diff --git a/platform/core-api/api-dump-unreviewed.txt b/platform/core-api/api-dump-unreviewed.txt
index d8cb7ede3f18..b4412decde0d 100644
--- a/platform/core-api/api-dump-unreviewed.txt
+++ b/platform/core-api/api-dump-unreviewed.txt
@@ -822,19 +822,6 @@ f:com.intellij.lang.tree.util.AstUtilKt
 - sf:children(com.intellij.lang.ASTNode):kotlin.sequences.Sequence
 - sf:parents(com.intellij.lang.ASTNode,Z):kotlin.sequences.Sequence
 - sf:siblings(com.intellij.lang.ASTNode,Z,Z):kotlin.sequences.Sequence
-c:com.intellij.lexer.DelegateLexer
-- com.intellij.lexer.LexerBase
-- pf:myDelegate:com.intellij.lexer.Lexer
-- <init>(com.intellij.lexer.Lexer):V
-- advance():V
-- getBufferEnd():I
-- f:getBufferSequence():java.lang.CharSequence
-- f:getDelegate():com.intellij.lexer.Lexer
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- start(java.lang.CharSequence,I,I,I):V
 com.intellij.lexer.DocCommentTokenTypes
 - a:badCharacter():com.intellij.psi.tree.IElementType
 - a:commentData():com.intellij.psi.tree.IElementType
@@ -871,36 +858,6 @@ c:com.intellij.lexer.DummyLexer
 c:com.intellij.lexer.EmptyLexer
 - com.intellij.lexer.DummyLexer
 - <init>():V
-c:com.intellij.lexer.FilterLexer
-- com.intellij.lexer.DelegateLexer
-- <init>(com.intellij.lexer.Lexer,com.intellij.lexer.FilterLexer$Filter):V
-- <init>(com.intellij.lexer.Lexer,com.intellij.lexer.FilterLexer$Filter,Z[]):V
-- advance():V
-- getCurrentPosition():com.intellij.lexer.LexerPosition
-- getOriginal():com.intellij.lexer.Lexer
-- getPrevTokenEnd():I
-- f:locateToken():V
-- restore(com.intellij.lexer.LexerPosition):V
-- start(java.lang.CharSequence,I,I,I):V
-com.intellij.lexer.FilterLexer$Filter
-- a:reject(com.intellij.psi.tree.IElementType):Z
-f:com.intellij.lexer.FilterLexer$SetFilter
-- com.intellij.lexer.FilterLexer$Filter
-- <init>(com.intellij.psi.tree.TokenSet):V
-- reject(com.intellij.psi.tree.IElementType):Z
-c:com.intellij.lexer.FlexAdapter
-- com.intellij.lexer.LexerBase
-- <init>(com.intellij.lexer.FlexLexer):V
-- advance():V
-- getBufferEnd():I
-- getBufferSequence():java.lang.CharSequence
-- getFlex():com.intellij.lexer.FlexLexer
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- p:locateToken():V
-- start(java.lang.CharSequence,I,I,I):V
 com.intellij.lexer.FlexLexer
 - a:advance():com.intellij.psi.tree.IElementType
 - a:getTokenEnd():I
@@ -908,22 +865,6 @@ com.intellij.lexer.FlexLexer
 - a:reset(java.lang.CharSequence,I,I,I):V
 - a:yybegin(I):V
 - a:yystate():I
-c:com.intellij.lexer.LayeredLexer
-- com.intellij.lexer.DelegateLexer
-- sf:ourDisableLayersFlag:java.lang.ThreadLocal
-- <init>(com.intellij.lexer.Lexer):V
-- advance():V
-- p:findLayerLexer(com.intellij.psi.tree.IElementType):com.intellij.lexer.Lexer
-- getCurrentPosition():com.intellij.lexer.LexerPosition
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- p:isLayerActive():Z
-- registerLayer(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType[]):V
-- registerSelfStoppingLayer(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType[],com.intellij.psi.tree.IElementType[]):V
-- restore(com.intellij.lexer.LexerPosition):V
-- start(java.lang.CharSequence,I,I,I):V
