[incrParse] Reparse a node if the next leaf node has been modified

include/swift/Parse/SyntaxParsingCache.h

@@ -15,6 +15,32 @@
 
 #include "swift/Syntax/SyntaxNodes.h"
 
+namespace {
+
+/// A single edit to the original source file in which a continuous range of
+/// characters have been replaced by a new string
+struct SourceEdit {
+  /// The byte offset from which on characters were replaced.
+  size_t Start;
+
+  /// The byte offset to which on characters were replaced.
+  size_t End;
+
+  /// The length of the string that replaced the range described above.
+  size_t ReplacementLength;
+
+  /// The length of the range that has been replaced
+  size_t originalLength() { return End - Start; }
+
+  /// Check if the characters replaced by this edit fall into the given range
+  /// or are directly adjacent to it
+  bool intersectsOrTouchesRange(size_t RangeStart, size_t RangeEnd) {
+    return !(End <= RangeStart || Start >= RangeEnd);
+  }
+};
+
+} // anonymous namespace
+
 namespace swift {
 
 using namespace swift::syntax;
@@ -23,11 +49,29 @@ class SyntaxParsingCache {
   /// The syntax tree prior to the edit
   SourceFileSyntax OldSyntaxTree;
 
+  /// The edits that were made from the source file that created this cache to
+  /// the source file that is now parsed incrementally
+  llvm::SmallVector<SourceEdit, 4> Edits;
+
 public:
   SyntaxParsingCache(SourceFileSyntax OldSyntaxTree)
       : OldSyntaxTree(OldSyntaxTree) {}
 
+  /// Add an edit that transformed the source file which created this cache into
+  /// the source file that is now being parsed incrementally. The order in which
+  /// the edits are added using this method needs to be the same order in which
+  /// the edits were applied to the source file.
+  void addEdit(size_t Start, size_t End, size_t ReplacementLength) {
+    Edits.push_back({Start, End, ReplacementLength});
+  }
+
+  /// Check if a syntax node of the given kind at the given position can be
+  /// reused for a new syntax tree.
   llvm::Optional<Syntax> lookUp(size_t NewPosition, SyntaxKind Kind) const;
+
+private:
+  llvm::Optional<Syntax> lookUpFrom(Syntax Node, size_t Position,
+                                    SyntaxKind Kind) const;
 };
 
 } // namespace swift

include/swift/Syntax/SyntaxKind.h.gyb

@@ -108,4 +108,8 @@ struct ScalarEnumerationTraits<swift::syntax::SyntaxKind> {
 
 } // end namespace yaml
 } // end namespace llvm
+
+namespace llvm {
+  raw_ostream &operator<<(raw_ostream &OS, swift::syntax::SyntaxKind Kind);
+} // end namespace llvm
 #endif // SWIFT_SYNTAX_KIND_H

lib/Parse/SyntaxParsingCache.cpp

@@ -15,12 +15,29 @@
 using namespace swift;
 using namespace swift::syntax;
 
-llvm::Optional<Syntax> lookUpFrom(Syntax Node, size_t Position,
-                                  SyntaxKind Kind) {
+llvm::Optional<Syntax> SyntaxParsingCache::lookUpFrom(Syntax Node,
+                                                      size_t Position,
+                                                      SyntaxKind Kind) const {
   if (Node.getAbsolutePosition().getOffset() == Position &&
       Node.getKind() == Kind) {
+    // Check if this node has been edited. If it has, we cannot reuse it.
+    bool NodeEdited = false;
+
+    auto NodeStart = Node.getAbsolutePosition().getOffset();
+    auto NodeEnd = NodeStart + Node.getTextLength();
+    for (auto Edit : Edits) {
+      if (Edit.intersectsOrTouchesRange(NodeStart, NodeEnd)) {
+        NodeEdited = true;
+      }
+    }
+
+    // FIXME: Node can also not be reused if an edit has been made in the next
+    // token's leading trivia
+
+    if (!NodeEdited) {
       return Node;
     }
+  }
 
   for (size_t I = 0, E = Node.getNumChildren(); I < E; ++I) {
     llvm::Optional<Syntax> Child = Node.getChild(I);
@@ -38,6 +55,15 @@ llvm::Optional<Syntax> lookUpFrom(Syntax Node, size_t Position,
 
