trisquel-icecat/icecat/intl/icu_capi/bindings/js/diplomat-runtime.mjs

export function readString8(wasm, ptr, len) {
  const buf = new Uint8Array(wasm.memory.buffer, ptr, len);
  return (new TextDecoder("utf-8")).decode(buf)
}

export function readString16(wasm, ptr, len) {
  const buf = new Uint16Array(wasm.memory.buffer, ptr, len);
  return String.fromCharCode.apply(null, buf)
}

export function withWriteable(wasm, callback) {
  const writeable = wasm.diplomat_buffer_writeable_create(0);
  try {
    callback(writeable);
    const outStringPtr = wasm.diplomat_buffer_writeable_get_bytes(writeable);
    const outStringLen = wasm.diplomat_buffer_writeable_len(writeable);
    return readString8(wasm, outStringPtr, outStringLen);
  } finally {
    wasm.diplomat_buffer_writeable_destroy(writeable);
  }
}

export class FFIError extends Error {
  constructor(error_value) {
    super("Error over FFI");
    this.error_value = error_value; // (2)
  }
}

export function extractCodePoint(str, param) {
  const cp = str.codePointAt?.(0);
  if ((!cp && cp !== 0) || [...str]?.length != 1) {
    throw new TypeError(`Expected single-character string for char parameter ${param}, found ${str}`);
  }
  return cp;
}

// Get the pointer returned by an FFI function
//
// It's tempting to call `(new Uint32Array(wasm.memory.buffer, FFI_func(), 1))[0]`.
// However, there's a chance that `wasm.memory.buffer` will be resized between
// the time it's accessed and the time it's used, invalidating the view.
// This function ensures that the view into wasm memory is fresh.
//
// This is used for methods that return multiple types into a wasm buffer, where
// one of those types is another ptr. Call this method to get access to the returned
// ptr, so the return buffer can be freed.
export function ptrRead(wasm, ptr) {
  return (new Uint32Array(wasm.memory.buffer, ptr, 1))[0];
}

// Get the flag of a result type.
export function resultFlag(wasm, ptr, offset) {
  return (new Uint8Array(wasm.memory.buffer, ptr + offset, 1))[0];
}

// Get the discriminant of a Rust enum.
export function enumDiscriminant(wasm, ptr) {
  return (new Int32Array(wasm.memory.buffer, ptr, 1))[0]
}

// A wrapper around a slice of WASM memory that can be freed manually or
// automatically by the garbage collector.
//
// This type is necessary for Rust functions that take a `&str` or `&[T]`, since
// they can create an edge to this object if they borrow from the str/slice,
// or we can manually free the WASM memory if they don't.
export class DiplomatBuf {
  static str8 = (wasm, string) => {
    var utf8Length = 0;
    for (const codepointString of string) {
      let codepoint = codepointString.codePointAt(0);
      if (codepoint < 0x80) {
        utf8Length += 1
      } else if (codepoint < 0x800) {
        utf8Length += 2
      } else if (codepoint < 0x10000) {
        utf8Length += 3
      } else {
        utf8Length += 4
      }
    }

    const ptr = wasm.diplomat_alloc(utf8Length, 1);

    const result = (new TextEncoder()).encodeInto(string, new Uint8Array(wasm.memory.buffer, ptr, utf8Length));
    console.assert(string.length == result.read && utf8Length == result.written, "UTF-8 write error");

    return new DiplomatBuf(ptr, utf8Length, () => wasm.diplomat_free(ptr, utf8Length, 1));
  }

  static str16 = (wasm, string) => {
    const byteLength = string.length * 2;
    const ptr = wasm.diplomat_alloc(byteLength, 2);

    const destination = new Uint16Array(wasm.memory.buffer, ptr, byteLength);
    for (var i; i < string.length; i++) {
      destination[i] = string.charCodeAt(i);
    }

    return new DiplomatBuf(ptr, string.length, () => wasm.diplomat_free(ptr, byteLength, 2));
  }

  static slice = (wasm, list, rustType) => {
    const elementSize = rustType == "u8" || rustType == "i8" || rustType == "bool" ? 1 :
      rustType == "u16" || rustType == "i16" ? 2 :
        rustType == "u64" || rustType == "i64" || rustType == "f64" ? 8 :
          4;

    const byteLength = list.length * elementSize;
    const ptr = wasm.diplomat_alloc(byteLength, elementSize);

    // Create an array view of the buffer. This gives us the `set` method which correctly handles untyped values
    const destination =
      rustType == "u8" || rustType == "bool" ? new Uint8Array(wasm.memory.buffer, ptr, byteLength) :
        rustType == "i8" ? new Int8Array(wasm.memory.buffer, ptr, byteLength) :
          rustType == "u16" ? new Uint16Array(wasm.memory.buffer, ptr, byteLength) :
            rustType == "i16" ? new Int16Array(wasm.memory.buffer, ptr, byteLength) :
              rustType == "i32" || rustType == "isize" ? new Int32Array(wasm.memory.buffer, ptr, byteLength) :
                rustType == "u64" ? new BigUint64Array(wasm.memory.buffer, ptr, byteLength) :
                  rustType == "i64" ? new BigInt64Array(wasm.memory.buffer, ptr, byteLength) :
                    rustType == "f32" ? new Float32Array(wasm.memory.buffer, ptr, byteLength) :
                      rustType == "f64" ? new Float64Array(wasm.memory.buffer, ptr, byteLength) :
                        new Uint32Array(wasm.memory.buffer, ptr, byteLength);
    destination.set(list);

    return new DiplomatBuf(ptr, list.length, () => wasm.diplomat_free(ptr, byteLength, elementSize));
  }

  constructor(ptr, size, free) {
    this.ptr = ptr;
    this.size = size;
    // Generated code calls one of methods these for each allocation, to either
    // free directly after the FFI call, to leak (to create a &'static), or to
    // register the buffer with the garbage collector (to create a &'a).
    this.free = free;
    this.leak = () => { };
    this.garbageCollect = () => DiplomatBufferFinalizer.register(this, this.free);
  }
}

const DiplomatBufferFinalizer = new FinalizationRegistry(free => free());