TASK-060: a function's name in the code is a link to its counterpart

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/CodePane.kt

@@ -28,6 +28,7 @@ import androidx.compose.runtime.mutableFloatStateOf
 import androidx.compose.runtime.mutableIntStateOf
 import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
+import androidx.compose.runtime.rememberUpdatedState
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
@@ -36,6 +37,9 @@ import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.layout.onSizeChanged
 import androidx.compose.ui.platform.LocalDensity
 import androidx.compose.ui.text.AnnotatedString
+import androidx.compose.ui.text.LinkAnnotation
+import androidx.compose.ui.text.TextLinkStyles
+import androidx.compose.ui.text.style.TextDecoration
 import androidx.compose.ui.text.SpanStyle
 import androidx.compose.ui.text.TextStyle
 import androidx.compose.ui.text.buildAnnotatedString
@@ -52,6 +56,8 @@ import com.ubisam.ubgitea.feature.codebrowser.content.SearchMatch
 import com.ubisam.ubgitea.feature.codebrowser.content.SyntaxLanguage
 import com.ubisam.ubgitea.feature.codebrowser.content.extractSymbols
 import com.ubisam.ubgitea.feature.codebrowser.content.highlightLines
+import com.ubisam.ubgitea.feature.codebrowser.content.SymbolKind
+import com.ubisam.ubgitea.feature.codebrowser.content.nameRangeOf
 import com.ubisam.ubgitea.feature.codebrowser.content.rememberCodeSyntaxColors
 import com.ubisam.ubgitea.feature.codebrowser.content.syntaxLanguageForPath
 import com.ubisam.ubgitea.ui.theme.UBGiteaTheme
@@ -131,8 +137,15 @@ fun CodePane(
     search: SearchHighlight = SearchHighlight.None,
     focusedLine: Int? = null,
     contentPadding: PaddingValues = PaddingValues(vertical = 8.dp),
+    // When given, the name of a function on the line that declares it is a link (TASK-060).
+    onFunctionTapped: ((CodeSymbol) -> Unit)? = null,
 ) {
     val colors = rememberCodeSyntaxColors()
+    val tapped by rememberUpdatedState(onFunctionTapped)
+    val linked = onFunctionTapped != null
+    val functionsByLine = remember(document.symbols, linked) {
+        if (linked) document.symbols.filter { it.kind == SymbolKind.METHOD }.associateBy(CodeSymbol::line) else emptyMap()
+    }
     val style = remember(fontSizeSp, colors.text) {
         TextStyle(
             fontFamily = FontFamily.Monospace,
@@ -165,8 +178,26 @@ fun CodePane(
         LazyColumn(state = listState, contentPadding = contentPadding, modifier = Modifier.fillMaxSize()) {
             items(document.lines.size, key = { it }) { index ->
                 val line = document.highlighted.getOrElse(index) { AnnotatedString(document.lines[index]) }
-                val shown = remember(line, search.byLine[index], search.current) {
+                val function = functionsByLine[index]
-                    withSearchHits(line, search.byLine[index], search.current, hit)
+                val shown = remember(line, search.byLine[index], search.current, function) {
+                    val marked = withSearchHits(line, search.byLine[index], search.current, hit)
+                    val name = function?.let { nameRangeOf(it, document.lines[index]) }
+                    if (function == null || name == null || name.last >= marked.length) {
+                        marked
+                    } else {
+                        buildAnnotatedString {
+                            append(marked)
+                            // Underlined and otherwise left in its own color: it is still code.
+                            addLink(
+                                LinkAnnotation.Clickable(
+                                    tag = "function",
+                                    styles = TextLinkStyles(SpanStyle(textDecoration = TextDecoration.Underline)),
+                                ) { tapped?.invoke(function) },
+                                name.first,
+                                name.last + 1,
+                            )
+                        }
+                    }
                 }
                 Row(
                     Modifier.fillMaxWidth().background(if (index == focusedLine) focusColor else Color.Transparent),