 a:com.intellij.lexer.Lexer
 - <init>():V
 - a:advance():V
@@ -948,86 +889,10 @@ a:com.intellij.lexer.LexerBase
 com.intellij.lexer.LexerPosition
 - a:getOffset():I
 - a:getState():I
-a:com.intellij.lexer.LookAheadLexer
-- com.intellij.lexer.LexerBase
-- <init>(com.intellij.lexer.Lexer):V
-- <init>(com.intellij.lexer.Lexer,I):V
-- p:addToken(I,com.intellij.psi.tree.IElementType):V
-- p:addToken(com.intellij.psi.tree.IElementType):V
-- advance():V
-- pf:advanceAs(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType):V
-- pf:advanceLexer(com.intellij.lexer.Lexer):V
-- getBufferEnd():I
-- getBufferSequence():java.lang.CharSequence
-- p:getCacheSize():I
-- pf:getCachedOffset(I):I
-- pf:getCachedType(I):com.intellij.psi.tree.IElementType
-- getCurrentPosition():com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- p:lookAhead(com.intellij.lexer.Lexer):V
-- replaceCachedType(I,com.intellij.psi.tree.IElementType):com.intellij.psi.tree.IElementType
-- p:resetCacheSize(I):V
-- f:restore(com.intellij.lexer.LexerPosition):V
-- p:restore(com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition):V
-- start(java.lang.CharSequence,I,I,I):V
-pc:com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition
-- com.intellij.lexer.LexerPosition
-- <init>(com.intellij.lexer.LookAheadLexer,com.intellij.util.containers.ImmutableUserMap):V
-- getCustomMap():com.intellij.util.containers.ImmutableUserMap
-- getOffset():I
-- getState():I
 com.intellij.lexer.MergeFunction
 - a:merge(com.intellij.psi.tree.IElementType,com.intellij.lexer.Lexer):com.intellij.psi.tree.IElementType
-c:com.intellij.lexer.MergingLexerAdapter
-- com.intellij.lexer.MergingLexerAdapterBase
-- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet):V
-- getMergeFunction():com.intellij.lexer.MergeFunction
-a:com.intellij.lexer.MergingLexerAdapterBase
-- com.intellij.lexer.DelegateLexer
-- <init>(com.intellij.lexer.Lexer):V
-- advance():V
-- getCurrentPosition():com.intellij.lexer.LexerPosition
-- a:getMergeFunction():com.intellij.lexer.MergeFunction
-- getOriginal():com.intellij.lexer.Lexer
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- restore(com.intellij.lexer.LexerPosition):V
-- start(java.lang.CharSequence,I,I,I):V
 com.intellij.lexer.RestartableLexer
 - a:getStartState():I
-c:com.intellij.lexer.StringLiteralLexer
-- com.intellij.lexer.LexerBase
-- sf:NO_QUOTE_CHAR:C
-- p:myBuffer:java.lang.CharSequence
-- p:myBufferEnd:I
-- p:myEnd:I
-- pf:myOriginalLiteralToken:com.intellij.psi.tree.IElementType
-- pf:myQuoteChar:C
-- p:myStart:I
-- <init>(C,com.intellij.psi.tree.IElementType):V
-- <init>(C,com.intellij.psi.tree.IElementType,Z,java.lang.String):V
-- <init>(C,com.intellij.psi.tree.IElementType,Z,java.lang.String,Z,Z):V
-- advance():V
-- getBufferEnd():I
-- getBufferSequence():java.lang.CharSequence
-- p:getHexCodedEscapeSeq():com.intellij.psi.tree.IElementType
-- p:getStandardLimitedHexCodedEscapeSeq(I):com.intellij.psi.tree.IElementType
-- getState():I
-- getTokenEnd():I
-- getTokenStart():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- p:getUnicodeEscapeSequenceType():com.intellij.psi.tree.IElementType
