rop (Runtime Operator Parser)

rop is a TypeScript/JavaScript library that parses and evaluates expressions via tagged template literals. It supports operator overloading for custom and built-in types, enabling custom behaviors for JS operators and Python-style array slicing.

Usage examples

Before reading the Quick Tutorial, these examples below can help you understand what rop can do:

$3

``ts
o2 + 3; // 5
`

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Python-style array slicing syntax:

`ts
Rop.INST.bind({ arr: [1, 2, 3, 4, 5] });

// Basic slicing
oarr[1:3]; // [2, 3]

// Negative indices
oarr[:-2]; // [1, 2, 3]

// With step
oarr[::2]; // [1, 3, 5]

// Reverse
oarr[::-1]; // [5, 4, 3, 2, 1]

// Multi-dimensional slicing (for custom types)
o${tensor}[2:5, 1:5, 4:7];
`

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`ts
o${[2, 3]} + ${[4, 5]}; // [2, 3, 4, 5]
`

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`ts
Rop.INST.bind({
a: new Set([1, 2, 3]),
b: new Set([3, 4, 5]),
});
oa + b; // Set { 1, 2, 3, 4, 5 }
`

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`ts
Rop.INST.bind({
obj: { name: 'Alice' },
arr: [1, 2, 3],
});

// access property name on obj
oobj.name; // Alice

// index obj with name
oobj['name']; // Alice
oarr[1]; // 2
`

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`ts
// bind identifiers a and b, so you can use them in the expression.
rop.bind({
a: new Vec2(2, 3),
b: new Vec2(3, 4),
});
rop.oa + b; // Vec2 { x: 5, y: 7 }
``