# TASK-049: C/C++ syntax highlighting and multi-line comment coloring

Status: implemented; required checks pass; confirmed by the human product owner on their Z Fold7 (2026-09-29)
Owner: Claude
Reviewer: human product owner

## Outcome

The human product owner's team mainly reads C# and C++ in this app. C/C++ files currently fall
back to plain, uncolored text, and a block comment that spans several lines is only colored on its
first and last line (TASK-048's recorded known limitation). After this task C/C++ sources are
highlighted, and a multi-line comment keeps its comment color on every line it covers, in every
language that has block comments.

## Scope

- Included: a `CPP` language (`.c .h .cc .cpp .cxx .hpp .hh .hxx .inl .ipp`) with its keyword set;
  preprocessor directives (`#include`, `#pragma`, `#define`, C#'s `#region` ...) in their own color,
  with an `#include <...>` target colored as a string; cross-line block-comment state (`/* */` and
  `<!-- -->`) carried from one line to the next; numbers with digit separators (`30_000`,
  `1'000'000`) and hex literals; unit tests for all of the above.
- Excluded: a real parser. Multi-line *strings* (C++ raw strings, C# verbatim/raw strings, Python
  triple quotes) still only color on the line where they start. Type/method coloring, the Visual
  Studio palette, the header/source pairing view and the standalone full-screen viewer belong to
  the redesign tasks that follow.

## Writable paths

- `app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/content/SyntaxHighlighter.kt`
- `app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/CodeBrowserScreen.kt` (`CodeBlock` only)
- `app/src/test/java/com/ubisam/ubgitea/feature/codebrowser/content/SyntaxHighlighterTest.kt`
- `tasks/049-cpp-highlighting-and-multiline-comments.md`, `docs/development-log.md`

## Acceptance criteria

- [x] `.c .h .cc .cpp .cxx .hpp .hh .hxx .inl .ipp` files resolve to the C/C++ language.
- [x] C/C++ keywords, strings, numbers, line comments and block comments are colored.
- [x] `#include <chrono>` colors the directive as preprocessor and `<chrono>` as a string.
- [x] Every line inside a multi-line `/* ... */` or `<!-- ... -->` comment is colored as a comment,
      and code after the closing delimiter on the same line is highlighted normally.
- [x] A `/*` inside a string literal or after `//` does not open a comment.
- [x] Highlighting is computed once per file, not on every recomposition.
- [x] Unit tests cover the criteria above.
- [ ] Confirmed on the human product owner's device against real C++ sources.

## Security and privacy

No additional concerns. No network, storage or logging is touched.

## Required checks

```text
./gradlew compileDebugKotlin compileDebugUnitTestKotlin testDebugUnitTest assembleDebug lintDebug
```

## Evidence

Recorded on 2026-09-28 in the worktree `awesome-pascal-3f2ada`, on top of `39be1b7` plus the
still-uncommitted TASK-045..048 changes copied from the main checkout, using Android Studio's
bundled JDK (`D:\AndroidStudio\jbr`, OpenJDK 21):

- `./gradlew compileDebugKotlin compileDebugUnitTestKotlin testDebugUnitTest` -- passed; 289 tests,
  0 failures, 0 errors, 0 skipped. New `SyntaxHighlighterTest`: 21 tests, all passing.
- `./gradlew assembleDebug lintDebug` -- passed; lint 0 errors, 40 warnings.
- `SyntaxHighlighter.kt`: new `CPP` language and extension mapping; `tokenizeLines` (Compose-free,
  carries open block-comment state across lines); `highlightLines`; preprocessor role and color;
  number pattern extended to hex and digit separators. `highlightLine` kept as a single-line
  wrapper.
- `CodeBrowserScreen.kt`: `CodeBlock` highlights the whole file once inside `remember` and renders
  the cached lines in both the wrap and no-wrap branches.
- Not done: installing on a device. No device was connected to this session.

## Review findings

None yet.