AST

Introduction

Abstract Syntax Trees (AST) are structured, tree-like representations of source content.
In Spry, ASTs are widely used to inspect, transform, and automate workflows involving Markdown-based runbooks, configuration, and documentation.

Spry internally parses Markdown into mdast (Markdown AST) so that automated tools can analyze nodes, extract metadata, transform blocks, or execute code cells in runbooks.

Concept of AST

An AST (Abstract Syntax Tree) is:

• A hierarchical representation of content
• Broken into nodes (heading, paragraph, code, list, table, etc.)
• Language-independent
• Ideal for transformations, validations, and querying

In Spry, the AST lets you:

• Inspect Markdown structure
• Query nodes
• Identify runbook cells
• Modify or extract information
• Understand flow and dependencies between cells (useful for DAG execution)

Spry mainly works with mdast, a Markdown AST format from the unified ecosystem.

How AST Is Used in SPRY

1. Runbook Analysis

Spry parses Markdown runbooks into AST to:

• Detect executable code blocks
• Determine DAG ordering
• Execute tasks in correct dependency order
• Validate metadata (YAML frontmatter, tags, identifiers)

2. Markdown Processing

Spry uses AST to:

• Inspect headings and structure
• Transform content programmatically
• Extract identifiers, links, or code samples

3. Spry CLI Tools

Commands like ./spry.ts mdast allow:

• Querying AST nodes
• Listing node hierarchies
• Inspecting Markdown documents before automation or execution

Possible SPRY AST Commands

1. List Nodes

./spry.ts mdast ls file.md

Shows a structured view of all nodes.

Example Output

1: root
 ├─ heading (level 1)
 ├─ paragraph
 ├─ code (lang: ts)
 └─ list (ordered: false)

2. List Identifiers

./spry.ts mdast identifiers file.md

Useful for:

• Extracting headings
• Getting reference anchors
• Documentation generation

3. Filter by Node Type

./spry.ts mdast ls file.md --type code

Shows only code blocks.

Example Use Cases

Example Markdown

# Sample Runbook

## Step 1
```ts
console.log("Hello")
```

## Step 2
- item 1
- item 2

AST Listing Example

./spry.ts mdast ls sample.md

Output Example

root
 ├─ heading (level 1): "Sample Runbook"
 ├─ heading (level 2): "Step 1"
 ├─ code: ts
 ├─ heading (level 2): "Step 2"
 └─ list

Summary