TeXmath support for cc98 markdown posts
目前為
此腳本不應該直接安裝，它是一個供其他腳本使用的函式庫。欲使用本函式庫，請在腳本 metadata 寫上： // @require https://update.gf.qytechs.cn/scripts/425661/926035/texmath.js
// ==UserScript==
// @name texmath
// @namespace https://www.cc98.org/
// @version 0.1
// @description TeXmath support for cc98 markdown posts
// @author Secant
// @match https://www.cc98.org/topic/*
// @grant none
// jshint esversion: 6
(function () {
"use strict";
function texmath(md, options) {
const delimiters = "dollars";
const imgtexOptions = (options && options.imgtexOptions) || {
apiBase: "https://math.now.sh",
color: "black",
};
if (!texmath.imgtex) {
// else ... depricated `use` method was used ...
if (options && typeof options.engine === "object") {
texmath.imgtex = options.engine;
}
// artifical error object.
else
texmath.imgtex = {
renderToString() {
return "No math renderer found.";
},
};
}
if (delimiters in texmath.rules) {
for (const rule of texmath.rules[delimiters].inline) {
md.inline.ruler.before("escape", rule.name, texmath.inline(rule)); // ! important
md.renderer.rules[rule.name] = (tokens, idx) =>
rule.tmpl.replace(
/\$1/,
texmath.render(
tokens[idx].content,
!!rule.displayMode,
imgtexOptions
)
);
}
for (const rule of texmath.rules[delimiters].block) {
md.block.ruler.before("fence", rule.name, texmath.block(rule)); // ! important for ```math delimiters
md.renderer.rules[rule.name] = (tokens, idx) =>
rule.tmpl.replace(
/\$1/,
texmath.render(tokens[idx].content, true, imgtexOptions)
);
}
}
}
texmath.inline = (rule) =>
function (state, silent) {
const pos = state.pos;
const str = state.src;
const pre =
str.startsWith(rule.tag, (rule.rex.lastIndex = pos)) &&
(!rule.pre || rule.pre(str, pos)); // valid pre-condition ...
const match = pre && rule.rex.exec(str);
const res =
!!match &&
pos < rule.rex.lastIndex &&
(!rule.post || rule.post(str, rule.rex.lastIndex - 1));
if (res) {
if (!silent) {
const token = state.push(rule.name, "math", 0);
token.content = match[1];
token.markup = rule.tag;
}
state.pos = rule.rex.lastIndex;
}
return res;
};
texmath.block = (rule) =>
function block(state, begLine, endLine, silent) {
const pos = state.bMarks[begLine] + state.tShift[begLine];
const str = state.src;
const pre =
str.startsWith(rule.tag, (rule.rex.lastIndex = pos)) &&
(!rule.pre || rule.pre(str, pos)); // valid pre-condition ....
const match = pre && rule.rex.exec(str);
const res =
!!match &&
pos < rule.rex.lastIndex &&
(!rule.post || rule.post(str, rule.rex.lastIndex - 1));
if (res && !silent) {
// match and valid post-condition ...
const endpos = rule.rex.lastIndex - 1;
let curline;
for (curline = begLine; curline < endLine; curline++)
if (
endpos >= state.bMarks[curline] + state.tShift[curline] &&
endpos <= state.eMarks[curline]
)
// line for end of block math found ...
break;
// "this will prevent lazy continuations from ever going past our end marker"
// s. https://github.com/markdown-it/markdown-it-container/blob/master/index.js
const lineMax = state.lineMax;
const parentType = state.parentType;
state.lineMax = curline;
state.parentType = "math";
if (parentType === "blockquote")
// remove all leading '>' inside multiline formula
match[1] = match[1].replace(/(\n*?^(?:\s*>)+)/gm, "");
// begin token
let token = state.push(rule.name, "math", 1); // 'math_block'
token.block = true;
token.markup = rule.tag;
token.content = match[1];
token.map = [begLine, curline];
// end token
token = state.push(rule.name + "_end", "math", -1);
token.block = true;
token.markup = rule.tag;
state.parentType = parentType;
state.lineMax = lineMax;
state.line = curline + 1;
}
return res;
};
texmath.render = function (tex, displayMode, options) {
options.displayMode = displayMode;
let res;
try {
res = texmath.imgtex.renderToString(tex, options);
} catch (err) {
res = tex + ": " + err.message;
}
return res;
};
// used for enable/disable math rendering by `markdown-it`
texmath.inlineRuleNames = ["math_inline"];
texmath.blockRuleNames = ["math_block"];
texmath.$_pre = (str, beg) => {
const prv = beg > 0 ? str[beg - 1].charCodeAt(0) : false;
return (
!prv ||
(prv !== 0x5c && // no backslash,
(prv < 0x30 || prv > 0x39))
); // no decimal digit .. before opening '$'
};
texmath.$_post = (str, end) => {
const nxt = str[end + 1] && str[end + 1].charCodeAt(0);
return !nxt || nxt < 0x30 || nxt > 0x39; // no decimal digit .. after closing '$'
};
texmath.rules = {
dollars: {
inline: [
{
name: "math_inline",
rex: /\$((?:\S)|(?:\S.*?\S))\$/gy,
tmpl: "$1",
tag: "$",
pre: texmath.$_pre,
post: texmath.$_post,
},
],
block: [
{
name: "math_block",
rex: /\${2}([^$]+?)\${2}/gmy,
tmpl: "<center>$1</center>",
tag: "$$",
},
],
},
};
window.texmath = texmath;
})();