Created
June 17, 2019 03:34
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Ajajha
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| package com.dkc.pp.util; | |
| import android.support.annotation.NonNull; | |
| import java.util.ArrayList; | |
| import java.util.List; | |
| import java.util.Map; | |
| public class BooleanPredicateProcessor { | |
| private boolean isNumeric(String text) { | |
| for (int i = 0; i < text.length(); i++) { | |
| char c = text.charAt(i); | |
| if (c < '0' || c > '9') { | |
| return false; | |
| } | |
| } | |
| return true; | |
| } | |
| String[] processArithmetic(String[] pieces) { | |
| for (int i = 2; i < pieces.length; i++) { | |
| if (pieces[i-1].equals("+")) { | |
| int left = Integer.parseInt(pieces[i-2]); | |
| int right = Integer.parseInt(pieces[i]); | |
| pieces[i] = Integer.toString(left + right); | |
| pieces[i-1] = null; | |
| pieces[i-2] = null; | |
| } | |
| else if (pieces[i-1].equals("-")) { | |
| int left = Integer.parseInt(pieces[i-2]); | |
| int right = Integer.parseInt(pieces[i]); | |
| pieces[i] = Integer.toString(left - right); | |
| pieces[i-1] = null; | |
| pieces[i-2] = null; | |
| } | |
| } | |
| List<String> withoutNulls = new ArrayList<>(pieces.length); | |
| for (String piece : pieces) { | |
| if (piece != null) withoutNulls.add(piece); | |
| } | |
| return withoutNulls.toArray(new String[0]); | |
| } | |
| public boolean processPredicate(String predicate, Map<String, Integer> variables) { | |
| String[] pieces = resolveVariables(predicate, variables); | |
| pieces = processArithmetic(pieces); | |
| String operation = pieces[1]; | |
| int leftOperand = Integer.parseInt(pieces[0]); | |
| int rightOperand = Integer.parseInt(pieces[2]); | |
| switch (operation) { | |
| case "<": | |
| return leftOperand < rightOperand; | |
| case ">": | |
| return leftOperand > rightOperand; | |
| case ">=": | |
| return leftOperand >= rightOperand; | |
| case "<=": | |
| return leftOperand <= rightOperand; | |
| case "==": | |
| return leftOperand == rightOperand; | |
| default: | |
| throw new RuntimeException(String.format("Listen you mother fucker, I'm not interested in that operation. Take your %s and fuck off!", operation)); | |
| } | |
| } | |
| @NonNull | |
| private String[] resolveVariables(String predicate, Map<String, Integer> variables) { | |
| String[] pieces = predicate.split(" "); | |
| for (int i = 0; i < pieces.length; i++) { | |
| if (variables.containsKey(pieces[i])) { | |
| pieces[i] = variables.get(pieces[i]).toString(); | |
| } | |
| else if (!isNumeric(pieces[i]) && !isAnOperator(pieces[i])) { | |
| throw new RuntimeException(String.format("Unable to resolve variable for string = '%s'", pieces[i])); | |
| } | |
| } | |
| return pieces; | |
| } | |
| private boolean isAnOperator(String piece) { | |
| switch (piece) { | |
| case "<": | |
| case ">": | |
| case ">=": | |
| case "<=": | |
| case "==": | |
| case "+": | |
| case "-": | |
| return true; | |
| default: | |
| return false; | |
| } | |
| } | |
| } |
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