From cb0e5b71e250c45bf0dcdc876461e12b4351b322 Mon Sep 17 00:00:00 2001
From: "Gregory.Shrago" <gregory.shrago@jetbrains.com>
Date: Mon, 30 May 2016 01:21:50 +0300
Subject: [PATCH] fault tolerance; correct getStartToken() for non-returning
 flex rules

---
 .../src/com/intellij/lexer/FlexAdapter.java   | 54 ++++++++++++-------
 1 file changed, 34 insertions(+), 20 deletions(-)

diff --git a/platform/core-api/src/com/intellij/lexer/FlexAdapter.java b/platform/core-api/src/com/intellij/lexer/FlexAdapter.java
index 593f68c7477d..c8b5b90688ea 100644
--- a/platform/core-api/src/com/intellij/lexer/FlexAdapter.java
+++ b/platform/core-api/src/com/intellij/lexer/FlexAdapter.java
@@ -15,23 +15,30 @@
  */
 package com.intellij.lexer;
 
+import com.intellij.openapi.diagnostic.Logger;
+import com.intellij.psi.TokenType;
 import com.intellij.psi.tree.IElementType;
 import org.jetbrains.annotations.NotNull;
 
-import java.io.IOException;
-
 /**
  * @author max
  */
 public class FlexAdapter extends LexerBase {
-  private FlexLexer myFlex = null;
-  private IElementType myTokenType = null;
+
+  private static final Logger LOG = Logger.getInstance(FlexAdapter.class);
+
+  private final FlexLexer myFlex;
+
+  private IElementType myTokenType;
   private CharSequence myText;
 
-  private int myEnd;
+  private int myTokenStart;
+  private int myTokenEnd;
+
+  private int myBufferEnd;
   private int myState;
 
-  public FlexAdapter(final FlexLexer flex) {
+  public FlexAdapter(@NotNull FlexLexer flex) {
     myFlex = flex;
   }
 
@@ -42,38 +49,39 @@ public class FlexAdapter extends LexerBase {
   @Override
   public void start(@NotNull final CharSequence buffer, int startOffset, int endOffset, final int initialState) {
     myText = buffer;
-    myEnd = endOffset;
+    myTokenStart = myTokenEnd = startOffset;
+    myBufferEnd = endOffset;
     myFlex.reset(myText, startOffset, endOffset, initialState);    
     myTokenType = null;
   }
 
   @Override
   public int getState() {
-    if (myTokenType == null) locateToken();
+    locateToken();
     return myState;
   }
 
   @Override
   public IElementType getTokenType() {
-    if (myTokenType == null) locateToken();
+    locateToken();
     return myTokenType;
   }
 
   @Override
   public int getTokenStart() {
-    if (myTokenType == null) locateToken();
-    return myFlex.getTokenStart();
+    locateToken();
+    return myTokenStart;
   }
 
   @Override
   public int getTokenEnd() {
-    if (myTokenType == null) locateToken();
-    return myFlex.getTokenEnd();
+    locateToken();
+    return myTokenEnd;
   }
 
   @Override
   public void advance() {
-    if (myTokenType == null) locateToken();
+    locateToken();
     myTokenType = null;
   }
 
@@ -85,21 +93,27 @@ public class FlexAdapter extends LexerBase {
 
   @Override
   public int getBufferEnd() {
-    return myEnd;
+    return myBufferEnd;
   }
 
   protected void locateToken() {
     if (myTokenType != null) return;
+
     try {
+      myTokenStart = myFlex.getTokenEnd();
       myState = myFlex.yystate();
       myTokenType = myFlex.advance();
+      myTokenEnd = myFlex.getTokenEnd();
+    }
+    catch (Exception e) {
+      LOG.error(myFlex.getClass().getName(), e);
+      myTokenType = TokenType.WHITE_SPACE;
+      myTokenEnd = myBufferEnd;
     }
-    catch (IOException e) { /*Can't happen*/ }
     catch (Error e) {
-      // add lexer class name to the error
-      final Error error = new Error(myFlex.getClass().getName() + ": " + e.getMessage());
-      error.setStackTrace(e.getStackTrace());
-      throw error;
+      LOG.error(myFlex.getClass().getName(), e);
+      myTokenType = TokenType.WHITE_SPACE;
+      myTokenEnd = myBufferEnd;
     }
   }
 }