Collect all candidates for completion

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/NewResolveOldInference.kt

@@ -89,6 +89,13 @@ class NewResolveOldInference(
                 }
             }
 
+        if (context.collectAllCandidates) {
+            val allCandidates = towerResolver.collectAllCandidates(baseContext, processor)
+            val result = OverloadResolutionResultsImpl.nameNotFound<CallableDescriptor>()
+            result.allCandidates = allCandidates.map { it.resolvedCall as MutableResolvedCall<CallableDescriptor> }
+            return result
+        }
+
         val candidates = towerResolver.runResolve(baseContext, processor, useOrder = kind != CallResolver.ResolveKind.CALLABLE_REFERENCE)
         return convertToOverloadResults(candidates, tracing, context)
     }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/TowerResolver.kt

@@ -20,6 +20,7 @@ import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.resolve.calls.tasks.ExplicitReceiverKind
 import org.jetbrains.kotlin.resolve.scopes.receivers.ReceiverValue
 import org.jetbrains.kotlin.utils.addToStdlib.check
+import java.util.*
 
 interface TowerContext<C> {
     val name: Name
@@ -60,9 +61,19 @@ class TowerResolver {
             processor: ScopeTowerProcessor<C>,
             useOrder: Boolean = true
     ): Collection<C> {
+        return run(context, processor, useOrder, SuccessfulResultCollector(context))
+    }
 
-        val resultCollector = ResultCollector<C> { context.getStatus(it) }
+    internal fun <C> collectAllCandidates(context: TowerContext<C>, processor: ScopeTowerProcessor<C>): Collection<C> {
+        return run(context, processor, false, AllCandidatesCollector(context))
+    }
 
+    private fun <C> run(
+            context: TowerContext<C>,
+            processor: ScopeTowerProcessor<C>,
+            useOrder: Boolean,
+            resultCollector: ResultCollector<C>
+    ): Collection<C> {
         fun collectCandidates(data: TowerData): Collection<C>? {
             val candidatesGroups = if (useOrder) {
                     processor.process(data)
@@ -96,12 +107,39 @@ class TowerResolver {
     }
 
 
-    //todo collect all candidates
-    internal class ResultCollector<C>(private val getStatus: (C) -> ResolutionCandidateStatus) {
+    internal abstract class ResultCollector<C>(val context: TowerContext<C>) {
+        abstract fun getResolved(): Collection<C>?
+
+        abstract fun getFinalCandidates(): Collection<C>
+
+        fun pushCandidates(candidates: Collection<C>) {
+            val filteredCandidates = candidates.filter {
+                context.getStatus(it).resultingApplicability != ResolutionCandidateApplicability.HIDDEN
+            }
+            if (filteredCandidates.isNotEmpty()) addCandidates(filteredCandidates)
+        }
+
+        protected abstract fun addCandidates(candidates: Collection<C>)
+    }
+
+    internal class AllCandidatesCollector<C>(context: TowerContext<C>): ResultCollector<C>(context) {
+        private val allCandidates = ArrayList<C>()
+
+        override fun getResolved(): Collection<C>? = null
+
+        override fun getFinalCandidates(): Collection<C> = allCandidates
+
+        override fun addCandidates(candidates: Collection<C>) {
+            allCandidates.addAll(candidates)
+        }
+
+    }
+
+    internal class SuccessfulResultCollector<C>(context: TowerContext<C>): ResultCollector<C>(context) {
         private var currentCandidates: Collection<C> = emptyList()
         private var currentLevel: ResolutionCandidateApplicability? = null
 
-        fun getResolved() = currentCandidates.check { currentLevel == ResolutionCandidateApplicability.RESOLVED }
+        override fun getResolved() = currentCandidates.check { currentLevel == ResolutionCandidateApplicability.RESOLVED }
 
         fun getSyntheticResolved() = currentCandidates.check { currentLevel == ResolutionCandidateApplicability.RESOLVED_SYNTHESIZED }
 
@@ -109,15 +147,13 @@ class TowerResolver {
             currentLevel == null || currentLevel!! > ResolutionCandidateApplicability.RESOLVED_SYNTHESIZED
         }
 
-        fun getFinalCandidates() = getResolved() ?: getSyntheticResolved() ?: getErrors() ?: emptyList()
+        override fun getFinalCandidates() = getResolved() ?: getSyntheticResolved() ?: getErrors() ?: emptyList()
 
-        fun pushCandidates(candidates: Collection<C>) {
-            val filteredCandidates = candidates.filter { getStatus(it).resultingApplicability != ResolutionCandidateApplicability.HIDDEN }
-            if (filteredCandidates.isEmpty()) return
-            val minimalLevel = filteredCandidates.map { getStatus(it).resultingApplicability }.min()!!
+        override fun addCandidates(candidates: Collection<C>) {
+            val minimalLevel = candidates.map { context.getStatus(it).resultingApplicability }.min()!!
             if (currentLevel == null || currentLevel!! > minimalLevel) {
                 currentLevel = minimalLevel
-                currentCandidates = filteredCandidates.filter { getStatus(it).resultingApplicability == minimalLevel }
+                currentCandidates = candidates.filter { context.getStatus(it).resultingApplicability == minimalLevel }
             }
         }
     }