InvalidPatternSyntax
Invalid syntax used for a regular expression

Category
Severity
ERROR
Maturity

The problem

This error is triggered by calls to regex-accepting methods with invalid string literals. These calls would cause a PatternSyntaxException at runtime.

We deliberately do not check java.util.regex.Pattern#compile as many of its users are deliberately testing the regex compiler or using a vacuously true regex.

Suppression

Suppress false positives by adding an @SuppressWarnings("InvalidPatternSyntax") annotation to the enclosing element.


Positive examples

InvalidPatternSyntaxPositiveCases.java

/*
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.errorprone.bugpatterns.testdata;

import com.google.common.base.Splitter;
import java.util.regex.Pattern;

/** @author mdempsky@google.com (Matthew Dempsky) */
public class InvalidPatternSyntaxPositiveCases {
  public static final String INVALID = "*";
  public static final String DOT = ".";

  {
    // BUG: Diagnostic contains: Unclosed character class
    Pattern.matches("[^\\]", "");
    // BUG: Diagnostic contains: Unclosed character class
    Pattern.matches("[a-z", "");
    // BUG: Diagnostic contains: Illegal repetition
    Pattern.matches("{", "");

    // BUG: Diagnostic contains:
    Pattern.matches(INVALID, "");
    // BUG: Diagnostic contains:
    "".matches(INVALID);
    // BUG: Diagnostic contains:
    "".replaceAll(INVALID, "");
    // BUG: Diagnostic contains:
    "".replaceFirst(INVALID, "");
    // BUG: Diagnostic contains:
    "".split(INVALID);
    // BUG: Diagnostic contains:
    "".split(INVALID, 0);

    // BUG: Diagnostic contains: "foo.bar".split("\\.")
    "foo.bar".split(".");
    // BUG: Diagnostic contains:
    "foo.bonk".split(DOT);

    // BUG: Diagnostic contains: Splitter.onPattern("\\.")
    Splitter.onPattern(".");
  }
}

Negative examples

InvalidPatternSyntaxNegativeCases.java

/*
 * Copyright 2012 Google Inc. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.errorprone.bugpatterns.testdata;

import java.util.regex.Pattern;

/** @author mdempsky@google.com (Matthew Dempsky) */
public class InvalidPatternSyntaxNegativeCases {
  public void foo(String x) {
    Pattern.compile("t");
    Pattern.compile("t", 0);
    Pattern.matches("t", "");
    "".matches("t");
    "".replaceAll("t", "");
    "".replaceFirst("t", "");
    "".split("t");
    "".split("t", 0);

    Pattern.compile(x);
    Pattern.compile(x, 0);
    Pattern.matches(x, "");
    "".matches(x);
    "".replaceAll(x, "");
    "".replaceFirst(x, "");
    "".split(x);
    "".split(x, 0);
  }
}