85 lines
2.3 KiB
Dart
85 lines
2.3 KiB
Dart
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import 'dart:collection';
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import 'dart:io';
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import 'dart:math';
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import 'package:combinator/combinator.dart';
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import 'package:string_scanner/string_scanner.dart';
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import 'package:tuple/tuple.dart';
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void main() {
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var expr = reference();
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var symbols = <String, dynamic>{};
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void registerFunction(String name, int nArgs, Function(List<num>) f) {
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symbols[name] = new Tuple2(nArgs, f);
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}
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registerFunction('**', 2, (args) => pow(args[0], args[1]));
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registerFunction('*', 2, (args) => args[0] * args[1]);
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registerFunction('/', 2, (args) => args[0] / args[1]);
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registerFunction('%', 2, (args) => args[0] % args[1]);
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registerFunction('+', 2, (args) => args[0] + args[1]);
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registerFunction('-', 2, (args) => args[0] - args[1]);
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registerFunction('.', 1, (args) => args[0].toDouble());
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registerFunction('print', 1, (args) {
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print(args[0]);
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return args[0];
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});
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var number = match(new RegExp(r'[0-9]+(\.[0-9]+)?'),
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errorMessage: 'Expected a number.')
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.map((r) => num.parse(r.span.text));
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var id = match(
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new RegExp(
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r'[A-Za-z_!\\$",\\+-\\./:;\\?<>%&\\*@\[\]\\{\}\\|`\\^~][A-Za-z0-9_!\\$",\\+-\\./:;\\?<>%&\*@\[\]\\{\}\\|`\\^~]*'),
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errorMessage: 'Expected an ID')
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.map((r) =>
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symbols[r.span.text] ??= throw "Undefined symbol: '${r.span.text}'");
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var atom = number.castDynamic().or(id);
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var list = expr.space().times(2, exact: false).map((r) {
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try {
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var out = [];
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var q = new Queue.from(r.value.reversed);
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while (q.isNotEmpty) {
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var current = q.removeFirst();
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if (current is! Tuple2)
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out.insert(0, current);
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else {
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var args = [];
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for (int i = 0; i < (current.item1 as num); i++)
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args.add(out.removeLast());
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out.add(current.item2(args));
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}
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}
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return out.length == 1 ? out.first : out;
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} catch (_) {
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return [];
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}
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});
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expr.parser = longest([
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list,
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atom,
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expr.parenthesized(),
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]); //list | atom | expr.parenthesized();
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while (true) {
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stdout.write('> ');
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var line = stdin.readLineSync();
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var result = expr.parse(new SpanScanner(line));
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if (result.errors.isNotEmpty) {
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for (var error in result.errors) {
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print(error.toolString);
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print(error.message);
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}
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} else {
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print(result.value);
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}
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}
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}
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