105 lines
2.7 KiB
JavaScript
105 lines
2.7 KiB
JavaScript
/**
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* @typedef {Notcl.Command[]} Notcl.Script
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* @typedef {Notcl.Word[]} Notcl.Command
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* @typedef {object} Notcl.Word
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* @property {string} text
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*/
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var Notcl = (() => {
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const { AtLeast, Choose, End, Regex, Sequence, Use, Hint } = Peg;
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const InterCommandWhitespace = Regex(/\s+/y).expects("whitespace");
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const Comment = Regex(/#[^\n]*/y).expects("#");
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const PreCommand = AtLeast(0, Choose(InterCommandWhitespace, Comment));
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const PreWordWhitespace = Regex(/[^\S\n;]+/y).expects("whitespace");
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const BasicWord = Regex(/(?!\{)[^\s;]+/y)
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.map(([word]) => ({ text: word }))
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.expects("BASIC_WORD");
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// WIP, need to be able to escape braces correctly
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/** @type {Peg.Pattern<string>} */
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const Brace = 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).map((text) => `{${text}}`),
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Regex(/[^{}]+/y).map(([text]) => text)
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)
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),
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Regex(/\}/y).expects("}")
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).map(([_left, fragments, _right]) => fragments.join(""));
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const Word = Choose(
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BasicWord,
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Brace.map((text) => ({ text }))
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);
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const CommandTerminator = Regex(/[\n;]/y).expects("NEWLINE | ;");
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/** @type {Peg.Pattern<Notcl.Command>} */
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const Command = 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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/** @type {Peg.Pattern<Notcl.Script>} */
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const Script = Sequence(
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PreCommand,
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AtLeast(0, Command),
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AtLeast(
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0,
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Sequence(CommandTerminator, PreCommand, Command).map(
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([, , command]) => command
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)
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),
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AtLeast(0, PreCommand),
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End()
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).map(([, command, moreCommands]) => command.concat(moreCommands));
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const ERROR_CONTEXT = /(?<=([^\n]{0,50}))([^\n]{0,50})/y;
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return {
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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 {string} code to parse
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* @returns {[true, Notcl.Script] | [false, string]} parsed list of commands, or error message on failure
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*/
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parse(code) {
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/* Preprocess */
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// fold line endings
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code = code.replace(/(?<!\\)((\\\\)*)\\\n/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] = /** @type {RegExpExecArray} */ (
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ERROR_CONTEXT.exec(code)
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);
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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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};
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})();
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