-- p:handleSingleSlashEscapeSequence():com.intellij.psi.tree.IElementType
-- p:locateAdditionalEscapeSequence(I,I):I
-- p:locateHexEscapeSequence(I,I):I
-- p:locateUnicodeEscapeSequence(I,I):I
-- p:shouldAllowSlashZero():Z
-- start(java.lang.CharSequence,I,I,I):V
 com.intellij.model.search.SearchRequest
 - getInjectionSearchScope():com.intellij.psi.search.SearchScope
 - getSearchScope():com.intellij.psi.search.SearchScope
diff --git a/platform/core-impl/api-dump-unreviewed.txt b/platform/core-impl/api-dump-unreviewed.txt
index 32bec7231f73..5b68333ebb99 100644
--- a/platform/core-impl/api-dump-unreviewed.txt
+++ b/platform/core-impl/api-dump-unreviewed.txt
@@ -765,6 +765,141 @@ a:com.intellij.lang.impl.PsiBuilderImpl$ProductionMarker
 - isCollapsed():Z
 - remapTokenType(com.intellij.psi.tree.IElementType):V
 - a:tokenTextMatches(java.lang.CharSequence):Z
+c:com.intellij.lexer.DelegateLexer
+- com.intellij.lexer.LexerBase
+- pf:myDelegate:com.intellij.lexer.Lexer
+- <init>(com.intellij.lexer.Lexer):V
+- advance():V
+- getBufferEnd():I
+- f:getBufferSequence():java.lang.CharSequence
+- f:getDelegate():com.intellij.lexer.Lexer
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- start(java.lang.CharSequence,I,I,I):V
+c:com.intellij.lexer.FilterLexer
+- com.intellij.lexer.DelegateLexer
+- <init>(com.intellij.lexer.Lexer,com.intellij.lexer.FilterLexer$Filter):V
+- <init>(com.intellij.lexer.Lexer,com.intellij.lexer.FilterLexer$Filter,Z[]):V
+- advance():V
+- getCurrentPosition():com.intellij.lexer.LexerPosition
+- getOriginal():com.intellij.lexer.Lexer
+- getPrevTokenEnd():I
+- f:locateToken():V
+- restore(com.intellij.lexer.LexerPosition):V
+- start(java.lang.CharSequence,I,I,I):V
+com.intellij.lexer.FilterLexer$Filter
+- a:reject(com.intellij.psi.tree.IElementType):Z
+f:com.intellij.lexer.FilterLexer$SetFilter
+- com.intellij.lexer.FilterLexer$Filter
+- <init>(com.intellij.psi.tree.TokenSet):V
+- reject(com.intellij.psi.tree.IElementType):Z
+c:com.intellij.lexer.FlexAdapter
+- com.intellij.lexer.LexerBase
+- <init>(com.intellij.lexer.FlexLexer):V
+- advance():V
+- getBufferEnd():I
+- getBufferSequence():java.lang.CharSequence
+- getFlex():com.intellij.lexer.FlexLexer
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- p:locateToken():V
+- start(java.lang.CharSequence,I,I,I):V
+c:com.intellij.lexer.LayeredLexer
+- com.intellij.lexer.DelegateLexer
+- sf:ourDisableLayersFlag:java.lang.ThreadLocal
+- <init>(com.intellij.lexer.Lexer):V
+- advance():V
+- p:findLayerLexer(com.intellij.psi.tree.IElementType):com.intellij.lexer.Lexer
+- getCurrentPosition():com.intellij.lexer.LexerPosition
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- p:isLayerActive():Z
+- registerLayer(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType[]):V
+- registerSelfStoppingLayer(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType[],com.intellij.psi.tree.IElementType[]):V
+- restore(com.intellij.lexer.LexerPosition):V
+- start(java.lang.CharSequence,I,I,I):V
+a:com.intellij.lexer.LookAheadLexer
+- com.intellij.lexer.LexerBase
+- <init>(com.intellij.lexer.Lexer):V
