ast-grep-find

AST-Grep Find

Structural code search that understands syntax. Find patterns like function calls, imports, class definitions - not just text.

When to Use

• Find code patterns (ignores strings/comments)
• Search for function calls, class definitions, imports
• Refactor code with AST precision
• Rename variables/functions across codebase

Usage

Search for a pattern

uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "import asyncio" --language python

Search in specific directory

uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "async def \$FUNC(\$\$\$)" --language python --path "./src"

Refactor/replace pattern

uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "console.log(\$MSG)" --replace "logger.info(\$MSG)" \
    --language javascript

Dry run (preview changes)

uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "print(\$X)" --replace "logger.info(\$X)" \
    --language python --dry-run

Parameters

| Parameter | Description |

|-----------|-------------|

| --pattern | AST pattern to search (required) |

| --language | Language: python, javascript, typescript, go, etc. |

| --path | Directory to search (default: .) |

| --glob | File glob pattern (e.g., **/*.py) |

| --replace | Replacement pattern for refactoring |

| --dry-run | Preview changes without applying |

| --context | Lines of context (default: 2) |

Pattern Syntax

| Syntax | Meaning |

|--------|---------|

| $NAME | Match single node (variable, expression) |

| $$$ | Match multiple nodes (arguments, statements) |

| $_ | Match any single node (wildcard) |

Examples

# Find all function definitions
uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "def \$FUNC(\$\$\$):" --language python

# Find console.log calls
uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "console.log(\$\$\$)" --language javascript

# Replace print with logging
uv run python -m runtime.harness scripts/ast_grep_find.py \
    --pattern "print(\$X)" --replace "logging.info(\$X)" \
    --language python --dry-run

vs morph/warpgrep

| Tool | Best For |

|------|----------|

| ast-grep | Structural patterns (understands code syntax) |

| warpgrep | Fast text/regex search (20x faster grep) |

Use ast-grep when you need syntax-aware matching. Use warpgrep for raw speed.

MCP Server Required

Requires ast-grep server in mcp_config.json.