C Through

See through your C/C++ codebase. Source Insight-style relational function trees, call graphs, CodeLens inline metrics, and cross-file reference analysis — all inside VS Code.

Current Version: 1.3.3

Features

🌳 Sidebar Tree View

A live, structured breakdown of every C/C++ file — organized into collapsible sections:

• Includes — all #include dependencies with system vs local distinction
• Structs / Types — every struct and typedef with field listings
• Macros — function-like and value macros with their expansions
• Global Variables — file-scope variable declarations
• Functions — every function with its callers, callees, return type, and line number

Click any item to jump directly to its definition in the source file.

🔍 Interactive Call Graph

A fully interactive visual graph of function call relationships.

• Pan — click and drag the canvas
• Zoom — scroll wheel or +/− buttons
• Click node — jump to source + inspect details in sidebar
• Double-click node — collapse or expand that node's children independently
• Click +N badge — toggle a single node without affecting siblings
• ⬇ Top→Down / ➡ Left→Right — toggle layout direction
• Drill down — re-root the tree on any node

Node colors:

💡 CodeLens Inline Metrics

Clickable annotations appear directly above every function definition — no panel switching required.

  ↑ 4 callers  ↓ 7 calls  🟡 complexity: 11  📄 main.c, driver.c
  int process_packet(PacketHeader *hdr, uint8_t *buf, int len) {

Complexity thresholds:

• 🟢 1–9 — Simple, easy to test
• 🟡 10–19 — High, consider refactoring
• 🔴 20+ — Very high, hard to maintain

📂 Flexible Scan Scope

Cross-file caller/callee relationships are fully resolved after any multi-file scan.

Installation

From VS Code Marketplace

1. Press Ctrl+Shift+X
2. Search "C Through"
3. Click Install

From VSIX

code --install-extension c-through-1.3.3.vsix

Usage

Quick Start

1. Open any .c or .h file — auto-analyzed, C Through panel appears in Explorer sidebar
2. Place cursor on any function name → right-click → C Through: Show Relational Tree

Commands (Ctrl+Shift+P)

Context Menus

• Editor — right-click inside any C/C++ file for tree commands
• Explorer — right-click any folder for Analyze This Directory

Settings

Example — scan only src/, skip build/ and vendor/:

{
  "cThrough.includeGlob": "src/**/*.{c,h}",
  "cThrough.excludeGlob": "{**/build/**,**/vendor/**,**/third_party/**}"
}

How It Works

C Through uses regex-based static analysis — no compiler, no language server, no build system required. Works on any C/C++ file that can be opened in VS Code.

The parser:

1. Strips comments and string literals
2. Extracts #include, #define, struct/typedef definitions
3. Identifies function definitions by signature pattern matching
4. Extracts all call sites inside each function body
5. Calculates cyclomatic complexity per function
6. Builds a cross-file caller/callee index across all scanned files

Known Limitations

• Function pointers are detected but cannot be statically resolved to targets
• Heavily macro-expanded signatures may not be fully parsed
• Very large files (10,000+ lines) may have partial symbol extraction
• C++ template specializations may be missed

Changelog

v1.3.3

• Added Sidebar toggle button (☰) — hide/show the right panel
• Theme and sidebar state now persist across panel re-opens via VS Code state
• Clicking Globals, Macros, and Includes in the sidebar now jumps to their exact source line
• Expanded global variable detection to support struct, typedef, and custom types
• Toolbar buttons are now icon-only for a cleaner, less crowded layout

v1.3.0

• Added Dark / Light mode toggle button in the call graph toolbar
• All UI elements switch theme instantly — background, sidebar, legend, links
• Node colors and function name labels are fully theme-aware
• Fixed function name labels becoming invisible in light mode

v1.2.2

• Added CodeLens inline annotations (callers, callees, complexity, dead code warning)
• Added cyclomatic complexity calculation per function
• Added Toggle CodeLens command and sidebar button

v1.1.0

• Added Analyze This Directory — right-click any folder in Explorer
• Removed 200-file scan cap — workspace scan now unlimited
• Added Re-scan Last Scope button
• Added includeGlob / excludeGlob settings
• Scope-aware auto-refresh on save

v1.0.0

• Initial release
• Sidebar tree: includes, structs, macros, globals, functions
• Interactive call graph with pan/zoom
• Cross-file caller/callee analysis
• Auto-analyze on file open

License

MIT © 2026