Feature: contract

dependencies.gradle

@@ -5,14 +5,14 @@ ext.versions = [
     versionCode      : 11,
     versionName      : '1.1.0',
 
-    gradleBuildTool  : '4.1.3',
-    spotlessGradle   : '5.14.0',
+    gradleBuildTool  : '7.0.2',
+    spotlessGradle   : '5.15.0',
     ktlintGradle     : '0.41.0',
     dokkaGradle      : '1.4.30',
     binaryValidator  : '0.7.1',
     mavenPublish     : '0.15.1',
 
-    kotlin           : '1.4.31',
+    kotlin           : '1.5.30',
     androidxAppcompat: '1.3.0',
 
     // for demo

gradle/wrapper/gradle-wrapper.properties

@@ -3,4 +3,4 @@ distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
 zipStoreBase=GRADLE_USER_HOME
 zipStorePath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-6.6.1-all.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-7.0.2-all.zip

whatif-android/build.gradle

@@ -24,7 +24,10 @@ android {
 }
 
 tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
-  kotlinOptions.freeCompilerArgs += ["-Xexplicit-api=strict"]
+  kotlinOptions.freeCompilerArgs += [
+      "-Xexplicit-api=strict",
+      "-Xopt-in=kotlin.contracts.ExperimentalContracts"
+  ]
 }
 
 dependencies {

whatif-android/src/main/java/com/skydoves/whatif_android/WhatIfActivity.kt

@@ -27,6 +27,8 @@ import android.os.Parcelable
 import com.skydoves.whatif.whatIfNotNull
 import com.skydoves.whatif.whatIfNotNullAs
 import java.io.Serializable
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 /**
  * An expression for invoking [whatIf] when the [Activity]'s intent extras is not null and not empty.
@@ -38,7 +40,9 @@ import java.io.Serializable
 public inline fun Activity.whatIfHasExtras(
   whatIf: (Bundle) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.whatIfHasExtras(
     whatIf = whatIf,
     whatIfNot = { }
@@ -58,7 +62,10 @@ public inline fun Activity.whatIfHasExtras(
   whatIf: (Bundle) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.extras.whatIfNotNull(
     whatIf = {
       if (!it.isEmpty) {
@@ -81,7 +88,9 @@ public inline fun Activity.whatIfHasExtras(
   name: String,
   whatIf: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.whatIfHasExtras(
     name = name,
     whatIf = whatIf,
@@ -104,7 +113,10 @@ public inline fun Activity.whatIfHasExtras(
   whatIf: () -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   if (intent.hasExtra(name)) {
     whatIf()
   } else {
@@ -124,7 +136,9 @@ public inline fun Activity.whatIfHasStringExtra(
   name: String,
   whatIf: (String) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getStringExtra(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = { }
@@ -146,7 +160,10 @@ public inline fun Activity.whatIfHasStringExtra(
   whatIf: (String) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getStringExtra(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -165,7 +182,9 @@ public inline fun Activity.whatIfHasCharSequenceExtra(
   name: String,
   whatIf: (CharSequence) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getCharSequenceExtra(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = { }
@@ -187,7 +206,10 @@ public inline fun Activity.whatIfHasCharSequenceExtra(
   whatIf: (CharSequence) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getCharSequenceExtra(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -206,7 +228,9 @@ public inline fun <reified T : Serializable> Activity.whatIfHasSerializableExtra
   name: String,
   whatIf: (T) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getSerializableExtra(name).whatIfNotNullAs(
     whatIf = whatIf,
     whatIfNot = { }
@@ -228,7 +252,10 @@ public inline fun <reified T : Serializable> Activity.whatIfHasSerializableExtra
   whatIf: (T) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getSerializableExtra(name).whatIfNotNullAs(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -247,7 +274,9 @@ public inline fun <reified T : Parcelable> Activity.whatIfHasParcelableExtra(
   name: String,
   whatIf: (T) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getParcelableExtra<T>(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = { }
@@ -269,7 +298,10 @@ public inline fun <reified T : Parcelable> Activity.whatIfHasParcelableExtra(
   whatIf: (T) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getParcelableExtra<T>(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -288,7 +320,9 @@ public inline fun <reified T : Parcelable> Activity.whatIfHasParcelableArrayList
   name: String,
   whatIf: (ArrayList<T>) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getParcelableArrayListExtra<T>(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = { }
@@ -310,7 +344,10 @@ public inline fun <reified T : Parcelable> Activity.whatIfHasParcelableArrayList
   whatIf: (ArrayList<T>) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.getParcelableArrayListExtra<T>(name).whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -327,7 +364,9 @@ public inline fun <reified T : Parcelable> Activity.whatIfHasParcelableArrayList
 public inline fun Activity.whatIfHasDeepLinkUri(
   whatIf: (Uri) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this.whatIfHasDeepLinkUri(whatIf, { })
 }
 
