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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+llcppg is an LLGo autogen tool for C/C++ libraries that automatically generates LLGo bindings for C/C++ libraries. The tool enhances integration between LLGo and the C ecosystem.
+
+**Key Technologies:**
+- Go 1.23.0 
+- LLGo (Go+ compiler for low-level programming)
+- LLVM 19 with clang/libclang for C/C++ parsing
+- Dependencies: gogen, llgo, mod, qiniu/x
+
+## Build and Development Commands
+
+### Installation and Setup
+```bash
+# Install system dependencies (required before building)
+# For macOS:
+brew install cjson llvm@19 bdw-gc openssl libffi libuv lld@19 zlib
+
+# Install all tools (REQUIRED for full functionality)
+bash ./install.sh
+```
+
+### Build Commands
+```bash
+# Build all Go components
+go build -v ./...
+
+# Install individual tools
+go install ./cmd/llcppcfg    # Configuration generator
+go install ./cmd/gogensig    # Go signature generator  
+go install ./cmd/llcppg      # Main binding generator
+llgo install ./_xtool/llcppsymg      # Symbol generator (LLGo)
+llgo install ./_xtool/llcppsigfetch  # Signature fetcher (LLGo)
+```
+
+### Test Commands
+```bash
+# Basic Go tests (fast, 2 seconds)
+go test -v ./config ./internal/name ./internal/arg ./internal/unmarshal
+
+# Full test suite (8-12 minutes, requires LLGo tools)
+go test -timeout=10m -v ./...
+
+# LLGo-specific tests (3-5 minutes)
+llgo test ./_xtool/internal/...
+llgo test ./_xtool/llcppsigfetch/internal/...
+llgo test ./_xtool/llcppsymg/internal/...
+
+# Demo validation (5-10 minutes)
+bash .github/workflows/test_demo.sh
+```
+
+### Usage Commands
+```bash
+# Generate configuration file
+llcppcfg [libname]
+
+# Generate LLGo bindings
+llcppg [config-file]  # Uses llcppg.cfg if not specified
+
+# Test a complete workflow
+llcppcfg cjson
+# Edit llcppg.cfg to add include files
+llcppg llcppg.cfg
+```
+
+## High-Level Architecture
+
+### Three-Stage Pipeline
+1. **llcppsymg** (`_xtool/llcppsymg/`) - Symbol table generator
+   - Analyzes C/C++ libraries and header files
+   - Extracts symbols using nm tool
+   - Matches library symbols with header declarations
+   - Outputs: `llcppg.symb.json`
+
+2. **llcppsigfetch** (`_xtool/llcppsigfetch/`) - Signature fetcher  
+   - Uses libclang to parse C/C++ header files
+   - Extracts type information and function signatures
+   - Outputs: JSON-formatted package information structure
+
+3. **gogensig** (`cmd/gogensig/`) - Go code generator
+   - Converts C/C++ declarations to Go code
+   - Generates functions, methods, types, and constants
+   - Uses symbol table to determine what to generate
+
+### Core Components
+
+**Parser Layer** (`parser/`, `_xtool/internal/parser/`)
+- C/C++ header file parsing using libclang
+- AST generation and traversal
+- Type extraction and analysis
+
+**Conversion Layer** (`cl/`, `cl/internal/convert/`)
+- Type mapping from C/C++ to Go
+- Function signature conversion
+- Method generation logic
+- Name transformation rules
+
+**Configuration** (`config/`)
+- Configuration file parsing (`llcppg.cfg`)
+- Dependency management
+- Type mapping configuration
+
+**Tool Layer** (`tool/`)
+- High-level APIs for binding generation
+- File composition and output management
+
+### Key File Types
+
+**Configuration Files:**
+- `llcppg.cfg` - Main configuration (cflags, libs, includes, deps)
+- `llcppg.pub` - Type mapping for dependencies  
+- `llcppg.symb.json` - Symbol table mapping
+
+**Generated Files:**
+- `{header}.go` - Go bindings for each header file
+- `{name}_autogen.go` - Implementation files
+- `{name}_autogen_link.go` - Linking information
+
+### Critical Dependencies
+
+**LLGo Tools** (compiled with LLGo, not Go):
+- `llcppsymg` - Symbol analysis
+- `llcppsigfetch` - Header parsing
+- These MUST be installed via `install.sh` for testing
+
+**System Dependencies:**
+- LLVM 19 development libraries
+- libclang-19-dev
+- Platform-specific C libraries (libcjson-dev, etc.)
+
+## Development Guidelines
+
+### Before Making Changes
+1. Run `bash ./install.sh` to ensure all tools are available
+2. Test with a known working example from `_llcppgtest/` or `_demo/`
+3. Verify the three-stage pipeline works end-to-end
+
+### After Making Changes  
+1. Build: `go build -v ./...`
+2. Install: `bash ./install.sh` (essential for testing)
+3. Test: `go test -timeout=10m -v ./...`
+4. Validate with demo: `bash .github/workflows/test_demo.sh`
+
+### Testing Strategy
+- Quick validation: `go test -v ./config ./internal/name ./internal/arg`
+- Full validation: Install tools + run full test suite
+- Real-world validation: Test with cjson, sqlite, or zlib examples
+
+### Common Patterns
+- Look at `_llcppgtest/` for real configuration examples
+- Follow existing type mapping patterns in `cl/internal/convert/`
+- Use naming conventions from `internal/name/`
+- Reference design documentation in `doc/en/dev/llcppg.md`
+
+## Important Notes
+
+- Never attempt to modify LLGo tools (`_xtool/llcppsymg`, `_xtool/llcppsigfetch`) without LLGo installed
+- Always run `install.sh` after changes - many tests depend on installed tools
+- Build times: 15 seconds for Go, 2-3 minutes for complete install
+- Test times: 2 seconds basic, 8-15 minutes full suite
+- The project requires specific LLVM 19 and LLGo versions - do not change these dependencies
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