Add REPL interfaces to scripting API

libraries/scripting/common/src/kotlin/script/experimental/api/scriptEvaluation.kt

@@ -22,7 +22,15 @@ object ScriptEvaluationEnvironmentParams {
 
 typealias ScriptEvaluationEnvironment = ChainedPropertyBag
 
-data class EvaluationResult(val returnValue: Any?, val environment: ScriptEvaluationEnvironment)
+sealed class ResultValue {
+    class Value(val name: String, val value: Any?, val type: String) : ResultValue() {
+        override fun toString(): String = "$name: $type = $value"
+    }
+
+    object Unit : ResultValue()
+}
+
+data class EvaluationResult(val returnValue: ResultValue, val environment: ScriptEvaluationEnvironment)
 
 interface ScriptEvaluator {
 

libraries/scripting/common/src/kotlin/script/experimental/host/BasicScriptingHost.kt

@@ -24,7 +24,6 @@ import kotlin.script.experimental.api.*
 
 abstract class BasicScriptingHost(
     val compiler: ScriptCompiler,
-    // TODO: does it belong here or to the definition?
     val evaluator: ScriptEvaluator
 ) {
     open fun <T> runInCoroutineContext(block: suspend CoroutineScope.() -> T): T = runBlocking { block() }

libraries/scripting/common/src/kotlin/script/experimental/repl/replCompilation.kt

@@ -0,0 +1,30 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.repl
+
+import kotlin.script.experimental.api.*
+
+interface ReplSnippetChecker {
+
+    suspend operator fun invoke(
+        snippet: ReplSnippetSource,
+        state: ReplStageState<*>,
+        scriptDefinition: ScriptDefinition,
+        additionalConfiguration: ScriptCompileConfiguration? = null // overrides properties from definition
+    ): ResultWithDiagnostics<Unit>
+}
+
+interface ReplSnippetCompiler {
+
+    suspend operator fun invoke(
+        snippet: ReplSnippetSource,
+        state: ReplStageState<*>,
+        scriptDefinition: ScriptDefinition,
+        additionalConfiguration: ScriptCompileConfiguration? = null // overrides properties from definition
+    ): ResultWithDiagnostics<CompiledReplSnippet<*>>
+}
+
+interface CompiledReplSnippet<ScriptBase : Any> : CompiledScript<ScriptBase>

libraries/scripting/common/src/kotlin/script/experimental/repl/replData.kt

@@ -0,0 +1,11 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.repl
+
+import kotlin.script.experimental.api.ScriptSource
+
+interface ReplSnippetSource : ScriptSource, ReplSnippetId
+

libraries/scripting/common/src/kotlin/script/experimental/repl/replEvaluation.kt

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.repl
+
+import kotlin.script.experimental.api.EvaluationResult
+import kotlin.script.experimental.api.ResultWithDiagnostics
+import kotlin.script.experimental.util.ChainedPropertyBag
+
+
+object ReplEvaluationEnvironmentParams {
+
+}
+
+typealias ReplEvaluationEnvironment = ChainedPropertyBag
+
+interface ReplSnippetEvaluator {
+
+    suspend operator fun invoke(
+        compiledSnippet: CompiledReplSnippet<*>,
+        replEvaluationEnvironment: ReplEvaluationEnvironment
+    ): ResultWithDiagnostics<EvaluationResult>
+}

libraries/scripting/common/src/kotlin/script/experimental/repl/replHistory.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.repl
+
+import java.util.concurrent.locks.ReentrantReadWriteLock
+import kotlin.concurrent.read
+import kotlin.concurrent.write
+
+const val REPL_CODE_LINE_FIRST_NO = 1
+const val REPL_CODE_LINE_FIRST_GEN = 1
+
+interface ReplSnippetId : Comparable<ReplSnippetId> {
+    val no: Int
+    val generation: Int
+}
+
+data class ReplHistoryRecord<out T>(val id: ReplSnippetId, val item: T)
+
+interface IReplStageHistory<T> : List<ReplHistoryRecord<T>> {
+
+    fun peek(): ReplHistoryRecord<T>? = lock.read { lastOrNull() }
+
+    fun push(id: ReplSnippetId, item: T)
+
+    fun pop(): ReplHistoryRecord<T>?
+
+    fun verifiedPop(id: ReplSnippetId): ReplHistoryRecord<T>? = lock.write {
+        if (lastOrNull()?.id == id) pop()
+        else null
+    }
+
+    fun reset(): Iterable<ReplSnippetId>
+
+    fun resetTo(id: ReplSnippetId): Iterable<ReplSnippetId>
+
+    val lock: ReentrantReadWriteLock
+}
+
+interface ReplStageState<T> {
+    val history: IReplStageHistory<T>
+
+    val lock: ReentrantReadWriteLock
+
+    val currentGeneration: Int
+
+    fun getNextLineNo(): Int =
+        history.peek()?.id?.no?.let { it + 1 } ?: REPL_CODE_LINE_FIRST_NO // TODO: it should be more robust downstream (e.g. use atomic)
+
+    fun <StateT : ReplStageState<*>> asState(target: Class<out StateT>): StateT =
+        if (target.isAssignableFrom(this::class.java)) this as StateT
+        else throw IllegalArgumentException("$this is not an expected instance of IReplStageState")
+}

libraries/scripting/common/src/kotlin/script/experimental/repl/replHost.kt

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+package kotlin.script.experimental.repl
+
+import kotlinx.coroutines.experimental.CoroutineScope
+import kotlinx.coroutines.experimental.runBlocking
+import kotlin.script.experimental.api.EvaluationResult
+import kotlin.script.experimental.api.ResultWithDiagnostics
+import kotlin.script.experimental.api.ScriptCompileConfiguration
+import kotlin.script.experimental.api.ScriptDefinition
+import kotlin.script.experimental.util.ChainedPropertyBag
+import kotlin.script.experimental.util.typedKey
+
+interface ReplCommandProcessor {
+    suspend operator fun invoke(
+        command: String,
+        state: ReplStageState<*>
+    ): ResultWithDiagnostics<EvaluationResult>
+}
+
+data class ReplCommand(val commandName: String, val processor: ReplCommandProcessor)
+
+object ReplHostEnvironmentParams {
+
+    val replCommands by typedKey<List<ReplCommand>>()
+}
+
+typealias ReplHostEnvironment = ChainedPropertyBag
+
+abstract class ReplHost(
+    val environment: ReplHostEnvironment,
+    val checker: ReplSnippetChecker,
+    val compiler: ReplSnippetCompiler,
+    val evaluator: ReplSnippetEvaluator
+) {
+    open fun <T> runInCoroutineContext(block: suspend CoroutineScope.() -> T): T = runBlocking { block() }
+
+    abstract fun eval(
+        snippet: ReplSnippetSource,
+        state: ReplStageState<*>,
+        scriptDefinition: ScriptDefinition,
+        additionalConfiguration: ScriptCompileConfiguration? = null, // overrides properties from definition
+        replEvaluationEnvironment: ReplEvaluationEnvironment
+    ): ResultWithDiagnostics<EvaluationResult>
+}