| // @flow | |
| import defineFunction from "../defineFunction"; | |
| import ParseError from "../ParseError"; | |
| import {assertNodeType} from "../parseNode"; | |
| // \@char is an internal function that takes a grouped decimal argument like | |
| // {123} and converts into symbol with code 123. It is used by the *macro* | |
| // \char defined in macros.js. | |
| defineFunction({ | |
| type: "textord", | |
| names: ["\\@char"], | |
| props: { | |
| numArgs: 1, | |
| allowedInText: true, | |
| }, | |
| handler({parser}, args) { | |
| const arg = assertNodeType(args[0], "ordgroup"); | |
| const group = arg.body; | |
| let number = ""; | |
| for (let i = 0; i < group.length; i++) { | |
| const node = assertNodeType(group[i], "textord"); | |
| number += node.text; | |
| } | |
| let code = parseInt(number); | |
| let text; | |
| if (isNaN(code)) { | |
| throw new ParseError(`\\@char has non-numeric argument ${number}`); | |
| // If we drop IE support, the following code could be replaced with | |
| // text = String.fromCodePoint(code) | |
| } else if (code < 0 || code >= 0x10ffff) { | |
| throw new ParseError(`\\@char with invalid code point ${number}`); | |
| } else if (code <= 0xffff) { | |
| text = String.fromCharCode(code); | |
| } else { // Astral code point; split into surrogate halves | |
| code -= 0x10000; | |
| text = String.fromCharCode((code >> 10) + 0xd800, | |
| (code & 0x3ff) + 0xdc00); | |
| } | |
| return { | |
| type: "textord", | |
| mode: parser.mode, | |
| text: text, | |
| }; | |
| }, | |
| }); | |