app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/CodeViewerScreen.kt

@@ -395,6 +395,15 @@ fun CodeViewerScreen(
                         counterpartPath = counterpartPath!!,
                         splitFraction = splitFraction,
                         onSplitChange = { splitFraction = it },
+                        // Beside each other, a function tapped in one pane is shown in the other.
+                        onFunctionTapped = { symbol ->
+                            otherDocument?.let { findSymbolNamed(it.symbols, symbol.name, symbol.kind) }?.let { match ->
+                                scope.launch { otherState.scrollToItem(match.line) }
+                            }
+                        },
+                        onOtherFunctionTapped = { symbol ->
+                            findSymbolNamed(document.symbols, symbol.name, symbol.kind)?.let { goToLine(it.line) }
+                        },
                     )
                     else -> {
                         if (layout == ViewerLayout.WIDE) {
@@ -424,6 +433,7 @@ fun CodeViewerScreen(
                                 search = highlight,
                                 focusedLine = focusedLine,
                                 contentPadding = PaddingValues(top = 8.dp, bottom = if (counterpartPath != null) 76.dp else 8.dp),
+                                onFunctionTapped = jump?.onJump,
                             )
                             if (counterpartPath != null && layout != ViewerLayout.WIDE && !searching) {
                                 val method = enclosingSymbols(document.symbols, firstVisibleLine).lastOrNull { it.kind == SymbolKind.METHOD }
@@ -843,6 +853,8 @@ private fun PairPanes(
     counterpartPath: RepositoryPath,
     splitFraction: Float,
     onSplitChange: (Float) -> Unit,
+    onFunctionTapped: (CodeSymbol) -> Unit,
+    onOtherFunctionTapped: (CodeSymbol) -> Unit,
 ) {
     if (syncPanes && otherDocument != null) {
         FollowSymbols(listState, document, otherState, otherDocument)
@@ -852,7 +864,10 @@ private fun PairPanes(
     val current: @Composable (Modifier) -> Unit = { modifier ->
         Column(modifier) {
             PaneHeader(document.name, state.path, document.lines.size, enclosingSymbols(document.symbols, listState.firstVisibleItemIndex))
-            CodePane(document, listState, preferences.wordWrap, preferences.fontSizeSp, search = highlight, focusedLine = focusedLine)
+            CodePane(
+                document, listState, preferences.wordWrap, preferences.fontSizeSp,
+                search = highlight, focusedLine = focusedLine, onFunctionTapped = onFunctionTapped,
+            )
         }
     }
     val other: @Composable (Modifier) -> Unit = { modifier ->
@@ -861,7 +876,7 @@ private fun PairPanes(
             when {
                 otherDocument != null -> {
                     PaneHeader(name, counterpartPath, otherDocument.lines.size, enclosingSymbols(otherDocument.symbols, otherState.firstVisibleItemIndex))
-                    CodePane(otherDocument, otherState, preferences.wordWrap, preferences.fontSizeSp)
+                    CodePane(otherDocument, otherState, preferences.wordWrap, preferences.fontSizeSp, onFunctionTapped = onOtherFunctionTapped)
                 }
                 else -> {
                     PaneHeader(name, counterpartPath, null, emptyList())

app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/content/SymbolOutline.kt

@@ -126,6 +126,21 @@ fun outlineTree(symbols: List<CodeSymbol>, collapsed: Set<Int> = emptySet()): Li
 fun methodCountOf(symbols: List<CodeSymbol>, container: CodeSymbol): Int =
     symbols.count { it.kind == SymbolKind.METHOD && it.line > container.line && it.line <= container.endLine }
 
+/**
+ * Where the name of [symbol] is written on [line], the line it is declared on, as `[start, end)`;
+ * null when it cannot be found there. The name is the last occurrence before the parameter list,
+ * so in `Retry Retry::Make(int n)` it is `Make`, and in `A::A()` the second `A`.
+ */
+fun nameRangeOf(symbol: CodeSymbol, line: String): IntRange? {
+    val parenthesis = line.indexOf('(')
+    if (parenthesis <= 0) return null
+    val start = line.lastIndexOf(symbol.name, parenthesis - 1)
+    if (start < 0 || start + symbol.name.length > parenthesis) return null
+    // Part of a longer word (`GetValue` inside `TryGetValue`) is not the name.
+    if (start > 0 && (line[start - 1].isLetterOrDigit() || line[start - 1] == '_')) return null
+    return start until start + symbol.name.length
+}
+
 /** The symbols enclosing [line], outermost first: what a "you are here" strip shows. */
 fun enclosingSymbols(symbols: List<CodeSymbol>, line: Int): List<CodeSymbol> =
     symbols.filter { it.kind != SymbolKind.FIELD && line in it.line..it.endLine }.sortedBy(CodeSymbol::depth)

app/src/test/java/com/ubisam/ubgitea/feature/codebrowser/content/SymbolOutlineTest.kt

@@ -157,6 +157,28 @@ class SymbolOutlineTest {
         assertEquals(9, symbols.first().endLine)
     }
 
