[clang] [clang][Diagnostics] Highlight code snippets (PR #66514)

[Konrad Kleine via cfe-commits]

Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>,
Timm =?utf-8?q?Bäder?= <tbaeder at redhat.com>
Message-ID:
In-Reply-To: <llvm/llvm-project/pull/66514/clang at github.com>


================
@@ -0,0 +1,135 @@
+
+#include "clang/Frontend/CodeSnippetHighlighter.h"
+#include "clang/Basic/DiagnosticOptions.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Lex/Lexer.h"
+#include "clang/Lex/Preprocessor.h"
+#include "clang/Lex/PreprocessorOptions.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace clang;
+
+static constexpr raw_ostream::Colors CommentColor = raw_ostream::GREEN;
+static constexpr raw_ostream::Colors LiteralColor = raw_ostream::CYAN;
+static constexpr raw_ostream::Colors KeywordColor = raw_ostream::BLUE;
+
+std::vector<StyleRange> CodeSnippetHighlighter::highlightLine(
+    unsigned LineNumber, const Preprocessor *PP, const LangOptions &LangOpts,
+    FileID FID, const SourceManager &SM) {
+  if (!PP)
+    return {};
+
+  // Might cause emission of another diagnostic.
+  if (PP->getIdentifierTable().getExternalIdentifierLookup())
+    return {};
+
+  // Classify the given token and append it to the given vector.
+  auto appendStyle = [PP, &LangOpts](std::vector<StyleRange> &Vec,
+                                     const Token &T, unsigned Start,
+                                     unsigned Length) -> void {
+    if (T.is(tok::raw_identifier)) {
+      StringRef RawIdent = T.getRawIdentifier();
+      // Special case true/false/nullptr literals, since they will otherwise be
+      // treated as keywords.
+      if (RawIdent == "true" || RawIdent == "false" || RawIdent == "nullptr") {
+        Vec.push_back(StyleRange{Start, Start + Length, LiteralColor});
+      } else {
+        const IdentifierInfo *II = PP->getIdentifierInfo(RawIdent);
+        assert(II);
+
+        if (II->isKeyword(LangOpts)) {
+          Vec.push_back(StyleRange{Start, Start + Length, KeywordColor});
+        }
+      }
+    } else if (tok::isLiteral(T.getKind())) {
+      Vec.push_back(StyleRange{Start, Start + Length, LiteralColor});
+    } else if (T.is(tok::comment)) {
+      Vec.push_back(StyleRange{Start, Start + Length, CommentColor});
+    }
+  };
+
+  auto Buff = SM.getBufferOrNone(FID);
+  assert(Buff);
+  Lexer L = Lexer(FID, *Buff, SM, LangOpts);
+  L.SetKeepWhitespaceMode(true);
+  std::vector<std::vector<StyleRange>> Lines;
+
+  bool Stop = false;
+  while (!Stop) {
+    Token T;
+    Stop = L.LexFromRawLexer(T);
+    if (T.is(tok::unknown))
+      continue;
+
+    bool Invalid;
+    unsigned StartCol =
+        SM.getSpellingColumnNumber(T.getLocation(), &Invalid) - 1;
+    if (Invalid)
+      continue;
+    unsigned StartLine =
+        SM.getSpellingLineNumber(T.getLocation(), &Invalid) - 1;
+    if (Invalid)
+      continue;
+
+    while (Lines.size() <= StartLine)
+      Lines.push_back({});
+
+    unsigned EndLine = SM.getSpellingLineNumber(T.getEndLoc(), &Invalid) - 1;
+    if (Invalid)
+      continue;
+
+    // Simple tokens.
+    if (StartLine == EndLine) {
+      appendStyle(Lines[StartLine], T, StartCol, T.getLength());
+      continue;
+    }
+    unsigned NumLines = EndLine - StartLine;
+
+    // For tokens that span multiple lines (think multiline comments), we
+    // divide them into multiple StyleRanges.
+    unsigned EndCol = SM.getSpellingColumnNumber(T.getEndLoc(), &Invalid) - 1;
+    if (Invalid)
+      continue;
+
+    std::string Spelling = Lexer::getSpelling(T, SM, LangOpts);
+
+    unsigned L = 0;
+    unsigned LineLength = 0;
+    for (unsigned I = 0; I <= Spelling.size(); ++I) {
+      // This line is done.
+      if (Spelling[I] == '\n' || Spelling[I] == '\r' || I == Spelling.size()) {
+        while (Lines.size() <= StartLine + L)
+          Lines.push_back({});
+
+        if (L == 0) // First line
+          appendStyle(Lines[StartLine + L], T, StartCol, LineLength);
+        else if (L == NumLines) // Last line
----------------
kwk wrote:

@tbaederr if you have 10 lines and the first number is 0, then the last number must be 9. But you check for `L == 10` which seems off by one. 

https://github.com/llvm/llvm-project/pull/66514