+- <init>(com.intellij.lexer.Lexer,I):V
+- p:addToken(I,com.intellij.psi.tree.IElementType):V
+- p:addToken(com.intellij.psi.tree.IElementType):V
+- advance():V
+- pf:advanceAs(com.intellij.lexer.Lexer,com.intellij.psi.tree.IElementType):V
+- pf:advanceLexer(com.intellij.lexer.Lexer):V
+- getBufferEnd():I
+- getBufferSequence():java.lang.CharSequence
+- p:getCacheSize():I
+- pf:getCachedOffset(I):I
+- pf:getCachedType(I):com.intellij.psi.tree.IElementType
+- getCurrentPosition():com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- p:lookAhead(com.intellij.lexer.Lexer):V
+- replaceCachedType(I,com.intellij.psi.tree.IElementType):com.intellij.psi.tree.IElementType
+- p:resetCacheSize(I):V
+- f:restore(com.intellij.lexer.LexerPosition):V
+- p:restore(com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition):V
+- start(java.lang.CharSequence,I,I,I):V
+pc:com.intellij.lexer.LookAheadLexer$LookAheadLexerPosition
+- com.intellij.lexer.LexerPosition
+- <init>(com.intellij.lexer.LookAheadLexer,com.intellij.util.containers.ImmutableUserMap):V
+- getCustomMap():com.intellij.util.containers.ImmutableUserMap
+- getOffset():I
+- getState():I
+c:com.intellij.lexer.MergingLexerAdapter
+- com.intellij.lexer.MergingLexerAdapterBase
+- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet):V
+- getMergeFunction():com.intellij.lexer.MergeFunction
+a:com.intellij.lexer.MergingLexerAdapterBase
+- com.intellij.lexer.DelegateLexer
+- <init>(com.intellij.lexer.Lexer):V
+- advance():V
+- getCurrentPosition():com.intellij.lexer.LexerPosition
+- a:getMergeFunction():com.intellij.lexer.MergeFunction
+- getOriginal():com.intellij.lexer.Lexer
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- restore(com.intellij.lexer.LexerPosition):V
+- start(java.lang.CharSequence,I,I,I):V
+c:com.intellij.lexer.StringLiteralLexer
+- com.intellij.lexer.LexerBase
+- sf:NO_QUOTE_CHAR:C
+- p:myBuffer:java.lang.CharSequence
+- p:myBufferEnd:I
+- p:myEnd:I
+- pf:myOriginalLiteralToken:com.intellij.psi.tree.IElementType
+- pf:myQuoteChar:C
+- p:myStart:I
+- <init>(C,com.intellij.psi.tree.IElementType):V
+- <init>(C,com.intellij.psi.tree.IElementType,Z,java.lang.String):V
+- <init>(C,com.intellij.psi.tree.IElementType,Z,java.lang.String,Z,Z):V
+- advance():V
+- getBufferEnd():I
+- getBufferSequence():java.lang.CharSequence
+- p:getHexCodedEscapeSeq():com.intellij.psi.tree.IElementType
+- p:getStandardLimitedHexCodedEscapeSeq(I):com.intellij.psi.tree.IElementType
+- getState():I
+- getTokenEnd():I
+- getTokenStart():I
+- getTokenType():com.intellij.psi.tree.IElementType
+- p:getUnicodeEscapeSequenceType():com.intellij.psi.tree.IElementType
+- p:handleSingleSlashEscapeSequence():com.intellij.psi.tree.IElementType
+- p:locateAdditionalEscapeSequence(I,I):I
+- p:locateHexEscapeSequence(I,I):I
+- p:locateUnicodeEscapeSequence(I,I):I
+- p:shouldAllowSlashZero():Z
+- start(java.lang.CharSequence,I,I,I):V
 c:com.intellij.mock.MockApplication
 - com.intellij.mock.MockComponentManager
 - com.intellij.openapi.application.ex.ApplicationEx