+    @Test
+    fun `the name of a function is found where it is written on its line`() {
+        fun named(line: String): String? {
+            val symbol = extractSymbols(listOf("class A", "{", line, "};"), SyntaxLanguage.CPP).firstOrNull { it.kind == SymbolKind.METHOD }
+                ?: extractSymbols(listOf(line, "{", "}"), SyntaxLanguage.CPP).first { it.kind == SymbolKind.METHOD }
+            return nameRangeOf(symbol, line)?.let { line.substring(it.first, it.last + 1) + "@" + it.first }
+        }
+
+        assertEquals("OnBnClickedOk@17", named("    afx_msg void OnBnClickedOk();"))
+        assertEquals("Make@13", named("Retry Retry::Make(int n)"))
+        assertEquals("A@3", named("A::A(int a)"))
+        assertEquals("~A@3", named("A::~A()"))
+    }
+
+    @Test
+    fun `a name that is only part of a longer word on the line is not the name`() {
+        val symbol = CodeSymbol("GetValue", "GetValue()", SymbolKind.METHOD, 0, 0, 0)
+
+        assertEquals(null, nameRangeOf(symbol, "bool TryGetValue();"))
+        assertEquals(null, nameRangeOf(symbol, "no parenthesis here"))
+    }
+
     @Test
     fun `a forward declaration is not listed`() {
         val symbols = extractSymbols(listOf("class Foo;"), SyntaxLanguage.CPP)

docs/development-log.md

@@ -1401,3 +1401,12 @@ This is the append-only implementation and handoff record shared by Codex and Cl
 - Checks and results: the required checks pass; 435 unit tests, 0 failures; lint 0 errors.
 - Live verification: installed on the SM-F966N; not seen on a screen by the implementer.
 - Next owner: the product owner, to confirm on the device.
+
+## 2026-09-28 (continued) — TASK-060: tapping a function in the code
+
+- Request: the human product owner asked for the jump of TASK-059 from the code itself.
+- What changed: see `tasks/060-tap-a-function-in-the-code.md`. Names are links where a function
+  is declared or defined, not where it is called.
+- Checks and results: the required checks pass; 437 unit tests, 0 failures; lint 0 errors.
+- Live verification: installed on the SM-F966N; not seen on a screen by the implementer.
+- Next owner: the product owner, to confirm on the device.

tasks/060-tap-a-function-in-the-code.md

@@ -0,0 +1,57 @@
+# TASK-060: Tapping a function's name in the code
+
+Status: implemented; required checks pass; installed on the product owner's Z Fold7, awaiting their confirmation
+Owner: Claude
+Reviewer: human product owner
+
+## Outcome
+
+TASK-059 put the jump from a header to its source on a button in the outline. The human product
+owner asked for it in the code itself.
+
+## Scope
+
+- Included:
+  - In a file that has a counterpart, the name of a function is underlined on the line that
+    declares or defines it. Tapping it opens the counterpart at the function of the same name:
+    `.h` to `.cpp`, and `.cpp` to `.h`.
+  - Side by side, tapping the name in one pane brings the same function into view in the other.
+- Excluded:
+  - A function's name where it is *called*. Going from a call to a definition needs to know which
+    file defines it, which means reading the whole repository; this app reads one file at a time.
+  - Files with no counterpart (C#, a lone `.cpp`): no names are links, as there is nowhere to go.
+  - Telling overloads apart: the first function of that name is the one shown.
+
+## Writable paths
+
+- `app/src/main/java/com/ubisam/ubgitea/feature/codebrowser/`
+- `app/src/test/java/com/ubisam/ubgitea/feature/codebrowser/`
+- `tasks/`, `docs/`
+
+## Acceptance criteria
+
+- [x] Only the name is the link, not the whole line; the rest of the line can still be selected.
+- [x] The name is found after a qualifier (`A::F`), for a constructor (`A::A`) and a destructor.
+- [x] A name that is only part of a longer word on the line is not linked.
+- [x] Unit tests cover where the name is found.
+
+## Security and privacy
+
+No additional concerns.
+
+## Required checks
+
+```text
+./gradlew compileDebugKotlin compileDebugUnitTestKotlin testDebugUnitTest assembleDebug lintDebug
+```
+
+## Evidence
+
+- Required checks pass: 437 unit tests, 0 failures; lint 0 errors.
+- Installed on the SM-F966N over wireless `adb`.
+- Not seen on a screen by the implementer. In particular, how a tap on a link and a long press to
+  select text get along inside the selectable code has not been tried on a device.
+
+## Review findings
+
+None yet.