null;
Match<TokenType> stringName = matches.remove(0);
String functionName = source.substring(stringName.getFrom(), stringName.getTo());
FunctionNode node = new FunctionNode(functionName);
while(!matches.isEmpty() && matches.get(0).getType() != TokenType.INTERNAL_FUNCTION_END){
TreeNode argument = fromStringRecursive(source, matches);
if(argument == null) return null;
node.addChild(argument);
}
if(matches.isEmpty()) return null;
matches.remove(0);
return node;
}
return null;
}
/**
* Creates a tree node from a string.
* @param string the string to create a node from.
* @return the resulting tree.
*/
public static TreeNode fromString(String string){
ArrayList<Match<TokenType>> matches = tokenize(string);
if(matches == null) return null;
matches = intoPostfix(string, matches);
if(matches == null) return null;
Collections.reverse(matches);
return fromStringRecursive(string, matches);
}
public abstract <T> T reduce(Reducer<T> reducer);
}