wasp-lib

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Pointer Classes ​

These are the core classes for managing data in WebAssembly memory.

StringPointer ​

Manages C-style null-terminated strings.

  • static from(wasm, length, input?): Creates a pointer from a JavaScript string with a specified buffer size.
  • static alloc(wasm, length): Allocates an empty string buffer of a specified length.
  • write(input): Writes new content to the buffer.
  • read(): Reads the content as a JavaScript string.
  • readAndFree(): Reads the content and immediately frees the memory.
  • free(): Deallocates the memory.

Example ​

typescript
const strPtr = StringPointer.from(wasm, 100, "Initial text");
strPtr.write("New content");
const content = strPtr.read(); // "New content"
strPtr.free();

NumberPointer<T> ​

A type-safe wrapper for single numeric values (i8, i16, i32, i64, float, double).

  • static from(wasm, type, input): Creates a pointer from a JavaScript number or bigint.
  • static alloc(wasm, type): Allocates memory for a number of the specified type.
  • write(value): Writes a new value.
  • read(): Reads the value.
  • readAndFree(): Reads the value and frees the memory.

Example ​

typescript
const intPtr = NumberPointer.from(wasm, "i32", 42);
intPtr.write(84);
const intValue: number = intPtr.read(); // 84
intPtr.free();

const bigIntPtr = NumberPointer.from(wasm, "i64", 9007199254740991n);
const bigIntValue: bigint = bigIntPtr.read();
bigIntPtr.free();

ArrayPointer<T, N> ​

A type-safe wrapper for numeric arrays.

  • static from(wasm, type, length, input?): Creates a pointer from a JavaScript array.
  • static alloc(wasm, type, length): Allocates an empty array of a given length.
  • write(values): Writes an entire new array to the buffer.
  • add(index, value): Sets the value at a specific index.
  • read(): Reads the entire array.
  • readAndFree(): Reads the array and frees the memory.

Example ​

typescript
const numbers = [1.1, 2.2, 3.3];
const arrayPtr = ArrayPointer.from(wasm, "double", numbers.length, numbers);
arrayPtr.add(0, 10.5); // Set first element
const result = arrayPtr.read(); // [10.5, 2.2, 3.3]
arrayPtr.free();

CharPointer ​

A wrapper for single character values.

  • static from(wasm, input): Creates a pointer from a single-character string.
  • static alloc(wasm): Allocates memory for one character.
  • write(input): Writes a new character.
  • read(): Reads the character.
  • readAndFree(): Reads the character and frees the memory.

Example ​

typescript
const charPtr = CharPointer.from(wasm, "A");
charPtr.write("Z");
const char = charPtr.read(); // 'Z'
charPtr.free();

BoolPointer ​

A wrapper for boolean values, stored as C integers (0 or 1).

  • static from(wasm, value): Creates a pointer from a boolean value.
  • static alloc(wasm): Allocates memory for a boolean, defaulting to false.
  • write(value): Writes a new boolean value.
  • read(): Reads the value as a boolean.
  • readAndFree(): Reads the value and frees the memory.

Example ​

typescript
const boolPtr = BoolPointer.from(wasm, true);
boolPtr.write(false);
const isTrue = boolPtr.read(); // false
boolPtr.free();

NullPointer ​

A special pointer that always points to 0, representing a safe "no memory" state within the pointer system. This is useful when an API requires a pointer instance, but you want to explicitly indicate the absence of allocated memory without using null or undefined.

  • constructor(): Creates a new NullPointer instance with no WASM memory allocation.
  • read(): Always throws an error because a NullPointer cannot read memory.

Example ​

typescript
const nullPtr = new NullPointer();
console.log(nullPtr.ptr); // 0