[Parser] Introduce PersistentParserState::ParserPos to encapsulate a Parser/Lexer independent info for restoring parsing from a certain token location.

Swift SVN r6593

Author: akyrtzi

include/swift/Parse/Parser.h

@@ -161,8 +161,9 @@ class Parser {
                           PreviousLoc);
   }
 
-  ParserPosition getParserPosition(SourceLoc Start, SourceLoc PrevLoc) {
-    return ParserPosition(L->getStateForBeginningOfTokenLoc(Start), PrevLoc);
+  ParserPosition getParserPosition(const PersistentParserState::ParserPos &Pos){
+    return ParserPosition(L->getStateForBeginningOfTokenLoc(Pos.Loc),
+                          Pos.PrevLoc);
   }
 
   void restoreParserPosition(ParserPosition PP) {

include/swift/Parse/PersistentParserState.h

@@ -26,10 +26,16 @@ namespace swift {
 
 /// \brief Parser state persistent across multiple parses.
 class PersistentParserState {
+public:
+  struct ParserPos {
+    SourceLoc Loc;
+    SourceLoc PrevLoc;
+
+    bool isValid() const { return Loc.isValid(); }
+  };
 
   class FunctionBodyState {
-    SourceRange BodyRange;
-    SourceLoc PreviousLoc;
+    ParserPos BodyPos;
     SavedScope Scope;
     friend class Parser;
 
@@ -40,16 +46,17 @@ class PersistentParserState {
   public:
     FunctionBodyState(SourceRange BodyRange, SourceLoc PreviousLoc,
                       SavedScope &&Scope)
-      : BodyRange(BodyRange), PreviousLoc(PreviousLoc), Scope(std::move(Scope))
+      : BodyPos{BodyRange.Start, PreviousLoc}, Scope(std::move(Scope))
     {}
   };
 
+private:
   ScopeInfo ScopeInfo;
   typedef llvm::DenseMap<FuncExpr *, std::unique_ptr<FunctionBodyState>>
       DelayedBodiesTy;
   DelayedBodiesTy DelayedBodies;
-  SourceLoc ParserPos;
-  SourceLoc PrevParserLoc;
+  /// \brief Parser sets this if it stopped parsing before the buffer ended.
+  ParserPos MarkedPos;
 
 public:
   swift::ScopeInfo &getScopeInfo() { return ScopeInfo; }
@@ -59,14 +66,13 @@ class PersistentParserState {
   std::unique_ptr<FunctionBodyState> takeBodyState(FuncExpr *FE);
 
   void markParserPosition(SourceLoc Loc, SourceLoc PrevLoc) {
-    ParserPos = Loc;
-    PrevParserLoc = PrevLoc;
+    MarkedPos = {Loc, PrevLoc};
   }
 
-  std::pair<SourceLoc, SourceLoc> takeParserPosition() {
-    auto Pos = std::make_pair(ParserPos, PrevParserLoc);
-    ParserPos = SourceLoc();
-    PrevParserLoc = SourceLoc();
+  /// \brief Returns the marked parser position and resets it.
+  ParserPos takeParserPosition() {
+    ParserPos Pos = MarkedPos;
+    MarkedPos = ParserPos();
     return Pos;
   }
 };

lib/Parse/ParseDecl.cpp

@@ -1377,11 +1377,8 @@ bool Parser::parseDeclFuncBodyDelayed(FuncDecl *FD) {
   if (!FunctionParserState)
     return false;
 
-  auto BeginParserPosition =
-      getParserPosition(FunctionParserState->BodyRange.Start,
-                        FunctionParserState->PreviousLoc);
-  auto EndLexerState =
-      L->getStateForBeginningOfTokenLoc(FunctionParserState->BodyRange.End);
+  auto BeginParserPosition = getParserPosition(FunctionParserState->BodyPos);
+  auto EndLexerState = L->getStateForBeginningOfTokenLoc(FE->getEndLoc());
 
   // Ensure that we restore the parser state at exit.
   ParserPositionRAII PPR(*this);

lib/Parse/Parser.cpp

@@ -229,10 +229,9 @@ Parser::Parser(unsigned BufferID, TranslationUnit *TU,
            TU, TU->getASTContext().Diags, SIL, PersistentState) {
   this->IsMainModule = IsMainModule;
   auto ParserPos = State->takeParserPosition();
-  if (ParserPos.first.isValid() &&
-      SourceMgr.FindBufferContainingLoc(ParserPos.first.Value)== int(BufferID)){
-    auto BeginParserPosition =
-        getParserPosition(ParserPos.first, ParserPos.second);
+  if (ParserPos.isValid() &&
+      SourceMgr.FindBufferContainingLoc(ParserPos.Loc.Value) == int(BufferID)) {
+    auto BeginParserPosition = getParserPosition(ParserPos);
     restoreParserPosition(BeginParserPosition);
   }
 }