dimpact

Fast, language-aware impact analysis for changed code. Feed it a git diff or seed it with specific symbols; get back changed symbols, impacted symbols, and optional reference edges.

Highlights

• Tree‑Sitter engine by default (Auto): robust and fast
• LSP engine (experimental): capability‑driven with TS fallback in non‑strict
• Flexible seeding: pass Symbol IDs or JSON
• Symbol ID generator: resolve IDs from file/line/name, with filters

Quick Start

• Build: cargo build --release
• Show parsed diff:
  • git diff --no-ext-diff | dimpact diff -f json
• Changed symbols:
  • git diff --no-ext-diff | dimpact changed --lang auto --engine auto -f json
• Impact from a diff (callers, with edges):
  • git diff --no-ext-diff | dimpact impact --direction callers --with-edges -f json
• Impact from seeds (no diff needed):
  • dimpact impact --seed-symbol 'rust:src/lib.rs:fn:foo:12' --direction callers -f json
  • dimpact impact --seed-json '["typescript:src/a.ts:fn:run:10"]' -f json
• Impact per changed-symbol grouping (direction=both, with edges):
  • git diff --no-ext-diff | dimpact impact --per-seed --direction both --with-edges -f json

Symbol ID generator

• Generate candidate IDs from file/line/name; filter by kind; print as JSON/YAML or plain IDs.
• Examples:
  • List IDs in a file: dimpact id --path src/lib.rs --raw
  • Narrow by line: dimpact id --path src/lib.rs --line 120 -f json
  • Narrow by name and kind, print single‑line raw ID: dimpact id --path src/lib.rs --name foo --kind fn --raw
  • Workspace search by name: dimpact id --name foo -f json

CLI Overview

• Subcommands:

  • diff: parse unified diff from stdin
  • changed: compute changed symbols from stdin diff
  • impact: compute impact from stdin diff or seeds (supports diff- and seed-based analyses)
  • id: generate Symbol IDs from file/line/name
  • cache: build/stats/clear the incremental cache

• Seeds:

  • --seed-symbol LANG:PATH:KIND:NAME:LINE (repeatable)
  • --seed-json <json|string|path|-> accepts array of strings or objects
  • When seeds are present, language is inferred from seeds (mixed languages error)

• Output formats: -f json|yaml|dot|html

• Impact Options (subcommand impact):

  • --direction callers|callees|both : traversal direction (default: callers)
  • --max-depth N : max traversal depth (default: 100)
  • --with-edges : include reference edges in output
  • --ignore-dir DIR : ignore directories by relative prefix (repeatable)
  • --with-pdg : use PDG-based dependence analysis (Rust/Ruby for DFG)
  • --with-propagation : enable symbolic propagation across variables and functions (implies PDG)
  • --engine auto|ts|lsp : analysis engine (default: auto)
  • --engine-lsp-strict : strict mode for LSP engine
  • --engine-dump-capabilities: dump engine capabilities to stderr
  • --seed-symbol LANG:PATH:KIND:NAME:LINE : seed symbols by ID (repeatable)
  • --seed-json PATH|'-'|JSON : seed symbols via JSON array or file or stdin
  • --per-seed : group impact per changed/seed symbol; direction=both時はcaller/calley別出力

PDG Visualization

• Generate PDG in dot format with --with-pdg and -f dot:

  git diff --no-ext-diff | dimpact impact --with-pdg -f dot
  

Path highlighting in DOT/HTML

• When running impact with --with-edges, the DOT and HTML outputs highlight edges that are on a shortest path from any changed symbol to any impacted symbol.
• This helps visually trace “how” the impact propagates from changes to affected code.
• HTML view provides filters and automatic layout; highlighted path edges are shown in red.

Engine Selection

• Auto: Tree‑Sitter by default (recommended)
• LSP (experimental): --engine lsp
  • --engine-lsp-strict: don’t fall back to TS on LSP issues
  • --engine-dump-capabilities: emit LSP capabilities JSON to stderr

Logging

• Uses env_logger. Set RUST_LOG=info (or debug|trace) to see diagnostics.

Usage Examples

• Callers from a diff (JSON with edges):
  • git diff --no-ext-diff | dimpact impact --direction callers --with-edges -f json
• Callees limited to depth 2 (YAML):
  • git diff --no-ext-diff | dimpact impact --direction callees --max-depth 2 -f yaml
• Force Tree‑Sitter engine (recommended default):
  • git diff --no-ext-diff | dimpact impact --engine ts -f json
• Try LSP engine (experimental) with strict mode and capability dump:
  • git diff --no-ext-diff | dimpact impact --engine lsp --engine-lsp-strict --engine-dump-capabilities -f json
  • Tip: RUST_LOG=info to see more diagnostics
• Seed via Symbol IDs (no diff needed):
  • dimpact impact --seed-symbol 'rust:src/lib.rs:fn:foo:12' --direction callers -f json
• Seed via JSON file:
  • echo '["typescript:src/a.ts:fn:run:10","typescript:src/b.ts:method:App::start:5"]' > seeds.json
  • dimpact impact --seed-json seeds.json --direction both -f json
• Seed via JSON from stdin (-):
  • printf '[{"lang":"rust","path":"src/lib.rs","kind":"fn","name":"foo","line":12}]' | dimpact impact --seed-json - --direction callers -f json
• Generate IDs then pipe directly into impact:
  • dimpact id --path src/lib.rs --name foo --kind fn --raw | dimpact impact --seed-json - --direction callers -f json
• Search workspace by name and list all candidate IDs:
  • dimpact id --name initialize --raw

License

• See repository license if present; otherwise contact maintainers. Cache
• Purpose: persist symbols and reference edges to speed up impact analysis.
• Storage: single SQLite DB index.db stored in either location:
  • Local (default): <repo_root>/.dimpact/cache/v1/index.db
  • Global: $XDG_CONFIG_HOME/dimpact/cache/v1/<repo_key>/index.db
• Control via subcommands:
  • Build: dimpact cache build --scope local|global [--dir PATH]
  • Stats: dimpact cache stats --scope local|global [--dir PATH]
  • Clear: dimpact cache clear --scope local|global [--dir PATH]
• Impact integration: the TS engine uses the cache by default. On first use it builds the cache; on subsequent runs it updates only changed files.
• Env overrides: DIMPACT_CACHE_SCOPE=local|global, DIMPACT_CACHE_DIR=/custom/dir.