1 files changed, 141 insertions, 0 deletions
diff --git a/linguistics/src/main/java/com/yahoo/language/process/SpecialTokens.java b/linguistics/src/main/java/com/yahoo/language/process/SpecialTokens.java
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+++ b/linguistics/src/main/java/com/yahoo/language/process/SpecialTokens.java
@@ -0,0 +1,141 @@
+// Copyright Verizon Media. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.language.process;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Objects;
+import java.util.stream.Collectors;
+
+import static com.yahoo.language.LinguisticsCase.toLowerCase;
+
+/**
+ * An immutable list of special tokens - strings which should override the normal tokenizer semantics
+ * and be tokenized into a single token. Special tokens are case insensitive.
+ *
+ * @author bratseth
+ */
+public class SpecialTokens {
+
+    private static final SpecialTokens empty = new SpecialTokens("(empty)", List.of());
+
+    private final String name;
+    private final int maximumLength;
+    private final List<Token> tokens;
+    private final Map<String, String> tokenMap;
+
+    public SpecialTokens(String name,  List<Token> tokens) {
+        tokens.stream().peek(token -> token.validate());
+        List<Token> mutableTokens = new ArrayList<>(tokens);
+        Collections.sort(mutableTokens);
+        this.name = name;
+        this.maximumLength = tokens.stream().mapToInt(token -> token.token().length()).max().orElse(0);
+        this.tokens = List.copyOf(mutableTokens);
+        this.tokenMap = tokens.stream().collect(Collectors.toUnmodifiableMap(t -> t.token(), t -> t.replacement()));
+    }
+
+    /** Returns the name of this special tokens list */
+    public String name() {
+        return name;
+    }
+
+    /**
+     * Returns the tokens of this as an immutable map from token to replacement.
+     * Tokens which do not have a replacement token maps to themselves.
+     */
+    public Map<String, String> asMap() { return tokenMap; }
+
+    /**
+     * Returns the special token starting at the start of the given string, or null if no
+     * special token starts at this string
+     *
+     * @param string the string to search for a special token at the start position
+     * @param substring true to allow the special token to be followed by a character which does not
+     *        mark the end of a token
+     */
+    public Token tokenize(String string, boolean substring) {
+        // XXX detonator pattern token.length may be != the length of the
+        // matching data in string, ref caseIndependentLength(String)
+        String input = toLowerCase(string.substring(0, Math.min(string.length(), maximumLength)));
+        for (Iterator<Token> i = tokens.iterator(); i.hasNext();) {
+            Token special = i.next();
+
+            if (input.startsWith(special.token())) {
+                if (string.length() == special.token().length() || substring || tokenEndsAt(special.token().length(), string))
+                    return special;
+            }
+        }
+        return null;
+    }
+
+    private boolean tokenEndsAt(int position, String string) {
+        return !Character.isLetterOrDigit(string.charAt(position));
+    }
+
+    public static SpecialTokens empty() { return empty; }
+
+    /** An immutable special token */
+    public final static class Token implements Comparable<Token> {
+
+        private final String token;
+        private final String replacement;
+
+        /** Creates a special token */
+        public Token(String token) {
+            this(token, null);
+        }
+
+        /** Creates a special token which will be represented by the given replacement token */
+        public Token(String token, String replacement) {
+            this.token = toLowerCase(token);
+            if (replacement == null || replacement.trim().equals(""))
+                this.replacement = this.token;
+            else
+                this.replacement = toLowerCase(replacement);
+        }
+
+        /** Returns the special token */
+        public String token() { return token; }
+
+        /** Returns the token to replace occurrences of this by, which equals token() unless this has a replacement. */
+        public String replacement() { return replacement; }
+
+        @Override
+        public int compareTo(Token other) {
+            if (this.token().length() < other.token().length()) return 1;
+            if (this.token().length() == other.token().length()) return 0;
+            return -1;
+        }
+
+        @Override
+        public boolean equals(Object other) {
+            if (other == this) return true;
+            if ( ! (other instanceof Token)) return false;
+            return Objects.equals(this.token, ((Token)other).token);
+        }
+
+        @Override
+        public int hashCode() { return token.hashCode(); }
+
+        @Override
+        public String toString() {
+            return "token '" + token + "'" + (replacement.equals(token) ? "" : " replacement '" + replacement + "'");
+        }
+
+        private void validate() {
+            // XXX not fool proof length test, should test codepoint by codepoint for mixed case user input? not even that will necessarily be 100% robust...
+            String asLow = toLowerCase(token);
+            // TODO: Put along with the global toLowerCase
+            String asHigh = token.toUpperCase(Locale.ENGLISH);
+            if (asLow.length() != token.length() || asHigh.length() != token.length()) {
+                throw new IllegalArgumentException("Special token '" + token + "' has case sensitive length. " +
+                                                   "Please report this to the Vespa team.");
+            }
+        }
+
+    }
+
+}