diff --git a/platform/core-api/src/com/intellij/lexer/DelegateLexer.java b/platform/core-impl/src/com/intellij/lexer/DelegateLexer.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/DelegateLexer.java
rename to platform/core-impl/src/com/intellij/lexer/DelegateLexer.java
diff --git a/platform/core-api/src/com/intellij/lexer/FilterLexer.java b/platform/core-impl/src/com/intellij/lexer/FilterLexer.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/FilterLexer.java
rename to platform/core-impl/src/com/intellij/lexer/FilterLexer.java
diff --git a/platform/core-api/src/com/intellij/lexer/FlexAdapter.java b/platform/core-impl/src/com/intellij/lexer/FlexAdapter.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/FlexAdapter.java
rename to platform/core-impl/src/com/intellij/lexer/FlexAdapter.java
diff --git a/platform/core-api/src/com/intellij/lexer/LayeredLexer.java b/platform/core-impl/src/com/intellij/lexer/LayeredLexer.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/LayeredLexer.java
rename to platform/core-impl/src/com/intellij/lexer/LayeredLexer.java
diff --git a/platform/core-api/src/com/intellij/lexer/LookAheadLexer.java b/platform/core-impl/src/com/intellij/lexer/LookAheadLexer.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/LookAheadLexer.java
rename to platform/core-impl/src/com/intellij/lexer/LookAheadLexer.java
diff --git a/platform/core-api/src/com/intellij/lexer/MergingLexerAdapter.java b/platform/core-impl/src/com/intellij/lexer/MergingLexerAdapter.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/MergingLexerAdapter.java
rename to platform/core-impl/src/com/intellij/lexer/MergingLexerAdapter.java
diff --git a/platform/core-api/src/com/intellij/lexer/MergingLexerAdapterBase.java b/platform/core-impl/src/com/intellij/lexer/MergingLexerAdapterBase.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/MergingLexerAdapterBase.java
rename to platform/core-impl/src/com/intellij/lexer/MergingLexerAdapterBase.java
diff --git a/platform/core-api/src/com/intellij/lexer/MutableRandomAccessQueue.java b/platform/core-impl/src/com/intellij/lexer/MutableRandomAccessQueue.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/MutableRandomAccessQueue.java
rename to platform/core-impl/src/com/intellij/lexer/MutableRandomAccessQueue.java
diff --git a/platform/core-api/src/com/intellij/lexer/StringLiteralLexer.java b/platform/core-impl/src/com/intellij/lexer/StringLiteralLexer.java
similarity index 100%
rename from platform/core-api/src/com/intellij/lexer/StringLiteralLexer.java
rename to platform/core-impl/src/com/intellij/lexer/StringLiteralLexer.java
diff --git a/platform/indexing-api/api-dump.txt b/platform/indexing-api/api-dump.txt
index e367eab02af8..578c92b2e839 100644
--- a/platform/indexing-api/api-dump.txt
+++ b/platform/indexing-api/api-dump.txt
@@ -91,14 +91,6 @@ e:com.intellij.find.FindModel$SearchContext
 - sf:IN_STRING_LITERALS:com.intellij.find.FindModel$SearchContext
 - s:valueOf(java.lang.String):com.intellij.find.FindModel$SearchContext
 - s:values():com.intellij.find.FindModel$SearchContext[]
-c:com.intellij.lang.cacheBuilder.DefaultWordsScanner
-- com.intellij.lang.cacheBuilder.VersionedWordsScanner
-- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
-- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
-- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
-- processWords(java.lang.CharSequence,com.intellij.util.Processor):V
-- setMayHaveFileRefsInLiterals(Z):V
-- s:stripWords(com.intellij.util.Processor,java.lang.CharSequence,I,I,com.intellij.lang.cacheBuilder.WordOccurrence$Kind,com.intellij.lang.cacheBuilder.WordOccurrence,Z):Z
 c:com.intellij.lang.cacheBuilder.SimpleWordsScanner
 - com.intellij.lang.cacheBuilder.VersionedWordsScanner
 - <init>():V
diff --git a/platform/indexing-impl/api-dump.txt b/platform/indexing-impl/api-dump.txt
index 74b48d93d82e..0c415da300a0 100644
--- a/platform/indexing-impl/api-dump.txt
+++ b/platform/indexing-impl/api-dump.txt
@@ -24,6 +24,14 @@ f:com.intellij.ide.todo.TodoFilter
 - removeTodoPattern(com.intellij.psi.search.TodoPattern):V
 - setName(java.lang.String):V
 - writeExternal(org.jdom.Element,com.intellij.psi.search.TodoPattern[]):V
+c:com.intellij.lang.cacheBuilder.DefaultWordsScanner
+- com.intellij.lang.cacheBuilder.VersionedWordsScanner
+- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
+- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
+- <init>(com.intellij.lexer.Lexer,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet,com.intellij.psi.tree.TokenSet):V
+- processWords(java.lang.CharSequence,com.intellij.util.Processor):V
+- setMayHaveFileRefsInLiterals(Z):V
+- s:stripWords(com.intellij.util.Processor,java.lang.CharSequence,I,I,com.intellij.lang.cacheBuilder.WordOccurrence$Kind,com.intellij.lang.cacheBuilder.WordOccurrence,Z):Z
 a:com.intellij.psi.impl.cache.impl.BaseFilterLexer
 - com.intellij.lexer.DelegateLexer
 - com.intellij.psi.impl.cache.impl.id.IdTableBuilding$ScanWordProcessor
diff --git a/platform/indexing-api/src/com/intellij/lang/cacheBuilder/DefaultWordsScanner.java b/platform/indexing-impl/src/com/intellij/lang/cacheBuilder/DefaultWordsScanner.java
similarity index 100%
rename from platform/indexing-api/src/com/intellij/lang/cacheBuilder/DefaultWordsScanner.java
rename to platform/indexing-impl/src/com/intellij/lang/cacheBuilder/DefaultWordsScanner.java
diff --git a/platform/lang-api/api-dump-unreviewed.txt b/platform/lang-api/api-dump-unreviewed.txt
index f67c7aec42ca..bc823b3bf126 100644
--- a/platform/lang-api/api-dump-unreviewed.txt
+++ b/platform/lang-api/api-dump-unreviewed.txt
@@ -3060,21 +3060,6 @@ com.intellij.lang.surroundWith.Surrounder
 - a:getTemplateDescription():java.lang.String
 - a:isApplicable(com.intellij.psi.PsiElement[]):Z
 - a:surroundElements(com.intellij.openapi.project.Project,com.intellij.openapi.editor.Editor,com.intellij.psi.PsiElement[]):com.intellij.openapi.util.TextRange
-f:com.intellij.lexer.LexerUtil
-- s:getRootLexer(com.intellij.lexer.Lexer):com.intellij.lexer.Lexer
-- s:getTokenText(com.intellij.lexer.Lexer):java.lang.CharSequence
-- s:internToken(com.intellij.lexer.Lexer,com.intellij.util.CharTable):java.lang.CharSequence
-c:com.intellij.lexer.StoppableLexerAdapter
-- com.intellij.lexer.DelegateLexer
-- <init>(com.intellij.lexer.StoppableLexerAdapter$StoppingCondition,com.intellij.lexer.Lexer):V
