mtcute/packages/tl-utils/src/calculator.ts

import { TlEntry } from './types.js'

const PRIMITIVES_SIZES: Record<string, number> = {
    int: 4,
    long: 8,
    int53: 8,
    int128: 16,
    int256: 32,
    double: 8,
    boolFalse: 4,
    boolTrue: 4,
    bool: 4,
    Bool: 4,
    '#': 4,
}

export function calculateStaticSizes(entries: TlEntry[]): Record<string, number> {
    const staticSizes: Record<string, number> = {}
    const unionSizes: Record<string, Record<string, number | null>> = {}
    let changedInLastIteration = true

    function getUnionStaticSize(name: string): number | null {
        const values = Object.values(unionSizes[name] ?? {})
        if (values.length === 0) return null

        const first = values[0]
        if (first === null) return null

        for (const value of values) {
            if (value !== first) return null
        }

        return first
    }

    function calculateStaticSize(entry: TlEntry): number | null {
        if (entry.generics) return null // definitely not static sized

        let size = 4 // constructor id

        for (const arg of entry.arguments) {
            if (arg.typeModifiers?.predicate) {
                if (arg.type === 'true') {
                    continue // zero-size type
                }

                // cant be static sized
                return null
            }

            if (arg.typeModifiers?.isVector || arg.typeModifiers?.isBareVector) {
                // cant be static sized
                return null
            }

            let unionSize

            if (arg.type in PRIMITIVES_SIZES) {
                size += PRIMITIVES_SIZES[arg.type]
            } else if (arg.type in staticSizes) {
                size += staticSizes[arg.type] - 4 // subtract constructor id
            } else if ((unionSize = getUnionStaticSize(arg.type))) {
                size += unionSize
            } else {
                // likely not static sized
                return null
            }
        }

        return size
    }

    while (changedInLastIteration) {
        changedInLastIteration = false

        for (const entry of entries) {
            if (staticSizes[entry.name] !== undefined) continue

            const size = calculateStaticSize(entry)

            if (entry.kind === 'class') {
                if (!unionSizes[entry.type]) {
                    unionSizes[entry.type] = {}
                }

                unionSizes[entry.type][entry.name] = size
            }

            if (size === null) {
                continue
            }

            staticSizes[entry.name] = size
            changedInLastIteration = true
        }
    }

    return staticSizes
}