[clang-format] Format raw string literals

Summary:
This patch adds raw string literal formatting.

Reviewers: djasper, klimek

Reviewed By: klimek

Subscribers: klimek, mgorny

Differential Revision: https://reviews.llvm.org/D35943

llvm-svn: 316903

1 files changed, 154 insertions, 5 deletions

diff --git a/clang/lib/Format/ContinuationIndenter.cpp b/clang/lib/Format/ContinuationIndenter.cpp
index b57b8de2e70..4f624dd2fb4 100644
--- a/clang/lib/Format/ContinuationIndenter.cpp
+++ b/clang/lib/Format/ContinuationIndenter.cpp
@@ -14,6 +14,7 @@
 
 #include "ContinuationIndenter.h"
 #include "BreakableToken.h"
+#include "FormatInternal.h"
 #include "WhitespaceManager.h"
 #include "clang/Basic/OperatorPrecedence.h"
 #include "clang/Basic/SourceManager.h"
@@ -76,6 +77,53 @@ static bool opensProtoMessageField(const FormatToken &LessTok,
            (LessTok.Previous && LessTok.Previous->is(tok::equal))));
 }
 
+// Returns the delimiter of a raw string literal, or None if TokenText is not
+// the text of a raw string literal. The delimiter could be the empty string.
+// For example, the delimiter of R"deli(cont)deli" is deli.
+static llvm::Optional<StringRef> getRawStringDelimiter(StringRef TokenText) {
+  if (TokenText.size() < 5 // The smallest raw string possible is 'R"()"'.
+      || !TokenText.startswith("R\"") || !TokenText.endswith("\""))
+    return None;
+
+  // A raw string starts with 'R"<delimiter>(' and delimiter is ascii and has
+  // size at most 16 by the standard, so the first '(' must be among the first
+  // 19 bytes.
+  size_t LParenPos = TokenText.substr(0, 19).find_first_of('(');
+  if (LParenPos == StringRef::npos)
+    return None;
+  StringRef Delimiter = TokenText.substr(2, LParenPos - 2);
+
+  // Check that the string ends in ')Delimiter"'.
+  size_t RParenPos = TokenText.size() - Delimiter.size() - 2;
+  if (TokenText[RParenPos] != ')')
+    return None;
+  if (!TokenText.substr(RParenPos + 1).startswith(Delimiter))
+    return None;
+  return Delimiter;
+}
+
+RawStringFormatStyleManager::RawStringFormatStyleManager(
+    const FormatStyle &CodeStyle) {
+  for (const auto &RawStringFormat : CodeStyle.RawStringFormats) {
+    FormatStyle Style;
+    if (!getPredefinedStyle(RawStringFormat.BasedOnStyle,
+                            RawStringFormat.Language, &Style)) {
+      Style = getLLVMStyle();
+      Style.Language = RawStringFormat.Language;
+    }
+    Style.ColumnLimit = CodeStyle.ColumnLimit;
+    DelimiterStyle.insert({RawStringFormat.Delimiter, Style});
+  }
+}
+
+llvm::Optional<FormatStyle>
+RawStringFormatStyleManager::get(StringRef Delimiter) const {
+  auto It = DelimiterStyle.find(Delimiter);
+  if (It == DelimiterStyle.end())
+    return None;
+  return It->second;
+}
+
 ContinuationIndenter::ContinuationIndenter(const FormatStyle &Style,
                                            const AdditionalKeywords &Keywords,
                                            const SourceManager &SourceMgr,
@@ -85,14 +133,18 @@ ContinuationIndenter::ContinuationIndenter(const FormatStyle &Style,
     : Style(Style), Keywords(Keywords), SourceMgr(SourceMgr),
       Whitespaces(Whitespaces), Encoding(Encoding),
       BinPackInconclusiveFunctions(BinPackInconclusiveFunctions),
-      CommentPragmasRegex(Style.CommentPragmas) {}
+      CommentPragmasRegex(Style.CommentPragmas), RawStringFormats(Style) {}
 
 LineState ContinuationIndenter::getInitialState(unsigned FirstIndent,
+                                                unsigned FirstStartColumn,
                                                 const AnnotatedLine *Line,
                                                 bool DryRun) {
   LineState State;
   State.FirstIndent = FirstIndent;
-  State.Column = FirstIndent;
+  if (FirstStartColumn && Line->First->NewlinesBefore == 0)
+    State.Column = FirstStartColumn;
+  else
+    State.Column = FirstIndent;
   // With preprocessor directive indentation, the line starts on column 0
   // since it's indented after the hash, but FirstIndent is set to the
   // preprocessor indent.
@@ -1216,6 +1268,89 @@ void ContinuationIndenter::moveStateToNewBlock(LineState &State) {
   State.Stack.back().BreakBeforeParameter = true;
 }
 