-- advance():V
-- getCurrentPosition():com.intellij.lexer.LexerPosition
-- getPrevTokenEnd():I
-- getTokenEnd():I
-- getTokenType():com.intellij.psi.tree.IElementType
-- restore(com.intellij.lexer.LexerPosition):V
-com.intellij.lexer.StoppableLexerAdapter$StoppingCondition
-- a:stopsAt(com.intellij.psi.tree.IElementType,I,I):Z
 com.intellij.navigation.ChooseByNameContributor
 - sf:CLASS_EP_NAME:com.intellij.openapi.extensions.ExtensionPointName
 - sf:FILE_EP_NAME:com.intellij.openapi.extensions.ExtensionPointName
diff --git a/platform/lang-api/src/com/intellij/lexer/StoppableLexerAdapter.java b/platform/lang-api/src/com/intellij/lexer/StoppableLexerAdapter.java
deleted file mode 100644
index b8936926077f..000000000000
--- a/platform/lang-api/src/com/intellij/lexer/StoppableLexerAdapter.java
+++ /dev/null
@@ -1,61 +0,0 @@
-// Copyright 2000-2023 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
-
-/*
- * @author max
- */
-package com.intellij.lexer;
-
-import com.intellij.psi.tree.IElementType;
-import org.jetbrains.annotations.NotNull;
-
-public class StoppableLexerAdapter extends DelegateLexer {
-
-  public interface StoppingCondition {
-    boolean stopsAt(IElementType token, int start, int end);
-  }
-
-  private final StoppingCondition myCondition;
-  private boolean myStopped;
-
-  public StoppableLexerAdapter(final StoppingCondition condition, final Lexer original) {
-    super(original);
-    myCondition = condition;
-    myStopped = myCondition.stopsAt(original.getTokenType(), original.getTokenStart(), original.getTokenEnd());
-  }
-
-  @Override
-  public void advance() {
-    if (myStopped) return;
-    super.advance();
-
-    if (myCondition.stopsAt(getDelegate().getTokenType(), getDelegate().getTokenStart(), getDelegate().getTokenEnd())) {
-      myStopped = true;
-    }
-  }
-
-  public int getPrevTokenEnd() {
-    Lexer delegate = getDelegate();
-    return delegate instanceof StoppableLexerAdapter ? ((StoppableLexerAdapter)delegate).getPrevTokenEnd() : ((FilterLexer)delegate).getPrevTokenEnd();
-  }
-
-  @Override
-  public int getTokenEnd() {
-    return myStopped ? super.getTokenStart() : super.getTokenEnd();
-  }
-
-  @Override
-  public IElementType getTokenType() {
-    return myStopped ? null : super.getTokenType();
-  }
-
-  @Override
-  public @NotNull LexerPosition getCurrentPosition() {
-    return getDelegate().getCurrentPosition();
-  }
-
-  @Override
-  public void restore(@NotNull LexerPosition position) {
-    getDelegate().restore(position);
-  }
-
-}
diff --git a/platform/lang-api/src/com/intellij/lexer/package.html b/platform/lang-api/src/com/intellij/lexer/package.html
deleted file mode 100644
index 9c8fceafb590..000000000000
--- a/platform/lang-api/src/com/intellij/lexer/package.html
+++ /dev/null
@@ -1,21 +0,0 @@
-<!--
-  ~ Copyright 2000-2007 JetBrains s.r.o.
-  ~
-  ~ 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.
-  -->
-
-<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
-<html><body bgcolor="white">
-Provides interfaces for implementing custom language lexers and utility classes for
-working with lexers.
