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Code Issues Releases Wiki Activity

Implement the negation operator.

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This commit is contained in:
Danila Fedorin
2017-08-02 11:26:59 -07:00
parent 9713f24ed2
commit d964fbfb6f
3 changed files with 30 additions and 6 deletions
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17
src/main/java/org/nwapw/abacus/parsing/ShuntingYardParser.java
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@@ -55,9 +55,12 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
public List<Match<TokenType>> intoPostfix(List<Match<TokenType>> from) {
ArrayList<Match<TokenType>> output = new ArrayList<>();
Stack<Match<TokenType>> tokenStack = new Stack<>();
TokenType previousType;
TokenType matchType = null;
while (!from.isEmpty()) {
Match<TokenType> match = from.remove(0);
TokenType matchType = match.getType();
previousType = matchType;
matchType = match.getType();
if (matchType == TokenType.NUM) {
output.add(match);
} else if (matchType == TokenType.FUNCTION) {
@@ -74,7 +77,13 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
continue;
}
while (!tokenStack.empty()) {
if(tokenString.equals("-") && (previousType == null || previousType == TokenType.OP ||
previousType == TokenType.OPEN_PARENTH)){
from.add(0, new Match<>("`", TokenType.OP));
continue;
}
while (!tokenStack.empty() && type == OperatorType.BINARY_INFIX) {
Match<TokenType> otherMatch = tokenStack.peek();
TokenType otherMatchType = otherMatch.getType();
if (!(otherMatchType == TokenType.OP || otherMatchType == TokenType.FUNCTION)) break;
@@ -103,8 +112,8 @@ public class ShuntingYardParser implements Parser<Match<TokenType>>, PluginListe
}
while (!tokenStack.empty()) {
Match<TokenType> match = tokenStack.peek();
TokenType matchType = match.getType();
if (!(matchType == TokenType.OP || matchType == TokenType.FUNCTION)) return null;
TokenType newMatchType = match.getType();
if (!(newMatchType == TokenType.OP || newMatchType == TokenType.FUNCTION)) return null;
output.add(tokenStack.pop());
}
return output;