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petitparser/lib/src/core/predicates.dart

-part of petitparser;
-
-/**
- * Returns a parser that accepts any input element.
- *
- * For example, `any()` succeeds and consumes any given letter. It only
- * fails for an empty input.
- */
-Parser any([String message = 'input expected']) {
-  return new AnyParser(message);
-}
-
-/**
- * A parser that accepts any input element.
- */
-class AnyParser extends Parser {
-  final String _message;
-
-  AnyParser(this._message);
-
-  @override
-  Result parseOn(Context context) {
-    var position = context.position;
-    var buffer = context.buffer;
-    return position < buffer.length
-        ? context.success(buffer[position], position + 1)
-        : context.failure(_message);
-  }
-
-  @override
-  Parser copy() => new AnyParser(_message);
-
-  @override
-  bool hasEqualProperties(Parser other) {
-    return other is AnyParser
-        && super.hasEqualProperties(other)
-        && _message == other._message;
-  }
-}
-
-/**
- * Returns a parser that accepts any of the [elements].
- *
- * For example, `anyIn('ab')` succeeds and consumes either the letter
- * `'a'` or the letter `'b'`. For any other input the parser fails.
- */
-Parser anyIn(elements, [String message]) {
-  return predicate(1, (each) => elements.indexOf(each) >= 0,
-      message != null ? message : 'any of $elements expected');
-}
-
-/**
- * Returns a parser that accepts the string [element].
- *
- * For example, `string('foo')` succeeds and consumes the input string
- * `'foo'`. Fails for any other input.
- */
-Parser string(String element, [String message]) {
-  return predicate(element.length, (String each) => element == each,
-      message != null ? message : '$element expected');
-}
-
-/**
- * Returns a parser that accepts the string [element] ignoring the case.
- *
- * For example, `stringIgnoreCase('foo')` succeeds and consumes the input
- * string `'Foo'` or `'FOO'`. Fails for any other input.
- */
-Parser stringIgnoreCase(String element, [String message]) {
-  final lowerElement = element.toLowerCase();
-  return predicate(element.length,
-      (String each) => lowerElement == each.toLowerCase(),
-      message != null ? message : '$element expected');
-}
-
-/**
- * A generic predicate function returning [true] or [false] for a given
- * [input] argument.
- */
-typedef bool Predicate(input);
-
-/**
- * Returns a parser that reads input of the specified [length], accepts
- * it if the [predicate] matches, or fails with the given [message].
- */
-Parser predicate(int length, Predicate predicate, String message) {
-  return new PredicateParser(length, predicate, message);
-}
-
-/**
- * A parser for a literal satisfying a predicate.
- */
-class PredicateParser extends Parser {
-  final int _length;
-  final Predicate _predicate;
-  final String _message;
-
-  PredicateParser(this._length, this._predicate, this._message);
-
-  @override
-  Result parseOn(Context context) {
-    final start = context.position;
-    final stop = start + _length;
-    if (stop <= context.buffer.length) {
-      var result = context.buffer is String
-          ? context.buffer.substring(start, stop)
-          : context.buffer.sublist(start, stop);
-      if (_predicate(result)) {
-        return context.success(result, stop);
-      }
-    }
-    return context.failure(_message);
-  }
-
-  @override
-  String toString() => '${super.toString()}[$_message]';
-
-  @override
-  Parser copy() => new PredicateParser(_length, _predicate, _message);
-
-  @override
-  bool hasEqualProperties(Parser other) {
-    return other is PredicateParser
-        && super.hasEqualProperties(other)
-        && _length == other._length
-        && _predicate == other._predicate
-        && _message == other._message;
-  }
-}