@@ -344,6 +383,9 @@ public inline fun Activity.whatIfHasDeepLinkUri(
   whatIf: (Uri) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this.intent.data.whatIfNotNull(whatIf, whatIfNot)
 }

whatif-android/src/main/java/com/skydoves/whatif_android/WhatIfFragment.kt

@@ -27,6 +27,8 @@ import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
 import com.skydoves.whatif.whatIfNotNull
 import com.skydoves.whatif.whatIfNotNullAs
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 /**
  * @author skydoves (Jaewoong Eum)
@@ -40,7 +42,9 @@ import com.skydoves.whatif.whatIfNotNullAs
 public inline fun Fragment?.whatIfNotNullContext(
   whatIf: (Context) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this?.context.whatIfNotNull {
     whatIf(it)
   }
@@ -80,7 +84,9 @@ public inline fun Fragment?.whatIfNotNullContext(
 public inline fun Fragment?.whatIfNotNullActivity(
   whatIf: (FragmentActivity) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   this?.activity.whatIfNotNull {
     whatIf(it)
   }
@@ -101,7 +107,10 @@ public inline fun Fragment?.whatIfNotNullActivity(
   whatIf: (FragmentActivity) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this?.activity.whatIfNotNull(
     whatIf = whatIf,
     whatIfNot = whatIfNot
@@ -120,7 +129,9 @@ public inline fun Fragment?.whatIfNotNullActivity(
 public inline fun Fragment?.whatIfHasArguments(
   whatIf: (Bundle) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   whatIfHasArguments(whatIf) { }
 }
 
@@ -138,7 +149,10 @@ public inline fun Fragment?.whatIfHasArguments(
   whatIf: (Bundle) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this?.arguments.whatIfNotNull(whatIf, whatIfNot)
 }
 
@@ -154,7 +168,9 @@ public inline fun Fragment?.whatIfHasArguments(
 public inline fun <reified T> Fragment?.whatIfFindParentInterface(
   whatIf: (T) -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+  }
   whatIfFindParentInterface(whatIf) { }
 }
 
@@ -172,6 +188,9 @@ public inline fun <reified T> Fragment?.whatIfFindParentInterface(
   whatIf: (T) -> Unit,
   whatIfNot: () -> Unit
 ) {
-
+  contract {
+    callsInPlace(whatIf, InvocationKind.AT_MOST_ONCE)
+    callsInPlace(whatIfNot, InvocationKind.AT_MOST_ONCE)
+  }
   this?.activity.whatIfNotNullAs(whatIf, whatIfNot)
 }

whatif-android/src/main/java/com/skydoves/whatif_android/WhatIfFragmentActivity.kt

@@ -20,6 +20,8 @@ import androidx.annotation.IdRes
 import androidx.fragment.app.Fragment
 import androidx.fragment.app.FragmentActivity
 import com.skydoves.whatif.whatIfNotNullAs
+import kotlin.contracts.InvocationKind
+import kotlin.contracts.contract
 
 /**
  * @author skydoves (Jaewoong Eum)
@@ -35,6 +37,9 @@ public inline fun <reified T : Fragment> FragmentActivity.whatIfFindFragment(
   @IdRes id: Int,
   whatIf: (T) -> Unit
 ) {
+  contract {
+    callsInPlace(whatIf, InvocationKind.EXACTLY_ONCE)
+  }
   whatIfFindFragment(id, whatIf, {})
 }
 
@@ -55,6 +60,9 @@ public inline fun <reified T : Fragment> FragmentActivity.whatIfFindFragment(
   whatIf: (T) -> Unit,
   whatIfNot: () -> Unit
 ) {
+  contract {
+    callsInPlace(whatIf, InvocationKind.EXACTLY_ONCE)
+  }
   supportFragmentManager.findFragmentById(id).whatIfNotNullAs(whatIf, whatIfNot)
 }
 
@@ -72,6 +80,9 @@ public inline fun <reified T : Fragment> FragmentActivity.whatIfFindFragment(
   tag: String?,
   whatIf: (T) -> Unit
 ) {
+  contract {
+    callsInPlace(whatIf, InvocationKind.EXACTLY_ONCE)
+  }
   whatIfFindFragment(tag, whatIf, {})
 }
 
@@ -92,5 +103,8 @@ public inline fun <reified T : Fragment> FragmentActivity.whatIfFindFragment(
   whatIf: (T) -> Unit,
   whatIfNot: () -> Unit
 ) {
+  contract {
+    callsInPlace(whatIf, InvocationKind.EXACTLY_ONCE)
+  }
   supportFragmentManager.findFragmentByTag(tag).whatIfNotNullAs(whatIf, whatIfNot)
 }

whatif/build.gradle

@@ -1,4 +1,3 @@
-apply plugin: 'java-library'
 apply plugin: 'kotlin'
 apply plugin: 'org.jetbrains.dokka'
 apply plugin: 'binary-compatibility-validator'
@@ -21,6 +20,13 @@ task coverageReport(type: JacocoReport, dependsOn: 'test') {
   }
 }
 
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
+  kotlinOptions.freeCompilerArgs += [
+      "-Xexplicit-api=strict",
+      "-Xopt-in=kotlin.contracts.ExperimentalContracts"
+  ]
+}
+
 dependencies {
   testImplementation "junit:junit:$versions.junit"
 }