Поиск SUBSTRING переписан на алгоритм Кнута-Моррриса-Пратта

src/main/java/ru/serega6531/packmate/utils/KMPStringSearcher.java

@@ -0,0 +1,62 @@
+package ru.serega6531.packmate.utils;
+
+import lombok.SneakyThrows;
+
+import java.io.StringReader;
+
+/**
+ * Based on <a href="https://github.com/twitter/elephant-bird/blob/master/core/src/main/java/com/twitter/elephantbird/util/StreamSearcher.java">StreamSearcher</a>
+ */
+public class KMPStringSearcher {
+
+    private char[] pattern;
+    private int[] borders;
+    private int lastEnd = 0;
+
+    public KMPStringSearcher(char[] pattern) {
+        setPattern(pattern);
+    }
+
+    public void setPattern(char[] pattern) {
+        this.pattern = pattern;
+        this.borders = new int[this.pattern.length + 1];
+        preProcess();
+    }
+
+    @SneakyThrows
+    public int search(StringReader reader) {
+        int bytesRead = 0;
+
+        int b;
+        int j = 0;
+
+        while ((b = reader.read()) != -1) {
+            bytesRead++;
+
+            while (j >= 0 && (char)b != pattern[j]) {
+                j = borders[j];
+            }
+            ++j;
+
+            if (j == pattern.length) {
+                lastEnd += bytesRead;
+                return lastEnd;
+            }
+        }
+
+        return -1;
+    }
+
+    private void preProcess() {
+        int i = 0;
+        int j = -1;
+        borders[i] = j;
+        while (i < pattern.length) {
+            while (j >= 0 && pattern[i] != pattern[j]) {
+                j = borders[j];
+            }
+            borders[++i] = ++j;
+        }
+    }
+
+}