151 lines
3.7 KiB
TypeScript
151 lines
3.7 KiB
TypeScript
import { escapeHtml } from "./helpers";
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import { AtLeast, Choose, End, Pattern, Regex, Sequence, Use } from "./peg";
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import {
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Script,
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Word as WordType,
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TextWord,
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EnchantedWord as EnchantedWordType,
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SimplifyWord,
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InterpolatedPiece,
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} from "./words";
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const Comment = Regex(/#[^\n]*/y)
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.expects("#")
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.map(() => []);
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const PreWordWhitespace = Regex(/[^\S\n;]+/y).expects("whitespace");
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const EnchantedWord = Regex(/[^\]\[\}\{$\\";\s]+(?=[\s;]|$)/y)
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.map(([enchanted]) => ({ enchanted } as EnchantedWordType))
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.expects("ENCHANTED_WORD");
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const BackslashEscape = Regex(/\\(.)/y)
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.expects("\\")
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.map(([, char]) => ({ text: char }));
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const BARE_WORD_CHAR = /[^\s\\;]+/y;
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function bareWordTmpl(charRegex: RegExp) {
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return Sequence(
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AtLeast(
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1,
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Choose<InterpolatedPiece>(
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BackslashEscape,
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Regex(charRegex)
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.expects("CHAR")
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.map(([text]) => ({ text }))
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)
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)
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).map(([pieces]) => SimplifyWord(pieces));
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}
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const QuotedWord = Sequence(
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Regex(/"/y).expects('"'),
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AtLeast(
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0,
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Choose<InterpolatedPiece>(
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BackslashEscape,
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Regex(/[^"\\]+/y)
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.expects("CHAR")
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.map(([text]) => ({ text }))
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)
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),
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Regex(/"/y).expects('"')
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).map(([, pieces]) => SimplifyWord(pieces));
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const Brace: Pattern<string> = Sequence(
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Regex(/\{/y).expects("{"),
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AtLeast(
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0,
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Choose(
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Use(() => Brace)
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.expects("{")
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.map((text) => `{${text}}`),
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Regex(/\\./y)
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.expects("\\")
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.map(([escape]) => escape),
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Regex(/[^\\{}]+/y)
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.expects("text")
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.map(([text]) => text)
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)
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),
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Regex(/\}/y).expects("}")
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).map(([, fragments]) => fragments.join(""));
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function wordTmpl(bareWordCharRegex: RegExp): Pattern<WordType> {
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return Choose<WordType>(
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EnchantedWord,
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Brace.map((text) => ({ text } as TextWord)),
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QuotedWord,
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bareWordTmpl(bareWordCharRegex)
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);
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}
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const CommandTerminator = Regex(/[\n;]/y)
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.expects("NEWLINE | ;")
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.map(() => true);
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function commandTmpl(bareWordCharRegex: RegExp) {
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const word = wordTmpl(bareWordCharRegex);
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return Sequence(
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word,
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AtLeast(
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0,
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Sequence(PreWordWhitespace, word).map(([, word]) => word)
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),
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AtLeast(0, PreWordWhitespace)
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).map(([word, moreWords]) => [word].concat(moreWords));
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}
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function scriptTmpl(bareWordCharRegex: RegExp, endPattern: Pattern<unknown>) {
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return Sequence(
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AtLeast(
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0,
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Choose(
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PreWordWhitespace.map(() => []),
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CommandTerminator.map(() => []),
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Sequence(Comment, Choose(CommandTerminator, endPattern)).map(() => []),
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Sequence(
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commandTmpl(bareWordCharRegex),
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Choose(CommandTerminator, endPattern)
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).map(([words]) => words)
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)
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),
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endPattern
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).map(([commands]) => commands.filter((command) => command.length > 0));
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}
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const Script = scriptTmpl(BARE_WORD_CHAR, End());
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const ERROR_CONTEXT = /(?<=([^\n]{0,50}))([^\n]{0,50})/y;
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/**
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* Parse out a Notcl script into an easier-to-interpret representation.
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* No script is actually executed yet.
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*
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* @param - code to parse
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* @returns - parsed list of commands, or error message on failure
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*/
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export function parse(code: string): [true, Script] | [false, string] {
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/* Preprocess */
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// fold line endings
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code = code.replace(/(?<!\\)((\\\\)*)\\\n[ \t]*/g, "$1 ");
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/* Parse */
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const [commands, errorPos, expected] = Script(code, 0);
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if (commands) {
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return [true, commands[0]];
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} else {
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ERROR_CONTEXT.lastIndex = errorPos;
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const [, before, after] = ERROR_CONTEXT.exec(code)!;
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return [
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false,
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`<pre>Error at position ${errorPos}
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${escapeHtml(before + "" + after)}
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${"-".repeat(before.length)}^
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Expected: ${escapeHtml(expected)}</pre>`,
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];
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}
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}
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