 llvm::Optional<Syntax> SyntaxParsingCache::lookUp(size_t NewPosition,
                                                   SyntaxKind Kind) const {
-  // FIXME: Transform the new position into the position in the old file
-  return lookUpFrom(OldSyntaxTree, NewPosition, Kind);
+  // Undo the edits in reverse order
+  size_t OldPosition = NewPosition;
+  for (auto I = Edits.rbegin(), E = Edits.rend(); I != E; ++I) {
+    auto Edit = *I;
+    if (Edit.End < OldPosition) {
+      OldPosition =
+          OldPosition - Edit.ReplacementLength + Edit.originalLength();
+    }
+  }
+
+  return lookUpFrom(OldSyntaxTree, OldPosition, Kind);
 }

lib/Syntax/SyntaxKind.cpp.gyb

@@ -19,6 +19,7 @@
 
 #include "swift/Syntax/SyntaxKind.h"
 #include "swift/Syntax/TokenKinds.h"
+#include "llvm/Support/raw_ostream.h"
 
 namespace swift {
 
@@ -123,3 +124,21 @@ SyntaxKind getUnknownKind(SyntaxKind Kind) {
 }
 } // end namespace syntax
 } // end namespace swift
+
+llvm::raw_ostream &llvm::operator<<(llvm::raw_ostream &OS,
+                                    swift::syntax::SyntaxKind Kind) {
+  switch (Kind) {
+% for node in SYNTAX_NODES:
+    case swift::syntax::SyntaxKind::${node.syntax_kind}:
+    OS << "${node.syntax_kind}";
+    break;
+% end
+    case swift::syntax::SyntaxKind::Token:
+    OS << "TokenSyntax";
+    break;
+    case swift::syntax::SyntaxKind::Unknown:
+    OS << "UnknownSyntax";
+    break;
+  }
+  return OS;
+}

tools/swift-syntax-test/swift-syntax-test.cpp

@@ -35,6 +35,7 @@
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/Regex.h"
 
 using namespace swift;
 using namespace swift::syntax;
@@ -111,6 +112,17 @@ OldSyntaxTreeFilename("old-syntax-tree-filename",
                       llvm::cl::desc("Path to the serialized syntax tree of "
                                      "the pre-edit file"));
 
+static llvm::cl::list<std::string>
+IncrementalEdits("incremental-edit",
+                 llvm::cl::desc("An edit that was applied to reach the input "
+                                "file from the source file that generated the "
+                                "old syntax tree in the format "
+                                "<start>:<end>=<replacement> where <start> and "
+                                "<end> are byte offsets in the original file "
+                                "and <replacement> is the string that shall "
+                                "replace the selected range. "
+                                "Can be passed multiple times."));
+
 static llvm::cl::opt<std::string>
 OutputFilename("output-filename",
                llvm::cl::desc("Path to the output file"));
@@ -321,6 +333,25 @@ int doIncrementalParse(const char *MainExecutablePath,
   }
   SyntaxParsingCache *Cache = new SyntaxParsingCache(OldSyntaxTree.getValue());
 
+  for (auto EditPattern : options::IncrementalEdits) {
+    llvm::Regex MatchRegex("([0-9]+):([0-9]+)=(.*)");
+    SmallVector<StringRef, 4> Matches;
+    if (!MatchRegex.match(EditPattern, &Matches)) {
+      llvm::errs() << "Invalid edit pattern: " << EditPattern;
+      return EXIT_FAILURE;
+    }
+    int EditStart, EditEnd;
+    if (Matches[1].getAsInteger(10, EditStart)) {
+      llvm::errs() << "Could not parse edit start as integer: " << EditStart;
+      return EXIT_FAILURE;
+    }
+    if (Matches[2].getAsInteger(10, EditEnd)) {
+      llvm::errs() << "Could not parse edit end as integer: " << EditStart;
+      return EXIT_FAILURE;
+    }
+    Cache->addEdit(EditStart, EditEnd, /*ReplacmentLength=*/Matches[3].size());
+  }
+
   // Parse the new libSyntax tree incrementally
   CompilerInstance Instance;
   SourceFile *SF =