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

bash

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

Search in specific directory

bash

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

Refactor/replace pattern

bash

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)

bash

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

bash

# 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.