-</body></html>
diff --git a/platform/lang-impl/api-dump-unreviewed.txt b/platform/lang-impl/api-dump-unreviewed.txt
index 7cdbad650770..79e8b87f44bf 100644
--- a/platform/lang-impl/api-dump-unreviewed.txt
+++ b/platform/lang-impl/api-dump-unreviewed.txt
@@ -13360,6 +13360,10 @@ f:com.intellij.largeFilesEditor.search.SearchResult
 com.intellij.largeFilesEditor.search.searchTask.FileDataProviderForSearch
 - a:getName():java.lang.String
 - a:getPagesAmount():J
+f:com.intellij.lexer.LexerUtil
+- s:getRootLexer(com.intellij.lexer.Lexer):com.intellij.lexer.Lexer
+- s:getTokenText(com.intellij.lexer.Lexer):java.lang.CharSequence
+- s:internToken(com.intellij.lexer.Lexer,com.intellij.util.CharTable):java.lang.CharSequence
 f:com.intellij.lexer.PrefixSuffixStripperLexer
 - com.intellij.lexer.LexerBase
 - <init>(java.lang.String,com.intellij.psi.tree.IElementType,java.lang.String,com.intellij.psi.tree.IElementType,com.intellij.psi.tree.IElementType):V
diff --git a/platform/lang-api/src/com/intellij/lexer/LexerUtil.java b/platform/lang-impl/src/com/intellij/lexer/LexerUtil.java
similarity index 100%
rename from platform/lang-api/src/com/intellij/lexer/LexerUtil.java
rename to platform/lang-impl/src/com/intellij/lexer/LexerUtil.java
diff --git a/plugins/env-files-support/src/main/java/ru/adelf/idea/dotenv/extension/DotEnvFindUsagesProvider.java b/plugins/env-files-support/src/main/java/ru/adelf/idea/dotenv/extension/DotEnvFindUsagesProvider.java
index a99adfc8359f..84ec3751ff3c 100644
--- a/plugins/env-files-support/src/main/java/ru/adelf/idea/dotenv/extension/DotEnvFindUsagesProvider.java
+++ b/plugins/env-files-support/src/main/java/ru/adelf/idea/dotenv/extension/DotEnvFindUsagesProvider.java
@@ -1,26 +1,27 @@
 package ru.adelf.idea.dotenv.extension;
 
-import com.intellij.lang.cacheBuilder.DefaultWordsScanner;
 import com.intellij.lang.cacheBuilder.WordsScanner;
 import com.intellij.lang.findUsages.FindUsagesProvider;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiNamedElement;
-import com.intellij.psi.tree.TokenSet;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 import ru.adelf.idea.dotenv.DotEnvBundle;
-import ru.adelf.idea.dotenv.grammars.DotEnvLexerAdapter;
 import ru.adelf.idea.dotenv.psi.DotEnvProperty;
-import ru.adelf.idea.dotenv.psi.DotEnvTypes;
 
 public class DotEnvFindUsagesProvider implements FindUsagesProvider {
     @Nullable
     @Override
     public WordsScanner getWordsScanner() {
+        throw new UnsupportedOperationException("Not yet implemented");
+        /*
+         TODO commented out because `DefaultWordsScanner` requires intellij.platform.indexing.impl dependency
+              but this class is unused
         return new DefaultWordsScanner(new DotEnvLexerAdapter(),
                 TokenSet.create(DotEnvTypes.PROPERTY),
                 TokenSet.create(DotEnvTypes.COMMENT),
                 TokenSet.EMPTY);
+        */
     }
 
     @Override
diff --git a/plugins/properties/properties-psi-api/src/com/intellij/lang/properties/PropertiesHighlightingLexer.java b/plugins/properties/properties-psi-impl/src/com/intellij/lang/properties/PropertiesHighlightingLexer.java
similarity index 100%
rename from plugins/properties/properties-psi-api/src/com/intellij/lang/properties/PropertiesHighlightingLexer.java
rename to plugins/properties/properties-psi-impl/src/com/intellij/lang/properties/PropertiesHighlightingLexer.java
diff --git a/plugins/properties/properties-psi-api/src/com/intellij/lang/properties/parsing/PropertiesLexer.java b/plugins/properties/properties-psi-impl/src/com/intellij/lang/properties/parsing/PropertiesLexer.java
similarity index 100%
rename from plugins/properties/properties-psi-api/src/com/intellij/lang/properties/parsing/PropertiesLexer.java
rename to plugins/properties/properties-psi-impl/src/com/intellij/lang/properties/parsing/PropertiesLexer.java