+static unsigned getLastLineEndColumn(StringRef Text, unsigned StartColumn,
+                                     unsigned TabWidth,
+                                     encoding::Encoding Encoding) {
+  size_t LastNewlinePos = Text.find_last_of("\n");
+  if (LastNewlinePos == StringRef::npos) {
+    return StartColumn +
+           encoding::columnWidthWithTabs(Text, StartColumn, TabWidth, Encoding);
+  } else {
+    return encoding::columnWidthWithTabs(Text.substr(LastNewlinePos),
+                                         /*StartColumn=*/0, TabWidth, Encoding);
+  }
+}
+
+unsigned ContinuationIndenter::reformatRawStringLiteral(
+    const FormatToken &Current, unsigned StartColumn, LineState &State,
+    StringRef Delimiter, const FormatStyle &RawStringStyle, bool DryRun) {
+  // The text of a raw string is between the leading 'R"delimiter(' and the
+  // trailing 'delimiter)"'.
+  unsigned PrefixSize = 3 + Delimiter.size();
+  unsigned SuffixSize = 2 + Delimiter.size();
+
+  // The first start column is the column the raw text starts.
+  unsigned FirstStartColumn = StartColumn + PrefixSize;
+
+  // The next start column is the intended indentation a line break inside
+  // the raw string at level 0. It is determined by the following rules:
+  //   - if the content starts on newline, it is one level more than the current
+  //     indent, and
+  //   - if the content does not start on a newline, it is the first start
+  //     column.
+  // These rules have the advantage that the formatted content both does not
+  // violate the rectangle rule and visually flows within the surrounding
+  // source.
+  bool ContentStartsOnNewline = Current.TokenText[PrefixSize] == '\n';
+  unsigned NextStartColumn = ContentStartsOnNewline
+                                 ? State.Stack.back().Indent + Style.IndentWidth
+                                 : FirstStartColumn;
+
+  // The last start column is the column the raw string suffix starts if it is
+  // put on a newline.
+  // The last start column is the intended indentation of the raw string postfix
+  // if it is put on a newline. It is determined by the following rules:
+  //   - if the raw string prefix starts on a newline, it is the column where
+  //     that raw string prefix starts, and
+  //   - if the raw string prefix does not start on a newline, it is the current
+  //     indent.
+  unsigned LastStartColumn = Current.NewlinesBefore
+                                 ? FirstStartColumn - PrefixSize
+                                 : State.Stack.back().Indent;
+
+  std::string RawText =
+      Current.TokenText.substr(PrefixSize).drop_back(SuffixSize);
+
+  std::pair<tooling::Replacements, unsigned> Fixes = internal::reformat(
+      RawStringStyle, RawText, {tooling::Range(0, RawText.size())},
+      FirstStartColumn, NextStartColumn, LastStartColumn, "<stdin>",
+      /*FormattingAttemptStatus=*/nullptr);
+
+  auto NewCode = applyAllReplacements(RawText, Fixes.first);
+  tooling::Replacements NoFixes;
+  if (!NewCode) {
+    State.Column += Current.ColumnWidth;
+    return 0;
+  }
+  if (!DryRun) {
+    SourceLocation OriginLoc =
+        Current.Tok.getLocation().getLocWithOffset(PrefixSize);
+    for (const tooling::Replacement &Fix : Fixes.first) {
+      auto Err = Whitespaces.addReplacement(tooling::Replacement(
+          SourceMgr, OriginLoc.getLocWithOffset(Fix.getOffset()),
+          Fix.getLength(), Fix.getReplacementText()));
+      if (Err) {
+        llvm::errs() << "Failed to reformat raw string: "
+                     << llvm::toString(std::move(Err)) << "\n";
+      }
+    }
+  }
+  unsigned RawLastLineEndColumn = getLastLineEndColumn(
+      *NewCode, FirstStartColumn, Style.TabWidth, Encoding);
+  State.Column = RawLastLineEndColumn + SuffixSize;
+  return Fixes.second;
+}
+
 unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
                                                  LineState &State) {
   if (!Current.IsMultiline)
@@ -1238,9 +1373,18 @@ unsigned ContinuationIndenter::addMultilineToken(const FormatToken &Current,
 unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
                                                     LineState &State,
                                                     bool DryRun) {
-  // Don't break multi-line tokens other than block comments. Instead, just
-  // update the state.
-  if (Current.isNot(TT_BlockComment) && Current.IsMultiline)
+  // Compute the raw string style to use in case this is a raw string literal
+  // that can be reformatted.
+  llvm::Optional<StringRef> Delimiter = None;
+  llvm::Optional<FormatStyle> RawStringStyle = None;
+  if (Current.isStringLiteral())
+    Delimiter = getRawStringDelimiter(Current.TokenText);
+  if (Delimiter)
+    RawStringStyle = RawStringFormats.get(*Delimiter);
+
+  // Don't break multi-line tokens other than block comments and raw string
+  // literals. Instead, just update the state.
+  if (Current.isNot(TT_BlockComment) && !RawStringStyle && Current.IsMultiline)
     return addMultilineToken(Current, State);
 
   // Don't break implicit string literals or import statements.
@@ -1275,6 +1419,11 @@ unsigned ContinuationIndenter::breakProtrudingToken(const FormatToken &Current,
     if (Current.IsUnterminatedLiteral)
       return 0;
 
+    if (RawStringStyle) {
+      RawStringStyle->ColumnLimit = ColumnLimit;
+      return reformatRawStringLiteral(Current, StartColumn, State, *Delimiter,
+                                      *RawStringStyle, DryRun);
+    } 
     StringRef Text = Current.TokenText;
     StringRef Prefix;
     StringRef Postfix;