Raw HTML tag markup for MarkupString: an anchor, a <pre>, a <div class="..."> — carried as a layer over a span of text and written as itself in the Html, Pueblo and Mxp formats.

A tag is written the same in all three, so use it for tags the three spell alike. A command link is not one of them — Pueblo writes <a xch_cmd>, MXP <send href> — so build that with MarkupString.Ansi's AnsiMarkup.Create(linkUrl: ..., linkKind: LinkKind.Command), which each format writes in its own dialect.

Where a tag has no meaning — a terminal — it does not vanish silently: b, strong, i, em, u, s, strike and del fold into the run's terminal styling through MarkupString.Ansi, and any other tag leaves its body untouched.

WithHtml() also writes core's shared vocabulary for a browser: a sound as <audio>, a picture as <img>, and what HTML has no element for — a pane, a gauge, clearing the screen — as an element with an ms- class for the page to act on. See the shared vocabulary.

dotnet add package MarkupString.Html

using MarkupString;
using MarkupString.Ansi;
using MarkupString.Html;

MarkupRegistry.Default = MarkupRegistry.Empty.WithAnsi().WithHtml();

var text = MarkupText.Wrap(
  HtmlMarkup.Tag("a", new HtmlAttribute("href", "https://example.org/")),
  MarkupText.Wrap(AnsiCodeParser.Parse("hr"), "north"));

text.Render(MarkupFormat.Html);   // <a href="/sitelet?url=https%3A%2F%2Fexample.org%2F"><span style="color: #ff5555">north</span></a>
text.Render(MarkupFormat.Ansi);   // \e[1;31mnorth\e[0m
text.Render(MarkupFormat.Plain);  // north

var json = MarkupTextSerializer.Serialize(text);
var back = MarkupTextSerializer.Deserialize(json);

WithAnsi() must be applied as well: the terminal fold for b/i/u/s comes from that package.

HtmlMarkup.Create(name, attributes) writes both exactly as given. For anything you did not write yourself:

• HtmlMarkup.Tag(name, params attributes) checks the name and encodes every value.
• HtmlTagPolicy.TryCreate(name, rawAttributes, out markup) reads a raw attribute string and keeps only what the policy allows, re-encoded.
• WithHtml(policy) holds every tag rendered in the Html format to that policy as it is written, so markup that arrived deserialised or built with Create is held to it too.

The library ships no security posture. HtmlTagPolicy.WellFormed allows any well-formed tag; what is safe in your application is your decision, and a policy is a record you narrow with with:

var policy = HtmlTagPolicy.WellFormed with
{
  AllowedTags = new HashSet<string> { "a", "b", "i", "u", "font", "pre", "span", "img" },
  AllowedAttributes = new HashSet<string> { "href", "src", "alt", "title", "color", "face", "size" },
  // Checked as addresses. HtmlTagPolicy.AddressAttributes is the list HTML gives an address to;
  // nothing applies it for you.
  UrlAttributes = HtmlTagPolicy.AddressAttributes,
  OnViolation = HtmlAttributeViolation.DropAllAttributes,
};

MarkupRegistry.Default = MarkupRegistry.Empty.WithAnsi().WithHtml(policy);

The HTML emitters write ms-* classes for the text attributes that have a fixed rendering, and inline style for colours, which are open-ended. Every one of those classes comes from MarkupString.Ansi, so the stylesheet does too: include AnsiCss.Fixed once per page, or copy its rules into your own sheet.

• IMarkup + IMarkupEmitter — register an emitter for HtmlMarkup in a format of your own, or replace this package's by adding yours to the registry afterwards.
• IMarkupCodec — HtmlMarkupCodec is the wire shape under kind "html".
• IAnsiStyleSource — HtmlMarkup implements it; that is how a tag becomes terminal styling.

IsAotCompatible; no reflection, no dynamic code. Registration is an explicit WithHtml() call.

Apache-2.0. Source, guides and issues: SharpMUSH/MarkupString.