boost::urls::resolve :: Boost Libraries Documentation

# boost::urls::resolve

Resolve a URL reference against a base URL

## Synopsis

Declared in `<boost/url/url_base.hpp>`

    system::result<void>
    resolve(
        url_view_base const& base,
        url_view_base const& ref,
        url_base& dest);

## Description

This function attempts to resolve a URL reference `ref` against the base URL `base` in a manner similar to that of a web browser resolving an anchor tag.

The base URL must satisfy the URI grammar. In other words, it must contain a scheme.

Relative references are only usable when in the context of a base absolute URI. This process of resolving a relative reference within the context of a base URI is defined in detail in rfc3986 (see below).

The resolution process works as if the relative reference is appended to the base URI and the result is normalized.

Given the input base URL, this function resolves the relative reference as if performing the following steps:

- Ensure the base URI has at least a scheme

- Normalizing the reference path

- Merge base and reference paths

- Normalize the merged path

This function places the result of the resolution into `dest`, which can be any of the url containers that inherit from `url_base`.

If an error occurs, the contents of `dest` is unspecified and `ec` is set.

| Abnormal hrefs where the number of ".." segments exceeds the number of segments in the base path are handled by including the unmatched ".." segments in the result, as described in https://www.rfc-editor.org/errata/eid4547.

## Example

    url dest;
    system::error_code ec;

    resolve("/one/two/three", "four", dest, ec);
    assert( dest.str() == "/one/two/four" );

    resolve("http://example.com/", "/one", dest, ec);
    assert( dest.str() == "http://example.com/one" );

    resolve("http://example.com/one", "/two", dest, ec);
    assert( dest.str() == "http://example.com/two" );

    resolve("http://a/b/c/d;p?q", "g#s", dest, ec);
    assert( dest.str() == "http://a/b/c/g#s" );

## BNF

    absolute-URI  = scheme ":" hier-part [ "?" query ]

## Exception Safety

Basic guarantee. Calls to allocate may throw.

## Specification

https://datatracker.ietf.org/doc/html/rfc3986#section-5

## Return Value

An empty `boost::system::result` upon success, otherwise an error code if `!base.has_scheme()`.

## Parameters

Name | Description
base | The base URL to resolve against.
ref | The URL reference to resolve.
dest | The container where the result is written, upon success.

## See Also

`url`, `url_view`.

Created with MrDocs