com.uber.lintchecks.StringToCaseNoLocaleDetector.kt Maven / Gradle / Ivy

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Set of opinionated and useful lint checks
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/*
 * Copyright (C) 2019. Uber Technologies
 *
 * 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.uber.lintchecks

import com.android.tools.lint.client.api.JavaEvaluator
import com.android.tools.lint.detector.api.Category
import com.android.tools.lint.detector.api.Detector
import com.android.tools.lint.detector.api.Issue
import com.android.tools.lint.detector.api.JavaContext
import com.android.tools.lint.detector.api.Severity
import com.android.tools.lint.detector.api.SourceCodeScanner
import com.intellij.psi.PsiMethod
import com.uber.lintchecks.android.createImplementation
import org.jetbrains.uast.UCallExpression

/**
 * Detector that checks for usage of String.toUpperCase without Locale
 */
class StringToCaseNoLocaleDetector : Detector(), SourceCodeScanner {
  companion object {
    private const val ISSUE_ID = "StringToCaseNoLocale"
    private const val BRIEF_DESCRIPTION = "Don't use toLowerCase/toUpperCase without a locale"
    const val LINT_ERROR_MESSAGE = """Calling String#toLowerCase() or #toUpperCase() without specifying an
        explicit locale is a common source of bugs. The reason for that is that
        those methods will use the current locale on the user's device, and even
        though the code appears to work correctly when you are developing the app,
        it will fail in some locales. For example, in the Turkish locale, the
        uppercase replacement for i is not I.
        If you want the methods to just perform ASCII replacement, for example to
        convert an enum name, call String#toUpperCase(Locale.US) instead. If you
        really want to use the current locale, call
        String#toUpperCase(Locale.getDefault()) instead."""

    val ISSUE = Issue.create(
        id = ISSUE_ID,
        briefDescription = BRIEF_DESCRIPTION,
        explanation = LINT_ERROR_MESSAGE,
        category = Category.CORRECTNESS,
        priority = 6,
        severity = Severity.ERROR,
        implementation = createImplementation())
  }

  override fun visitMethodCall(context: JavaContext, node: UCallExpression, method: PsiMethod) {
    if (!getApplicableMethodNames().contains(node.methodName)) return

    if (isStringType(context.evaluator, node) && node.valueArgumentCount == 0) {
      context.report(ISSUE, context.getLocation(node), BRIEF_DESCRIPTION)
    }
  }

  private fun isStringType(evaluator: JavaEvaluator, node: UCallExpression): Boolean {
    return evaluator.isMemberInClass(node.resolve(), "java.lang.String") ||
        node.receiverType?.canonicalText == "java.lang.String"
  }

  override fun getApplicableMethodNames(): List = listOf("toUpperCase", "toLowerCase")
}