1 files changed, 50 insertions, 0 deletions
diff --git a/container-search/src/main/java/com/yahoo/search/yql/CaseInsensitiveInputStream.java b/container-search/src/main/java/com/yahoo/search/yql/CaseInsensitiveInputStream.java
new file mode 100644
index 00000000000..e15fe04bb39
--- /dev/null
+++ b/container-search/src/main/java/com/yahoo/search/yql/CaseInsensitiveInputStream.java
@@ -0,0 +1,50 @@
+// Copyright 2016 Yahoo Inc. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.search.yql;
+
+import org.antlr.v4.runtime.ANTLRInputStream;
+import org.antlr.v4.runtime.CharStream;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+/**
+ * Enable ANTLR to do case insensitive comparisons when reading from files without throwing away the case in the token.
+ */
+class CaseInsensitiveInputStream extends ANTLRInputStream {
+
+    public CaseInsensitiveInputStream() {
+        super();
+    }
+
+    public CaseInsensitiveInputStream(InputStream input) throws IOException {
+        super(input);
+    }
+
+    public CaseInsensitiveInputStream(InputStream input, int size) throws IOException {
+        super(input, size);
+    }
+    
+    public CaseInsensitiveInputStream(char[] data, int numberOfActualCharsInArray) throws IOException {
+        super(data, numberOfActualCharsInArray);
+    }
+    
+    public CaseInsensitiveInputStream(String input) throws IOException {
+        super(input);
+    }
+
+    @Override
+    public int LA(int i) {
+        if (i == 0) {
+            return 0;
+        }
+        if (i < 0) {
+            i++; // e.g., translate LA(-1) to use offset 0
+        }
+
+        if ((p + i - 1) >= n) {
+            return CharStream.EOF;
+        }
+        return Character.toLowerCase(data[p + i - 1]);
+    }
+
+}