CharacterSet.negate()

Author: fluentfuture

dot-parse/src/main/java/com/google/common/labs/parse/CharacterSet.java

@@ -2,9 +2,13 @@
 
 import static com.google.common.labs.parse.Utils.checkArgument;
 import static com.google.mu.util.CharPredicate.isNot;
+import static com.google.mu.util.Substring.after;
+import static com.google.mu.util.Substring.prefix;
+import static com.google.mu.util.Substring.suffix;
 import static java.util.stream.Collectors.reducing;
 
 import com.google.mu.util.CharPredicate;
+import com.google.mu.util.Substring;
 
 /**
  * Represents a set of characters specified by a regex-like character set string.
@@ -61,6 +65,12 @@ public boolean contains(char ch) {
     return predicate.test(ch);
   }
 
+  @Override public CharacterSet not() {
+    String content = Substring.between(prefix("["), suffix("]")).from(string).get();
+    return new CharacterSet(
+        "[" + after(prefix("^")).from(content).orElse("^" + content) + "]", predicate.not());
+  }
+
   @Override public boolean equals(Object obj) {
     return (obj instanceof CharacterSet that) && string.equals(that.string);
   }

dot-parse/src/main/java/com/google/common/labs/parse/Parser.java

@@ -849,17 +849,6 @@ public final Parser<T> notImmediatelyFollowedBy(CharPredicate predicate, String
     return notFollowedBy(literally(single(predicate, name)), name);
   }
 
-  /**
-   * A form of negative lookahead such that the match is rejected if <em>immediately</em> followed
-   * by (no skippable characters as specified by {@link #parseSkipping parseSkipping()} in between)
-   * a character contained in {@code characterSet}.
-   *
-   * @since 9.4
-   */
-  public final Parser<T> notImmediatelyFollowedBy(CharacterSet characterSet) {
-    return notImmediatelyFollowedBy(characterSet, characterSet.toString());
-  }
-
   /**
    * Starts a fluent chain for matching the current parser optionally. {@code defaultValue} will be
    * the result in case the current parser doesn't match.

dot-parse/src/test/java/com/google/common/labs/parse/CharacterSetTest.java

@@ -60,6 +60,64 @@ public void test_missingBrackets_throws() {
     assertThat(thrown).hasMessageThat().contains("Use [a-z] instead.");
   }
 
+  @Test
+  public void not_positiveSet() {
+    CharacterSet positive = charsIn("[ab]");
+    CharacterSet negated = positive.not();
+    assertThat(negated.contains('a')).isFalse();
+    assertThat(negated.contains('b')).isFalse();
+    assertThat(negated.contains('c')).isTrue();
+    assertThat(negated.toString()).isEqualTo("[^ab]");
+  }
+
+  @Test
+  public void not_negativeSet() {
+    CharacterSet negative = charsIn("[^ab]");
+    CharacterSet negated = negative.not();
+    assertThat(negated.contains('a')).isTrue();
+    assertThat(negated.contains('b')).isTrue();
+    assertThat(negated.contains('c')).isFalse();
+    assertThat(negated.toString()).isEqualTo("[ab]");
+  }
+
+  @Test
+  public void not_rangeSet() {
+    CharacterSet range = charsIn("[a-c]");
+    CharacterSet negated = range.not();
+    assertThat(negated.contains('a')).isFalse();
+    assertThat(negated.contains('b')).isFalse();
+    assertThat(negated.contains('c')).isFalse();
+    assertThat(negated.contains('d')).isTrue();
+    assertThat(negated.toString()).isEqualTo("[^a-c]");
+  }
+
+  @Test
+  public void not_negatedRangeSet() {
+    CharacterSet negatedRange = charsIn("[^a-c]");
+    CharacterSet negated = negatedRange.not();
+    assertThat(negated.contains('a')).isTrue();
+    assertThat(negated.contains('b')).isTrue();
+    assertThat(negated.contains('c')).isTrue();
+    assertThat(negated.contains('d')).isFalse();
+    assertThat(negated.toString()).isEqualTo("[a-c]");
+  }
+
+  @Test
+  public void not_emptySet() {
+    CharacterSet empty = charsIn("[]");
+    CharacterSet negated = empty.not();
+    assertThat(negated.contains('a')).isTrue();
+    assertThat(negated.toString()).isEqualTo("[^]");
+  }
+
+  @Test
+  public void not_fullSet() {
+    CharacterSet full = charsIn("[^]");
+    CharacterSet negated = full.not();
+    assertThat(negated.contains('a')).isFalse();
+    assertThat(negated.toString()).isEqualTo("[]");
+  }
+
   @Test
   public void testEquals() {
     new EqualsTester()