Buffers

This page introduces the buffer types that represent contiguous memory regions.

Code snippets assume using namespace boost::capy; is in effect.

What are Buffers?

A buffer is a view into a contiguous region of memory. Capy provides two fundamental buffer types:

Type Description

const_buffer

A view into read-only memory

mutable_buffer

A view into writable memory

Buffers do not own memory. They are lightweight handles (pointer + size) that refer to memory owned elsewhere.

const_buffer

A const_buffer represents a contiguous region of read-only bytes:

char const data[] = "Hello, World!";
const_buffer buf(data, sizeof(data) - 1);

void const* p = buf.data();   // Pointer to first byte
std::size_t n = buf.size();   // Number of bytes

Construction

// From pointer and size
const_buffer buf1(ptr, size);

// From mutable_buffer (implicit conversion)
mutable_buffer mbuf(ptr, size);
const_buffer buf2 = mbuf;  // Read-only view of same memory

Operations

const_buffer buf(data, 100);

// Remove prefix (advance start, reduce size)
buf += 10;  // Now points to data+10, size is 90

mutable_buffer

A mutable_buffer represents a contiguous region of writable bytes:

char data[1024];
mutable_buffer buf(data, sizeof(data));

void* p = buf.data();         // Pointer to first byte
std::size_t n = buf.size();   // Number of bytes

Construction

// From pointer and size
mutable_buffer buf(ptr, size);

Operations

mutable_buffer buf(data, 100);

// Remove prefix (advance start, reduce size)
buf += 10;  // Now points to data+10, size is 90

When to Use Each

Use const_buffer when:

  • You need to read data without modifying it

  • Passing data to functions that only read

  • Creating views of string literals or constant data

Use mutable_buffer when:

  • You need to write data into the buffer

  • Receiving data from I/O operations

  • The underlying memory must be modified

Summary

Type Purpose

const_buffer

Read-only view of contiguous bytes

mutable_buffer

Writable view of contiguous bytes

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