JIT Compiler vs Fast VM

SmartCal offers a dual execution strategy to combine maximum performance and universal compatibility.

1. JIT Compiler (Just-In-Time)

The JIT compiler translates the AST directly into native JavaScript source code, then instantiates a function via new Function.

Transformation Example

For the formula:

score > 100 ? (bonus * 1.5) : (bonus * 1.0)

The JIT generates the following JavaScript code:

function anonymous(d, r) {
  return ((d['score'] ?? 0) > 100 ? ((d['bonus'] ?? 0) * 1.5) : ((d['bonus'] ?? 0) * 1.0));
}

Advantages:

• TurboFan/V8 Optimization: The JavaScript engine compiles this function into native machine instructions with inline caching.
• Exceptional throughput: Over 2.5 to 10 million operations per second.
• Zero interpretation overhead: No tree traversal during evaluation.

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2. Fast VM Interpreter (CSP-Safe)

In certain strict contexts (Content Security Policy blocking unsafe-eval, browser extensions, Cloudflare Workers, QuickJS environments), new Function is forbidden.

SmartCal therefore includes a Fast VM interpreter that evaluates the AST without ever using eval:

// Fast VM evaluation loop example
evaluateNode(node: ASTNode, data: Record<string, any>): number | string {
  switch (node.type) {
    case 'Literal': return node.value;
    case 'Identifier': return data[node.name] ?? 0;
    case 'Binary': {
      const left = this.evaluateNode(node.left, data);
      const right = this.evaluateNode(node.right, data);
      return this.applyOp(node.operator, left, right);
    }
    case 'Conditional': {
      const cond = this.evaluateNode(node.condition, data);
      return cond ? this.evaluateNode(node.consequent, data) : this.evaluateNode(node.alternate, data);
    }
  }
}

Advantages:

• 100% Secure (Zero-Eval).
• High throughput: Over 500,000 to 1,200,000 ops/s, which remains significantly higher than v1.0.14.

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Mode Comparison

Criterion	JIT Mode ('jit')	VM Mode ('vm')	Auto Mode ('auto')
Speed (Hot)	~2.5M - 10M ops/s	~500k - 1.2M ops/s	JIT if available, else VM
CSP Security	Requires unsafe-eval	100% CSP-Safe	Adapts automatically
Recommended for	Servers, Node.js, Bun, Intensive calculations	Web extensions, Cloudflare Workers	Standard universal use